Prevalence of virulence genes in strains of Campylobacter jejuni isolated from human, bovine and broiler

Molecular Detection of Virulence-Associated Markers in Campylobacter coli and Campylobacter jejuni Isolates From Water, Cattle, and Chicken Faecal Samples From Kajiado County, Kenya

Campylobacter is a zoonotic foodborne pathogen that is often linked with gastroenteritis and other extraintestinal infections in humans. This study is aimed at determining the genetic determinants of virulence-encoding genes responsible for flagellin motility protein A (flaA), Campylobacter adhesion to fibronectin F (cadF), Campylobacter invasion antigen B (ciaB) and cytolethal distending toxin (cdt) A (cdtA) in Campylobacter species. A total of 29 Campylobacter coli isolates (16 from cattle, 9 from chicken, and 4 from water samples) and 74 Campylobacter jejuni isolates (38 from cattle, 30 from chicken, and 6 from water samples) described in an earlier study in Kajiado County, Kenya, were examined for the occurrence of virulence-associated genes using polymerase chain reaction (PCR) and amplicon sequencing. The correlations among virulence genes were analyzed using Pearson's correlation coefficient (R) method. Among the 103 Campylobacter strains screened, 89 were found to harbour a single or multiple virulence gene(s), giving an overall prevalence of 86.4%. C. jejuni strains had the highest prevalence of multivirulence at 64.9% (48/74), compared to C. coli (58.6%, 17/29). The ciaB and flaA genes were the most common virulence genes detected in C. jejuni (81.1% [60/74] and 62.2% [46/74], respectively) and in C. coli (each at 62.1%; 18/29). Campylobacter isolates from chicken harboured the most virulence-encoding genes. C. jejuni strains from chicken and cattle harboured the highest proportions of the cdtA and ciaB genes, respectively. All the C. coli strains from water samples harboured the cadF and flaA genes. The results obtained further revealed a significant positive correlation between cadF and flaA (R = 0.733). C. jejuni and C. coli strains from cattle, chicken, and water harbour virulence markers responsible for motility/colonization, invasion, adherence, and toxin production, evoking their important role in campylobacteriosis development among humans and livestock. The identification of cattle, chicken, and water samples as reservoirs of virulent Campylobacter spp. highlights the possible risk to human health. These data on some virulence genes of Campylobacter will assist food safety and public health officials in formulating policy statements.

Campylobacter jejuni and Campylobacter coli infection, determinants and antimicrobial resistance patterns among under-five children with diarrhea in Amhara National Regional State, Northwest Ethiopia

BACKGROUND

Children with under-five year age disproportionally affected with foodborne illness. Campylobacteriosis is the most common foodborne disease next to Norovirus infection. Macrolides are commonly prescribed as the first line of treatment for Campylobacter gastroenteritis, with fluoroquinolone and tetracycline as secondary options. However, resistance to these alternatives has been reported in various regions worldwide.

OBJECTIVE

To determine the prevalence, associated risk-factors and antimicrobial resistance of Campylobacter jejuni and C. coli among under-five children with diarrhea.

METHODS

Institution-based cross-sectional study was conducted from November, 2022 to April 2023. The study sites were selected using a random sampling technique, while the study subjects were included using a convenient sampling technique. The data were collected using a structured questionnaire. Stool samples were inoculated onto modified charcoal cefoperazone deoxycholate agar and incubated for 48 hours. The suspected colonies were analyzed using matrix-assisted laser desorption ionization-time of flight mass spectrometry to confirm the species. Antimicrobial susceptibility testing was performed using a disc diffusion technique. All potential covariates (independent variables) were analyzed one by one using bivariate logistic regression model to identify candidate variables with P value < 0.25. Multivariable logistic analysis was used to identify potential associated factors using the candidate variables. A p value ≤ 0.05 at a 95% confidence interval was statistically significant.

RESULT

Among the 428 samples, 7.0% (CI: 4.5-9.3) were confirmed Campylobacter species. The prevalence of C. jejuni and C. coli among under-five children was 5.1% (CI: 3.0-7.0) and 1.9% (CI: 0.7-3.3), respectively. C. jejuni (73.3%) was dominant over C. coli (26.7%). The resident, contact with domestic animals, and parents/guardians education level were significantly associated with campylobacteriosis among under-five children. One-third of the Campylobacter isolates (33.3%, 10/30) were resistant to ciprofloxacin and tetracycline whereas 10.0% (3/30) were resistant to erythromycin. Furthermore, 3.3% (1/30) of the Campylobacter were found to be multidrug-resistant.

CONCLUSION

The prevalence of Campylobacter species was 7.0%. The resistance rate of Campylobacter species of ciprofloxacin and tetracycline-resistance strains was 33.3%. Peri-urban residence, contact with domestic animals, and low parental educational statuses were significantly associated factors with increased risk of Campylobacter infection. Continuous surveillance on antimicrobial resistance and health education of personal and environmental hygiene should be implemented in the community.

Isolation, characterization, and antimicrobial resistance profiles of Campylobacter jejuni and Campylobacter coli from raw meat of large livestock in Shahrekord, Iran

Campylobacter spp. genera is one of the most common causes of microbial enteritis worldwide. This study aimed to find out how common Campylobacter organisms were in raw meat from large livestock in Iran, as well as to determine their antibiotic susceptibility profiles. Several 550 fresh, ready-to-eat meat samples were collected from slaughterhouses, butcher shops, and restaurants in the study region. The samples were collected from cattle (n=138), goats (n=102), camels (n=56), and sheep (n=254). Campylobacter spp. were isolated and identified using normal bacteriological methods and polymerase chain reaction (PCR). Genotyping was performed using PCR to identify virulence genes. The disc diffusion technique was used to determine antibiotic susceptibility. The two Campylobacter spp. were found in 84 (15.27%) of the 550 meat samples tested. Cattle and camel samples accounted for the highest (52.38%) and lowest (3.57%) frequencies of Campylobacter spp., respectively. There were significant differences in the prevalence of Campylobacter spp. in cattle (2=43.04 or OR=7.68, CI=3.40-17.30, P<0.01). Campylobacter jejuni and Campylobacter coli accounted for 82.14% (n=69) of Campylobacter spp. isolated from raw meat. While C. jejuni was found in 39.28% of the samples (n=33), C. coli was observed in 42.85% (n=36). Other Campylobacter spp. formed 17.85 % (n=15) of the samples. The most common genotypes observed in C. jejuni bacteria collected from different types of large animal samples were ciaB (100%) and flaA (100%). On the other hand, virbll (7.69%) was the C. jejuni strain found with the lowest incidence in different large animal samples. The most frequent genotypes found in C. coli bacteria were ciaB (100%) and flaA (100%). C. coli isolates dnaJ (0%), wlaN (0%), virbll (0%), and ceuE (0%) were detected with the lowest frequency in several samples from large livestock. Campylobacter spp. isolated from different sample types and sources were 100% sensitive to aphA-3-1 and GM10. The isolates were reported to be resistant to E15 (76.93%), cmeB (69.24%), aadE1 (69.24%), CIP5 (69.24%), and AM10 (69.24%). According to this study, Campylobacter was found in food from factory farming. Consequently, the disease can be transmitted by eating raw or undercooked meat. Therefore, proper handling and preparation of meat meals, as well as hygiene measures from the slaughterhouse to the retailer, are critical in preventing Campylobacter infections.

Genomic and clinical characteristics of campylobacteriosis in Australia

Campylobacter spp. are a common cause of bacterial gastroenteritis in Australia, primarily acquired from contaminated meat. We investigated the relationship between genomic virulence characteristics and the severity of campylobacteriosis, hospitalisation, and other host factors.We recruited 571 campylobacteriosis cases from three Australian states and territories (2018-2019). We collected demographic, health status, risk factors, and self-reported disease data. We whole genome sequenced 422 C. jejuni and 84 C. coli case isolates along with 616 retail meat isolates. We classified case illness severity using a modified Vesikari scoring system, performed phylogenomic analysis, and explored risk factors for hospitalisation and illness severity.On average, cases experienced a 7.5 day diarrhoeal illness with additional symptoms including stomach cramps (87.1 %), fever (75.6 %), and nausea (72.0 %). Cases aged ≥75 years had milder symptoms, lower Vesikari scores, and higher odds of hospitalisation compared to younger cases. Chronic gastrointestinal illnesses also increased odds of hospitalisation. We observed significant diversity among isolates, with 65 C. jejuni and 21 C. coli sequence types. Antimicrobial resistance genes were detected in 20.4 % of isolates, but multidrug resistance was rare (0.04 %). Key virulence genes such as cdtABC (C. jejuni) and cadF were prevalent (>90 % presence) but did not correlate with disease severity or hospitalisation. However, certain genes (e.g. fliK, Cj1136, and Cj1138) appeared to distinguish human C. jejuni cases from food source isolates.Campylobacteriosis generally presents similarly across cases, though some are more severe. Genotypic virulence factors identified in the literature to-date do not predict disease severity but may differentiate human C. jejuni cases from food source isolates. Host factors like age and comorbidities have a greater influence on health outcomes than virulence factors.

Molecular structures mediating adhesion of Campylobacter jejuni to abiotic and biotic surfaces

Microaerophilic, Gram-negative Campylobacter jejuni is the causative agent of campylobacteriosis, the most common bacterial gastrointestinal infection worldwide. Adhesion is the crucial first step in both infection or interaction with the host and biofilm formation, and is a critical factor for bacterial persistence. Here we describe the proteins and other surface structures that promote adhesion to various surfaces, including abiotic surfaces, microorganisms, and animal and human hosts. In addition, we provide insight into the distribution of adhesion proteins among strains from different ecological niches and highlight unexplored proteins involved in C. jejuni adhesion. Protein-protein, protein-glycan, and glycan-glycan interactions are involved in C. jejuni adhesion, with different factors contributing to adhesion to varying degrees under different circumstances. As adhesion is essential for survival and persistence, it represents an interesting target for C. jejuni control. Knowledge of the adhesion process is incomplete, as different molecular and functional aspects have been studied for different structures involved in adhesion. Therefore, it is important to strive for an integration of different approaches to obtain a clearer picture of the adhesion process on different surfaces and to consider the involvement of proteins, glycoconjugates, and polysaccharides and their cooperation.

Campylobacter spp. isolated from poultry in Iran: Antibiotic resistance profiles, virulence genes, and molecular mechanisms

Campylobacter spp. genera is one of the most common causes of microbial enteritis worldwide. The objective of this work was to investigate the antimicrobial resistance (AMR) patterns, virulence genes, and genetic variation of thermophilic Campylobacter species collected from chicken meat samples in Iran. A total of 255 meat specimens were taken and transferred to the laboratory. Culture methods were utilized to identify the Campylobacter genus, and PCR and sequencing were performed to confirm the organisms. Antimicrobial susceptibility evaluation was performed using broth microdilution for six antimicrobials [ciprofloxacin (CIP), nalidixic acid (NAL), sitafloxacin (SIT), erythromycin (ERY), tetracycline (TET), and gentamicin (GEN)]. By using PCR, AMR and virulence genes were detected. The detection rate of Campylobacter spp. was 64 (25.09%) out of 255 meat samples, with C. jejuni and C. coli accounting for 41 (64.06%) and 14 (21.87%), respectively. Other Campylobacter isolates accounted for 14.06% of the total (nine samples). The antibiotic susceptibility of all Campylobacter isolates was tested using six antibiotics, and all (100%) were resistant to CIP and NAL. However, TET resistance was observed in 93.9% and 83.3% of C. jejuni and C. coli isolates, respectively. Four (8.2%) C. jejuni isolates were multidrug-resistant (MDR), while none of the C. coli isolates were MDR. Two of the four MDR isolates were resistant to CIP, NAL, TET, and ERY, whereas the other two isolates were resistant to CIP, NAL, TET, and GEN. The values of the Minimum Inhibitory Concentration (MIC) were as follows: CIP, 64-256 μg/ml; NAL, 128-512 μg/ml; TET, 2-1024 μg/ml; SIT, 0.25-1 μg/ml; ERY, 1-32 μg/ml; and GEN, 1-256 μg/ml. recR, dnaJ, cdtC, cdtB, cdtA, flaA, ciaB, cadF, and pidA were discovered in more than 50% of C. jejuni isolates, although wlaN, virbll, cgtB, and ceuE were found in <50%. flaA, cadF, pidA, and ciaB were discovered in more than 50% of the C. coli samples, whereas recR, cdtC, cdtB, cdtA, and cgtB were found in less than half. For C. coli, the percentages for wlaN, dnaJ, virbll, and ceuE were all zero. The results of this study show Campylobacter isolates obtained from poultry have higher resistance to quinolones and TET, pathogenicity potential, and varied genotypes.

Wildlife Waterfowl as a Source of Pathogenic Campylobacter Strains

BACKGROUND

The aim of the study was to determine whether free-living birds belonging to game species whose meat is used for human consumption can constitute a reservoir of pathogenic Campylobacter strains, spreading these bacteria to other hosts or directly contributing to human infection.

METHODS

A total of 91 cloacal swabs were taken from different species of wildlife waterfowl to estimate the Campylobacter prevalence, the genetic diversity of the isolates, and the presence of virulence genes and to evaluate the antimicrobial resistance.

RESULTS

The presence of Campylobacter spp. was confirmed in 32.9% of samples. Based on flaA-SVR sequencing, a total of 19 different alleles among the tested Campylobacter isolates were revealed. The virulence genes involved in adhesion were detected at high frequencies among Campylobacter isolates regardless of the host species. The highest resistance was observed for ciprofloxacin. The resistance rates to erythromycin and tetracycline were observed at the same level.

CONCLUSIONS

These results suggest that wildlife waterfowl belonging to game species may constitute a reservoir of Campylobacter, spreading these bacteria to other hosts or directly contributing to human disease. The high distribution of virulence-associated genes among wildlife waterfowl Campylobacter isolates make them potentially able to induce infection in humans.

Characterization of Campylobacter jejuni isolated from dogs and humans using flaA-SVR fragment sequencing in Ismailia, Egypt

INTRODUCTION

Dogs are known as asymptomatic carriers forCampylobacter jejuni. The number of pet dogs is increasing in Egypt in the last decade.

OBJECTIVE

This study aimed to investigate the frequency ofC. jejuni infection in dogs and humans, molecular typing of associated virulence genes, and flaA-SVR gene using sequencing.

METHODOLOGY

152 unpaired fecal swabs from dogs (n = 72) and humans (80) were examined for the presence of C. jejuni and Campylobacter 23S rRNA, and the pathogenicity genes including mapA genes, virB11, flaA, wlaN, iam, tetO, and aadA genes. Sequencing of the flaA- amplicon was also performed for the representative isolates.

RESULTS

The isolation rate ofC. jejuni was 20.8 % and 31.2 %, respectively in dogs and humans, and all isolates were tested positive for 23S rRNA and mapA genes. C. jejuni harbor virB11 and wlaN (20 %, 0%), iam (10 %, 20 %), tetO and aadA1 (40 %, both), and flaA (40 %, 20 %) in human and dog strains, respectively. The flaA-SVR sequences revealed high identity between human and dog isolates (94.8 %), but revealed 18 substitutions in the amino acid sequence, and showed that the dog and human C. jejuni were close to strains isolated from human and poultry sources.

CONCLUSION

this study demonstrated the comparative sequence analysis ofC. jejuni flaA-SVR fragment in dogs and some Egyptians, which indicated a high identity percentage between them. The results suggest that C. jejuni reservoirs dogs is an alarming public health concern and effective hygienic measures are necessary for house-holding pets to prevent C. jejuni zoonosis in Egypt's community.

Antimicrobial Resistance Profiles, Virulence Genes, and Genetic Diversity of Thermophilic Campylobacter Species Isolated From a Layer Poultry Farm in Korea

Thermophilic Campylobacter species are among the major etiologies of bacterial enteritis globally. This study aimed at assessing the antimicrobial resistance (AMR) profiles, virulence genes, and genetic diversity of thermophilic Campylobacter species isolated from a layer poultry farm in South Korea. One hundred fifty-three chicken feces were collected from two layer poultry farms in Gangneung, South Korea. The Campylobacter species were isolated by cultural techniques, while PCR and sequencing were used for species confirmation. Antimicrobial susceptibility testing for six antimicrobials [ciprofloxacin (CIP), nalidixic acid (NAL), sitafloxacin (SIT), erythromycin (ERY), tetracycline (TET), and gentamicin (GEN)] was carried out by broth microdilution. Three AMR and nine virulence genes were screened by PCR. Genotyping was performed by flaA-restriction fragment length polymorphism (RFLP) and multilocus sequence typing (MLST). Of the 153 samples, Campylobacter spp. were detected in 55 (35.9%), with Campylobacter jejuni and Campylobacter coli being 49 (89.1%) and six (10.9%), respectively. High-level resistance was observed for CIP (100%), NAL (100%), and TET (C. jejuni, 93.9%; C. coli: 83.3%). No resistance was observed for SIT. The missense mutation (C257T) in gyrA gene was confirmed by sequencing, while the tet(O) gene was similar to known sequences in GenBank. The rate of multidrug-resistant (MDR) strains was 8.2%, and they all belonged to C. jejuni. All Campylobacter isolates possessed five virulence genes (cdtB, cstII, flaA, cadF, and dnaJ), but none possessed ggt, while the rates for other genes (csrA, ciaB, and pldA) ranged between 33.3 and 95.9%. The flaA-RFLP yielded 26 flaA types (C. jejuni: 21 and C. coli: five), while the MLST showed 10 sequence types (STs) for C. jejuni and three STs for C. coli, with CC-607 (STs 3611) and CC-460 (ST-460) being predominant. Among the 10 STs of C. jejuni, three were newly assigned. The findings of this study highlight the increased resistance to quinolones and TET, the virulence potential, and the diverse genotypes among Campylobacter strains isolated from the layer poultry farm.

Prevalence, Characterization, and Control of Campylobacter jejuni Isolated from Raw Milk, Cheese, and Human Stool Samples in Beni-Suef Governorate, Egypt

Our study aimed to determine the prevalence of Campylobacter jejuni isolated from raw milk, cheese, and human stool samples in Beni-Suef Governorate, Egypt, and to characterize the antibiotic resistance profile and virulence genes of the isolates. An additional objective was to evaluate the effectiveness of cinnamon oil and Lactobacillus acidophilus La5 for controlling C. jejuni in cheese. A total of 200 samples of raw milk and dairy products, including 50 samples of raw milk and 150 samples of three different types of cheese were used. Fifty-three human stool samples were also collected. The samples were tested for the presence of C. jejuni using culture and molecular methods. Campylobacter spp. were isolated from 9.5% (19/200) of the raw milk and cheese samples. The highest prevalence was observed in milk samples (18%), followed by Kareish cheese (14%) and Talaga cheese (6%). In contrast, C. jejuni was not found in any of the Feta cheese samples. Of the human stool samples, 21 (39.6%) were positive for C. jejuni. Of the isolates, 60-90% were highly resistant to the antimicrobial agents tested, that is, nalidixic acid, ciprofloxacin, and tetracycline. Virulent cadF and cdtA genes were detected in all isolates. As milk and dairy products are important sources of contamination, reducing the level of C. jejuni in them will lower the risk to consumers. We showed that L. acidophilus La5 was able to control C. jejuni in Kareish cheese, but cinnamon oil was less effective.

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.

Molecular determination of genetic diversity among Campylobacter jejuni and Campylobacter coli isolated from milk, water, and meat samples using enterobacterial repetitive intergenic consensus PCR (ERIC-PCR)

Consumption of contaminated meat, milk, and water are among the major routes of human campylobacteriosis. This study aimed to determined the genetic diversity of C. coli and C. jejuni isolated from meat, milk, and water samples collected from different locations. From the 376 samples (meat = 248, cow milk = 72, and water = 56) collected, a total of 1238 presumptive Campylobacter isolates were recovered and the presence of the genus Campylobacter were detected in 402 isolates, and from which, 85 and 67 isolates were identified asC. jejuni and C. coli respectively. Of which, 71 isolates identified as C. coli (n = 35) and C. jejuni (n = 36) were randomly selected from meat, milk, and water samples and were genotyped using enterobacterial repetitive intergenic consensus PCR (ERIC-PCR). The digital images of the ERIC-PCR genotype were analyzed by GelJ v.2.0 software. The diversity and similarity of the isolates were assessed via an unweighted-pair group method using average linkages clustering algorithm. The results showed that the 36 C. jejuni strains separated into 29 ERIC-genotypes and 4 clusters while the 35 C. coli were delineated into 29 ERIC-genotypes and 6 clusters. The study revealed the genetic diversity among C. coli and C. jejuni strains recovered from different matrices characterized by Gelj.

Pathogenicity of Campylobacter strains of poultry and human origin from Poland

The aim of this study was to determine the pathogenic markers associated with Campylobacter infection in humans. A total of 104 Campylobacter isolates obtained from poultry and humans were examined for the presence of nine virulence genes and their ability to adhere to, invade and produce cytotoxin were defined using HeLa cells. The diversity of the Campylobacter spp. isolates was studied based on sequencing of the SVR-region of flaA gene. Altogether 45 flaA-SVR alleles were identified among 104 Campylobacter isolates of poultry and human origin. All Campylobacter isolates possessed flaA, cadF and racR genes involved in adherence. Accordingly, all poultry and human isolates exhibited adherence towards HeLa cells at mean levels of 0.95% and 0.82% of starting viable inoculum, respectively. The genes involved in invasion (iam and pldA) and cytotoxin production (cdtA, cdtB and cdtC) were also widely distributed among the human and poultry Campylobacter isolates. Significantly higher invasiveness was observed for poultry isolates (mean level of 0.002% of starting bacterial inoculum) compared to human isolates (0.0005%). Interestingly the iam gene, associated with invasion, was more common in human (100%) than poultry (84%) isolates, and the poultry isolates lacking the iam gene showed a marked reduction in their ability to invade HeLa cells. Moreover, virB11 was present in 22% of the poultry and 70.4% of the human isolates. Strains lacking virB11 showed a slight reduction in invasion, however in the absence of iam even the poultry isolates containing virB11 were unable to invade HeLa cells. The mean cytotoxicity of Campylobacter isolates from poultry and human was 26.7% and 38.7%, respectively. Strains missing both the cdtB and cdtC genes were non-cytotoxic compared to strains containing all three cdtABC genes, which were the most cytotoxic among the C. jejuni and C. coli isolates from both sources. No cytotoxic effect was observed in only 4% of poultry and 5.6% of human isolates.

Prevalence, molecular detection, and virulence gene profiles of Campylobacter species in humans and foods of animal origin

BACKGROUND AND AIM

Campylobacteriosis is one of the most well-characterized bacterial foodborne infections worldwide that arise chiefly due to the consumption of foods of animal origin such as poultry, milk, and their products. The disease is caused by numerous species within the genus Campylobacter, but Campylobacter jejuni is the most commonly isolated species from established cases of human campylobacteriosis. This study was conducted to determine the prevalence and virulence of Campylobacter isolates from human, chicken, and milk and milk products in Egypt.

MATERIALS AND METHODS

A total of 1299 samples (547 chicken intestine and liver, 647 milk and milk products, and 105 human stool) were collected and microbiologically investigated, confirmed by multiplex polymerase chain reaction (PCR) targeting the 23S rRNA, hipO, and glyA genes specific for Campylobacter spp., C. jejuni, and Campylobacter Coli, respectively, followed by virulence genes (Campylobacter adhesion to fibronectin F [cadF] and cdtB) detection using PCR.

RESULTS

About 38.09%, 37.84%, and 8.5% of human stool, chicken, and milk and milk product samples, respectively, were bacteriologically positive, with a total of 302 Campylobacter isolates. All isolates were molecularly confirmed as Campylobacter spp. (100%) where 285 isolates (94.37%) were identified as C. jejuni and 17 isolates (5.62%) as C. coli. Regarding the virulence pattern, all isolates (100%) carried cadF gene while cytolethal distending toxin B gene was definite in 284/302 isolates (94%), concisely, 282/285 (98.94%) C. jejuni isolates, and in 2/17 (11.76%) C. coli isolates.

CONCLUSION

The widespread presence of these highly virulent Campylobacter, especially C. jejuni, proofs the urgent need for the implementation of stringent control, public health, and food protection strategies to protect consumers from this zoonotic pathogen. The availability of information about pathogen virulence will enable enhanced local policy drafting by food safety and public health officials.

Virulence Traits of Inpatient Campylobacter jejuni Isolates, and a Transcriptomic Approach to Identify Potential Genes Maintaining Intracellular Survival

There are still major gaps in our understanding of the bacterial factors that influence the outcomes of human Campylobacter jejuni infection. The aim of this study was to compare the virulence-associated features of 192 human C. jejuni strains isolated from hospitalized patients with diarrhoea (150/192, 78.1%), bloody diarrhoea (23/192, 11.9%), gastroenteritis (3/192, 1.6%), ulcerative colitis (3/192, 1.5%), and stomach ache (2/192, 1.0%). Traits were analysed with genotypic and phenotypic methods, including PCR and extracellular matrix protein (ECMP) binding, adhesion, and invasion capacities. Results were studied alongside patient symptoms, but no distinct links with them could be determined. Since the capacity of C. jejuni to invade host epithelial cells is one of its most enigmatic attributes, a high throughput transcriptomic analysis was performed in the third hour of internalization with a C. jejuni strain originally isolated from bloody diarrhoea. Characteristic groups of genes were significantly upregulated, outlining a survival strategy of internalized C. jejuni comprising genes related (1) to oxidative stress; (2) to a protective sheath formed by the capsule, LOS, N-, and O- glycosylation systems; (3) to dynamic metabolic activity supported by different translocases and the membrane-integrated component of the flagellar apparatus; and (4) to hitherto unknown genes.

The Wild Mouse (Micromys minutus): Reservoir of a Novel Campylobacter jejuni Strain

Campylobacter jejuni is one of the most common zoonotic pathogens worldwide. Although the main sources of human C. jejuni infection are livestock, wildlife can also affect C. jejuni transmission in humans. However, it remains unclear whether wild mice harbor C. jejuni and are involved in the "environment-wildlife-livestock-human" transmission cycle of C. jejuni in humans. Here, we characterized C. jejuni from wild mice and identified genetic traces of wild mouse-derived C. jejuni in other hosts using a traditional approach, along with comparative genomics. We captured 115 wild mice (49 Mus musculus and 66 Micromys minutus) without any clinical symptoms from 22 sesame fields in Korea over 2 years. Among them, M. minutus were typically caught in remote areas of human houses and C. jejuni was solely isolated from M. minutus (42/66, 63.6%). We identified a single clone (MLST ST-8388) in all 42 C. jejuni isolates, which had not been previously reported, and all isolates had the same virulence/survival-factor profile, except for the plasmid-mediated virB11 gene. No isolates exhibited antibiotic resistance, either in phenotypic and genetic terms. Comparative-genomic analysis and MST revealed that C. jejuni derived from M. minutus (strain SCJK2) was not genetically related to those derived from other sources (registered in the NCBI genome database and PubMLST database). Therefore, we hypothesize that C. jejuni from M. minutus is a normal component of the gut flora following adaptation to the gastro-intestinal tract. Furthermore, M. minutus-derived C. jejuni had different ancestral lineages from those derived from other sources, and there was a low chance of C. jejuni transmission from M. minutus to humans/livestock because of their habitat. In conclusion, M. minutus may be a potential reservoir for a novel C. jejuni, which is genetically different from those of other sources, but may not be involved in the transmission of C. jejuni to other hosts, including humans and livestock. This study could form the basis for further studies focused on understanding the transmission cycle of C. jejuni, as well as other zoonotic pathogens originating from wild mice.

Prevalence, Virulence, and Antimicrobial Resistance of Campylobacter spp. in Raw Milk, Beef, and Pork Meat in Northern Poland

The purpose of this study was to determine whether raw milk, unpasteurized dairy products, pork, and beef available for sale in the Kujawsko-Pomorskie and Wielkopolska regions in Poland are contaminated with Campylobacter spp. bacteria and may be a potential source of infection. For isolated strains, antibiotic susceptibility and the presence of genes responsible for virulence were examined. Material for research included 1058 food samples collected between 2014 and 2018 with 454 samples of raw milk and unpasteurized dairy products (milk from vending machines, milk from owners of dairy cows, cheese, milk cream) and 604 samples of raw meat (pork, beef). The results indicated that 9.3% of the samples were positive for Campylobacter spp., and Campylobacter jejuni was predominant in this study. Campylobacter bacteria was not found in milk collected from vending machines, as well as cheese and milk cream samples. Campylobacter was noted in 12.7% of beef samples, 11.8% of raw milk purchased from individual suppliers, and 10.9% of pork samples. Resistance to erythromycin (2.0%), azithromycin (3.1%), gentamicin (4.1%), tetracycline (65.3%), and ciprofloxacin (71.4%) was determined using the disc diffusion method. Furthermore, the prevalence of racR, sodB, csrA, virB11, cdtB, iam, and wlaN genes were examined using the PCR method. The sodB, csrA, and cdtB genes exhibited the highest detection rate, but none of the genes were identified in 100% of the isolates. Statistically significant differences between the presence of virulence marker genes, including for iam, racR, and csrA markers, were noted among different sources of the isolates. Differences in the distribution of iam, wlaN, and virB11 were also shown between C. jejuni and C. coli strains. As a result of the analysis, it has been concluded that unpasteurized milk, beef, and pork could be a sources of Campylobacter pathogens. Moreover, this study revealed virulent properties of Campylobacter isolated from such food products and high resistance rates to fluoroquinolones, which may represent difficulties in campylobacteriosis treatment.

Dairy Cattle, a Potential Reservoir of Human Campylobacteriosis: Epidemiological and Molecular Characterization of Campylobacter jejuni From Cattle Farms

Campylobacter jejuni is a major foodborne pathogen that is increasingly found worldwide and that is transmitted to humans through meat or dairy products. A detailed understanding of the prevalence and characteristics of C. jejuni in dairy cattle farms, which are likely to become sources of contamination, is imperative and is currently lacking. In this study, a total of 295 dairy cattle farm samples from 15 farms (24 visits) in Korea were collected. C. jejuni prevalence at the farm level was 60% (9/15) and at the animal level was 23.8% (68/266). Using the multivariable generalized estimating equation (GEE) model based on farm-environmental factors, we estimated that a high density of cattle and average environmental temperature (7 days prior to sampling) below 24°C affects the presence and survival of C. jejuni in the farm environment. Cattle isolates, together with C. jejuni from other sources (chicken and human), were genetically characterized based on analysis of 10 virulence and survival genes. A total of 19 virulence profile types were identified, with type 01 carrying eight genes (all except hcp and virB11) being the most prevalent. The prevalence of virB11 and hcp was significantly higher in isolates from cattle than in those from other sources (p < 0.05). Multilocus sequence typing (MLST) of C. jejuni isolates from three different sources mainly clustered in the CC-21 and CC-48. Within the CC-21 and CC-48 clusters, cattle isolates shared an indistinguishable pattern with human isolates according to pulsed-field gel electrophoresis (PFGE) and flaA-restriction fragment length polymorphism (RFLP) typing. This suggests that CC-21 and CC-48 C. jejuni from dairy cattle are genetically related to clinical campylobacteriosis isolates. In conclusion, the farm environment influences the presence and survival of C. jejuni, which may play an important role in cycles of cattle re-infection, and dairy cattle represent potential reservoirs of human campylobacteriosis. Thus, environmental management practices could be implemented on cattle farms to reduce the shedding of C. jejuni from cattle, subsequently reducing the potential risk of the spread of cattle-derived C. jejuni to humans through the food chain.

Presence of genes associated with adhesion, invasion, and toxin production in Campylobacter jejuni isolates and effect of temperature on their expression

The aims of this study were to evaluate the presence of genes associated with adhesion (cadF), invasion (ciaB), and cytotoxin production (cdtA, cdtB, and cdtC) among Campylobacter jejuni isolates from a poultry slaughterhouse and to investigate the effect of different temperatures on the expression of these virulence-associated genes. A total of 88 C. jejuni isolates from cecum, liver, chicken carcasses, chilled water, and scalding water were submitted to PCR assay for detection of virulence genes. Representative isolates were selected for gene expression evaluation at 37 and 42 °C, according to their virulence gene profile and genotypic typing. All C. jejuni isolates carried the five virulence-associated genes, which play an important role in the infectious process. Differential gene expression by RT-qPCR was observed among C. jejuni isolates at 37 and 42 °C. The expression levels at 37 °C showed upregulation of the ciaB, cdtA, cdtB, and cdtC genes in five isolates, with the exception of ciaB for isolate 4. At 42 °C, upregulation was observed for ciaB and cdtC, cdtA and cdtB, and cadF in four, three, and two isolates, respectively. The C. jejuni isolates expressed the virulence genes evaluated, and the expression is gene- and isolate-dependent and varied according the temperature.

Antibiotic Sensitivity Profiling and Virulence Potential of Campylobacter jejuni Isolates from Estuarine Water in the Eastern Cape Province, South Africa

Campylobacter jejuni (CJ) is a zoonotic microbe and a major causative organism of diarrheal infection in humans that often has its functional characteristics inactivated in stressed conditions. The current study assessed the correlation between recovered CJ and water quality parameters and the drug sensitivity patterns of the pathogen to frontline antibiotics in human and veterinary medicine. Water samples (n = 244) from rivers/estuarines were collected from April⁻September 2016, and physicochemical conditions were recorded on-site. CJ was isolated from the samples using standard microbiological methods and subjected to sensitivity testing to 10 antibiotics. Mean CJ counts were between 1 and 5 logs (CFU/mL). Ninety-five isolates confirmed as CJ by PCR showed varying rates of resistance. Sensitivity testing showed resistance to tetracycline (100%), azithromycin (92%), clindamycin (84.2%), clarithromycin and doxycycline (80%), ciprofloxacin (77.8%), vancomycin (70.5%), erythromycin (70%), metronidazole (36.8%) and nalidixic acid (30.5%). Virulence encoding genes were detected in the majority 80/95, 84.2%) of the confirmed isolates from cdtB; 60/95 (63.2%) from cstII; 49/95 (51.6%) from cadF; 45/95 (47.4%) from clpP; 30/95 (31.6%) from htrB, and 0/95 (0%) from csrA. A multiple resistance cmeABC active efflux pump system was present in 69/95 (72.6) isolates. The presence of CJ was positively correlated with temperature (r = 0.17), pH (r = 0.02), dissolved oxygen (r = 0.31), and turbidity (r = 0.23) but negatively correlated with salinity (r = −0.39) and conductivity (r = −0.28). The detection of multidrug resistant CJ strains from estuarine water and the differential gene expressions they possess indicates a potential hazard to humans. Moreover, the negative correlation between the presence of the pathogen and physicochemical parameters such as salinity indicates possible complementary expression of stress tolerance response mechanisms by wild-type CJ strains.

Genotyping and antibiotic resistance of thermophilic Campylobacter isolated from chicken and pig meat in Vietnam

BACKGROUND

Campylobacter species are recognized as the most common cause of foodborne bacterial gastroenteritis in humans. In this study nine Campylobacter strains isolated from chicken meat and pork in Hanoi, Vietnam, were characterized using molecular methods and tested for antibiotic resistance.

RESULTS

The nine isolates (eight C. jejuni and one C. coli) were identified by multiplex PCR, and tested for the presence or absence of 29 gene loci associated with virulence, lipooligosaccharide (LOS) biosynthesis and further functions. flaA typing, multilocus sequence typing and microarray assay investigation showed a high degree of genetic diversity among these isolates. In all isolates motility genes (flaA, flaB, flhA, fliM), colonization associated genes (cadF, docB), toxin production genes (cdtA, cdtB, secD, secF), and the LOS biosynthesis gene pglB were detected. Eight gene loci (fliY, virB11, Cje1278, Cj1434c, Cj1138, Cj1438c, Cj1440c, Cj1136) could not be detected by PCR. A differing presence of the gene loci ciaB (22.2 %), Cje1280 (77.8 %), docC (66.7 %), and cgtB (55.6 %) was found. iamA, cdtC, and the type 6 secretion system were present in all C. jejuni isolates but not in C. coli. flaA typing resulted in five different genotypes within C. jejuni, MLST classified the isolates into seven sequence types (ST-5155, ST-6736, ST-2837, ST-4395, ST-5799, ST-4099 and ST-860). The microarray assay analysis showed a high genetic diversity within Vietnamese Campylobacter isolates which resulted in eight different types for C. jejuni. Antibiotic susceptibility profiles showed that all isolates were sensitive to gentamicin and most isolates (88.8 %) were sensitive to chloramphenicol, erythromycin and streptomycin. Resistance rates to nalidixic acid, tetracycline and ciprofloxacin were 88.9, 77.8 and 66.7 %, respectively.

CONCLUSIONS

To the best of our knowledge, this study is the first report that shows high genetic diversity and remarkable antibiotic resistance of Campylobacter strains isolated from meat in Vietnam which can be considered of high public health significance. These preliminary data show that large scale screenings are justified to assess the relevance of Campylobacter infections on human health in Vietnam.

A transferable plasticity region in Campylobacter coli allows isolates of an otherwise non-glycolytic food-borne pathogen to catabolize glucose

Thermophilic Campylobacter species colonize the intestine of agricultural and domestic animals commensally but cause severe gastroenteritis in humans. In contrast to other enteropathogenic bacteria, Campylobacter has been considered to be non-glycolytic, a metabolic property originally used for their taxonomic classification. Contrary to this dogma, we demonstrate that several Campylobacter coli strains are able to utilize glucose as a growth substrate. Isotopologue profiling experiments with (13) C-labeled glucose suggested that these strains catabolize glucose via the pentose phosphate and Entner-Doudoroff (ED) pathways and use glucose efficiently for de novo synthesis of amino acids and cell surface carbohydrates. Whole genome sequencing of glycolytic C. coli isolates identified a genomic island located within a ribosomal RNA gene cluster that encodes for all ED pathway enzymes and a glucose permease. We could show in vitro that a non-glycolytic C. coli strain could acquire glycolytic activity through natural transformation with chromosomal DNA of C. coli and C. jejuni subsp. doylei strains possessing the ED pathway encoding plasticity region. These results reveal for the first time the ability of a Campylobacter species to catabolize glucose and provide new insights into how genetic macrodiversity through intra- and interspecies gene transfer expand the metabolic capacity of this food-borne pathogen.

The role of probiotics in the inhibition of Campylobacter jejuni colonization and virulence attenuation

Campylobacter jejuni is one of the most common bacterial causes of human gastroenterocolitis worldwide, leading to diarrhea and other serious post-infectious complications. Probiotics form an attractive alternative intervention strategy for most of the enteric infections. However, the role of probiotics in C. jejuni infections requires detailed investigations in order to delineate the probiotic strains that are effective against C. jejuni. Although there are several biological mechanisms involved in the inhibition of pathogenic bacterial growth, the strains of probiotics and their mechanisms of actions through which they combat C. jejuni invasion have not been studied in greater detail. This mini review details the factors that are involved in the colonization and establishment of C. jejuni infection, with special reference to chickens, the natural host of C. jejuni, and the studies that have investigated the effect of different probiotic strains against C. jejuni colonization and growth. This review has collated the studies conducted using probiotics to inhibit C. jejuni colonization and growth to date to provide a collective knowledge about the role of probiotics as an alternative intervention strategy for campylobacteriosis.