Genotyping and distribution of putative virulence factors and antibiotic resistance genes of Acinetobacter baumannii strains isolated from raw meat

Prevalence, seasonal variation, and proteomic relationship of β-lactamase-producing Escherichia coli, Klebsiella pneumoniae, and Acinetobacter spp. in poultry meat at the abattoir level in Greece

Extended-spectrum-β-lactamase (ESBL) and carbapenemase-producing Enterobacterales and Acinetobacter spp. are important nosocomial pathogens that are frequently isolated from patients and food matrices. Nevertheless, comprehensive data on the prevalence, spatiotemporal variations, and characterization of β-lactam-resistant bacteria in poultry meat products are limited. This study provides the first comprehensive assessment in Greece of the prevalence, characteristics, and proteomic relationships of β-lactam-resistant strains in poultry meat at the abattoir level. Strains were selectively isolated using β-lactams and identified via MALDI-TOF MS. Antimicrobial susceptibility and the presence of common β-lactamase genes were assessed, and protein profiles were analyzed to determine strain relationships, whereas E. coli isolates were further classified into phylogenetic groups. The overall prevalence was 40.8% for E. coli, 3.3% for K. pneumoniae, and 46.7% for Acinetobacter spp., with notable seasonal and regional fluctuations especially in Acinetobacter spp. Most strains (97.9% of E. coli, 100.0% of K. pneumoniae and 88.1% of Acinetobacter spp.) were classified as multidrug or extensively drug-resistant. All E. coli and K. pneumoniae strains were phenotypically confirmed as ESBL/AmpC producers, whereas one K. pneumoniae strain showed additional resistance to ertapenem. The majority of E. coli strains (91.49%) and all K. pneumoniae strains carried β-lactamase genes, predominantly blaCTX-M group 1 in E. coli and blaSHV in K. pneumoniae. Conversely, only 10.2% of Acinetobacter strains harbored β-lactamase genes. Most E. coli isolates belonged to phylogroups A (46.9%) and B1 (34.7%). Protein profile analysis indicated relatedness among isolates across different regions and seasons. These findings underscore poultry meat's role as a reservoir of resistant strains of E. coli, K. pneumoniae, and Acinetobacter spp. and highlight the need for enhanced surveillance and mitigation strategies to reduce public health risks.

Isolation and characterization of Acinetobacter baumannii from environmental waters in Dhaka City, Bangladesh

Acinetobacter baumannii, a gram-negative bacterium commonly associated with nosocomial infections, has been relatively unexplored in the environmental context. The present study was conducted in Dhaka City, Bangladesh, with the primary objective of isolating and characterizing A. baumannii in environmental water sources. Surface water samples were collected from various water reservoirs to detect the presence of A. baumannii. Isolates were confirmed as A. baumannii using culture and PCR. Confirmed isolates were screened for antimicrobial susceptibility, antimicrobial resistance genes, and serum resistance. Results revealed that 32% of the water samples tested positive for A. baumannii. In total, 23 A. baumannii isolates were obtained. All isolates showed resistance to Cefepime. Varying degrees of resistance to other antibiotics were observed, and 56% showed resistance to the bactericidal effect of serum. This study underscored the remarkable adaptability of A. baumannii and its ability to flourish in diverse environmental conditions, highlighting public health concerns of increasing antibiotic resistant bacteria. The study concluded that, given the significance of effective infection control and sanitation and waste management measures, understanding the presence and behavior of A. baumannii in the environment is paramount. This study acts as the first report on environmental A. baumannii in Bangladesh and further research is warranted to elucidate the underlying mechanisms of antibiotic resistance and their implications for human health.

Epidemiological and genomic analysis of Acinetobacter baumannii strains from retailed raw meat

Acinetobacter baumannii causes hospital-acquired infections in human patients with compromised immune system. Strains associated to nosocomial infections are often resistant to carbapenems and belong to few international clones (IC1-11). A. baumannii strains have been found in extra-hospital sources including food products. While molecular epidemiology of A. baumannii is well described in hospital settings, extra-hospital settings remain poorly investigated. In the frame of two screening campaigns for the presence of Gram-negative bacteria in retailed raw meat, we collected 70 A. baumannii isolates. To investigate if there was a genetic link between food isolates and those causing infections in humans, a core-genome pyMLST analysis was conducted including genomes from different sources as well as representatives of the IC1-11 (n = 224) retrieved from the NCBI database. Strains from raw meat were genetically diverse with 49 sequence types present among the 70 isolates. The core-genome phylogenetic analysis demonstrated that some A. baumannii strains from raw meat shared high genomic similarity with strains associated to human infections carrying carbapenem-resistance genes and belonging to IC11 and other clonal complexes (CC) that are emerging globally, like CC33. Strains from raw meat were able to acquire genes conferring carbapenem-resistance in vitro. If A. baumannii cannot be considered as a food-borne pathogen, colonization of raw meat can favor the propagation of this species in the community, facilitating the entrance of novel clones in the hospital environment. Once entering hospital settings, susceptible clones could turn into multidrug-resistant lineages under strong selective pressure. To avoid this risk, accurate hands and kitchen utensils hygiene should be recommended to all those in contact with raw meat.

Antimicrobial resistance and virulence factors analysis of a multidrug-resistant Acinetobacter baumannii isolated from chickens using whole-genome sequencing

Multidrug-resistant (MDR) Acinetobacter baumannii (A. baumannii) is currently recognized not only as a significant nosocomial pathogen but also is an emerging bacterial infection in food-producing animals, posing a critical threat to global health. However, this is a hindrance to detailed bioinformatic studies of MDR A. baumannii of chicken origin due to the lack of its complete genome sequence. Here, we report whole-genome sequencing analysis of MDR A. baumannii Y03 isolated from chickens. The Y03 genome consists of 1 circular chromosome and 4 circular plasmids, The Y03 chromosome harbors 41 antimicrobial resistance genes conferring resistance to major classes of antibiotics, including β-lactams, phenicols, macrolides, lincosamides, aminoglycosides, and nitrofurans, as well as 135 virulence factors involved in effector delivery system, immune modulation, adherence, stress survival, biofilm, exotoxin, and nutritional/metabolic factor. The in vivo infection experiments certificated that Y03 was virulent to chickens. Meanwhile, we used PCR amplification method to detect 10 antimicrobial resistance genes including abeM, adeB, adeH, adeK, blaapmC, blaOXA-90, catB9, macB, folP, and parE, as well as 14 virulence genes including lpxC, pilO, fimT, ompA, basA, bauA, gspL, csu, pgaC, plc2, tssA, tviB, bap, and vgrG. Whole-genome sequencing analysis revealed that Y03 contained 46 horizontal gene transfer elements, including 11 genomic islands, 30 transposons, and 5 prophages, as well as 518 mutations associated with reduced virulence and 44 mutations resulting in loss of pathogenicity. Furthermore, there were 22 antibiotic targets and 28 lethal mutations on the Y03 chromosome that could be used as potential targets to prevent, control, and treat infections caused by MDR A. baumannii Y03. Therefore, this study contributes to the development of strategies for the prevention, control, and treatment of A. baumannii infections and their spread in chickens.

Acinetobacter baumannii, a Multidrug-Resistant Opportunistic Pathogen in New Habitats: A Systematic Review

In recent years, humanity has begun to face a growing challenge posed by a rise in the prevalence of antibiotic-resistant bacteria. This has resulted in an alarming surge in fatalities and the emergence of increasingly hard-to-manage diseases. Acinetobacter baumannii can be seen as one of these resilient pathogens due to its increasing prevalence in hospitals, its resistance to treatment, and its association with elevated mortality rates. Despite its clinical significance, the scientific understanding of this pathogen in non-hospital settings remains limited. Knowledge of its virulence factors is also lacking. Therefore, in this review, we seek to shed light on the latest research regarding the ecological niches, microbiological traits, and antibiotic resistance profiles of Acinetobacter baumannii. Recent studies have revealed the presence of this bacterium in a growing range of environmental niches, including rivers, treatment plants, and soils. It has also been discovered in diverse food sources such as meat and vegetables, as well as in farm animals and household pets such as dogs and cats. This broader presence of Acinetobacter baumannii, i.e., outside of hospital environments, indicates a significant risk of environmental contamination. As a result, greater levels of awareness and new preventive measures should be promoted to address this potential threat to public health.

Predominance of Acinetobacter pseudolwoffii among Acinetobacter species in domestic animals in the Czech Republic

The aim of this study was to map the spectrum of microorganisms belonging to the genus Acinetobacter in domestic animals with a specific focus on the prevalence of Acinetobacter pseudolwoffii. Additionally, the susceptibility of isolates to antimicrobial agents was determined. In the period from January 1, 2014, to August 31, 2015, a total of 9 544 samples originating from gross lesions and pathological processes of animals exhibiting clinical symptoms of the disease were examined across 41 districts in the Czech Republic. The examinations were carried out using culture methods involving meat-peptone blood agar and Endo agar under aerobic conditions at a temperature of 37 ± 1 °C for 18-24 hours. Isolates were confirmed using molecular phenotypic method MALDI-TOF MS with the MBT Compass Library Revision L 2020 covering 3 239 species/entries (9 607 MSP) from Bruker Daltonics company. Out of the 108 isolates (prevalence 1.13%), 14 species of Acinetobacter spp. were identified, with 5 isolates remaining unclassified as species. A. pseudolwoffii was the predominant species isolated in 25 cases (prevalence 0.26%). Antimicrobial susceptibility was determined for 12 antimicrobials by the disc diffusion method, with A. pseudolwoffii isolates exhibiting the lowest susceptibility to ceftazidime (32%) and co-trimoxazole (60%).

Virulence genes and plasmid replicon profiles of selected β-lactamase-producing Acinetobacter baumannii from orthopaedic patients and the environment in a tertiary referral hospital in Tanzania, East Africa

Acinetobacter baumannii has emerged as an important nosocomial pathogen due to its high resistance to multi-drugs and disinfectants plus its ability to survive in hospital environments. Rectal swabs were collected for screening β-lactamases-producing Acinetobacter baumannii among hospitalized orthopedic patients at a tertiary referral hospital in Tanzania. Swabs were also taken from patients' caretakers, healthcare workers, and the neighboring inanimate environment. A total of 26 confirmed β-lactamases producing Acinetobacter baumannii were isolated, of which 4 representative isolates (two from patients and two from hospital environment) underwent whole-genome sequencing (WGS) to detect sequence types (ST), β-lactamases genes, plasmid replicon types, and virulence genes. All four isolates harbored multiple β-lactamases genes including blaADC-25(3), blaOXA(4), blaCTX-M-15(2) and blaNDM-1(2). Furthermore, isolates harbored virulence genes encoding outer membrane protein (ompA), curli protein (csg), siderophore biosynthesis systems (enterobactin [entABCDEFS, fepABCDG, fes]; yersiniabactin [ybtAEPQSTUX, irp1, irp2, fyuA] and aerobactin [iucABCD, iutA]), transport secretion system type II (T2SS) and type III (T3SS), E. coli common pilus (ecpRABCDE operon), type 1 fimbriae (fim), arylsulfatase (aslA) and adhesions (fedC). Only isolates from patients harbored 4 plasmid replicons each, with the most common plasmid replicons being IncFIA_1; IncY_1 and IncFIB(AP001918)_1. Admitted orthopedic patients and the hospital environment act as a reservoir of multiple β-lactamases producing Acinetobacter baumannii (including those against carbapenems like blaOXA and blaNDM-1) endowed with virulence genes, highlighting the necessity to routinely screening of orthopedic patients with open fractures on admission as well as reinforcing infection prevention and control measures to reduce the dissemination of nosocomial infection within the hospital environment.

Virulence Signatures, Integrons, and Antibiotic Resistance Genes in Bacterial Strains Recovered from Selected Commercial Dairy Products and Fresh Raw Meat

Bacterial species responsible for food infections and intoxication are sometimes carried through the food production and processing. Very few published literatures exist on integrons among antibiotic-resistant staphylococcal strains from foods of animal origin in Gauteng Province, South Africa, hence this study. A total of 720 samples (360 meat and 360 dairies) from a community abattoir of a research farm in South Africa, using conventional bacteriological and molecular methods. Nine (9) bacterial strains, including Bacillus subtilis AYO-123, Acinetobacter baumannii AYO-241, Staphylococcus lentus AYO-352, among others were identified and submitted to GenBank. More bacterial strains were recovered from raw meat (90.5%) than dairy products (9.5%). Resistance was shown (0-100%) to Imipenem, Meropenem, Norfloxacin, Clindamycin, and 22 other antibiotics, without any carbapenem-resistant Acinetobacter baumannii and methicillin/vancomycin-resistant Staphylococcus species (MRSS/VRSS). Virulence genes for fibronectin-binding protein A (FnbA) were predominant (56.24%) followed by the circulating nucleic acids (cna) gene (43.75%). Others were staphylococcal enterotoxin A (sea, 41%), staphylococcal enterotoxin B (seb, 23.5%). Co-presence of sea and seb genes occurred in 11.76% of the isolates, but no coa genes was amplified. Antibiotic resistance genes (ARGs), tetK (70.58%), linA (29.4%), and ermA (11.76%) were detected, but none of the mecA and vat genes was amplified. Class 2 integron (50%) was more predominantly detected than integron 1 (25%), but no Class 3 integron was detected. Bacteria with both the detected virulence and antibiotic resistance genes are of potential risks to human health.

Acinetobacter baumannii from Samples of Commercially Reared Turkeys: Genomic Relationships, Antimicrobial and Biocide Susceptibility

Acinetobacter baumannii is especially known as a cause of nosocomial infections worldwide. It shows intrinsic and acquired resistances to numerous antimicrobial agents, which can render the treatment difficult. In contrast to the situation in human medicine, there are only few studies focusing on A. baumannii among livestock. In this study, we have examined 643 samples from turkeys reared for meat production, including 250 environmental and 393 diagnostic samples, for the presence of A. baumannii. In total, 99 isolates were identified, confirmed to species level via MALDI-TOF-MS and characterised with pulsed-field gel electrophoresis. Antimicrobial and biocide susceptibility was tested by broth microdilution methods. Based on the results, 26 representative isolates were selected and subjected to whole-genome sequencing (WGS). In general, A. baumannii was detected at a very low prevalence, except for a high prevalence of 79.7% in chick-box-papers (n = 118) of one-day-old turkey chicks. The distributions of the minimal inhibitory concentration values were unimodal for the four biocides and for most of the antimicrobial agents tested. WGS revealed 16 Pasteur and 18 Oxford sequence types, including new ones. Core genome MLST highlighted the diversity of most isolates. In conclusion, the isolates detected were highly diverse and still susceptible to many antimicrobial agents.

Investigation of factors related to biofilm formation in Providencia stuartii

Providencia stuartii is one of the Enterobacteriaceae species of medical importance commonly associated with urinary infections, which can also cause other ones, including uncommon ones, such as liver abscess and septic vasculitis. This bacterium stands out in the expression of intrinsic and acquired resistance to antimicrobials. Besides, it uses mechanisms such as biofilm for its persistence in biotic and abiotic environments. This study investigated the cellular hydrophobicity profile of clinical isolates of P. stuartii. It also analyzed genes related to the fimbrial adhesin in this species comparing with other reports described for other bacteria from Enterobacteriaceae family. The investigated isolates to form biofilm and had a practically hydrophilic cell surface profile. However, fimH and mrkD genes were not found in P. stuartii, unlike observed in other species of Enterobacteriaceae. These results show that P. stuartii has specificities regarding its potential for biofilm formation, which makes it difficult to destabilize the infectious process and increases the permanence of this pathogen in hospital units.

Detection of the aadA1 and aac (3)-1V resistance genes in Acinetobacter baumannii

Acinetobacter baumannii is a gram-negative aerobic bacterium that can be found in different environments, such as food, containing vegetables, meat, and fish; moreover, it can be present in soil and freshwater. A. baumannii has globally considered an opportunistic nosocomial bacterium in the healthcare setting contributing to increased morbidity and mortality. The current study aimed to detect the aminoglycoside genes in A. baumannii isolated from different clinical causes. In total, 20 isolates of A. baumannii were obtained from different clinical cases. Bacterial isolate DNA was extracted using a DNA extraction kit. Quantus Fluorometer was used to detect the concentration of the extracted DNA in order to detect the goodness of samples. 1 μl of DNA and 199 μl of diluted QuantiFlour Dye were mixed. After 5 min incubation at room temperature, DNA concentration values were evaluated, and following the initial amplification of the A. baumannii aadA1 gene, 20 μl of PCR product with F and R primers were sent to Sanger sequencing. The results of the antimicrobial susceptibility revealed that A. baumannii isolates were resistant to Gentamicin (95%), Amikacin (90%), and Tobramycin (60%). Molecular investigation of the aadA1 and aac (3)-IV genes exhibited that the aadA1 gene was detected in 15% of the isolates. However, the aac (3)-IV gene was not detected in any of the isolates. The gel electrophoresis revealed that the molecular weight of the aadA1 gene was 490bp. The DNA sequence of the aadA1 gene was conducted in this study, and the results exhibited no mutations in all isolates.

The Spread of Insertion Sequences Element and Transposons in Carbapenem Resistant Acinetobacter baumannii in a Hospital Setting in Southwestern Iran

BACKGROUND

Acinetobacter baumannii is one of the most important hospital pathogenic bacteria that cause infectious diseases. The present study aimed to determine the frequency of carbapenem resistance genes in association with transposable elements and molecular typing of carbapenem-resistant A. baumannii bacteria collected from patients in Shiraz, Iran.

MATERIALS AND METHODS

A total of 170 carbapenem-resistant A. baumannii isolates were obtained from different clinical specimens in two hospitals. The minimum inhibitory concentrations (MIC) of imipenem were determined and the prevalence of OXA Carbapenemases, Metallo-β-lactamases genes, insertion sequences (IS) elements, and transposons were evaluated by the polymerase chain reaction (PCR) method. Finally, molecular typing of the isolates was performed by the Enterobacterial Repetitive Intergenic Consensus-PCR method.

RESULTS

The MICs ranged from 16 to 1,024 µg/mL for imipenem-resistant A. baumannii isolates. Out of the 170 carbapenem resistant A. baumannii isolates, blaOXA-24-like (94, 55.3%) followed by blaOXA-23-like (71, 41.7%) were predominant. In addition, A. baumannii isolates carried blaVIM (71, 41.7%), blaGES (32, 18.8%), blaSPM (4, 2.3%), and blaKPC (1, 0.6%). Moreover, ISAba1 (94.2%) and Tn2009 (39.2%) were the most frequent transposable elements. Furthermore, (71, 44.0%) and (161, 94.7%) of the ISAba1 of the isolates were associated with blaOXA-23 and blaOXA-51 genes, respectively. Besides (3, 1.7%), (1, 0.6%) and (5, 2.9%) of blaOXA-23 were associated with IS18, ISAba4, and ISAba2, respectively. Considering an 80.0% cut off, clusters and four singletons were detected.

CONCLUSION

According to the results, transposable elements played an important role in the development of resistance genes and resistance to carbapenems. The results also indicated carbapenem-resistant A. baumannii bacteria as a public health concern.

The First Saudi Study Investigating the Plasmid-borne Aminoglycoside and Sulfonamide Resistance among Acinetobacter baumannii Clinical Isolates Genotyped by RAPD-PCR: the Declaration of a Novel Allelic Variant Called aac(6')-SL and Three Novel Mutations in the sul1 Gene in the Acinetobacter Plasmid (s)

Background

Acinetobacter baumannii (A. baumannii) is one of the most important nosocomial pathogens responsible for a wide range of infections.

Aim

This study aimed to investigate the existence of the plasmidic genes encoding for aminoglycoside modifying enzymes (AMEs), 16S rRNA methyltransferases (RMT), and the altered dihydropetroate synthase (DHPS) encoded by the sul1 gene among A. baumannii clinical isolates collected from Taif, Kingdom of Saudi Arabia (KSA). The mutations in aac(6ʹ)-Ib and sul1 genes were also investigated.

Methods

Forty A. baumannii clinical isolates were investigated for their susceptibility to ten antibiotics. The plasmid DNA was extracted and screened for nine genes encoding for aminoglycoside resistance in addition to the sul1 gene. The clonal relatedness was determined by random amplified polymorphic DNA (RAPD)-PCR. Mutation in aac(6ʹ)-Ib and the sul1 genes were detected by capillary electrophoresis sequencing (CES).

Results

All isolates were A. baumannii in which 42.5% of them exhibited a high level of aminoglycoside resistance (HLAR). The most prevalent AMEs and RMT encoding genes were aph(3ʹ)-VI, the two aac(6ʹ) gene variants [aac(6ʹ)-Ib and aac(6ʹ)-SL], ant(3ʹʹ)-I, and armA in which 90%, 87.5%, 85%, and 45% of isolates tested positive, respectively. The other investigated aminoglycoside resistant encoding genes, namely aac(3)-II, aac(6ʹ)-II, and rmtB, were not detected. Only 15% of isolates harbored the sul1 gene. RAPD-PCR classified the 40 isolates into three clusters in which cluster II was the main cluster. DNA sequencing revealed that 34.29% (12/35) of isolates tested positive for aac(6ʹ)-Ib were found to harbor a common missense mutation in position 102 indicating a novel allelic variant named aac(6ʹ)-SL. Also, DNA sequencing revealed three missense mutations in the sul1 gene.

Conclusion

This is the first Saudi study to investigate the plasmid borne aminoglycoside and sulfonamide resistance genes among A. baumannii clinical isolates. A novel allelic variant for aac(6ʹ)-Ib was detected in addition to novel mutations in the sul1 gene.

Antibiofilm and antivirulence potential of silver nanoparticles against multidrug-resistant Acinetobacter baumannii

We aimed to isolate Acinetobacter baumannii (A. baumannii) from wound infections, determine their resistance and virulence profile, and assess the impact of Silver nanoparticles (AgNPs) on the bacterial growth, virulence and biofilm-related gene expression. AgNPs were synthesized and characterized using TEM, XRD and FTIR spectroscopy. A. baumannii (n = 200) were isolated and identified. Resistance pattern was determined and virulence genes (afa/draBC, cnf1, cnf2, csgA, cvaC, fimH, fyuA, ibeA, iutA, kpsMT II, PAI, papC, PapG II, III, sfa/focDE and traT) were screened using PCR. Biofilm formation was evaluated using Microtiter plate method. Then, the antimicrobial activity of AgNPs was evaluated by the well-diffusion method, growth kinetics and MIC determination. Inhibition of biofilm formation and the ability to disperse biofilms in exposure to AgNPs were evaluated. The effect of AgNPs on the expression of virulence and biofilm-related genes (bap, OmpA, abaI, csuA/B, A1S_2091, A1S_1510, A1S_0690, A1S_0114) were estimated using QRT-PCR. In vitro infection model for analyzing the antibacterial activity of AgNPs was done using a co-culture infection model of A. baumannii with human fibroblast skin cell line HFF-1 or Vero cell lines. A. baumannii had high level of resistance to antibiotics. Most of the isolates harbored the fimH, afa/draBC, cnf1, csgA and cnf2, and the majority of A. baumannii produced strong biofilms. AgNPs inhibited the growth of A. baumannii efficiently with MIC ranging from 4 to 25 µg/ml. A. baumannii showed a reduced growth rate in the presence of AgNPs. The inhibitory activity and the anti-biofilm activity of AgNPs were more pronounced against the weak biofilm producers. Moreover, AgNPs decreased the expression of kpsMII , afa/draBC,bap, OmpA, and csuA/B genes. The in vitro infection model revealed a significant antibacterial activity of AgNPs against extracellular and intracellular A. baumannii. AgNPs highly interrupted bacterial multiplication and biofilm formation. AgNPs downregulated the transcription level of important virulence and biofilm-related genes. Our findings provide an additional step towards understanding the mechanisms by which sliver nanoparticles interfere with the microbial spread and persistence.

Acinetobacter baumannii as a community foodborne pathogen: Peptide mass fingerprinting analysis, genotypic of biofilm formation and phenotypic pattern of antimicrobial resistance

Acinetobacter baumannii (A. baumannii) is one of the most common Gram-negative pathogens that represent a major threat to human life. Because the prevalence of Multidrug-resistant biofilm-forming A. baumannii is increasing all over the world, this may lead to outbreaks of hospital infections. Nonetheless, the role of raw meat as a reservoir for A. baumannii remains unclear. Here our research was aimed to exhibit the frequency, precise identification, and genotyping of biofilm-related genes as well as antimicrobial resistance of A. baumannii isolates of raw meat specimens. Fifty-five A. baumannii strains were recovered from 220 specimens of different animal meat and then identified by Peptide Mass Fingerprinting Technique (PMFT). All identified isolates were genotyped by the qPCR method for the existence of biofilm-related genes (ompA, bap, blaPER-1, csuE, csgA, and fimH). In addition, the antimicrobial resistance against A. baumannii was detected by the Kirby-Bauer method. Based on our findings, the frequency rate of 55 A. baumannii isolates was 46.55%, 32.50%, 15.00%, and 9.68% of sheep, chicken, cow, and camel raw meat samples, respectively. The PMFT was able to identify all strains by 100%. the percentages of csuE, ompA, bla_PER-1, bap, and csgA genes in biofilm and non-biofilm producer A. baumannii were 72.73%, 60%, 58.2%, 52.74%, and 25.45%, respectively. In contrast, the fimH was not detected in all non-biofilm and biofilm producer strains. The ompA, bap, blaPER-1, csgA were detected only in biofilm-producing A. baumannii isolates. The maximum degree of resistance was observed against amoxicillin/clavulanic acid (89.10%), gentamicin (74.55%), tetracycline (72.73%), ampicillin (65.45%), and tobramycin (52.73%). In conclusion, our investigation demonstrated the high incidence of multi-drug resistant A. baumannii in raw meat samples, with a high existence of biofilm-related virulence genes of ompA, bap, blaPER-1, csgA. Therefore, it has become necessary to take the control measures to limit the development of A. baumannii.

Acinetobacter spp. in food and drinking water - A review

Acinetobacter spp. has emerged as a pathogen of major public health concern due to their increased resistance to antibiotics and their association with a wide range of nosocomial infections, community-acquired infections and war and natural disaster-related infections. It is recognized as a ubiquitous organism however, information about the prevalence of different pathogenic species of this genus in food sources and drinking water is scarce. Since the implementation of molecular techniques, the role of foods as a source of several species, including the Acinetobacter baumannii group, has been elucidated. Multidrug resistance was also detected among Acinetobacter spp. isolated from food products. This highlights the importance of foods as potential sources of dissemination of Acinetobacter spp. between the community and clinical environments and reinforces the need for further investigations on the potential health risks of Acinetobacter spp. as foodborne pathogens. The aim of this review was to summarize the published data on the occurrence of Acinetobacter spp. in different food sources and drinking water. This information should be taken into consideration by those responsible for infection control in hospitals and other healthcare facilities.

Multidrug-resistance in methicillin-resistant Staphylococcus aureus (MRSA) isolated from a subtropical river contaminated by nearby livestock industries

Methicillin-resistant Staphylococcus aureus (MRSA) is a major threat to public health that causes infections in hospitals, communities, and animal husbandry. Livestock-associated MRSA (LA-MRSA) is defined as MRSA possessing staphylococcal cassette chromosome mec (SCCmec) IV or V, both of which lacks the Panton-Valentine leukocidin (PVL) gene but has variable combinations of antimicrobial susceptibility. This study focused on Taiwan's subtropical river basin and the Puzih River, which converges from tributaries flowing through downtown and animal husbandry areas. MRSA was detected at a rate of 7.8% in the tributaries, which was higher than downstream (2.1%). The ratio of multidrug-resistant (MDR) MRSA (n = 30) to total MRSA isolates (n = 39) was 0.769, and most of the MDR MRSA isolates (66.7%, 20/30) exhibited resistance to chloramphenicol, ciprofloxacin, clindamycin, erythromycin, sulfamethoxazole-trimethoprim, and tetracycline. The number of MDR MRSA isolates in the tributaries was also higher than the downstream regions of the Puzih River. The majority of MRSA isolates (64.1%) observed in this study possessed SCCmec type IV without PVL, which is typical for LA-MRSA. Enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) typing aided the discrimination of resistance patterns among SCCmec types. This study highlights the threat to human health posed by the waterborne transmission of MDR LA-MRSA.

ESKAPE Bacteria and Extended-Spectrum-β-Lactamase-Producing Escherichia coli Isolated from Wastewater and Process Water from German Poultry Slaughterhouses

The wastewater of livestock slaughterhouses is considered a source of antimicrobial-resistant bacteria with clinical relevance and may thus be important for their dissemination into the environment. To get an overview of their occurrence and characteristics, we investigated process water (n = 50) from delivery and unclean areas as well as wastewater (n = 32) from the in-house wastewater treatment plants (WWTPs) of two German poultry slaughterhouses (slaughterhouses S1 and S2). The samples were screened for ESKAPE bacteria (Enterococcus spp., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp.) and Escherichia coli Their antimicrobial resistance phenotypes and the presence of extended-spectrum-β-lactamase (ESBL), carbapenemase, and mobilizable colistin resistance genes were determined. Selected ESKAPE bacteria were epidemiologically classified using different molecular typing techniques. At least one of the target species was detected in 87.5% (n = 28/32) of the wastewater samples and 86.0% (n = 43/50) of the process water samples. The vast majority of the recovered isolates (94.9%, n = 448/472) was represented by E. coli (39.4%), the A. calcoaceticus-A. baumannii (ACB) complex (32.4%), S. aureus (12.3%), and K. pneumoniae (10.8%), which were widely distributed in the delivery and unclean areas of the individual slaughterhouses, including their wastewater effluents. Enterobacter spp., Enterococcus spp., and P. aeruginosa were less abundant and made up 5.1% of the isolates. Phenotypic and genotypic analyses revealed that the recovered isolates exhibited diverse resistance phenotypes and β-lactamase genes. In conclusion, wastewater effluents from the investigated poultry slaughterhouses exhibited clinically relevant bacteria (E. coli, methicillin-resistant S. aureus, K. pneumoniae, and species of the ACB and Enterobacter cloacae complexes) that contribute to the dissemination of clinically relevant resistances (i.e., blaCTX-M or blaSHV and mcr-1) in the environment.IMPORTANCE Bacteria from livestock may be opportunistic pathogens and carriers of clinically relevant resistance genes, as many antimicrobials are used in both veterinary and human medicine. They may be released into the environment from wastewater treatment plants (WWTPs), which are influenced by wastewater from slaughterhouses, thereby endangering public health. Moreover, process water that accumulates during the slaughtering of poultry is an important reservoir for livestock-associated multidrug-resistant bacteria and may serve as a vector of transmission to occupationally exposed slaughterhouse employees. Mitigation solutions aimed at the reduction of the bacterial discharge into the production water circuit as well as interventions against their further transmission and dissemination need to be elaborated. Furthermore, the efficacy of in-house WWTPs needs to be questioned. Reliable data on the occurrence and diversity of clinically relevant bacteria within the slaughtering production chain and in the WWTP effluents in Germany will help to assess their impact on public and environmental health.

Drug resistance and virulence traits of Acinetobacter baumannii from Turkey and chicken raw meat

Acinetobacter baumannii (A. baumannii) is a miscellaneous bacterium with ability of extensive antibiotic resistance. A. baumannii strains have also been isolated from animal origins. The objective of our atudy was characterization of A. baumannii antibiotic resistance and virulence traits from turkey and chicken raw meat. Of 576 turkey and 424 chicken specimens during 2017-2019, 200 (120 from turkey and 80 from chicken) isolates were identified as A. baumannii. Virulence factors and antibiotic resistance patterns of A. baumannii were determined using polymerase chain reaction (PCR) technique and Kirby-Bauer test. All the isolates were resistant to tetracycline and cefoxitin and 81 % and 56 % of them produced ESBLs and carbapenemases. Also 74 % of them (34 % from chicken and 40 % from turkey) were multidrug-resistant (MDR) A. baumannii. Colistin and fosfomycin non-susceptibility was detected among 12 % and 10 % of them, respectively. The existence of tetA, dfrA, tetB, bla_oxa-51-like, bla_oxa-23-like, sul1, bla_oxa-24-like, bla_oxa-58-like, fosA3 and mcr-1 genes accounted for 80 %, 71 %, 70.5 %, 66 %, 62 %, 43 %, 34 %, 22 %, 11 % and 13 % of them, repectively. Additionally, predominant virulence factors included the fimH, afa/draBC, sfa/foc DE, cnfI and cnf2 genes. The rate of antibiotic resistance genes and virulence factors was not significantly different between turkey and chicken (p > 0.05). High rate of antibiotic non-susceptibility even against last-line resorts in poultry products is a concern and suggest that animals play a potential role as reservoirs of transmission of MDR A. baumannii.

Genetic Diversity of Imipenem-Resistant Acinetobacter baumannii Infections at an Intensive Care Unit

Introduction. Imipenem-resistant Acinetobacter baumannii (IRAB) represents a major clinical threat. Dissemination in critical care areas necessitates effective action measures including genotyping tools to study the clonality of these strains and trace their origin. The main aim of this study is to assess the genetic relatedness between IRAB isolates in our institution intensive care units (ICU) which are at a particular risk of outbreaks.

Coexistence of genes encoding aminoglycoside modifying enzymes among clinical Acinetobacter baumannii isolates in Ahvaz, Southwest Iran

Aminoglycosides are widely recommended for treatment of Acinetobacter baumannii infections in combination with β-lactams or quinolones. This cross-sectional study was aimed to investigate the coexistence of aminoglycoside modifying enzyme (AME) genes among A. baumannii isolates from clinical samples in Ahvaz, Iran. A total of 85 clinical A. baumannii isolates typed by ERIC-PCR were investigated for the presence of AME genes, including ant(3″)-Ia, aac(6')-Ib, aac(3')-Ia, ant(2″)-Ia, and aph(3')-VIa by PCR. The resistance rates to aminoglycoside agents were evaluated by disk diffusion. In this study, 84 out of 85 A. baumannii isolates were resistant to at least one of the aminoglycosides and harbored at least one AME gene. The most common gene encoding AMEs was aph (3')VIa, followed by aac(3')-Ia, ant(3″)-Ia, ant (2″)-Ia, and aac(6')-Ib. The aminoglycoside-resistant genotypes were completely matched to resistant phenotypes to each one of the aminoglycoside agents. There was a clear association between AME gene types and the phenotype of resistance to aminoglycosides with their ERIC-PCR types. Our findings highlight the coexistence of AME genes and clonal dissemination of multiresistant A. baumannii in hospital setting.

Association Between Biofilm Formation, Structure, and the Expression Levels of Genes Related to biofilm formation and Biofilm-Specific Resistance of Acinetobacter baumannii Strains Isolated from Burn Infection in Ahvaz, Iran

Background

The ability of biofilm formation is an effective way for Acinetobacter baumannii survival from stressed conditions. This present study was aimed to evaluate the association between biofilm formation, structure, the expression levels of genes related to biofilm formation and biofilm-specific resistance of A. baumannii strains isolated from burn infections in Ahvaz, Iran.

Methods

In this study, we assessed the antibiotic susceptibilities, ERIC-PCR typing, capacity of biofilm formation and biofilm structure of 64 A. baumannii isolates collected from burn infections. The distribution and the expression levels of genes involved in the biofilm formation including bap, ompA, abaI, pgaA and csuE were assessed by PCR and real-time PCR, respectively.

Results

We classified A. baumannii isolates in 14 clonal types of ERIC-PCR. Most A. baumannii isolates were resistant to all antibiotics tested except to tigecycline and colistin and had the biofilm formation capability but with different capacities. There was a significant inverse relationship between resistance to antibiotic agents and biofilm formation. The biofilm matrix of 50 strains consisted of polysaccharides together with DNA or proteins. The genes involved in the biofilm formation were detected in both biofilm-forming and non-biofilm forming; however, the expression levels of these genes were higher in biofilm producers compared with non-producers.

Conclusion

The biofilm cells exhibited dramatically decreased susceptibility to antibiotic agents; hence, they have great significance for public health. Therefore, the determination of antibiotic susceptibilities in biofilm and planktonic mode, molecular typing, and capacity of biofilm formation in clinical setting is essential.

Metabolite Profile Differences Among Different Storage Time in Beef Preserved at Low Temperature

Storage temperature influences meat color stability and quality. This study was performed to quality change-associated metabolites profiles using a nontargeted liquid chromatography-mass spectrometry (LC-MS/MS)-based method. Beef longissimus dorsi samples were purchased immediately after slaughter, and then stored at room temperature, 4 °C and 0 °C. Water holding capacity (WHC), moisture content and pH value of the muscle samples were detected. Muscle samples and quality control samples were then prepared for nontargeted LC-MS/MS system, followed by identification of distinct metabolites. Pearson correlation coefficients between metabolites and quality indexes were calculated. Storage reduced pH values of beef, and room temperature and 4 °C displayed the lowest pH value. Moisture content and WHC in beef muscles, especially WHC declined obviously during the first 24 hr. The significantly altered metabolites profiles in meat samples at 0, 3.5, and 7 days during 4 °C storage were identified using LC-MS/MS. Most metabolites showed linear changes during storage (0 to 7 days). Using Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, we found 1(α)-naphthol, urocanic acid, tyramine, guanine, histamine, picolinic acid, 4-hydroxybenzaldehyde, and hypoxanthine were increased, and 2-(S-glutathionyl)acetyl glutathione and glutathione were decreased in beef during 4 °C storage. Correlation analysis showed there were significantly correlations between metabolites and meat quality indexes (WHC, moisture content, and pH). In summary, 1(α)-naphthol, urocanic acid, tyramine, guanine, histamine, picolinic acid, 4-hydroxybenzaldehyde, and hypoxanthine, proved to be harmful to human body, accumulated gradually, especially after 3.5 days during storage at 4 °C. While the contents of beneficial substances, including 2-(S-glutathionyl)acetyl glutathione and glutathione, were decreased, which provided reference for the nutrition guidance of using beef meat.

Prevalence and phenotypic pattern of antibiotic resistance of Acinetobacter baumannii isolated from different types of raw meat samples in Isfahan, Iran

Resistant Acinetobacter baumannii isolates are not only known as opportunistic nosocomial bacteria but may also be regarded as emerging bacterial contaminants in foods of animal origins. The present investigation was done to assess the prevalence and antibiotic resistance pattern of A. baumannii isolated from different types of raw meat samples. One hundred and ninety-four raw meat samples were collected and cultured for A. baumannii isolates. Culture-positive bacteria were also approved using the loop-mediated isothermal amplification (LAMP) technique. The disc diffusion method was used for antibiotic susceptibility testing. Out of 194 raw meat samples, 39 (20.10%) were positive for A. baumannii isolates. Ovine raw meat was the most commonly contaminated samples (32.14%). All of the culture-positive A. baumannii isolates were also approved using the LAMP assay. A. baumannii isolates harboured the highest prevalence of resistance against gentamicin (87.17%), tetracycline (79.48%), erythromycin (74.35%), azithromycin (66.66%), ciprofloxacin (58.97%), trimethoprim/sulphamethoxazole (56.41%) and rifampin (51.28%). The lowest prevalence of resistance was found against imipenem (17.94%) and chloramphenicol (28.20%). Raw bovine, ovine, caprine, camel and poultry meat samples were considered as the important sources of isolates resistant to some of the categories of antimicrobials used to treat infections caused by A. baumannii. Further studies are required to find the exact role of resistant A. baumannii isolates in the dissemination of antibiotic resistance to human population.

Acinetobacter baumannii in sheep, goat, and camel raw meat: virulence and antibiotic resistance pattern

Acinetobacter genus belongs to a group of Gram-negative coccobacillus. These bacteria are isolated from human and animal origins. Antimicrobial agents play a vital role in treating infectious diseases in both humans and animals, and Acinetobacter in this regard is defined as an organism of low virulence. The current study aimed to evaluate antibiotic resistance properties and virulence factor genes in Acinetobacterbaumannii strains isolated from raw animal meat samples. Fresh meat samples from 124 sheep, 162 goat, and 95 camels were randomly collected from Isfahan and Shahrekord cities in Iran. Most A. baumannii strains isolated from sheep meat samples represented fimH (82.35%), aac(3)-IV (78.43%), sul1 (78.43%) and Integron Class I (96.07%) genes. Moreover, more than 50% of A. baumannii strains isolated from sheep samples were resistant to streptomycin (54.90%), gentamycin (74.50%), co-trimoxazole (70.58%), tetracycline (82.35%), and trimethoprim (62.74%). Current findings revealed significant association between the presence of fimH, cnfI, afa/draBC, dfrA1, sulI, aac(3)-IV genes in sheep samples. Furthermore, significant association was observed between fimH, cnfI, sfa/focDE and dfrA1genes in goat meat samples. In sheep meat samples, significant differences were identified in resistance to gentamicin, tetracycline, and co-trimoxazole in comparison with other antibiotics. Finally, there were statistically significant differences between the incidences of resistance to gentamicin, tetracycline, and co-trimoxazole in comparison with other antibiotics in all strains. In conclusion, the presence of virulence factors and antibiotic resistance in A. baumannii strains isolated from animal meat samples showed that animals should be considered as a potential reservoir of multidrug-resistant A. baumannii.

Association of the genes encoding Metallo-β-Lactamase with the presence of integrons among multidrug-resistant clinical isolates of Acinetobacter baumannii

Background: Metallo-β-Lactamases (MBL) are usually encoded on the gene cassettes harboring integrons and disseminated easily among Acinetobacter baumannii isolates. This study was aimed to investigate the association of the genes encoding MBL with the presence of class 1 and 2 integrons among multidrug-resistant (MDR) A.baumannii isolates.

Methodology: A total of 85 non-duplicated A.baumannii isolates were collected and evaluated for the amplification of bla_OXA-51. The presence of genes encoding MBLs, including bla_IMP, bla_VIM, bla_SIM, bla_SPM, bla_GIM, bla_DIM and bla_NDM, as well as intI 1 and intI 2 was evaluated by PCR. Also, the production of MBLs was screened phenotypically by the combination of EDTA and meropenem.

Results: In this study, 77 out of 85 isolates were MDR. Also, 34 isolates had only intI 1, 10 had only intI 2 and 15 had both intI 1 and intI 2. The phenotypic detection of MBLs was found in 30 isolates, among which bla_VIM was as the most common the gene encoding MBL followed by bla_IMP, bla_SPM and bla_SIM. The gene cassettes analysis revealed that class 1 integron is often responsible for transferring the genes harboring MBLs.

Conclusion: The production of MBLs among A. baumannii strains is one of the main mechanisms of resistance to carbapenems. Therefore, the development of inexpensive screening methods for the phenotypic detection of MBLs in clinical laboratories settings is essential. Also, our data revealed that the class 1 integron is often responsible for the dissemination of the MBL genes among A. baumannii isolates.