Resistance mechanisms in Campylobacter jejuni

Antimicrobial Activity of a Synthetic Brevibacillin Analog Against Multidrug-Resistant Campylobacter spp

Campylobacter spp. is one of the most prevalent causes of zoonotic foodborne infections associated with diarrhea in humans. The growing threat of antibiotic resistance calls for innovative approaches. The antimicrobial lipopeptide brevibacillin produced by Brevibacillus laterosporus and its synthetic analog brevibacillin Thr1 showed promising activity against Salmonella and E. coli. The latter is a 1602.13 Da positively charged (+3) synthetic peptide of 13 residues that showed reduced cytotoxicity (IC50 of 32.2 µg/mL against Caco-2 cells) and hemolytic activity (1.2% hemolysis at 128 µg/mL) compared to the native peptide. It contains an N-terminal L-isoleucic fatty acid chain and four non-proteinogenic amino acids and ends with valinol at its C-terminus. One key structural modification is the substitution of α,β-dehydrobutyric acid with threonine. We investigated the antimicrobial potential of the synthetic brevibacillin Thr1 analog against a collection of 44 clinical Campylobacter spp. that were obtained from two reference laboratories. Susceptibility testing revealed marked resistance to ciprofloxacin, tetracycline, and ampicillin among the strains, with more than half expressing a multidrug-resistant phenotype. The genomes of the 44 strains were sequenced to study the genes responsible for their antimicrobial resistance. Tetracycline resistance was associated with tet(O), ciprofloxacin resistance with mutations in gyrA and regulatory sequences modulating the expression of an efflux system, and aminoglycoside resistance with genes of the aph family. The brevibacillin Thr1 analog was produced by chemical synthesis, and evaluation of its activity against a subset of clinical strains by microdilution revealed minimum inhibitory concentration and minimum bactericidal concentration ranging from 8 µg/mL to 64 µg/mL. The peptide was active against multidrug-resistant isolates with a bactericidal effect. Of note, despite numerous attempts, it proved impossible to select Campylobacter spp. for resistance to the brevibacillin Thr1 analog. These results underline the potential of lipopeptides, notably brevibacillin, as antimicrobial alternatives against antibiotic-resistant Campylobacter bacterial infections.

Antimicrobial resistance in Campylobacter spp. focussing on C. jejuni and C. coli - A Narrative Review

OBJECTIVES

Campylobacter species represent one of the leading causes of human foodborne infections, including gastroenteritis and bloody diarrhoea. Overuse of antibiotics in veterinary, agriculture, and humans has led to an increase in multidrug antimicrobial resistance (AMR). Fluoroquinolones and macrolides resistant Campylobacters are WHO and CDC priority pathogens, with fluoroquinolone resistance doubling in the past 20 years, complicating treatment.

METHODS

Published studies relating to AMR and associated molecular mechanisms in both Campylobacter jejuni and C. coli from animals, humans and environment (1981 - 2024), were retrieved from PubMed and Google Scholar using relevant keywords. In addition, genomic analyses of publicly available C. jejuni and C. coli genomes along with multi-locus sequence typing results from the PubMLST database were used to analyse these AMR determinants and their phylogenomic relationships. Review articles were excluded from the analyses.

RESULTS

A total of 429 research papers were reviewed to get insights into multidrug resistance in C. jejuni and C. coli. Fluroquinolone resistance has been predominantly associated with international travel. The gyrA subunits were associated with ecological niches and overall, it is suggestive that C. coli might be the donor. A positive synergism was observed between cmeA gene expression and quinolone resistance. Additionally, the results speculated the possibility of horizontal gene transfers in chromosomal resistance clusters between C. coli and C. jejuni.

CONCLUSION

This review indicated significant concern of multidrug resistance in C. jejuni and C. coli. This requires continent-wide surveillance and research for standard practices to achieve effective antimicrobial stewardship.

Virulence Genes, Antimicrobial Resistance, and Genotypes of Campylobacter jejuni Isolated from Chicken Slaughterhouses in South Korea

Campylobacter jejuni represents one of the leading causes of bacterial gastroenteritis in humans and is primarily linked to chicken meat contamination. In the present study, we analyzed the virulence and survival genes, antimicrobial resistance, and the clonal distribution of 50 C. jejuni isolates obtained from various sources in 14 chicken slaughterhouses across 8 provinces in South Korea from 2019 to 2022. Furthermore, we determined their genetic relatedness to human-derived isolates registered in PubMLST using multilocus sequence typing (MLST). All isolates harbored various virulence and survival genes (flhA, cadF, cdtA, cdtC, cmeA, and sodB) out of 17 tested genes, as confirmed via polymerase chain reaction analysis. Adherence factor gene virB11 was not detected in any isolate. All isolates harbored 12 or more virulence and survival genes. Antimicrobial susceptibility testing indicated that ciprofloxacin resistance was the most prevalent (84.0%), followed by nalidixic acid (82.0%) and tetracycline (52.0%) resistance. MLST analysis of the isolates revealed 18 sequence types (STs), including four new ones. Overlapping STs between chicken slaughterhouse and human-derived isolates included ST42, ST45, ST50, ST137, ST354, and ST464. Our study identified 11 clonal complexes (CCs), with CC-21 being the most prevalent in both human and chicken slaughterhouse-derived isolates. This study provides comprehensive insights into recent C. jejuni isolates from chicken slaughterhouses, including data on quinolone resistance and virulence factors. The MLST-based genetic relatedness between isolates from humans and chicken slaughterhouses in this study suggests the potential of C. jejuni transmission from chickens to humans through the food chain. This study suggests the need for improved management practices in chicken slaughterhouses to reduce the transmission of chicken slaughterhouse-derived C. jejuni to humans.

High prevalence of antibiotic resistant Campylobacter among patients attending clinical settings in Kigali, Rwanda

BACKGROUND

Thermophilic Campylobacter species are important causes of human gastroenteritis and inappropriate use of antimicrobials has led to the emergence of antimicrobial resistance (AMR). In Rwanda, data is limited on the prevalence and AMR carriage rate of Campylobacter strains. This study aimed at assessing the prevalence and antimicrobial susceptibility profiles of Campylobacter species among isolates obtained from different clinical settings in Kigali city, Rwanda.

METHODS

This cross-sectional study used a purposive sampling method to collect 385 stool samples from consenting patients attending the Microbiology Department at Kigali University Teaching Hospital (CHUK), Nyarugenge District Hospital, Muhima and Biryogo Health Centers (HC). Campylobacter species were isolated using culture and characterized with biochemical tests and multiplex Polymerase Chain Reaction (PCR) for species confirmation. Antimicrobial susceptibility testing (AST) with six antimicrobials [ciprofloxacin (CIP), tetracycline (TET), chloramphenicol (CHL), streptomycin (STR), erythromycin (ERY), and gentamicin (GEN)] was carried out by using Kirby-Bauer disk diffusion.

RESULTS

The overall prevalence of Campylobacter spp. was 7.0% (27/385) and the highest prevalence of 77.8% (21/27) was recorded at Biryogo HC. The prevalence of C. jejuni and C. coli were 92.6% (25/27) and 7.4% (2/27), respectively. Infection was significantly associated with diarrhea (p < 0.0001). Campylobacter isolates showed high resistance to STR (85.2%, 23/27), followed by ERY (66.7%, 18/27), and CIP (37.1%, 10/27). The isolates were sensitive to CHL at 88.9% (24/27), TET at 66.7% (18/27), and GEN at 66.7% (18/27).

CONCLUSION

The prevalence of campylobacteriosis in Kigali City is not negligible and is associated with diarrhea. Campylobacter strains isolated from clinical settings were resistant to commonly used antimicrobials. Larger studies will provide insights into the national status of Campylobacter-related AMR. Routine monitoring of antimicrobial use is recommended to mitigate this public health threat. Molecular analyses of resistant strains are warranted to characterize the genomic drive of antibiotic resistance.

Comparative Genomic Analysis of Livestock-Derived Campylobacter jejuni: Antimicrobial Resistance, Virulence, Mobile Genetic Elements, and Genetic Relatedness

Campylobacter jejuni is a major cause of foodborne illnesses, and its increasing antimicrobial resistance (AMR) poses serious public health risks. Owing to their high genetic diversity and frequent intraspecific recombination, understanding the virulence traits of Campylobacter remains challenging. We elucidated the resistance and virulence mechanisms of C. jejuni in livestock using comparative genomic and phenotypic analyses. We analyzed C. jejuni strains isolated from chicken meat, chicken slaughterhouses, and dairy cattle farms. High resistance rates were observed for nalidixic acid, ciprofloxacin, and tetracycline. The chicken-derived strains showed significantly higher tetracycline resistance and marginally higher nalidixic acid resistance, whereas the cattle-derived strains showed marginally higher ciprofloxacin resistance. The key AMR determinants included gyrA and tet(O), which were correlated with resistance phenotypes. Ten virulence factor families were identified with prevalences exceeding 90%. Biofilm formation was observed in 31.9% of strains and correlated with flagella-associated virulence factors. Eighteen plasmid types were detected, primarily in the pTet family, which carried various AMR genes and components of the Type IV secretion system, potentially facilitating the co-transfer of resistance and virulence traits. Conjugation experiments confirmed the horizontal transfer of two pTet plasmid types into the wild-type C. jejuni strain. Further, our analyses revealed over 95% genetic similarity with European C. jejuni strains in a public database-supporting the hypothesis of zoonotic transmission via global food chains-and the zoonotic risks of livestock-derived Campylobacter jejuni. These findings emphasize the need for extended global surveillance to mitigate the risk of zoonotic transmission.

Sharing of cmeRABC alleles between C. coli and C. jejuni associated with extensive drug resistance in Campylobacter isolates from infants and poultry in the Peruvian Amazon

Campylobacter is a serious health threat because of the rapid progressive evolution of antimicrobial resistance and efficient transmission from zoonotic as well as human sources. Resistance to fluoroquinolones and macrolides is particularly concerning as this compromises the two most effective oral antibiotic agents currently available for human campylobacteriosis. Here, we report on the prevalence and worldwide distribution of the operon cmeRABC, which encodes an efflux pump conferring high levels of combined resistance to fluoroquinolones and macrolides in Campylobacter strains isolated from poultry (n = 75) and children (n = 177). These mutations were found to be highly prevalent in isolates from poultry (62.7%) and children (29.4%) in Iquitos, Peru. We investigated the population structure of genes in the cmeRABC operon and identified a potential genetic bottleneck for the cmeA and cmeB genes. While most cmeB alleles segregate by species, alleles associated with high resistance to fluoroquinolones and macrolides were found in both Campylobacter jejuni and Campylobacter coli. We inferred that the likely ancestry of these alleles was from C. jejuni and was later acquired by C. coli through recombination. Publicly accessible global genomic data from 16,120 Campylobacter genomes identified these mutations in approximately 6% of C. jejuni and C. coli isolates globally, with higher prevalence in samples from poultry in many countries, including Peru. Our findings suggest that these extensively drug-resistant Campylobacter strains originated from C. jejuni in poultry.IMPORTANCEAntimicrobial resistance in Campylobacter is a growing public health concern, driven by the rapid evolution and zoonotic transmission of resistant strains. This study focuses on mutations in the cmeABC efflux pump, which confer high resistance to fluoroquinolones and macrolides, the two most effective oral antibiotics for human campylobacteriosis. By analyzing genomes from poultry and children in Iquitos, Peru, as well as global genomic data sets, we identified a significant prevalence of these resistance-associated mutations, particularly in poultry and children. Our findings suggest that these mutations originated in Campylobacter jejuni and spread to C. coli through recombination. Globally, these mutations are found in approximately 6% of isolates, with higher prevalence in poultry in multiple countries. This research underscores the critical role of genomic epidemiology in understanding the origins, evolution, and dissemination of antimicrobial resistance and highlights the need to address poultry as a reservoir for resistant Campylobacter.

The Global Challenge of Campylobacter: Antimicrobial Resistance and Emerging Intervention Strategies

Antimicrobial resistance (AMR) in Campylobacter species, particularly C. jejuni and C. coli, poses a significant public health threat. These bacteria, which are commonly found in livestock, poultry, companion animals, and wildlife, are the leading causes of foodborne illnesses, often transmitted through contaminated poultry. Extensive exposure to antibiotics in human and veterinary medicine creates selection pressure, driving resistance through mechanisms such as point mutations, horizontal gene transfer, and efflux pumps. Resistance to fluoroquinolones, macrolides, and tetracyclines complicates treatment and increases the risk of severe infections. Drug-resistant Campylobacter is transmitted to humans via contaminated food, water, and direct contact with animals, highlighting its zoonotic potential. Addressing this challenge requires effective interventions. Pre-harvest strategies like biosecurity and immune-based methods reduce bacterial loads on farms, while post-harvest measures, including carcass decontamination and freezing, limit contamination. Emerging approaches, such as bacteriocins and natural antimicrobials, offer chemical-free alternatives. Integrated, multidisciplinary interventions across the food chain are essential to mitigate AMR transmission and enhance food safety. Sustainable agricultural practices, antimicrobial stewardship, and innovative solutions are critical to curbing Campylobacter resistance and protecting global public health. Our review examines the dynamics of antimicrobial resistance in Campylobacter and presents current strategies to mitigate Campylobacter-related AMR, offering valuable insights for antimicrobial control in the poultry industry.

Campylobacter jejuni/coli Infection: Is It Still a Concern?

Campylobacteriosis is a leading cause of infectious diarrhea and foodborne illness worldwide. Campylobacter infection is primarily transmitted through the consumption of contaminated food, especially uncooked meat, or untreated water; contact with infected animals or contaminated environments; poultry is the primary reservoir and source of human transmission. The clinical spectrum of Campylobacter jejuni/coli infection can be classified into two distinct categories: gastrointestinal and extraintestinal manifestations. Late complications are reactive arthritis, Guillain-Barré syndrome, and Miller Fisher syndrome. In the pediatric population, the 0-4 age group has the highest incidence of campylobacteriosis. Regarding the use of specific antimicrobial therapy, international guidelines agree in recommending it for severe intestinal infections. Host factors, including malnutrition, immunodeficiency, and malignancy, can also influence the decision to treat. The Centers for Disease Control and Prevention (CDC) has identified antibiotic resistance in Campylobacter as a 'significant public health threat' due to increasing resistance to FQs or macrolides. Although numerous vaccines have been proposed in recent years to reduce the intestinal colonization of poultry, none have shown sufficient efficacy to provide a definitive solution.

Natural Solutions to Antimicrobial Resistance: The Role of Essential Oils in Poultry Meat Preservation with Focus on Gram-Negative Bacteria

The increase in antimicrobial resistance (AMR) is a major global health problem with implications on human and veterinary medicine, as well as food production. In the poultry industry, the overuse and misuse of antimicrobials has led to the development of resistant or multi-drug resistant (MDR) strains of bacteria such as Salmonella spp., Escherichia coli and Campylobacter spp., which pose a serious risk to meat safety and public health. The genetic transfer of resistance elements between poultry MDR bacteria and human pathogens further exacerbates the AMR crisis and highlights the urgent need for action. Traditional methods of preserving poultry meat, often based on synthetic chemicals, are increasingly being questioned due to their potential impact on human health and the environment. This situation has led to a shift towards natural, sustainable alternatives, such as plant-derived compounds, for meat preservation. Essential oils (EOs) have emerged as promising natural preservatives in the poultry meat industry offering a potential solution to the growing AMR problem by possessing inherent antimicrobial properties making them effective against a broad spectrum of pathogens. Their use in the preservation of poultry meat not only extends shelf life, but also reduces reliance on synthetic preservatives and antibiotics, which contribute significantly to AMR. The unique chemical composition of EOs, that contains a large number of different active compounds, minimizes the risk of bacteria developing resistance. Recent advances in nano-encapsulation technology have further improved the stability, bioavailability and efficacy of EOs, making them more suitable for commercial use. Hence, in this manuscript, the recent literature on the mechanisms of AMR in the most important Gram-negative poultry pathogens and antimicrobial properties of EOs on these meat isolates was reviewed. Additionally, chemical composition, extraction methods of EOs were discussed, as well as future directions of EOs as natural food preservatives. In conclusion, by integrating EOs into poultry meat preservation strategies, the industry can adopt more sustainable and health-conscious practices and ultimately contribute to global efforts to combat AMR.

Antimicrobial resistance in Klebsiella pneumoniae: an overview of common mechanisms and a current Canadian perspective

Klebsiella pneumoniae is a ubiquitous opportunistic pathogen of the family Enterobacteriaceae. K. pneumoniae is a member of the ESKAPEE pathogens (Enterococcus faecium, Staphylococcus aureus, K. pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp., and Escherichia coli), a group of bacteria that cause nosocomial infections and are able to resist killing by commonly relied upon antimicrobial agents. The acquisition of antimicrobial resistance (AMR) genes is increasing among community and clinical isolates of K. pneumoniae, making K. pneumoniae a rising threat to human health. In addition to the increase in AMR, K. pneumoniae is also thought to disseminate AMR genes to other bacterial species. In this review, the known mechanisms of K. pneumoniae AMR will be described and the current state of AMR K. pneumoniae within Canada will be discussed, including the impact of the coronavirus disease-2019 pandemic, current perspectives, and outlook for the future.

Carbapenem resistant Campylobacter jejuni bacteremia in a Bruton's X-linked agammaglobulinemia patient

Immunocompromised patients are prone to recurrent Campylobacter infections. We report a case of recurrent multi-drug resistant Campylobactor jejuni bloodstream infections in a Bruton's X-linked agammaglobulinemia patient with prolonged ertapenem treatment. The isolate from the fifth recurrence developed carbapenem resistance, which is associated with mutations in a porin gene porA, and promoter changes and duplication of chromosomal blaOXA-61 gene. Combination therapy using cefepime and doxycycline (later switched to moxifloxacin) cleared the infection.

Diversity of Campylobacter spp. circulating in a rhesus macaque (Macaca mulatta) breeding colony using culture and molecular methods

Campylobacter jejuni and Campylobacter coli represent the leading causes of bacterial gastroenteritis in humans, and infections can produce post-infectious irritable bowel syndrome (PI-IBS). Rhesus macaques (Macaca mulatta) (RM) are similarly susceptible to acute campylobacteriosis and represent a potential model of PI-IBS. We characterized the Campylobacter species circulating in an RM breeding colony using culture, qPCR, and whole genome sequencing (WGS). We also compared the C. jejuni and C. coli prevalence in RM as detected with qPCR versus culture and identified risk factors for bacteria presence and intestinal disease. Culture of 275 samples yielded C. coli (103) and C. jejuni (8), of which 21.6% were resistant to quinolones and 3.6% were resistant to macrolides. Multidrug-resistant isolates were obtained exclusively from animals exhibiting diarrhea or with histologically confirmed chronic enterocolitis. WGS revealed a non-clonal population of Campylobacter spp. Genotypic predictions of resistance were excellent except for aminoglycosides. All sequenced isolates contained genes for all subunits of cytolethal distending toxin. qPCR detected a prevalence of 45.9% for C. coli and 29.6% for C. jejuni. The quantity of either bacteria was significantly higher (P < 0.05) in animals with intestinal disease compared to healthy animals, though only young age was significantly associated with the presence of Campylobacter sp. or intestinal disease. Significantly more C. jejuni positive animals were detected with qPCR than with culture. These results provide a comprehensive characterization of Campylobacter spp. circulating in a breeding colony of RM in the United States and suggest that qPCR is superior for the detection of C. jejuni in RM.

IMPORTANCE

Gastrointestinal disease is one of the most common reasons for hospitalization in non-human primate colonies and accounts for over one-third of non-research related euthanasia. In rhesus macaques, this manifests as both acute diarrhea and chronic enterocolitis (CE), a syndrome of chronic diarrhea resulting in poor weight gain or weight loss which is minimally responsive to treatment. Campylobacter spp. are major causes of acute enterocolitis in rhesus macaques and may predispose individuals to the development of CE, similar to post-infectious irritable bowel syndrome in humans. Despite these concerns, there are few studies characterizing Campylobacter in rhesus macaque colonies, in particular utilizing whole genome sequencing and assessing findings with respect to the health status of the host. Our findings provide insight into Campylobacter strains circulating in rhesus macaque colonies, which can improve clinical monitoring, assist in treatment decisions, and provide new avenues of investigation into campylobacteriosis as a catalyst for CE.

The point mutation A1387G in the 16S rRNA gene confers aminoglycoside resistance in Campylobacter jejuni and Campylobacter coli

Thermotolerant Campylobacter spp. are the most frequent cause of foodborne bacterial diarrhea and high-priority antibiotic-resistant pathogens, according to the World Health Organization (WHO). Monitoring revealed current low prevalence of gentamicin resistance in European Campylobacter spp. isolates but substantial presence of gentamicin modifying genes circulating globally. Using a combined approach of natural transformation and whole-genome sequencing, we revealed a novel gentamicin resistance mechanism, namely the point mutation A1387G in the 16S rRNA gene, originally identified in a C. coli isolate from turkey caecal content. The transformation rate of the resistance using genomic DNA of the resistant donor to sensitive recipient C. jejuni and C. coli was ~2.5 log10 lower compared to the control rpsL-A128G point mutation conferring streptomycin resistance. Antimicrobial susceptibility tests showed cross-resistance to apramycin, kanamycin, and tobramycin, with transformants exhibiting more than 4- to 8-fold increased MICs to apramycin and tobramycin and over 64-fold higher MICs to kanamycin compared to wild-type isolates. Although transformants showed 177-1,235 variations relative to the recipient, only the A1387G point mutation in the 16S rRNA was in common. This mutation was causal for resistance, as transformation of a 16S rRNA_A1387G PCR fragment into susceptible isolates also led to resistant transformants. Sanger sequencing of the 16S rRNA genes and Oxford nanopore whole-genome sequencing of transformants identified clones harboring either all three copies with A1387G or a mixed population of wild-type and mutated 16S rRNA gene alleles. Within 15 passages on non-selective medium, transformants with mixed populations of the 16S rRNA gene copies partially reverted to wild type, both geno- and phenotypically. In contrast, transformants harboring the A1387G point mutation in all three 16S rRNA gene copies kept full resistance within at least 45 passages. We speculate that partial acquisition and rapid loss of the point mutation limited its spread among C. spp. isolates. In-depth knowledge on resistance mechanisms contributes to optimal diagnosis and preventative measures.

Genotypic characterization and antimicrobial susceptibility of human Campylobacter jejuni isolates in Southern Spain

Campylobacter jejuni is the main cause of bacterial gastroenteritis and a public health problem worldwide. Little information is available on the genotypic characteristics of human C. jejuni in Spain. This study is based on an analysis of the resistome, virulome, and phylogenetic relationship, antibiogram prediction, and antimicrobial susceptibility of 114 human isolates of C. jejuni from a tertiary hospital in southern Spain from October 2020 to June 2023. The isolates were sequenced using Illumina technology, and a bioinformatic analysis was subsequently performed. The susceptibility of C. jejuni isolates to ciprofloxacin, tetracycline, and erythromycin was also tested. The resistance rates for each antibiotic were 90.3% for ciprofloxacin, 66.7% for tetracycline, and 0.88% for erythromycin. The fluoroquinolone resistance rate obtained is well above the European average (69.1%). CC-21 (n = 23), ST-572 (n = 13), and ST-6532 (n = 13) were the most prevalent clonal complexes (CCs) and sequence types (STs). In the virulome, the cadF, ciaB, and cdtABC genes were detected in all the isolates. A prevalence of 20.1% was obtained for the genes wlaN and cstIII, which are related to the pathogenesis of Guillain-Barré syndrome (GBS). The prevalence of the main antimicrobial resistance markers detected were CmeABC (92.1%), RE-cmeABC (7.9%), the T86I substitution in gyrA (88.9%), blaOXA-61 (72.6%), tet(O) (65.8%), and ant (6)-Ia (17.1%). High antibiogram prediction rates (>97%) were obtained, except for in the case of the erythromycin-resistant phenotype. This study contributes significantly to the knowledge of C. jejuni genomics for the prevention, treatment, and control of infections caused by this pathogen.IMPORTANCEDespite being the pathogen with the greatest number of gastroenteritis cases worldwide, Campylobacter jejuni remains a poorly studied microorganism. A sustained increase in fluoroquinolone resistance in human isolates is a problem when treating Campylobacter infections. The development of whole genome sequencing (WGS) techniques has allowed us to better understand the genotypic characteristics of this pathogen and relate them to antibiotic resistance phenotypes. These techniques complement the data obtained from the phenotypic analysis of C. jejuni isolates. The zoonotic transmission of C. jejuni through the consumption of contaminated poultry supports approaching the study of this pathogen through "One Health" approach. In addition, due to the limited information on the genomic characteristics of C. jejuni in Spain, this study provides important data and allows us to compare the results with those obtained in other countries.

WQ-3810, a fluoroquinolone with difluoropyridine derivative as the R1 group exerts high potency against quinolone-resistant Campylobacter jejuni

Quinolone-resistant Campylobacter jejuni have been increasing worldwide. Quinolones exert their antibacterial activity by inhibiting DNA gyrase, but most of the isolates acquire quinolone resistance via an amino acid substitution in the A subunit of DNA gyrase. WQ-3810 is a quinolone antibiotic that has been reported to have high potency even to DNA gyrase with amino acid substitutions in several bacterial species; however, there was no information on C. jejuni. Hence, this study aimed to evaluate the activity of WQ-3810 to inhibit wild-type/mutant DNA gyrases of C. jejuni and the bacterial growth for accessing the potency for the treatment of quinolone-resistant C. jejuni infection. The inhibitory activity of WQ-3810 was assessed and compared with ciprofloxacin and nalidixic acid by calculating the half maximal inhibitory concentration (IC50) against wild-type/mutant DNA gyrases. Next, the minimum inhibitory concentration (MIC) of WQ-3810 and five other quinolones was determined for C. jejuni including quinolone-resistant strains with amino acid substitutions in GyrA. Furthermore, the interaction between WQ-3810 and wild-type/mutant DNA gyrase was speculated using docking simulations. The IC50 of WQ-3810 against wild-type DNA gyrase was 1.03 µg/mL and not different from that of ciprofloxacin. However, those of WQ-3810 against mutant DNA gyrases were much lower than ciprofloxacin. The MICs of WQ-3810 ranged <0.016-0.031 µg/mL and were the lowest against both quinolone-susceptible and quinolone-resistant strains among the examined quinolones. The results obtained by the docking simulation agreed well with this observation. WQ-3810 seems to be a promising antimicrobial agent for the infections caused by quinolone-resistant C. jejuni.

IMPORTANCE

WQ-3810, a relatively new quinolone antibiotic, demonstrates exceptional antibacterial properties against certain pathogens in previous studies. However, its efficacy against quinolone-resistant Campylobacter jejuni was not previously reported. The prevalence of quinolone-resistant C. jejuni as a cause of foodborne illnesses is increasing, prompting this investigation into the effectiveness of WQ-3810 as a countermeasure. This study revealed high inhibitory activity of WQ-3810 against both wild-type and mutant DNA gyrases of C. jejuni. WQ-3810 was equally efficacious as ciprofloxacin against wild-type DNA gyrases but showed superior effectiveness against mutant DNA gyrases. WQ-3810 also demonstrated the lowest minimum inhibitory concentrations, highlighting its enhanced potency against both susceptible and resistant strains of C. jejuni. This observation was well supported by the results of the in silico analysis. Consequently, WQ-3810 exhibits a higher level of bactericidal activity compared to existing quinolones in combating both susceptible and resistant C. jejuni isolates.

Harnessing medicinal plant compounds for the control of Campylobacter in foods: a comprehensive review

Campylobacter is a major foodborne and zoonotic pathogen, causing severe human infections and imposing a substantial economic burden on global public health. The ongoing spread and emergence of multidrug-resistant (MDR) strains across various fields exacerbate therapeutic challenges, raising the incidence of diseases and fatalities. Medicinal plants, renowned for their abundance in secondary metabolites, exhibit proven efficacy in inhibiting various foodborne and zoonotic pathogens, presenting sustainable alternatives to ensure food safety. This review aims to synthesize recent insights from peer-reviewed journals on the epidemiology and antimicrobial resistance of Campylobacter species, elucidate the in vitro antibacterial activity of medicinal plant compounds against Campylobacter by delineating underlying mechanisms, and explore the application of these compounds in controlling Campylobacter in food. Additionally, we discuss recent advancements and future prospects of employing medicinal plant compounds in food products to mitigate foodborne pathogens, particularly Campylobacter. In conclusion, we argue that medicinal plant compounds can be used as effective and sustainable sources for developing new antimicrobial alternatives to counteract the dissemination of MDR Campylobacter strains.

Transmission of dominant strains of Campylobacter jejuni and Campylobacter coli between farms and retail stores in Ecuador: Genetic diversity and antimicrobial resistance

Thermotolerant Campylobacter is an important zoonotic pathogen known for causing gastroenteritis in humans, with poultry as its primary reservoir. A total of 468 samples were collected, of which 335 were chicken carcass samples (representing the food component), and 133 were chicken caeca samples (representing the animal component). These samples underwent culture, with colonies examined under a microscope. Species identification was achieved through multiplex PCR. Additionally, antimicrobial susceptibility profiles were determined using the Kirby-Bauer method, testing for sensitivity to gentamicin, ciprofloxacin, tetracycline, and erythromycin. Additionally, 55 C. jejuni (62.5%) and 33 C. coli (37.5%) isolates were selected for whole genome sequencing (WGS). A High prevalence of Campylobacter was observed, with rates of 95.5% (n = 127, CI95%: 92.5% - 98.5%) in the animal component and 72.5% (n = 243, CI95%: 69.9% - 75.1%) in the food component. Specifically, C. jejuni was detected in 33.1% (n = 42) of poultry farms and 38.3% (n = 93) of chicken carcasses, while C. coli was found in 64.6% (n = 82) of poultry farms and 60.5% (n = 147) of chicken carcasses. Antimicrobials with the highest rates of resistance (67%-100%) were ciprofloxacin and tetracycline, in both animal and food component isolates. Erythromycin resistance was notable, ranging from 22% to 33%, with only two C. jejuni isolates from retail were resistant to gentamicin. Furthermore, multidrug resistance was identified in 23% (20 isolates) of the Campylobacter isolates. Genetic analysis revealed the presence of fourteen resistance genes in both C. jejuni and C. coli isolates, including tet(O), blaOXA-460, blaOXA-184, blaOXA-489, blaOXA-193, blaOXA-784, blaOXA-603, aph(3')-IIIa, aad9, aph(2'')-If, aadE-Cc, sat4, and ant(6)-Ia. Additionally, twenty-five plasmids were detected in the 88 Campylobacter isolates examined. Interestingly, most isolates also harbored genes encoding putative virulence factors associated with pathogenicity, invasion, adherence, and production of cytolethal distending toxin (cdt): cheV, cheA, cheW, cheY, flaA, flgR, flaC, flaD, flgB, flgC, ciaB, ciaC. The WGS analysis showed the presence of several cgSTs in both animal and food components, with nine of them widely disseminated between components. Moreover, C. coli and C. jejuni isolates from different sources presented less than 11 single nucleotide polymorphisms (SNPs), suggesting clonality (16 isolates). Further analysis using SNP tree demonstrated widespread distribution of certain C. jejuni and C. coli clones across multiple farms and retail stores. This study presents, for the first-time, insights into the clonality, plasmid diversity, virulence, and antimicrobial resistance (AMR) of thermotolerant Campylobacter strains originating from the Ecuadorian poultry industry. The identification of AMR genes associated with the main antibiotics used in the treatment of campylobacteriosis in humans, highlights the importance of the prudent use of antimicrobials in the poultry industry. Additionally, this research remarks the need for regional studies to understand the epidemiology of this pathogen.

Diagnosis of Campylobacter spp. Isolates and Their Antimicrobial Susceptibility Patterns

This study aimed to reveal antibiotic resistance patterns and molecular characterization of quinolone resistance Campylobacter isolates in patients with diarrhea. Campylobacter spp. isolated from 35.33% of the total samples, most of which were from male patients aged 3 months to 10 years. Identifying isolates at the species level made in MALDI-TOF MS, 82.4% were C. jejuni, and 17.6% were C. coli. Respectively 94% (47/50), 58% (29/50), and 2% (1/50) resistance rates were determined for ciprofloxacin, tetracycline, and erythromycin. While C. jejuni isolates were more resistant to ciprofloxacin and tetracycline than C. coli, they showed no resistance to erythromycin. Quinolone resistance determining region (QRDR) were evaluated by mismatch amplification mutation test and all quinolone resistant strains gave positive results. One of the seven silent mutations identified was specific to this study, and two other novel mutations were also identified.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-024-01199-5.

Epidemiology of Campylobacter Species Infection in Kidney Transplant Recipients: A Retrospective Multicentric Case-Control Study in France

Background

Campylobacteriosis in kidney transplant recipients (KTRs) is the most common identified bacterial cause of diarrhea. Risk factors in KTRs are unknown.

Methods

A 10-year multicentric, retrospective 1:1 case-control study was performed in France between 2010 and 2020. The main aim was to identify factors associated with Campylobacter-related infection in KTRs. The KTRs with a functional graft and campylobacteriosis (positive stool culture and/or blood culture and/or positive nucleic amplification test) and their controls matched on transplantation date within the same center were included.

Results

We identified 326 patients with campylobacteriosis. The estimated incidence rate of campylobacteriosis was 2.3/1000 patient-years. The infection occurred at a median of 2.4 years posttransplantation. The independent risk factors for campylobacteriosis were use of corticosteroids as maintenance regimen (75.8% vs 66%; P < .001), acute rejection (8.9% vs 4%; P = .048), low lymphocyte count (0.96 vs 1.4 giga/liter (G/L); P < .001), and low basal estimated glomerular filtration rate (eGFR) (44.2 vs 57.5 mL/minute/1.73 m2; P < .001). A fluoroquinolone was initiated in 64 (21.4%) patients, with 51.1% of antimicrobial resistance, whereas almost all strains were erythromycin sensitive.

Conclusions

Campylobacteriosis has a higher incidence in the 2 first years of transplantation. The factors independently associated with campylobacteriosis are corticosteroids as maintenance immunosuppressive regimen, low lymphocyte counts, low eGFR, and a history of acute rejection. Due to high antimicrobial resistance with fluoroquinolone, the first line of treatment should be azithromycin.

High Campylobacter diversity in retail chicken: epidemiologically important strains may be missed with current sampling methods

Campylobacter spp. are leading bacterial gastroenteritis pathogens. Infections are largely underreported, and the burden of outbreaks may be underestimated. Current strategies of testing as few as one isolate per sample can affect attribution of cases to epidemiologically important sources with high Campylobacter diversity, such as chicken meat. Multiple culture method combinations were utilized to recover and sequence Campylobacter from 45 retail chicken samples purchased across Norwich, UK, selecting up to 48 isolates per sample. Simulations based on resampling were used to assess the impact of Campylobacter sequence type (ST) diversity on outbreak detection. Campylobacter was recovered from 39 samples (87%), although only one sample was positive through all broth, temperature, and plate combinations. Three species were identified (Campylobacter jejuni, Campylobacter coli, and Campylobacter lari), and 33% of samples contained two species. Positive samples contained 1-8 STs. Simulation revealed that up to 87 isolates per sample would be required to detect 95% of the observed ST diversity, and 26 isolates would be required for the average probability of detecting a random theoretical outbreak ST to reach 95%. An optimized culture approach and selecting multiple isolates per sample are essential for more complete Campylobacter recovery to support outbreak investigation and source attribution.

Emergence of Plasmid-Mediated Quinolone Resistance (PMQR) Genes in Campylobacter coli in Tunisia and Detection of New Sequence Type ST13450

The aim of this study is to investigate the occurrence of plasmid mediated quinolone resistance (PMQR) determinants in Campylobacter coli isolates collected from broilers, laying hens and poultry farm environments. One hundred and thirty-nine C. coli isolates were isolated from broilers (n = 41), laying hens (n = 53), eggs (n = 4) and the environment (n = 41) of 23 poultry farms located in northeastern of Tunisia. Antimicrobial susceptibility testing was performed on all isolates according to the recommendation of the European Committee on Antimicrobial Susceptibility Testing guidelines. The detection of PMQR genes: qnrA, qnrB, qnrC, qnrD, qnrS, qepA, and aac(6)-Ib gene was performed using polymerase chain reaction (PCR) and specific primers. aac(6')-Ib amplicons were further analyzed by digestion with BtsCI to identify the aac(6')-Ib-cr variant. Mutations in GyrA and the occurrence of RE-CmeABC efflux pump were determined by mismatch amplification mutation assay (MAMA) PCR and PCR, respectively. In addition, eleven isolates were selected to determine their clonal lineage by MLST. The 139 C. coli isolates were resistant to ciprofloxacin, and 86 (61.8%) were resistant to nalidixic acid. High rates of resistance were also observed toward erythromycin (100%), azithromycin (96.4%), tetracycline (100%), chloramphenicol (98.56%), ampicillin (66.1%), amoxicillin-clavulanic acid (55.39%), and kanamycin (57.55%). However, moderate resistance rates were observed for gentamicin (9.35%) and streptomycin (22.3%). All quinolone-resistant isolates harbored the Thr-86-Ile amino acid substitution in GyrA, and the RE-CmeABC efflux pump was detected in 40.28% of isolates. Interestingly, the qnrB, qnrS, qepA, and aac(6')-Ib-cr were detected in 57.7%, 61.15%, 21.58%, and 10% of isolates, respectively. The eleven isolates studied by MLST belonged to a new sequence type ST13450. This study described for the first time the occurrence of PMQR genes in C. coli isolates in Tunisia and globally.

Molecular characterization of Campylobacter spp. isolates obtained from commercial broilers and native chickens in Southern Thailand using whole genome sequencing

Chickens are the primary reservoirs of Campylobacter spp., mainly C. jejuni and C. coli, that cause human bacterial gastrointestinal infections. However, genomic characteristics and antimicrobial resistance of Campylobacter spp. in low- to middle-income countries need more comprehensive exploration. This study aimed to characterize 21 C. jejuni and 5 C. coli isolates from commercial broilers and native chickens using whole genome sequencing and compare them to 28 reference Campylobacter sequences. Among the 26 isolates, 13 sequence types (ST) were identified in C. jejuni and 5 ST in C. coli. The prominent ST was ST 2274 (5 isolates, 19.2%), followed by ST 51, 460, 2409, and 6455 (2 isolates in each ST, 7.7%), while all remaining ST (464, 536, 595, 2083, 6736, 6964, 8096, 10437, 828, 872, 900, 8237, and 13540) had 1 isolate per ST (3.8%). Six types of antimicrobial resistance genes (ant(6)-Ia, aph(3')-III, blaOXA, cat, erm(B), and tet(O)) and one point mutations in the gyrA gene (Threonine-86-Isoleucine) and another in the rpsL gene (Lysine-43-Arginine) were detected. The blaOXA resistance gene was present in all isolates, the gyrA mutations was in 95.2% of C. jejuni and 80.0% of C. coli, and the tet(O) resistance gene in 76.2% of C. jejuni and 80.0% of C. coli. Additionally, 203 virulence-associated genes linked to 16 virulence factors were identified. In terms of phenotypic resistance, the C. jejuni isolates were all resistant to ciprofloxacin, enrofloxacin, and nalidixic acid, with lower levels of resistance to tetracycline (76.2%), tylosin (52.3%), erythromycin (23.8%), azithromycin (22.2%), and gentamicin (11.1%). Most C. coli isolates were resistant to all tested antimicrobials, while 1 C. coli was pan-susceptible except for tylosin. Single-nucleotide polymorphisms concordance varied widely, with differences of up to 13,375 single-nucleotide polymorphisms compared to the reference Campylobacter isolates, highlighting genetic divergence among comparative genomes. This study contributes to a deeper understanding of the molecular epidemiology of Campylobacter spp. in Thai chicken production systems.

Identification and functional characterization of putative ligand binding domain(s) of JlpA protein of Campylobacter jejuni

Among the major Surface Exposed Colonization Proteins (SECPs) of Campylobacter jejuni (C. jejuni), Jejuni lipoprotein A (JlpA) plays a crucial role in host cell adhesion specifically by binding to the N-terminal domain of the human heat shock protein 90α (Hsp90α-NTD). Although the JlpA binding to Hsp90α activates NF-κB and p38 MAP kinase pathways, the underlying mechanism of JlpA association with the cellular receptor remains unclear. To this end, we predicted two potential receptor binding sites within the C-terminal domain of JlpA: one spanning from amino acid residues Q332-A354 and the other from S258-T295; however, the latter exhibited weaker binding. To assess the functional attributes of these predicted sequences, we generated two JlpA mutants (JlpAΔ1: S258-T295; JlpAΔ2: Q332-A354) and assessed the Hsp90α-binding affinity-kinetics by in vitro and ex vivo experiments. Our findings confirmed that the residues Q332-A354 are of greater importance in host cell adhesion with a measurable impact on cellular responses. Further, thermal denaturation by circular dichroism (CD) confirmed that the reduced binding affinity of the JlpAΔ2 to Hsp90α is not associated with protein folding or stability. Together, this study provides a possible framework for determining the molecular function of designing rational inhibitors efficiently targeting JlpA.

Antimicrobial resistance patterns and genes of Campylobacter jejuni isolated from chickens in Pasuruan, Indonesia

Background

Poultry is one of the most prominent sources of Campylobacter jejuni, which is also a major means of transmission to people. Campylobacter jejuni contamination in chicken meat comes from chicken feces because it naturally exists in the intestines of chickens.

Aim

The purpose of this study is to identify the antibiotic resistance patterns and genes of C. jejuni, which was found in chickens in Pasuruan, Indonesia.

Methods

The samples used in this study were 200 contents of the small intestine of broiler chickens from 40 farms in Pasuruan Regency. The enriched sample was streaked on the selective media of modified charcoal cefoperazone deoxycholate agar containing the CCDA selective supplement. Antimicrobial susceptibility test utilizing the Kirby-Bauer diffusion test method in accordance with Clinical and Laboratory Standards Institute standards. The polymerase chain reaction (PCR) method was used to detect the (hipO), which encodes the C. jejuni strain, fluoroquinolone resistance (gyrA), beta-lactam resistance (blaOXA-61), and tetracycline resistance (tetO) genes.

Results

The findings revealed a 14% (28/200) prevalence of C. jejuni in the small intestine of broiler chickens. These isolates showed high resistance to enrofloxacin (92.9%). All isolates (100%) were susceptible to amoxicillin-clavulanate. The PCR results showed all C. jejuni isolates (100%) detected the gyrA gene, 96.4% detected the blaOXA-61 gene, and 50% detected the tetO gene.

Conclusion

The findings of antimicrobial resistance at a high level from the small intestine of broiler chickens illustrate the potential threat to human health. To lessen the effects now and in the future, coordinated and suitable action is needed, as well as steps to guarantee the poultry industry's economic survival and public health insurance.

Beta-lactamase genes in bacteria from food animals, retail meat, and human surveillance programs in the United States from 2002 to 2021

The spread of beta-lactamase-producing bacteria is a global public-health concern. This study aimed to explore the distribution of beta-lactamases reported in three sampling sources (cecal, retail meat, and human) collected as part of integrated surveillance in the United States. We retrieved and analyzed data from the United States National Antimicrobial Resistance Monitoring Systems (NARMS) from 2002 to 2021. A total of 115 beta-lactamase genes were detected in E. coli, Salmonella enterica, Campylobacter, Shigella and Vibrio: including 35 genes from cecal isolates, 32 genes from the retail meat isolates, and 104 genes from the human isolates. Three genes in E. coli (blaCMY-2,blaTEM-1A, and blaTEM-1B), 6 genes in Salmonella enterica (blaCARB-2, blaCMY-2, blaCTXM-65, blaTEM-1A, blaTEM-1B, and blaHERA-3), and 2 genes in Campylobacter spp. (blaOXA-61 and blaOXA-449) have been detected across food animals (cattle, chicken, swine, and turkey) and humans over the study period. blaCTXM-55 has been detected in E. coli isolates from the four food animal sources while blaCTXM-15 and blaCTXM-27 were found only in cattle and swine. In Salmonella enterica, blaCTXM-2, blaCTXM-9, blaCTXM-14, blaCTXM-15, blaCTXM-27, blaCTXM-55, and blaNDM-1 were only detected among human isolates. blaOXAs and blaCARB were bacteria-specific and the only beta-lactamase genes detected in Campylobacter spp. and Vibrio spp respectively. The proportions of beta-lactamase genes detected varies from bacteria to bacteria. This study provided insights on the beta-lactamase genes detected in bacteria in food animals and humans in the United States. This is necessary for better understanding the molecular epidemiology of clinically important beta-lactamases in one health interface.

Gene expression profile of Campylobacter jejuni in response to macrolide antibiotics

Campylobacter jejuni is a foodborne pathogen that causes gastroenteritis in humans and has developed resistance to various antibiotics. The primary objective of this research was to examine the network of antibiotic resistance in C. jejuni. The study involved the wild and antibiotic-resistant strains placed in the presence and absence of antibiotics to review their gene expression profiles in response to ciprofloxacin via microarray. Differentially expressed genes (DEGs) analysis and Protein-Protein Interaction (PPI) Network studies were performed for these genes. The results showed that the resistance network of C. jejuni is modular, with different genes involved in bacterial motility, capsule synthesis, efflux, and amino acid and sugar synthesis. Antibiotic treatment resulted in the down-regulation of cluster genes related to translation, flagellum formation, and chemotaxis. In contrast, cluster genes involved in homeostasis, capsule formation, and cation efflux were up-regulated. The study also found that macrolide antibiotics inhibit the progression of C. jejuni infection by inactivating topoisomerase enzymes and increasing the activity of epimerase enzymes, trying to compensate for the effect of DNA twisting. Then, the bacterium limits the movement to conserve energy. Identifying the antibiotic resistance network in C. jejuni can aid in developing drugs to combat these bacteria. Genes involved in cell division, capsule formation, and substance transport may be potential targets for inhibitory drugs. Future research must be directed toward comprehending the underlying mechanisms contributing to the modularity of antibiotic resistance and developing strategies to disrupt and mitigate the growing threat of antibiotic resistance effectively.

The characterization and correlation between the phenotypic and genotypic resistance of Campylobacter spp. isolates from commercial broilers and native chickens in the south of Thailand

RESEARCH HIGHLIGHTS

High Campylobacter prevalence in chickens; C. jejuni more prevalent than C. coli.Susceptibility to macrolides but resistance to quinolones/tetracyclines in isolates.Homogeneous resistance patterns within farms; higher in broilers than in native birds.Partial association between phenotypic and genotypic resistance among isolates.

Bacterial Efflux Pump Inhibitors Reduce Antibiotic Resistance

Bacterial resistance is a growing problem worldwide, and the number of deaths due to drug resistance is increasing every year. We must pay great attention to bacterial resistance. Otherwise, we may go back to the pre-antibiotic era and have no drugs on which to rely. Bacterial resistance is the result of several causes, with efflux mechanisms widely recognised as a significant factor in the development of resistance to a variety of chemotherapeutic and antimicrobial medications. Efflux pump inhibitors, small molecules capable of restoring the effectiveness of existing antibiotics, are considered potential solutions to antibiotic resistance and have been an active area of research in recent years. This article provides a review of the efflux mechanisms of common clinical pathogenic bacteria and their efflux pump inhibitors and describes the effects of efflux pump inhibitors on biofilm formation, bacterial virulence, the formation of bacterial persister cells, the transfer of drug resistance among bacteria, and mismatch repair. Numerous efforts have been made in the past 20 years to find novel efflux pump inhibitors which are known to increase the effectiveness of medicines against multidrug-resistant strains. Therefore, the application of efflux pump inhibitors has excellent potential to address and reduce bacterial resistance.

Antibiotic resistance, plasmids, and virulence-associated markers in human strains of Campylobacter jejuni and Campylobacter coli isolated in Italy

Campylobacteriosis, a prevalent foodborne gastrointestinal infection in Europe, is primarily caused by Campylobacter jejuni and Campylobacter coli, with rising global concerns over antimicrobial resistance in these species. This study comprehensively investigates 133 human-origin Campylobacter spp. strains (102 C. jejuni and 31 C. coli) collected in Italy from 2013 to 2021. The predominant Multilocus Sequence Typing Clonal complexes (CCs) were ST-21 CC and ST-206 CC in C. jejuni and ST-828 CC in C. coli. Ciprofloxacin and tetracycline resistance, mainly attributed to GyrA (T86I) mutation and tet(O) presence, were prevalent, while erythromycin resistance was associated with 23S rRNA gene mutation (A2075G), particularly in C. coli exhibiting multidrug-resistant pattern CipTE. Notable disparities in virulence factors among strains were observed, with C. jejuni exhibiting a higher abundance compared to C. coli. Notably, specific C. jejuni sequence types, including ST-21, ST-5018, and ST-1263, demonstrated significantly elevated counts of virulence genes. This finding underscores the significance of considering both the species and strain-level variations in virulence factor profiles, shedding light on potential differences in the pathogenicity and clinical outcomes associated with distinct C. jejuni lineages. Campylobacter spp. plasmids were classified into three groups comprising pVir-like and pTet-like plasmids families, exhibiting diversity among Campylobacter spp. The study underscores the importance of early detection through Whole Genome Sequencing to identify potential emergent virulence, resistance/virulence plasmids, and new antimicrobial resistance markers. This approach provides actionable public health data, supporting the development of robust surveillance programs in Italy.

Antimicrobial Susceptibility Patterns and Genetic Diversity of Campylobacter spp. Isolates from Patients with Diarrhea in South Korea

This study aimed to characterize the latest antimicrobial resistance patterns and genetic diversity of Campylobacter spp. isolated from patients with acute diarrhea in Korea. In total, 371 clinical isolates (361 Campylobacter jejuni and 10 Campylobacter coli) were collected from patients with diarrhea in 106 medical institutions of six provinces during the seasonal peak (April-September 2022) in South Korea. We then assessed their antimicrobial susceptibility to eight antimicrobial agents and performed multilocus sequence typing (MLST). This study investigated the antimicrobial resistance (AMR) profiles to tetracycline (32.3%), nalidixic acid (64.9%), and ciprofloxacin (83.3%), confirming high levels of the latter even after its Korean ban in 2010. However, tetracycline resistance displayed a decreasing trend. Alternatively, significantly lower resistance rates to clindamycin (0.8%), azithromycin (0.53%), erythromycin (0.53%), and gentamicin (0.53%) as well as absolute susceptibility to florfenicol (0%) were observed. Four C. jejuni and three C. coli isolates (7/371, 1.88%) were classified as multidrug-resistant (MDR) to at least three antimicrobial classes. MLST identified a high genetic diversity with 21 clonal complexes (CCs) and sixty-six sequence types (STs), including eight novel STs. The high CC frequency of C. jejuni comprised CC21 (37.7%), CC22 (13.8%), and CC206 (9.4%), while C. coli was predominated by CC828 (90%). The high CC21 and CC828 strain prevalence in this study was consistent with their worldwide distribution. This study highlights that quinolone- and tetracycline-resistant Campylobacter circulate in Korea with diverse genotypes, providing important information that could contribute to controlling and preventing increasing antimicrobial resistance in patients.

Prevalence and antimicrobial resistance of Campylobacter species in shelter-housed healthy and diarrheic cats and dogs in Turkey

BACKGROUND

Campylobacter spp. are among the leading foodborne bacterial pathogens. Pet animals may be an important reservoir for human infection.

OBJECTIVES

To determine the prevalence and antimicrobial resistance profiles and mechanisms of Campylobacter isolates recovered from shelter-housed healthy and diarrheic cats and dogs in Erzurum province in Turkey.

METHODS

A total of 250 rectal swabs (from 124 cats and 126 dogs) collected between 2020 and 2021 were included in this study. The samples were cultured using a Campylobacter-selective agar medium. A single suspect colony from each plate was purified and species identification was performed by PCR. Minimum inhibitory concentration (MIC) values were determined against eight antibiotics. Specific antimicrobial resistance genes (tetO and aphA-3) and mutations (in gyrA) were screened by PCR and/or sequencing.

RESULTS

A total of 26 (10.4%) isolates (25 Campylobacter jejuni and 1 Campylobacter coli) were obtained from the dogs; no Campylobacter was isolated from the cats. Of the C. jejuni isolates, 19.2% were resistant to nalidixic acid, 7.7% to ciprofloxacin and 3.8% to tetracycline and gentamicin per the CLSI interpretative criteria. The C. coli isolate was susceptible to all of the tested antibiotics. Thr-86-Ile mutation was the most common change detected in the gyrA gene in the quinolone-resistant isolates.

CONCLUSION

While geographic and population differences exist, Campylobacter carriage and associated antibiotic resistance in dogs is common, emphasising the need for continuous surveillance in this species, particularly given its zoonotic potential.

Detection of multidrug-resistant Campylobacter species from food-producing animals and humans in Nigeria: Public health implications and one health control measures

Antimicrobial-resistant thermophilic Campylobacter species (TCS) pose tremendous public health problems because they are zoonotic, difficult to treat and usually harboured by food-producing animals (FPAs). This study ascertained the phenotypic antimicrobial resistance (AMR) in 56 phenotypically identified TCS from slaughtered cattle, poultry, and humans in Enugu State, Nigeria. The presence of selected AMR and virulence genes harboured by the animal and human isolates were also detected and compared in 36 PCR-confirmed Campylobacter species. All the 56 TCS were multidrug-resistant as none were susceptible to ampicillin, penicillin-G, amoxicillin-clavulanic acid, cephalothin and metronidazole. The isolates were 92.9 %, 62.5 %, 92.9 %, 42.9 %, 26.8 %, 25 %, 28.6 %, 53.7 %, 30.1 %, 32.1 % and 55.4 % resistant to ceftriaxone, nalidixic acid, cefotaxime, enrofloxacin, ciprofloxacin, streptomycin, gentamycin, erythromycin, azithromycin, chloramphenicol and tetracycline, respectively. The top four most effective classes of antimicrobials were aminoglycosides > macrolides > amphenicol > fluoroquinolones. The AMR genes detected and the percentage of the isolates that harboured them were: aadE-1 (33.3 %), aphA-3-1 (36.1 %), tetO (44.4%), Blaoxa-61 (61.1 %) and the multidrug efflux pump, cmeB (86.1%). Virulence genes detected and the corresponding percentage of TCS that harboured them were: cdtB (61.1 %), flaA (47.2 %), ciaB (38.9 %), and pldA (38.9 %). The cmeB was significantly detected in animal isolates (p = 0.018, OR = 5.1, CI = 0.7-6.6) while BlaOXA-61 predominated in human isolates (p = 0.019, OR = 6.2). Likewise, ciaB virulence gene was mostly detected (p = 0.019, OR = 6.4, CI = 1.3-25) in animal isolates. The findings underscore the roles of FPAs in the zoonotic dissemination of Campylobacter-associated AMR and virulence genes in the study area. This warrants the adoption of One Health control strategies to limit spread of the multidrug-resistant zoonotic Campylobacter species.

Prevalence of ciprofloxacin resistance and associated genetic determinants differed among Campylobacter isolated from human and poultry meat sources in Pennsylvania

Poultry is the primary source of Campylobacter infections and severe campylobacteriosis cases are treated with macrolides and fluoroquinolones. However, these drugs are less effective against antimicrobial-resistant strains. Here, we investigated the prevalence of phenotypic antimicrobial resistance and associated resistance genetic determinants in Campylobacter isolates collected from human clinical (N = 123) and meat (N = 80) sources in Pennsylvania in 2017 and 2018. Our goal was to assess potential differences in the prevalence of antimicrobial resistance in Campylobacter isolated from human and poultry meat sources in Pennsylvania and to assess the accuracy of predicting antimicrobial resistance phenotypes based on resistance genotypes. We whole genome sequenced isolates and identified genetic resistance determinants using the National Antimicrobial Resistance Monitoring System Campylobacter AMR workflow v2.0 in GalaxyTrakr. Phenotypic antimicrobial susceptibility testing was carried out using the E-Test and Sensititre CAMPYCMV methods for human clinical and poultry meat isolates, respectively, and the results were interpreted using the EUCAST epidemiological cutoff values. The 193 isolates were represented by 85 MLST sequence types and 23 clonal complexes, suggesting high genetic diversity. Resistance to erythromycin was confirmed in 6% human and 4% meat isolates. Prevalence of ciprofloxacin resistance was significantly higher in human isolates as compared to meat isolates. A good concordance was observed between phenotypic resistance and the presence of the corresponding known resistance genetic determinants.

Case Commentary: An espresso, a free puppy, and multidrug-resistant Campylobacter

Campylobacter species infections in immunocompromised patients have the potential to progress to bacteremia and other extra-intestinal diseases. There is a sparsity of robust data, including antibiotic susceptibility data for contemporary agents, upon which to base treatment decisions. Moreover, intrinsic antimicrobial resistance in Campylobacter spp. further limits treatment options. The current publication by Bonilla-Moreno et al. elaborates on this clinical dilemma through the development, treatment, and molecular investigation of the putative mechanisms of carbapenem resistance in an immunocompromised patient with Campylobacter coli bacteremia.

Whole-Genome Sequencing-Based Profiling of Antimicrobial Resistance Genes and Core-Genome Multilocus Sequence Typing of Campylobacter jejuni from Different Sources in Lithuania

Campylobacter jejuni is known as one of the main causative agents of gastroenteritis in humans worldwide, and the rise of antimicrobial resistance (AMR) in Campylobacter is a growing public health challenge of special concern. Whole-genome sequencing (WGS) was used to characterize genetic determinants of AMR in 53 C. jejuni isolates from dairy cattle, broiler products, wild birds, and humans in Lithuania. The WGS-based study revealed 26 C. jejuni AMR markers that conferred resistance to various antimicrobials. Genetic markers associated with resistance to beta-lactamases, tetracycline, and aminoglycosides were found in 79.3%, 28.3%, and 9.4% of C. jejuni isolates, respectively. Additionally, genetic markers associated with multidrug resistance (MDR) were found in 90.6% of C. jejuni isolates. The WGS data analysis revealed that a common mutation in the quinolone resistance-determining region (QRDR) was R285K (854G > A) at 86.8%, followed by A312T (934G > A) at 83% and T86I (257C > T) at 71.7%. The phenotypic resistance analysis performed with the agar dilution method revealed that ciprofloxacin (CIP) (90.6%), ceftriaxone (CRO) (67.9%), and tetracycline (TET) (45.3%) were the predominant AMR patterns. MDR was detected in 41.5% (22/53) of the isolates tested. Fifty-seven virulence genes were identified in all C. jejuni isolates; most of these genes were associated with motility (n = 28) and chemotaxis (n = 10). Additionally, all C. jejuni isolates harbored virulence genes related to adhesion, invasion, LOS, LPS, CPS, transportation, and CDT. In total, 16 sequence types (STs) and 11 clonal complexes (CC) were identified based on core-genome MLST (cgMLST) analysis. The data analysis revealed distinct diversity depending on phenotypic and genotypic antimicrobial resistance of C. jejuni.

First report of phenotypic and genotypic (blaOXA-61) beta-lactam resistance in Campylobacter jejuni from broilers in Indonesia

Background and Aim

Campylobacter is a zoonotic bacterium that is a major source of foodborne diseases. In humans, most cases of campylobacteriosis are caused by Campylobacter jejuni. Poultry is the main reservoir of Campylobacter for humans, because Campylobacter is part of the normal flora of the digestive tract of poultry. Antimicrobial resistance to several antibiotics in Campylobacter isolated from humans and food animals has increased rapidly. Beta-lactam is an antibiotic with a high prevalence of resistance in Campylobacter. This study aimed to investigate phenotypic and genotypic (blaOXA-61) beta-lactam resistance in C. jejuni from broilers in Indonesia.

Materials and Methods

A total of 100 samples of broiler intestinal contents were obtained from 10 broiler farms in Pasuruan Regency, Indonesia. Campylobacter jejuni was identified using conventional and polymerase chain reaction (PCR)-based methods. Phenotypic detection of beta-lactam resistance was performed using an antimicrobial susceptibility test with antibiotic disks of aztreonam, ampicillin, and amoxicillin-clavulanic acid. Genotypic detection by PCR was performed using the blaOXA-61 gene, which encodes beta-lactamase.

Results

Campylobacter jejuni was identified in 23% of the samples. Phenotypically, 100% (23/23) and 73.9% (17/23) C. jejuni isolates had high resistance to aztreonam and ampicillin, respectively, but all isolates were susceptible to amoxicillin-clavulanic acid. Genotypically, all isolates carried blaOXA-61, indicated by the presence of a 372-bp PCR product.

Conclusion

Campylobacter jejuni is highly resistant to beta-lactams and is a serious threat to human health. Resistance to beta-lactams should be monitored because beta-lactamase genes can be transferred between bacteria. Public awareness must also be increased on the importance of using antibiotics rationally in humans and animals.

Campylobacter jejuni and Campylobacter coli in human stool samples: antibiotic resistance profiles, putative virulence determinants and molecular characterization of the isolates

Campylobacters, especially C. jejuni and C. coli, have become one of the leading causes of acute gastroenteritis in humans worldwide in recent years. We aimed to investigate the presence, antimicrobial resistance, putative virulence genes, and molecular characterization of C. jejuni and C. coli recovered from human acute gastroenteritis cases in the study. In the study, suspected Campylobacter spp. isolates were obtained in 43 (5%) feces samples collected from a total of 850 patients who applied to the Erciyes University Medical Faculty acute clinic between March 2019 and February 2020. As a result of the phenotypic tests, these isolates were determined to be Campylobacter spp. According to the multiplex PCR, 33 of 43 Campylobacter spp. isolates were identified as C. jejuni (76%) and ten isolates were as C. coli (24%). In the disc diffusion test, the highest resistance rate was found in the trimethoprim/sulfamethoxazole (90.1%) and ciprofloxacin (90.1%), and the lowest rate was found in the amoxicillin-clavulanic acid (9.3%). In Campylobacter spp. isolates, the virulence genes cdtA, virB11, cdtB, cadF, iam, ceu, and flaA were found to be positive at rates of 26 (60%), 28 (65.6%), 13 (30%), 4 (9%), 27 (62%), 17 (39%), and 7 (16%), respectively. However, the cdtC gene was not detected in any of the isolates. The study searched tetO gene to examine the genetic aspect of tetracycline resistance, which was found in all Campylobacter spp. isolates. In the PCR reactions to investigate A2074C and A2075G mutations of macrolide resistance, it was determined as 7 (16%) and 21 (48%) of the isolates. To detect quinolone resistance, the rates of quinolone resistance-determining regions (QRDR) were 20 (45.4%) and the gyrA gene mutations in the mismatch amplification mutation assay PCR (MAMA-PCR), were 19 (43.1%) of isolates. In addition, the quinolone resistance gene (qnr) carried by plasmid in Campylobacter isolates was not found in the study. BlaOXA-61 and CmeB (multi-drug efflux pump) genes were detected as 28 (63.6%) and 30 (68.1), respectively. The Enterobacterial Repetitive Intergenic Consensus PCR (ERIC-PCR) used for typing the isolates revealed that the band profiles obtained from the isolates were different. In conclusion, this was a very comprehensive study revealing the presence of antibiotic-resistant C. jejuni and C. coli with various virulence genes in patients admitted to a university hospital with acute gastroenteritis. This is of utmost significance for public health. Since campylobacteria are foodborne, zoonotic pathogens and transmission occurs mostly through food. People should have detailed information about the transmission routes of campylobacteria and risky foods. In addition, staff, food processors and caterers, should be trained in hygiene.

Genetic characteristics, antimicrobial susceptibility, and virulence genes distribution of Campylobacter isolated from local dual-purpose chickens in central China

Food-borne antibiotic-resistant Campylobacter poses a serious threat to public health. To understand the prevalence and genetic characteristics of Campylobacter in Chinese local dual-purpose (meat and eggs) chickens, the genomes of 30 Campylobacter isolates, including 13 C. jejuni and 17 C. coli from Jianghan-chickens in central China, were sequenced and tested for antibiotic susceptibility. The results showed that CC-354 and CC-828 were the dominant clonal complexes of C. jejuni and C. coli, respectively, and a phylogenetic analysis showed that three unclassified multilocus sequence types of C. coli were more closely genetically related to C. jejuni than to other C. coli in this study. Of the six antibiotics tested, the highest resistance rates were to ciprofloxacin and tetracycline (100%), followed by lincomycin (63.3%), erythromycin (30.0%), amikacin (26.7%), and cefotaxime (20.0%). The antibiotic resistance rate of C. coli was higher than that of C. jejuni. The GyrA T86I mutation and 15 acquired resistance genes were detected with whole-genome sequencing (WGS). Among those, the GyrA T86I mutation and tet(O) were most prevalent (both 96.7%), followed by the blaOXA-type gene (90.0%), ant(6)-Ia (26.7%), aac(6')-aph(3'') (23.3%), erm(B) (13.3%), and other genes (3.3%). The ciprofloxacin and tetracycline resistance phenotypes correlated strongly with the GyrA T86I mutation and tet(O)/tet(L), respectively, but for other antibiotics, the correlation between genes and resistance phenotypes were weak, indicating that there may be resistance mechanisms other than the resistance genes detected in this study. Virulence gene analysis showed that several genes related to adhesion, colonization, and invasion (including cadF, porA, ciaB, and jlpA) and cytolethal distending toxin (cdtABC) were only present in C. jejuni. Overall, this study extends our knowledge of the epidemiology and antibiotic resistance of Campylobacter in local Chinese dual-purpose chickens.

Pangenomic analyses of antibiotic-resistant Campylobacter jejuni reveal unique lineage distributions and epidemiological associations

Application of whole-genome sequencing (WGS) to characterize foodborne pathogens has advanced our understanding of circulating genotypes and evolutionary relationships. Herein, we used WGS to investigate the genomic epidemiology of Campylobacter jejuni, a leading cause of foodborne disease. Among the 214 strains recovered from patients with gastroenteritis in Michigan, USA, 85 multilocus sequence types (STs) were represented and 135 (63.1 %) were phenotypically resistant to at least one antibiotic. Horizontally acquired antibiotic resistance genes were detected in 128 (59.8 %) strains and the genotypic resistance profiles were mostly consistent with the phenotypes. Core-gene phylogenetic reconstruction identified three sequence clusters that varied in frequency, while a neighbour-net tree detected significant recombination among the genotypes (pairwise homoplasy index P<0.01). Epidemiological analyses revealed that travel was a significant contributor to pangenomic and ST diversity of C. jejuni, while some lineages were unique to rural counties and more commonly possessed clinically important resistance determinants. Variation was also observed in the frequency of lineages over the 4 year period with chicken and cattle specialists predominating. Altogether, these findings highlight the importance of geographically specific factors, recombination and horizontal gene transfer in shaping the population structure of C. jejuni. They also illustrate the usefulness of WGS data for predicting antibiotic susceptibilities and surveillance, which are important for guiding treatment and prevention strategies.

An integrated computational approach to infer therapeutic targets from Campylobacter concisus and peptidomimetic based inhibition of its pyrimidine metabolism pathway

Campylobacter concisus is a commensal of the human oral flora that has been allied with persistent diarrhea and inflammatory bowel disease (IBD). In children under the age of two, Campylobacter infections are common in the developing countries and have frequently been associated with mortality. They are becoming a prevalent cause of bacterial diarrhea in early adulthood in developed countries as well. The need for identifying new therapeutic targets and drugs is crucial for curbing such infections. Therefore, we identified 18 cytoplasmic potential therapeutic candidates against the type strain of C. concisus and deoxycytidine triphosphate deaminase (dCTP deaminase), involved in pyrimidine synthesis was selected for screening of peptidomimetic inhibitors (n > 30,000 peptidomimetics) against it. To the best of our knowledge, this target has not been studied for Campylobacter spp. Three potent inhibitors of this enzyme were prioritized i.e. peptidomimetic 27, 64, and 150. Dynamics simulation of 100 ns was carried out to validate findings for top-scored inhibitors along with physiology-based pharmacokinetics to estimate behavior in human body and predict dosing parameters. This verification demonstrates a first-in-human pharmacokinetic simulation for these peptidomimetics and can help enhance confidence in these peptide-like structures. Moiety 27 (IUPAC name: 5-[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]-N-{[2-(2-methoxyethyl)-1-oxo-1H,2H,3H,4H-pyrrolo[1,2-a]pyrazin-3-yl]methyl}furan-2-carboxamide), 64 (IUPAC name: 3-(2-methylpropyl)-1-{3-[5-(5-oxo-1-phenylpyrrolidin-3-yl)-1,2,4-oxadiazol-3-yl]phenyl}urea), and 150 (IUPAC name: N-(3-methoxypropyl)-1-[6-(4-methylphenyl)-4H,6H,7H-[1,2,3]triazolo[4,3-c][1,4]oxazine-3-carbonyl]piperidine-4-carboxamide) were identified as potent inhibitors of C. concisus.Communicated by Ramaswamy H. Sarma.

Fish Epidermal Mucus as a Source of Diverse Therapeutical Compounds

Microbes are helpful and destructive to human health and other living organisms. Microbes can be eliminated by using antibiotics against them, but their capability to resist regularly encountering antibiotics makes them more injurious. Microbes can adjust and adapt according to the chemicals used against them and become antibiotic resistant. Thus, the requirement for novel antimicrobial compounds increases with time to treat antibiotic-resistant microbes. Fish epidermal mucus encounters various pathogens present in their surrounding environment. It has become a rich source of novel antimicrobial compounds mainly antimicrobial peptides that can be used against various antibiotic-resistant pathogenic microbes. Compounds extracted from epidermal mucus can be used synergistically with other antibiotics or resistance modifying agents to inhibit the growth of resistant microbes. Fishes are consumed as a protein-rich food source worldwide and contribute to the world economy. Diseases in fish cause significant losses in the economic benefits exploited by fishermen and industries based on fisheries products. This paper will review compounds from fish epidermal mucus and their use to control the growth of antibiotic-resistant or non-resistant pathogenic microbes of humans and fishes. So, to increase fisheries' economic benefits and decrease infections involving resistant microbes.

Combination of organic acids benzoate, butyrate, caprylate, and sorbate provides a novel antibiotics-independent treatment option in the combat of acute campylobacteriosis

Introduction

The food-borne Gram-negative bacterial pathogen Campylobacter jejuni may cause the acute enterocolitis syndrome campylobacteriosis in infected humans. Given that human C. jejuni infections are rising globally which hold also true for resistance rates against antibiotic compounds such as macrolides and fluoroquinolones frequently prescribed for the treatment of severe infectious enteritis, novel antibiotics-independent therapeutic strategies are needed. Distinct organic acids are well known for their health-beneficial including anti-microbial and immunomodulatory properties. In our present study, we investigated potential pathogen-lowering and anti-inflammatory effects of benzoic acid, butyric acid, caprylic acid, and sorbic acid either alone or in combination during acute murine campylobacteriosis.

Methods

Therefore, secondary abiotic IL-10–/– mice were perorally infected with C. jejuni strain 81–176 and subjected to a 4-day-course of respective organic acid treatment.

Results and discussion

On day 6 post-infection, mice from the combination cohort displayed slightly lower pathogen loads in the duodenum, but neither in the stomach, ileum nor large intestine. Remarkably, the clinical outcome of C. jejuni induced acute enterocolitis was significantly improved after combined organic acid treatment when compared to the placebo control group. In support, the combinatory organic acid treatment dampened both, macroscopic and microscopic inflammatory sequelae of C. jejuni infection as indicated by less colonic shrinkage and less pronounced histopathological including apoptotic epithelial cell changes in the colon on day 6 post-infection. Furthermore, mice from the combination as compared to placebo cohort exhibited lower numbers of innate and adaptive immune cells such as neutrophilic granulocytes, macrophages, monocytes, and T lymphocytes in their colonic mucosa and lamina propria, respectively, which also held true for pro-inflammatory cytokine secretion in the large intestines and mesenteric lymph nodes. Notably, the anti-inflammatory effects were not restricted to the intestinal tract, but could also be observed systemically given pro-inflammatory mediator concentrations in C. jejuni infected mice from the combination organic acid treatment that were comparable to basal values. In conclusion, our in vivo study provides first evidence that an oral application of distinct organic acids in combination exhibits pronounced anti-inflammatory effects and hence, constitutes a promising novel antibiotics-independent therapeutic strategy in the combat of acute campylobacteriosis.

Antibiotic Resistance in Campylobacter: A Systematic Review of South American Isolates

In recent years, Campylobacter has become increasingly resistant to antibiotics, especially those first-choice drugs used to treat campylobacteriosis. Studies in South America have reported cases of antibiotic-resistant Campylobacter in several countries, mainly in Brazil. To understand the current frequency of antibiotic-resistant Campylobacter in humans, farm animals, and food of animal origin in South America, we systematically searched for different studies that have reported Campylobacter resistance. The most commonly reported species were C. jejuni and C. coli. Resistance to ciprofloxacin was found to be ubiquitous in the isolates. Nalidixic acid and tetracycline showed a significantly expressed resistance. Erythromycin, the antibiotic of first choice for the treatment of campylobacteriosis, showed a low rate of resistance in isolates but was detected in almost all countries. The main sources of antibiotic-resistant Campylobacter isolates were food of animal origin and farm animals. The results demonstrate that resistant Campylobacter isolates are disseminated from multiple sources linked to animal production in South America. The level of resistance that was identified may compromise the treatment of campylobacteriosis in human and animal populations. In this way, we are here showing all South American communities the need for the constant surveillance of Campylobacter resistance and the need for the strategic use of antibiotics in animal production. These actions are likely to decrease future difficulties in the treatment of human campylobacteriosis.

Overview of Virulence and Antibiotic Resistance in Campylobacter spp. Livestock Isolates

Campylobacter remains the most prevalent foodborne pathogen bacterium responsible for causing gastroenteritis worldwide. Specifically, this pathogen colonises a ubiquitous range of environments, from poultry, companion pets and livestock animals to humans. The bacterium is uniquely adaptable to various niches, leading to complicated gastroenteritis and, in some cases, difficult to treat due to elevated resistance to certain antibiotics. This increased resistance is currently detected via genomic, clinical or epidemiological studies, with the results highlighting worrying multi-drug resistant (MDR) profiles in many food and clinical isolates. The Campylobacter genome encodes a rich inventory of virulence factors offering the bacterium the ability to influence host immune defences, survive antimicrobials, form biofilms and ultimately boost its infection-inducing potential. The virulence traits responsible for inducing clinical signs are not sufficiently defined because several populations have ample virulence genes with physiological functions that reflect their pathogenicity differences as well as a complement of antimicrobial resistance (AMR) systems. Therefore, exhaustive knowledge of the virulence factors associated with Campylobacter is crucial for collecting molecular insights into the infectivity processes, which could pave the way for new therapeutical targets to combat and control the infection and mitigate the spread of MDR bacteria. This review provides an overview of the spread and prevalence of genetic determinants associated with virulence and antibiotic resistance from studies performed on livestock animals. In addition, we have investigated the relevant coincidental associations between the prevalence of the genes responsible for pathogenic virulence, horizontal gene transfer (HGT) and transmissibility of highly pathogenic Campylobacter strains.

Whole-Genome and Plasmid Comparative Analysis of Campylobacter jejuni from Human Patients in Toyama, Japan, from 2015 to 2019

Campylobacter jejuni is a major causative agent of food poisoning, and increasing antimicrobial resistance is a concern. This study investigated 116 clinical isolates of C. jejuni from Toyama, Japan, which were isolated from 2015 to 2019. Antimicrobial susceptibility testing and whole-genome sequencing were used for phenotypic and genotypic characterization to compare antimicrobial resistance (AMR) profiles and phylogenic linkage. The multilocus sequence typing approach identified 37 sequence types (STs) and 15 clonal complexes (CCs), including 7 novel STs, and the high frequency CCs were CC21 (27.7%), CC48 (10.9%), and CC354 (9.9%). The AMR profiles and related resistant factors were as follows: fluoroquinolones (51.7%), mutation in quinolone resistance-determining region (QRDRs) (GyrA T86I); tetracyclines (27.6%), acquisition of tet(O); ampicillin (7.8%), harboring blaOXA184 or a promoter mutation in blaOXA193; aminoglycosides (1.7%), acquisition of ant(6)-Ia and aph(3')-III; chloramphenicol (0.9%), acquisition of cat. The acquired resistance genes tet(O), ant(6)-Ia, aph(3')-III, and cat were located on pTet family plasmids. Furthermore, three pTet family plasmids formed larger plasmids that incorporated additional genes such as the type IV secretion system. Sequence type 4526 (ST4526; 10.9%), which is reported only in Japan, was the most predominant, suggesting continued prevalence. This study reveals the sequences of the pTet family plasmids harbored by C. jejuni in Japan, which had been unclear, and the acquisition of the insertion sequences in a part of the pTet family plasmids. Because pTet family plasmids can be horizontally transmitted and are a major factor in acquired resistance in Campylobacter, the risk of spreading pTet that has acquired further resistance should be considered. IMPORTANCE Campylobacter jejuni is among the major causes of enteritis and diarrhea in humans in many countries. Drug-resistant Campylobacter is increasing in both developing and developed countries, and in particular, fluoroquinolone-resistant Campylobacter was one of the species included on the priority list of antibiotic-resistant bacteria. Campylobacter drug resistance surveillance is important and has been conducted worldwide. In this study, we performed whole-genome analysis of Campylobacter jejuni isolated from diarrhea patients at a hospital in Toyama, Japan. This revealed the continued prevalence of Campylobacter jejuni ST4526, which has been reported to be prevalent in Japan, and the acquisition of resistance and virulence factors in the pTet family plasmids. The diversity of pTet family plasmids, the major resistance transmission factor, is expected to potentially increase the risk of Campylobacter. The usefulness of whole-genome sequencing in Campylobacter surveillance was also demonstrated.

Conformational dynamics and putative substrate extrusion pathways of the N-glycosylated outer membrane factor CmeC from Campylobacter jejuni

The outer membrane factor CmeC of the efflux machinery CmeABC plays an important role in conferring antibiotic and bile resistance to Campylobacter jejuni. Curiously, the protein is N-glycosylated, with the glycans playing a key role in the effective function of this system. In this work we have employed atomistic equilibrium molecular dynamics simulations of CmeC in a representative model of the C. jejuni outer membrane to characterise the dynamics of the protein and its associated glycans. We show that the glycans are more conformationally labile than had previously been thought. The extracellular loops of CmeC visit the open and closed states freely suggesting the absence of a gating mechanism on this side, while the narrow periplasmic entrance remains tightly closed, regulated via coordination to solvated cations. We identify several cation binding sites on the interior surface of the protein. Additionally, we used steered molecular dynamics simulations to elucidate translocation pathways for a bile acid and a macrolide antibiotic. These, and additional equilibrium simulations suggest that the anionic bile acid utilises multivalent cations to climb the ladder of acidic residues that line the interior surface of the protein.

The rise of antibiotic resistance in Campylobacter

PURPOSE OF REVIEW

Campylobacter is a major foodborne pathogen that infects the human intestinal tract. This review discusses the current status of antibiotic resistance, transmission of antibiotic resistance genes, and strategies to combat the global Campylobacter epidemic.

RECENT FINDINGS

Over the past 18 months, articles on Campylobacter antibiotic resistance have been published in ∼39 countries. Antibiotic-resistant Campylobacter have been detected in humans, livestock, poultry, wild animals, the environment, and food. Campylobacter spp. are resistant to a wide spectrum of antimicrobial agents, including the antibiotics quinolones, macrolides, tetracyclines, aminoglycosides, and chloramphenicols. Multidrug resistance is a globally emerging problem. Continuous antibiotic pressure promotes the spread of drug-resistant Campylobacter spp. Additionally, Campylobacter is well adapted to acquiring foreign drug resistance genes, including ermB, optrA, fexA, and cfrC, which are usually acquired from gram-positive bacteria.

SUMMARY

The widespread use of antibiotics has caused a global epidemic of drug-resistant Campylobacter infections. Many countries are actively reducing the use of antibiotics and adopting alternatives in the livestock and poultry industries to control the spread of drug-resistant Campylobacter spp.

Genomic insight into Campylobacter jejuni isolated from commercial turkey flocks in Germany using whole-genome sequencing analysis

Campylobacter (C.) jejuni is a zoonotic bacterium of public health significance. The present investigation was designed to assess the epidemiology and genetic heterogeneity of C. jejuni recovered from commercial turkey farms in Germany using whole-genome sequencing. The Illumina MiSeq^® technology was used to sequence 66 C. jejuni isolates obtained between 2010 and 2011 from commercial meat turkey flocks located in ten German federal states. Phenotypic antimicrobial resistance was determined. Phylogeny, resistome, plasmidome and virulome profiles were analyzed using whole-genome sequencing data. Genetic resistance markers were identified with bioinformatics tools (AMRFinder, ResFinder, NCBI and ABRicate) and compared with the phenotypic antimicrobial resistance. The isolates were assigned to 28 different sequence types and 11 clonal complexes. The average pairwise single nucleotide-polymorphisms distance of 14,585 SNPs (range: 0-26,540 SNPs) revealed a high genetic distinction between the isolates. Thirteen virulence-associated genes were identified in C. jejuni isolates. Most of the isolates harbored the genes flaA (83.3%) and flaB (78.8%). The wlaN gene associated with the Guillain-Barré syndrome was detected in nine (13.6%) isolates. The genes for resistance to ampicillin (bla _OXA), tetracycline [tet(O)], neomycin [aph(3')-IIIa], streptomycin (aadE) and streptothricin (sat4) were detected in isolated C. jejuni using WGS. A gene cluster comprising the genes sat4, aph(3')-IIIa and aadE was present in six isolates. The single point mutation T86I in the housekeeping gene gyrA conferring resistance to quinolones was retrieved in 93.6% of phenotypically fluoroquinolone-resistant isolates. Five phenotypically erythromycin-susceptible isolates carried the mutation A103V in the gene for the ribosomal protein L22 inferring macrolide resistance. An assortment of 13 β-lactam resistance genes (bla _OXA variants) was detected in 58 C. jejuni isolates. Out of 66 sequenced isolates, 28 (42.4%) carried plasmid-borne contigs. Six isolates harbored a pTet-like plasmid-borne contig which carries the tet(O) gene. This study emphasized the potential of whole-genome sequencing to ameliorate the routine surveillance of C. jejuni. Whole-genome sequencing can predict antimicrobial resistance with a high degree of accuracy. However, resistance gene databases need curation and updates to revoke inaccuracy when using WGS-based analysis pipelines for AMR detection.

Evaluation of efflux pump inhibitory activity of some plant extracts and using them as adjuvants to potentiate the inhibitory activity of some antibiotics against Staphylococcus aureus

Background

Antibiotic-resistant pathogens became a real global threat to human and animal health. This needs to concentrate the efforts to minimize and control these organisms. Efflux pumps are considered one of the important strategies used by bacteria to exclude harmful materials from the cell. Inhibition of these pumps can be an active strategy against multidrug resistance pathogens. There are two sources of efflux pump inhibitors that can be used, chemical and natural inhibitors. The chemical origin efflux pump inhibitors have many toxic side effects while the natural origin is characterized by a wide margin of safety for the host cell.

Aim

In this study, the ability of some plant extracts like (propolis show rosemary, clove, capsaicin, and cumin) to potentiate the inhibitory activity of some antibiotics such as (ciprofloxacin, erythromycin, gentamycin, tetracycline, and ampicillin) against Staphylococcus aureus pathogen were tested.

Methods

Efflux pump inhibitory activity of the selected plant extracts was tested using an ethidium bromide (EtBr) accumulation assay.

Results

The results have shown that Propolis has a significant synergistic effect in combination with ciprofloxacin, erythromycin, and gentamycin. While it has no effect with tetracycline or ampicillin. Also, no synergic effect was noticed in a combination of the minimum inhibitory concentration for the selected plant extracts (rosemary, clove, capsaicin, and cumin) with any of the tested antibiotics. Interestingly, according to the results of the EtBr accumulation assay, Propolis has potent inhibitory activity against the S. aureus (MRS usa300) pump system.

Conclusion

This study suggests that Propolis might act as a resistance breaker that is able to restore the activity of ciprofloxacin, erythromycin, and gentamycin against S. aureus strains, in case of the efflux-mediated antimicrobial resistance mechanisms.

Olive Leaf as a Source of Antibacterial Compounds Active against Antibiotic-Resistant Strains of Campylobacter jejuni and Campylobacter coli

Campylobacter spp. are the main cause of bacterial gastroenteritis worldwide, and broiler chicks are the main vector of transmission to humans. The high prevalence of Campylobacter in poultry meat and the increase of antibiotic resistant strains have raised the need to identify new antimicrobial agents. For this reason, the aim of the current study was to evaluate the antibacterial activity of two extracts of olive leaf against antibiotic-resistant Campylobacter strains (C. jejuni and C. coli) isolated from poultry food chain. The extracts of olive leaf (E1 and E2) were markedly different in their chemical compositions. While E1 was composed predominantly of highly hydrophilic compounds such as hydroxytyrosol and hydroxytyrosol glucosides (14,708 mg/100 g), E2 mainly contained moderately hydrophilic compounds, with oleuropein (20,471 mg/100 g) being prevalent. All Campylobacter strains exhibited similar antibiotic profiles, being resistant to ciprofloxacin and tetracycline. E1 showed strong antibacterial activity and reduced bacterial growth from 4.12 to 8.14 log CFU/mL, depending on the strain. Hydroxytyrosol was the main compound responsible, causing the inhibition of growth of Campylobacter strains at low concentrations (0.1-0.25 mg/mL). E2 demonstrated a lower antibacterial effect than E1, reducing growth from 0.52 to 2.49 log CFU/mL. The results of this study suggest that the optimization of the composition of olive-leaf extracts can provide improved treatment results against Campylobacter strains.