Genomic Analysis of Chilean Strains of Campylobacter jejuni from Human Faeces

Colourimetric and SERS dual-mode aptasensor using Au@Ag and magnetic nanoparticles for the detection of Campylobacter jejuni

A dual-mode aptasensor has been developed for the effective detection of Campylobacter jejuni (C. jejuni), a major cause of gastrointestinal disease worldwide. The aptasensor utilizes nanoparticles, specifically a core-shell structure consisting of gold and silver (Au@Ag NPs), along with magnetic nanoparticles (MNPs). When Campylobacter jejuni is introduced, "Au@Ag NPs-Aptamer-Campylobacter jejuni-Aptamer-MNPs" sandwich complexes are formed due to the high affinity of the aptamer for the bacterial surface membrane proteins. The dual-mode aptasensor can magnetically enrich the sample in just 15 min, and the presence of Campylobacter jejuni is determined by observing a color change. Additionally, the concentration of Campylobacter jejuni can be quantified using surface-enhanced Raman spectroscopy (SERS) and standard curves. This results in a wider linear range (1.8 × 101-108 CFU/mL) under optimal conditions, a lower limit of detection (6 CFU/mL), and a higher selectivity for the detection of bacteria compared to previously reported sensors. Compared with traditional microbial culture counting methods, the dual-mode aptasensor does not require Raman reporters. The physical action of magnetic enrichment, along with the application of Au@Ag NPs, improves the accuracy of the dual-mode aptasensor, offering the advantages of convenience and high sensitivity. Moreover, by utilizing different types of aptamers, this aptasensor can be modified to detect a wider range of harmful pathogens in various environments.

Whole-genome sequencing reveals changes in genomic diversity and distinctive repertoires of T3SS and T6SS effector candidates in Chilean clinical Campylobacter strains

Campylobacter is the leading cause of bacterial gastroenteritis worldwide and an emerging and neglected pathogen in South America. This zoonotic pathogen colonizes the gastrointestinal tract of a wide range of mammals and birds, with poultry as the most important reservoir for human infections. Apart from its high morbidity rates, the emergence of resistant strains is of global concern. The aims of this work were to determine genetic diversity, presence of antimicrobial resistance determinants and virulence potential of Campylobacter spp. isolated from patients with acute gastrointestinal disease at 'Clinica Alemana', Santiago de Chile. The study considered the isolation of Campylobacter spp., from stool samples during a 20-month period (January 2020 to September 2021). We sequenced (NextSeq, Illumina) and performed an in-depth analysis of the genome sequences of 88 Campylobacter jejuni and 2 Campylobacter coli strains isolated from clinical samples in Chile. We identified a high genetic diversity among C. jejuni strains and the emergence of prevalent clonal complexes, which were not identified in our previous reports. While ~40% of strains harbored a mutation in the gyrA gene associated with fluoroquinolone resistance, no macrolide-resistance determinants were detected. Interestingly, gene clusters encoding virulence factors such as the T6SS or genes associated with long-term sequelae such as Guillain-Barré syndrome showed lineage-relatedness. In addition, our analysis revealed a high degree of variability regarding the presence of fT3SS and T6SS effector proteins in comparison to type strains 81-176, F38011, and NCTC 11168 and 488. Our study provides important insights into the molecular epidemiology of this emerging foodborne pathogen. In addition, the differences observed regarding the repertoire of fT3SS and T6SS effector proteins could have an impact on the pathogenic potential and transmissibility of these Latin American isolates, posing another challenge in characterizing the infection dynamics of this emergent and neglected bacterial pathogen.

Head-to-head comparison of CAMPYAIR aerobic culture medium versus standard microaerophilic culture for Campylobacter isolation from clinical samples

Campylobacter spp. are considered the most frequent cause of acute gastroenteritis worldwide. However, outside high-income countries, its burden is poorly understood. Limited published data suggest that Campylobacter prevalence in low- and middle-income countries is high, but their reservoirs and age distribution are different. Culturing Campylobacter is expensive due to laboratory equipment and supplies needed to grow the bacterium (e.g., selective culture media, microaerophilic atmosphere, and a 42°C incubator). These requirements limit the diagnostic capacity of clinical laboratories in many resource-poor regions, leading to significant underdiagnosis and underreporting of isolation of the pathogen. CAMPYAIR, a newly developed selective differential medium, permits Campylobacter isolation without the need for microaerophilic incubation. The medium is supplemented with antibiotics to allow Campylobacter isolation in complex matrices such as human feces. The present study aims to evaluate the ability of the medium to recover Campylobacter from routine clinical samples. A total of 191 human stool samples were used to compare the ability of CAMPYAIR (aerobic incubation) and a commercial Campylobacter medium (CASA, microaerophilic incubation) to recover Campylobacter. All Campylobacter isolates were then identified by MALDI-TOF MS. CAMPYAIR showed sensitivity and specificity values of 87.5% (95% CI 47.4%-99.7%) and 100% (95% CI 98%-100%), respectively. The positive predictive value of CAMPYAIR was 100% and its negative predictive value was 99.5% (95% CI 96.7%-99.9%); Kappa Cohen coefficient was 0.93 (95% CI 0.79-1.0). The high diagnostic performance and low technical requirements of the CAMPYAIR medium could permit Campylobacter culture in countries with limited resources.

Distribution of Virulence Genes in Campylobacter spp. Isolated from Agaricus Mushrooms in Iran

The white button mushroom (Agaricus) is a significant nutritional and therapeutic species utilized in the human diet and could transmit various bacterial infections. Campylobacter species are the most common cause of foodborne illness across the world. The present study has been planned to determine the frequency of virulence genes and antibiotic susceptibility test in Campylobacter spp. recovered from Agaricus mushroom. In this study, 740 Agaricus mushroom samples were gathered randomly from various markets from June 2020 to December 2020. Confirmation of Campylobacter spp. using biochemical analyses and 23S rRNA-based PCR was performed. The agar dilution technique was used to determine resistance to antibiotics using gentamicin (GM10μg), ciprofloxacin (CIP5μg), nalidixic acid (NA30μg), tetracycline (TE30μg), ampicillin (AM10μg), amoxicillin+ clavulanic acid (AMC30μg), erythromycine (E15μg), azithromycin (AZM15μg), clindamycin (CC2μg), and chloramphenicol (C30μg). Multiplex PCR was utilized to determine the prevalence of the recR, dnaJ, wlaN, virBll, cdtC, cdtB, cdtA, flaA, cadF, pidA, ciaB, ceuE, and cgtB genes. Campylobacter spp. were detected in 74 out of 740 Agaricus mushroom samples (10%). According to the data, Agaricus mushroom samples included 32 (4.32%) C. jejuni, 11 (1.48%) C. coli, and 31 (4.18%) other Campylobacter spp. Antimicrobial resistance was most common in C. jejuni isolates. C. jejuni isolates also had the lowest resistance rate to gentamycin, ciprofloxacin, and nalidixic acid. C. coli isolates were reported to have the highest antimicrobial resistance to ciprofloxacin, ampicillin, and erythromycine. Resistance to gentamycin and amoxicillin+ clavulanic acid was likewise lowest among C. coli strains. The flaA and ciaB genes were found in 100% of B-lactams-susceptible C. jejuni and C. coli strains. When examining the relationship between antibiotic resistance and the existence of virulence genes, it was observed that there is a statistically significant relationship (p < 0.001) between bacterial resistance and virulence genes. Our findings indicated that changes in resistance patterns in Campylobacter strains have emerged from multiple treatment approaches in Agaricus mushrooms.

CAMPYAIR, a New Selective, Differential Medium for Campylobacter spp. Isolation without the Need for Microaerobic Atmosphere

Campylobacter spp. are considered the most frequent bacterial cause of acute gastroenteritis worldwide. Although the diarrhea produced by these bacteria is self-limiting, the pathogen has been associated with severe long-term sequelae following acute signs and symptoms of the illness. However, research on Campylobacter is hampered by costs and technical requirements for isolating and culturing the bacterium, especially in low and middle-income countries. Therefore, attempts have been made to simplify these culture methods and to reduce costs associated with conducting research on Campylobacter. Recently, a liquid medium which allows selective enrichment of Campylobacter using aerobic incubation has been described. However, a solid medium is also needed for the isolation of pure colonies, enumeration of bacterial populations, and other studies on the pathogen. Therefore, a new medium (CAMPYAIR) was developed, based on the formulation of the liquid medium. CAMPYAIR is a solid chromogenic medium that supports the growth of Campylobacter isolates within 48 h of incubation in aerobic atmospheres. Moreover, CAMPYAIR contains antibiotic supplements with an enhanced ability to recover Campylobacter from environmental samples that may also contain non-campylobacter bacteria. The addition of the indicator 2,3,5-triphenyltetrazolium (TTC) to the medium differentiates Campylobacter from other bacteria growing on the media. The findings from studies on CAMPYAIR suggest that the utilization of the new selective, differential medium could help to reduce the costs, equipment, and technical training required for Campylobacter isolation from clinical and environmental samples.

Comparison of transport crates contamination with Campylobacter spp. before and after the cleaning and disinfection procedure in broiler slaughterhouses

Campylobacteriosis is one of the most common types of bacterial gastroenteritis affecting humans, and poultry is considered a major source of the causative organism, Campylobacter spp. Broilers may arrive contaminated at slaughterhouses, and transport crates could be considered a potential source of contamination. Thus, cleaning and disinfection procedures are crucial to avoid cross-contamination among flocks. Despite its public health importance in Latin American countries, virulence factors of Campylobacter jejuni remain poorly studied in this region. Thus, this study aimed to: 1) determine the occurrence of contaminated crates at a poultry slaughterhouse, 2) compare the contamination before and after the cleaning and disinfection procedures, and 3) detect virulence-associated genes in C. jejuni strains by PCR. Campylobacter spp. were recovered from 8 of the 10 flocks evaluated, and C. jejuni was detected as the main species. There was no significant difference in the Campylobacter detection or quantification between crates at the reception platform and crates after the cleaning/disinfection processes. However, crates after 24 h of natural drying, presented a significant (P < 0.05) lower amount of Campylobacter cells than before the cleaning and disinfection processes. A negative relationship (R² = 0.210, P = 0.045) between environmental conditions and Campylobacter quantification was found for transport crates after 24 h of natural drying. There was no significant difference (P > 0.05) in the detection of two C. jejuni virulence genes, flaA (encode a major flagellin protein) and cadF (encode an adhesion and fibronectin-binding protein), among various stages of the cleaning and disinfection processes. Our results demonstrate the high contamination levels of Campylobacter strains in broiler flocks and the potential involvement of poultry transport crates in transmitting these bacteria. This study also suggests that ineffective cleaning and disinfection procedures can increase Campylobacter contamination and facilitate the spread of bacteria in poultry establishments.

Campylobacter coli isolated in Brazil typed by core genome Multilocus Sequence Typing shows high genomic diversity in a global context

Campylobacter has been one of the most common causative agent of bacterial food-borne gastroenteritis in humans worldwide. However, in Brazil the campylobacteriosis has been a neglected disease and there is insufficient data to estimate the incidence of this pathogen in the country.

AIMS

The current study aimed to determine the phylogenetic relationships among Campylobacter coli strains isolated in Brazil and to compare them with international Campylobacter isolates available in some public databases.

METHODS AND RESULTS

A total of 63C. coli strains isolated in Brazil were studied. The MLST analysis showed 18 different STs including three STs not yet described in the PubMLST database. The cgMLST allocated the Brazilian strains studied into five main clusters and each cluster comprised groups of strains with nearly identical cgMLST profiles and with significant genetic distance observed among the distinct clusters. The comparison of the Brazilian strains with 3401 isolates from different countries showed a wide distribution of these strains isolated in this country.

CONCLUSIONS

The results showed a high similarity among some strains studied and a wide distribution of the Brazilian strains when compared to isolates from different countries, which is an interesting data set since it showed a high genetic diversity of these strains from Brazil in a global context. This study contributed for a better genomic characterization of C. coli strains isolated in Brazil and provided important information about the diversity of this clinically-relevant pathogen.

Identification of pathogenic genes in Campylobacter jejuni isolated from broiler carcasses and broiler slaughterhouses

Campylobacter jejuni is one of the most common causes of foodborne diseases worldwide. There are few reports on Campylobacter strains isolated from Latin-American countries. Here, 140 C. jejuni strains isolated from cloacal and transport boxes swabs, water from chiller tanks, and broiler carcasses of five poultry companies in Southern Brazil were identified using phenotypic and genotypic methods. Polymerase chain reaction (PCR) was used to analyze eight C. jejuni virulence markers: flaA, cadF, and invasion-associated (iam) genes, cdtABC operon (associated with the cytolethal distending toxin), and plasmidial virB11 and wlaN genes were present in 78.5%, 77.8%, 0%, 74.2%, 22.1%, and 10.7% of samples, respectively. There were 25 different virulence profiles: 1 (cdtA, cdtB, cdtC, flaA, and cadF), 2 (cdtA, cdtB, cdtC, flaA, cadF, and virB11), and 3 (cdtA, cdtB, cdtC, flaA, cadF, and wlaN) were the most common (> 60% of strains). We provide insight into factors related to the occurrence of this pathogen and their epidemiology.

Genomic analysis of the diversity, antimicrobial resistance and virulence potential of clinical Campylobacter jejuni and Campylobacter coli strains from Chile

Campylobacter jejuni and Campylobacter coli are the leading cause of human gastroenteritis in the industrialized world and an emerging threat in developing countries. The incidence of campylobacteriosis in South America is greatly underestimated, mostly due to the lack of adequate diagnostic methods. Accordingly, there is limited genomic and epidemiological data from this region. In the present study, we performed a genome-wide analysis of the genetic diversity, virulence, and antimicrobial resistance of the largest collection of clinical C. jejuni and C. coli strains from Chile available to date (n = 81), collected in 2017–2019 in Santiago, Chile. This culture collection accounts for more than one third of the available genome sequences from South American clinical strains. cgMLST analysis identified high genetic diversity as well as 13 novel STs and alleles in both C. jejuni and C. coli. Pangenome and virulome analyses showed a differential distribution of virulence factors, including both plasmid and chromosomally encoded T6SSs and T4SSs. Resistome analysis predicted widespread resistance to fluoroquinolones, but low rates of erythromycin resistance. This study provides valuable genomic and epidemiological data and highlights the need for further genomic epidemiology studies in Chile and other South American countries to better understand molecular epidemiology and antimicrobial resistance of this emerging intestinal pathogen.

Campylobacter is the leading cause of bacterial gastroenteritis worldwide and an emerging and neglected pathogen in South America. In this study, we performed an in-depth analysis of the genome sequences of 69 C. jejuni and 12 C. coli clinical strains isolated from Chile, which account for over a third of the sequences from clinical strains available from South America. We identified a high genetic diversity among C. jejuni strains and the unexpected identification of clade 3 C. coli strains, which are infrequently isolated from humans in other regions of the world. Most strains harbored the virulence factors described for Campylobacter. While ~40% of strains harbored mutation in the gyrA gene described to confer fluoroquinolone resistance, very few strains encoded the determinants linked to macrolide resistance, currently used for the treatment of campylobacteriosis. Our study contributes to our knowledge of this important foodborne pathogen providing valuable data from South America.

Complete Genome Sequences of 17 Clinical Campylobacter jejuni Strains from Chile

Campylobacter jejuni is the leading cause of bacterial foodborne disease worldwide. Here, we report the complete annotated genomes and plasmid sequences of 17 Campylobacter jejuni strains isolated from patients with gastroenteritis in Santiago, Chile.

Campylobacter jejuni is the leading cause of bacterial foodborne disease worldwide. Here, we report the complete annotated genomes and plasmid sequences of 17 Campylobacter jejuni strains isolated from patients with gastroenteritis in Santiago, Chile.

Draft Whole-Genome Sequences of 51 Campylobacter jejuni and 12 Campylobacter coli Clinical Isolates from Chile

Campylobacter species are the leading cause of gastroenteritis worldwide and an emerging threat in developing countries. Here, we report the draft whole-genome sequences of 51 Campylobacter jejuni and 12 Campylobacter coli strains isolated from patients with gastroenteritis in Santiago, Chile.

Campylobacter species are the leading cause of gastroenteritis worldwide and an emerging threat in developing countries. Here, we report the draft whole-genome sequences of 51 Campylobacter jejuni and 12 Campylobacter coli strains isolated from patients with gastroenteritis in Santiago, Chile.

Taking Control: Campylobacter jejuni Binding to Fibronectin Sets the Stage for Cellular Adherence and Invasion

Campylobacter jejuni, a foodborne pathogen, is one of the most common bacterial causes of gastroenteritis in the world. Undercooked poultry, raw (unpasteurized) dairy products, untreated water, and contaminated produce are the most common sources associated with infection. C. jejuni establishes a niche in the gut by adhering to and invading epithelial cells, which results in diarrhea with blood and mucus in the stool. The process of colonization is mediated, in part, by surface-exposed molecules (adhesins) that bind directly to host cell ligands or the extracellular matrix (ECM) surrounding cells. In this review, we introduce the known and putative adhesins of the foodborne pathogen C. jejuni. We then focus our discussion on two C. jejuni Microbial Surface Components Recognizing Adhesive Matrix Molecule(s) (MSCRAMMs), termed CadF and FlpA, which have been demonstrated to contribute to C. jejuni colonization and pathogenesis. In vitro studies have determined that these two surface-exposed proteins bind to the ECM glycoprotein fibronectin (FN). In vivo studies have shown that cadF and flpA mutants exhibit impaired colonization of chickens compared to the wild-type strain. Additional studies have revealed that CadF and FlpA stimulate epithelial cell signaling pathways necessary for cell invasion. Interestingly, CadF and FlpA have distinct FN-binding domains, suggesting that the functions of these proteins are non-redundant. In summary, the binding of FN by C. jejuni CadF and FlpA adhesins has been demonstrated to contribute to adherence, invasion, and cell signaling.