Epidemiology, Relative Invasive Ability, Molecular Characterization, and Competitive Performance of Campylobacter jejuni Strains in the Chicken Gut

One hundred forty-one Campylobacter jejuni isolates from humans with diarrhea and 100 isolates from retailed poultry meat were differentiated by flaA typing. The bacteria were isolated in a specific geographical area (Dunedin) in New Zealand over a common time period. Twenty nine flaA types were detected, one of which (flaA restriction fragment length polymorphism type 15 [flaA-15]) predominated among isolates from humans (~30% of isolates). This strain was of low prevalence (5% of isolates) among poultry isolates. flaA-15 strains were five to six times more invasive of HEp2 cells in an in vitro assay than a flaA type (flaA-3) that was commonly encountered on poultry meat (23% of isolates) but was seldom associated with human illness (5%). Competitive-exclusion experiments with chickens, utilizing real-time quantitative PCR to measure the population sizes of specific strains representing flaA-15 (T1016) and flaA-3 (Pstau) in digesta, were carried out. These experiments showed that T1016 always outcompeted Pstau in the chicken intestine. Genomic comparisons of T1016 and Pstau were made using DNA microarrays representing the genome of C. jejuni NCTC 11168. These comparisons revealed differences between the strains in the gene content of the Cj1417c-to-Cj1442c region of the genome, which is associated with the formation of capsular polysaccharide. The strains differed in Penner type (T1016, O42; Pstau, O53). It was concluded that poultry meat was at least one source of human infection with C. jejuni, that some Campylobacter strains detected in poultry meat are of higher virulence for humans than others, and that bacterial attributes affecting strain virulence and commensal colonization ability may be linked.     

Differentiation of Campylobacter Populations as Demonstrated by Flagellin Short Variable Region Sequences

The DNA sequence of the flaA short variable region (SVR) was used to analyze a random population of Campylobacter isolates to investigate the weakly clonal population structure of members of the genus. The SVR sequence from 197 strains of C. jejuni and C. coli isolated from humans, bovine, swine, and chickens identified a group of 43 strains containing disparate short variable region sequences compared to the rest of the population. This group contains both C. jejuni and C. coli strains but disproportionately consisted of bovine isolates. Relative synonymous codon usage analysis of the sequences identified two groups: one group typified C. jejuni, and the second group was characteristic for C. coli and the disparate alleles were not clustered. The data show that there is significant differentiation of Campylobacter populations according to the source of the isolate even without considering the disparate isolates. Even though there is significant differentiation of chicken and bovine isolates, the bovine isolates did not show any difference in ability to colonize chickens. It is possible that disparate sequences were obtained through the lateral transfer of DNA from Campylobacter species other than C. jejuni and C. coli. It is evident that recombination within the flaA SVR occurs rapidly. However, the rate of migration between populations appears to limit the distribution of sequences and results in a weakly clonal population structure.     

Distribution and Genetic Profiles of Campylobacter in Commercial Broiler Production from Breeder to Slaughter in Thailand

Poultry and poultry products are commonly considered as the major vehicle of Campylobacter infection in humans worldwide. To reduce the number of human cases, the epidemiology of Campylobacter in poultry must be better understood. Therefore, the objective of the present study was to determine the distribution and genetic relatedness of Campylobacter in the Thai chicken production industry. During June to October 2012, entire broiler production processes (i.e., breeder flock, hatchery, broiler farm and slaughterhouse) of five broiler production chains were investigated chronologically. Representative isolates of C. jejuni from each production stage were characterized by flaA SVR sequencing and multilocus sequence typing (MLST). Amongst 311 selected isolates, 29 flaA SVR alleles and 17 sequence types (STs) were identified. The common clonal complexes (CCs) found in this study were CC-45, CC-353, CC-354 and CC-574. C. jejuni isolated from breeders were distantly related to those isolated from broilers and chicken carcasses, while C. jejuni isolates from the slaughterhouse environment and meat products were similar to those isolated from broiler flocks. Genotypic identification of C. jejuni in slaughterhouses indicated that broilers were the main source of Campylobacter contamination of chicken meat during processing. To effectively reduce Campylobacter in poultry meat products, control and prevention strategies should be aimed at both farm and slaughterhouse levels.     

Typing of Campylobacter jejuni and Campylobacter coli isolated from live broilers and retail broiler meat by flaA-RFLP, MLST, PFGE and REP-PCR

We analyzed 100 Campylobacter spp. isolates (C. jejuni and C. coli) from Grenada, Puerto Rico and Alabama, which were collected from live broilers or retail broiler meat. We analyzed these isolates with four molecular typing methods: restriction fragment length polymorphism of the flaA gene (flaA-RFLP), multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), and automated repetitive extragenic palindromic polymerase chain reaction (REP-PCR) using the DiversiLab system. All methods performed similarly for the typing of C. jejuni and C. coli. The DNA extraction method appears to influence the results obtained with REP-PCR. This method was better for the typing of C. jejuni than C. coli, however both REP-PCR and flaA-RFLP generated types that were indistinguishable between C. jejuni and C. coli and appeared to be random, without any relationship to species, location, or source of isolates. PFGE and MLST generated typing results that had a better correlation with the geographic location of the isolates and showed higher concordance with the Wallace coefficient. The adjusted Rand coefficient did not show higher concordance among the methods, although the PFGE/MLST combination exhibited the highest concordance. PFGE and MLST revealed a better discriminatory power for C. coli isolates than REP-PCR or flaA-RFLP. The use of readily available online tools to calculate the confidence interval of the Simpson's index of diversity and the adjusted Rand and Wallace coefficients helped estimate the discriminatory power of typing methods. Further studies using different C. jejuni and C. coli strains may expand our understanding of the benefits and limitations of each of these typing methods for epidemiological studies of Campylobacter spp.     

Competitive exclusion of heterologous Campylobacter spp. in chicks

Chicken and human isolates of Campylobacter jejuni were used to provide oral challenge of day-old broiler chicks. The isolation ratio of the competing challenge strains was monitored and varied, depending upon the isolates used. A PCR-restriction fragment length polymorphism assay of the flagellin gene (flaA) was used to discriminate between the chick-colonizing isolates. Our observations indicated that the selected C. jejuni colonizers dominated the niche provided by the chicken ceca. Chicken isolates from the flaA type 7 grouping generally had numerical superiority over the human isolates when they were administered in our 1-day-old chick model. Our results suggest that it is possible to use combinations of C. jejuni chicken isolates as a defined bacterial preparation for the competitive exclusion of human-pathogenic C. jejuni in poultry.     

Detection of Cytolethal Distending Toxin Activity and cdt Genes in Campylobacter spp. Isolated from Chicken Carcasses

This study was designed to determine whether isolates from chicken carcasses, the primary source of Campylobacter jejuni and Campylobacter coli in human infections, commonly carry the cdt genes and also whether active cytolethal distending toxin (CDT) is produced by these isolates. Campylobacter spp. were isolated from all 91 fresh chicken carcasses purchased from local supermarkets. Campylobacter spp. were identified on the basis of both biochemical and PCR tests. Of the 105 isolates, 70 (67%) were identified as C. jejuni, and 35 (33%) were identified as C. coli. PCR tests amplified portions of the cdt genes from all 105 isolates. Restriction analysis of PCR products indicated that there appeared to be species-specific differences between the C. jejuni and C. coli cdt genes, but that the restriction patterns of the cdt genes within strains of the same species were almost invariant. Quantitation of active CDT levels produced by the isolates indicated that all C. jejuni strains except four (94%) had mean CDT titers greater than 100. Only one C. jejuni strain appeared to produce no active CDT. C. coli isolates produced little or no toxin. These results confirm the high rate of Campylobacter sp. contamination of fresh chicken carcasses and indicate that cdt genes may be universally present in C. jejuni and C. coli isolates from chicken carcasses.     

Genetic Diversity and Antibiotic Resistance Patterns in a Campylobacter Population Isolated from Poultry Farms in Switzerland

The diversity and genetic interrelation of Campylobacter jejuni and C. coli isolated from Swiss poultry were assessed by three independent typing methods. Samples were derived prior to slaughter from 100 randomly selected flocks (five birds per flock) raised on three different farm types. The observed flock prevalence was 54% in total, with 50% for conventional and 69% for free-range farms. Birds held on farms with a confined roaming area had the lowest prevalence of 37%. Campylobacter isolates were characterized by amplified fragment length polymorphism (AFLP), restriction fragment length polymorphism of flaA PCR fragments (flaA-RFLP), and disk diffusion testing for eight antimicrobial agents that are commonly used in veterinary or human medicine in Switzerland. Analysis of the genotypic results indicates that the Campylobacter population in Swiss poultry is genetically highly diverse. Nevertheless, occasionally, isolates with identical or nearly identical characteristics were isolated from different farms or farm types in different locations. Genetic typing by AFLP and flaA-RFLP was found to be complementary. The majority of isolates (67%) were susceptible to all tested antibiotics; however, single, double, and triple resistances were observed in 7%, 23%, and 2% of the strains, respectively. There was no correlation between genotype and antibiotic resistance. Surprisingly, sulfonamide resistance was frequently found together with streptomycin resistance. Our findings illustrate the results of common genetic exchange in the studied bacterial population.     

Predominant Campylobacter jejuni Sequence Types Persist in Finnish Chicken Production

Consumption and handling of chicken meat are well-known risk factors for acquiring campylobacteriosis. This study aimed to describe the Campylobacter jejuni population in Finnish chickens and to investigate the distribution of C. jejuni genotypes on Finnish chicken farms over a period of several years. We included 89.8% of the total C. jejuni population recovered in Finnish poultry during 2004, 2006, 2007, 2008, and 2012 and used multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) to characterize the 380 isolates. The typing data was combined with isolate information on collection-time and farm of origin. The C. jejuni prevalence in chicken slaughter batches was low (mean 3.0%, CI_95% [1.8%, 4.2%]), and approximately a quarter of Finnish chicken farms delivered at least one positive chicken batch yearly. In general, the C. jejuni population was diverse as represented by a total of 63 sequence types (ST), but certain predominant MLST lineages were identified. ST-45 clonal complex (CC) accounted for 53% of the isolates while ST-21 CC and ST-677 CC covered 11% and 9% of the isolates, respectively. Less than half of the Campylobacter positive farms (40.3%) delivered C. jejuni-contaminated batches in multiple years, but the genotypes (ST and PFGE types) generally varied from year to year. Therefore, no evidence for a persistent C. jejuni source for the colonization of Finnish chickens emerged. Finnish chicken farms are infrequently contaminated with C. jejuni compared to other European Union (EU) countries, making Finland a valuable model for further epidemiological studies of the C. jejuni in poultry flocks.     

Detection of Genetic Diversity in Campylobacter jejuni Isolated from a Commercial Turkey Flock Using flaA Typing,MLST Analysis and Microarray Assay

Campylobacter is genetically highly diverse and undergoes frequent intraspecific recombination. Turkeys have been identified as an important reservoir for Campylobacter jejuni which is of public health significance. The assessment of the genetic diversity among Campylobacter population is critical for our understanding of the epidemiology of this bacterium. The genetic profiles were different according to the molecular typing methods used. The performance of established flaA genotyping, multilocus sequencing typing (MLST) and DNA microarray assay based on the ArrayTube™ technology was evaluated using 14 Campylobacter jejuni isolated from a commercial turkey flock. The flaA typing was performed using PCR-RFLP with restriction enzymes Sau3AI, AluI, a ‘composite’ flaA analysis of AluI and Sau3AI and DdeI. The 14 isolates were differentiated into 3, 5, 7 and 9 genotypes, respectively. Entire flaA gene and short variable region (SVR) sequences were analysed. Sequencing of the entire flaA provided 11 different genotypes. flaA-SVR sequence analysis detected 8 flaA alleles and 4 flaA peptides. One new flaA allele type (528) was identified. MLST analysis represented 10 different sequence types (STs) and 5 clonal complexes (CCs). The microarray assay recognised 14 different genotypes. The discriminatory indices were 0.560, 0.802, 0.857, and 0.912 for flaA-RFLP depending on the used enzymes, 0.890 for flaA-SVR, 0.967 for entire flaA sequencing, 0.945 for MLST and 1.00 for the DNA microarray assay. The flaA gene was genetically stable over 20 passages on blood agar. In conclusion, the different typing tools demonstrated a high level of genetic heterogeneity of Campylobacter jejuni in a turkey flock, indicating that a single flock can be infected by multiple genotypes within one rearing cycle. DNA microarray-based assays had the highest discriminatory power when compared with other genotyping tools.     

Prevalence and Genetic Diversity of Campylobacter spp. in Environmental Water Samples from a 100-Square-Kilometer Predominantly Dairy Farming Area

Water samples were taken systematically from a 100-km² area of mainly dairy farmland in northwestern England and examined for Campylobacter spp. Pulsed-field gel electrophoresis-restriction fragment length polymorphism (PFGE-RFLP) and flaA strain typing of Campylobacter jejuni and Campylobacter coli isolates were done. Data on the water source and the adjacent environment were recorded and examined as explanatory variables. Campylobacter spp. were isolated from 40.5% (n = 119) of the water samples tested. C. jejuni was isolated from 14.3%, C. coli was isolated from 18.5%, and Campylobacter lari was isolated from 4.2% of the samples. Campylobacter hyointestinalis was not isolated from any water source. The difference in prevalence between water types (trough, running, and standing) was significant (P = 0.001). C. jejuni was the species most commonly isolated from trough-water and running-water sources, while C. coli was the most frequently isolated from standing water (P < 0.001). No association was found between the presence of Escherichia coli and that of Campylobacter spp. The final multivariable logistic regression model for Campylobacter spp. included the following variables: water source, soil type, aspect, and amount of cattle fecal material in the environment (fecal pat count). Strain typing demonstrated a diverse population of C. jejuni and the presence of a common C. coli flaA type that was widely distributed throughout the area. Most of the isolates within the common flaA type were discriminated by PFGE-RFLP. These findings suggest a possible role for environmental water in the epidemiology of Campylobacter spp. in a farming environment.     

A newly constructed primer pair for the PCR amplification,cloningand sequencing of the flagellin (<Emphasis Type="Italic">flaA</Emphasis>) gene from isolatesof urease-negative <Emphasis Type="Italic">Campylobacter lari</Emphasis>

A newly constructed primer pair (lari-Af/lari-Ar) designed to generate a product of the flagellin (flaA) gene for urease-negative Campylobacter lari produced a PCR amplicon of about 1700 bp for 16 isolates from 7 seagulls, 5 humans, 3 food animals and one mussel in Japan and Northern Ireland. Nucleotide sequencing and alignments of the flaA amplicons from these isolates demonstrated that the deduced amino acid sequences of the possible open reading frame were 564–572 amino acid residues in length with calculated molecular weights of 58,804 to 59,463. The deduced amino acid sequence similarity analysis strongly suggested that the ORF of the flaA from the 16 isolates showed 70–75% sequence similarities to those of Campylobacter jejuni isolates. The approximate Mr of the flagellin purified from some of the isolates of urease-negative C. lari was estimated to range from 59.6 to 61.8 kDa. Thus, flagellin from the isolates of urease-negative C. lari was shown for the first time to have a molecular size similar to those of C. jejuni and Campylobacter coli isolates, but to be different from the shorter flaA and smaller flagellin of urease-positive thermophilic Campylobacter (UPTC) isolates. Flagellins from C. lari spp., consisting of the two representative taxa of urease-negative C. lari and UPTC, thus show genotypic and phenotypic diversity.     

Heterogeneity in the Infection Biology of Campylobacter jejuni Isolates in Three Infection Models Reveals an Invasive and Virulent Phenotype in a ST21 Isolate from Poultry

Although Campylobacter is the leading cause of bacterial foodborne gastroenteritis in the world and the importance of poultry as a source of infection is well understood we know relatively little about its infection biology in the broiler chicken. Much of what we know about the biology of Campylobacter jejuni is based on infection of inbred or SPF laboratory lines of chickens with a small number of isolates used in most laboratory studies. Recently we have shown that both the host response and microbial ecology of C. jejuni in the broiler chicken varies with both the host-type and significantly between C. jejuni isolates. Here we describe heterogeneity in infection within a panel of C. jejuni isolates in two broiler chicken breeds, human intestinal epithelial cells and the Galleria insect model of virulence. All C. jejuni isolates colonised the chicken caeca, though colonisation of other parts of the gastrointestinal tract varied between isolates. Extra-intestinal spread to the liver varied between isolates and bird breed but a poultry isolate 13126 (sequence type 21) showed the greatest levels of extra-intestinal spread to the liver in both broiler breeds with over 70% of birds of the fast growing breed and 50% of the slower growing breed having C. jejuni in their livers. Crucially 13126 is significantly more invasive than other isolates in human intestinal epithelial cells and gave the highest mortality in the Galleria infection model. Taken together our findings suggest that not only is there considerable heterogeneity in the infection biology of C. jejuni in avian, mammalian and alternative models, but that some isolates have an invasive and virulent phenotype. Isolates with an invasive phenotype would pose a significant risk and increased difficulty in control in chicken production and coupled with the virulent phenotype seen in 13126 could be an increased risk to public health.     

Tracing the source of campylobacteriosis

Campylobacter jejuni is the leading cause of bacterial gastro-enteritis in the developed world. It is thought to infect 2–3 million people a year in the US alone, at a cost to the economy in excess of US $4 billion. C. jejuni is a widespread zoonotic pathogen that is carried by animals farmed for meat and poultry. A connection with contaminated food is recognized, but C. jejuni is also commonly found in wild animals and water sources. Phylogenetic studies have suggested that genotypes pathogenic to humans bear greatest resemblance to non-livestock isolates. Moreover, seasonal variation in campylobacteriosis bears the hallmarks of water-borne disease, and certain outbreaks have been attributed to contamination of drinking water. As a result, the relative importance of these reservoirs to human disease is controversial. We use multilocus sequence typing to genotype 1,231 cases of C. jejuni isolated from patients in Lancashire, England. By modeling the DNA sequence evolution and zoonotic transmission of C. jejuni between host species and the environment, we assign human cases probabilistically to source populations. Our novel population genetics approach reveals that the vast majority (97%) of sporadic disease can be attributed to animals farmed for meat and poultry. Chicken and cattle are the principal sources of C. jejuni pathogenic to humans, whereas wild animal and environmental sources are responsible for just 3% of disease. Our results imply that the primary transmission route is through the food chain, and suggest that incidence could be dramatically reduced by enhanced on-farm biosecurity or preventing food-borne transmission.     

Epidemiological relationships of <Emphasis Type="Italic">Campylobacter jejuni</Emphasis> strains isolated from humans and chickens in South Korea

Thirty-nine human isolates of Campylobacter jejuni obtained from a national university hospital during 2007–2010 and 38 chicken isolates of C. jejuni were collected from poultry farms during 2009–2010 in South Korea were used in this study. Campylobacter genomic species and virulence-associated genes were identified by PCR. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were performed to compare their genetic relationships. All isolates were highly resistant to ciprofloxacin, nalidixic acid, and tetracycline. Of all isolates tested, over 94% contained seven virulence associated genes (flaA, cadF, racR, dnaJ, cdtA, cdtB, and cdtC). All isolates were classified into 39 types by PFGE clustering with 90% similarity. Some chicken isolates were incorporated into some PFGE types of human isolates. MLST analysis for the 39 human isolates and 38 chicken isolates resulted in 14 and 23 sequence types (STs), respectively, of which 10 STs were new. STs overlapped in both chicken and human isolates included ST-21, ST-48, ST-50, ST-51, and ST-354, of which ST-21 was the predominant ST in both human and chicken isolates. Through combined analysis of PFGE types and STs, three chicken isolates were clonally related to the three human isolates associated with food poisoning (VII-ST-48, XXII-ST-354, and XXVIII-ST-51). They were derived from geographically same or distinct districts. Remarkably, clonal spread of food poisoning pathogens between animals and humans was confirmed by population genetic analysis. Consequently, contamination of campylobacters with quinolone resistance and potential virulence genes in poultry production and consumption may increase the risk of infections in humans.     

Bovine Campylobacter jejuni Strains Differ from Human and Chicken Strains in an Analysis of Certain Molecular Genetic Markers

The association of four new genetic markers with a chicken, bovine, or human host was studied among 645 Campylobacter jejuni isolates. The γ-glutamate transpeptidase gene and dmsA were common in human and chicken isolates but uncommon among bovine isolates. In the t test, bovine isolates differed significantly (P < 0.05) from human and chicken isolates.     

Campylobacteriosis in Urban versus Rural Areas: A Case-Case Study Integrated with Molecular Typing to Validate Risk Factors and to Attribute Sources of Infection

Campylobacter infection is a leading cause of bacterial gastroenteritis worldwide, and most clinical cases appear as isolated, sporadic infections for which the source is rarely apparent. From July 2005 to December 2007 we conducted a prospective case-case study of sporadic, domestically-acquired Campylobacter enteritis in rural versus urban areas and a prevalence study of Campylobacter in animal and environmental sources in the Eastern Townships, Quebec. Isolates were typed using Multilocus Sequence Typing (MLST) to reinforce the case-case findings and to assign a source probability estimate for each human isolate. The risk of human campylobacteriosis was 1.89-fold higher in rural than urban areas. Unconditional multivariate logistic regression analysis identified two independent risk factors associated with human Campylobacter infections acquired in rural area: occupational exposure to animals (OR = 10.6, 95% CI: 1.2–91, p = 0.032), and household water coming from a private well (OR = 8.3, 95% CI: 3.4–20.4, p<0.0001). A total of 851 C. jejuni isolates (178 human, 257 chicken, 87 bovine, 266 water, 63 wild bird) were typed using MLST. Among human isolates, the incidence rates of clonal complexes (CC) CC-21, CC-45, and CC-61 were higher in rural than urban areas. MLST-based source attribution analysis indicated that 64.5% of human C. jejuni isolates were attributable to chicken, followed by cattle (25.8%), water (7.4%), and wild birds (2.3%). Chicken was the attributable source for the majority of cases, independent of residential area, sex and age. The increased incidence in rural compared to urban areas was associated with occupational exposure to animals, particularly cattle among those aged 15–34 years, and with consumption of private well water. Both bovine and water exposure appeared to contribute to the seasonal variation in campylobacteriosis. These results provide a basis for developing public education and preventive programs targeting the risk factors identified.     

Genetic Diversity of Campylobacter jejuni Isolates from Farm Animals and the Farm Environment

The genetic diversity of Campylobacter jejuni isolates from farm animals and their environment was investigated by multilocus sequence typing (MLST). A total of 30 genotypes, defined by allelic profiles (assigned to sequence types [STs]), were found in 112 C. jejuni isolates originating in poultry, cattle, sheep, starlings, and slurry. All but two of these genotypes belonged to one of nine C. jejuni clonal complexes previously identified in isolates from human disease and retail food samples and one clonal complex previously associated with an environmental source. There was some evidence for the association of certain clonal complexes with particular farm animals: isolates belonging to the ST-45 complex predominated among poultry isolates but were absent among sheep isolates, while isolates belonging to the ST-61 and ST-42 complexes were predominant among sheep isolates but were absent from the poultry isolates. In contrast, ST-21 complex isolates were distributed among the different isolation sources. Comparison with MLST data from 91 human disease isolates showed small but significant genetic differentiation between the farm and human isolates; however, representatives of six clonal complexes were found in both samples. These data demonstrate that MLST and the clonal complex model can be used to identify and compare the genotypes of C. jejuni isolates from farm animals and the environment with those from retail food and human disease.     

Source Attribution of Human Campylobacter Isolates by MLST and Fla-Typing and Association of Genotypes with Quinolone Resistance

Campylobacteriosis is the most frequent zoonosis in developed countries and various domestic animals can function as reservoir for the main pathogens Campylobacter jejuni and Campylobacter coli. In the present study we compared population structures of 730 C. jejuni and C. coli from human cases, 610 chicken, 159 dog, 360 pig and 23 cattle isolates collected between 2001 and 2012 in Switzerland. All isolates had been typed with multi locus sequence typing (MLST) and flaB-typing and their genotypic resistance to quinolones was determined. We used complementary approaches by testing for differences between isolates from different hosts with the proportion similarity as well as the fixation index and by attributing the source of the human isolates with Bayesian assignment using the software STRUCTURE. Analyses were done with MLST and flaB data in parallel and both typing methods were tested for associations of genotypes with quinolone resistance. Results obtained with MLST and flaB data corresponded remarkably well, both indicating chickens as the main source for human infection for both Campylobacter species. Based on MLST, 70.9% of the human cases were attributed to chickens, 19.3% to cattle, 8.6% to dogs and 1.2% to pigs. Furthermore we found a host independent association between sequence type (ST) and quinolone resistance. The most notable were ST-45, all isolates of which were susceptible, while for ST-464 all were resistant.     

Comparison of Campylobacter Isolates from Poultry and Humans: Association between In Vitro Virulence Properties, Biotypes, and Pulsed-Field Gel Electrophoresis Clusters

The in vitro virulence properties of 197 temporally and geographically related Campylobacter isolates from chicken broilers and humans were compared. Comparisons of the virulence properties associated with genotypes and biotypes were made. All isolates adhered to, and 63% invaded, INT-407 cells, whereas 13% were cytotoxic for CHO cells. CHO cell-cytotoxic extracts were also cytotoxic for INT-407 cells, but the sensitivity for Vero cells was variable. The proportion of isolates demonstrating a high invasiveness potential (>1,000 CFU ml⁻¹) or Vero cell cytotoxicity was significantly higher for human than for poultry isolates. Invasiveness was associated with Campylobacter jejuni isolates of biotypes 1 and 2, whereas CHO and INT-407 cell cytotoxicity was associated with C. jejuni isolates of biotypes 3 and 4. Cytotoxic isolates were also clustered according to pulsed-field gel electrophoresis profiles.     

Detection of Campylobacter jejuni and Salmonella typhimurium in chicken using PCR for virulence factor hipO and invA genes (Saudi Arabia)

Campylobacter jejuni and Salmonella typhimurium are the leading causes of bacterial food contamination in chicken carcasses. Contamination is particularly associated with the slaughtering process. The present study isolated C. jejuni and S. typhimurim from fifty chicken carcass samples, all of which were acquired from different companies in Riyadh, Saudi Arabia. The identification of C. jejuni was performed phenotypically by using a hippurate test and genetically using a polymerase chain reaction with primers for 16S rRNA and hippurate hydrolase (hipO gene). For the dentification of S. typhimurim, a serological Widal test was carried out using serum anti-S. typhimurium antibodies. Strains were genetically detected using invA gene primers. The positive isolates for C. jejuni showed a specific molecular size of 1448 bp for 16S rRNA and 1148 bp for hipO genes. However, the positive isolates of the invA gene exhibited a specific molecular size at 244 bp using polymerase chain reaction (PCR). Comparing sequencing was performed with respect to the invA gene and the BLAST nucleotide isolates that were identified as Salmonella enterica subsp. enterica serovar typhimurium strain ST45, thereby producing a similarity of 100%. The testing identified C. jejuni for hippuricase, GenBank: {"type":"entrez-nucleotide","attrs":{"text":"Z36940.1","term_id":"535805"}}Z36940.1. While many isolates of Salmonella spp. that contained the invA gene were not necessarily identified as S. typhimurim, the limiting factor for the Widal test used antiS. typhimurum antibodies. The multidrug resistance (MDR) of C. jejuni isolates in chickens was compared with the standard C. jejuni strain ATCC 22931. Similarly, S. typhimurium isolates were compared with the standard S. typhimurium strain ATCC 14028.