Use of pulsed-field gel electrophoresis and flagellin gene typing in identifying clonal groups of Campylobacter jejuni and Campylobacter coli in farm and clinical environments

Zoonotic Transmission of Campylobacter jejuni to Caretakers From Sick Pen Calves Carrying a Mixed Population of Strains With and Without Guillain Barré Syndrome-Associated Lipooligosaccharide Loci

Campylobacter jejuni causes foodborne gastroenteritis and may trigger acute autoimmune sequelae including Guillain Barré Syndrome. Onset of neuromuscular paralysis is associated with exposure to C. jejuni lipooligosaccharide (LOS) classes A, B, C, D, and E that mimic and evoke antibodies against gangliosides on myelin and axons of peripheral nerves. Family members managing a Michigan dairy operation reported recurring C. jejuni gastroenteritis. Because dairy cattle are known to shed C. jejuni, we hypothesized that calves in the sick pen were the source of human infections. Fecal samples obtained from twenty-five calves, one dog, and one asymptomatic family member were cultured for Campylobacter. C. jejuni isolates were obtained from thirteen calves and the family member: C. coli from two calves, and C. hyointestinalis from two calves. Some calves had diarrhea; most were clinically normal. Typing of lipooligosaccharide biosynthetic loci showed that eight calf C. jejuni isolates fell into classes A, B, and C. Two calf isolates and the human isolate possessed LOS class E, associated mainly with enteric disease and rarely with Guillain Barré Syndrome. Multi-locus sequence typing, porA and flaA typing, and whole genome comparisons of the thirteen C. jejuni isolates indicated that the three LOS class E strains that included the human isolate were closely related, indicating zoonotic transmission. Whole-genome comparisons revealed that isolates differed in virulence gene content, particularly in loci encoding biosynthesis of surface structures. Family members experienced diarrheal illness repeatedly over 2 years, yet none experienced GBS despite exposure to calves carrying invasive C. jejuni with LOS known to elicit antiganglioside autoantibodies.

Typing of Campylobacter jejuni isolated from poultry on the basis of flaA-RFLP by various restriction enzymes

RFLP analysis of the flagellin (flaA) gene was compared using three different restriction endonucleases i.e DdeI, HinfI and DpnII to determine the genetic diversity among 43 Campylobacter jejuni isolates of poultry origin from the same geographical area. flaA gene was amplified in all the isolates and RFLP analysis showed variations. Dde-based RFLP was found most efficient in discriminating C. jejuni isolates by generating 15 different Dde-RFLP patterns with discriminatory index (D.I) of 0.9258 whereas DpnII produced seven Dpn-RFLP patterns (D.I .= 0.8427). While HinfI enzyme produced only six Hinf-RFLP patterns (D.I .= 0.6977). The discrimination of Dpn-RFLP was comparable to discrimination given by Dde-RFLP analysis, which is generally used to study flaA gene RFLP.

Genome-wide association of functional traits linked with Campylobacter jejuni survival from farm to fork

Campylobacter jejuni is a major cause of bacterial gastroenteritis worldwide, primarily associated with the consumption of contaminated poultry. C. jejuni lineages vary in host range and prevalence in human infection, suggesting differences in survival throughout the poultry processing chain. From 7343 MLST-characterised isolates, we sequenced 600 C. jejuni and C. coli isolates from various stages of poultry processing and clinical cases. A genome-wide association study (GWAS) in C. jejuni ST-21 and ST-45 complexes identified genetic elements over-represented in clinical isolates that increased in frequency throughout the poultry processing chain. Disease-associated SNPs were distinct in these complexes, sometimes organised in haplotype blocks. The function of genes containing associated elements was investigated, demonstrating roles for cj1377c in formate metabolism, nuoK in aerobic survival and oxidative respiration, and cj1368-70 in nucleotide salvage. This work demonstrates the utility of GWAS for investigating transmission in natural zoonotic pathogen populations and provides evidence that major C. jejuni lineages have distinct genotypes associated with survival, within the host specific niche, from farm to fork.

Rising fluoroquinolone resistance in Campylobacter isolated from feedlot cattle in the United States

Antibiotic resistance, particularly to fluoroquinolones and macrolides, in the major foodborne pathogen Campylobacter is considered a serious threat to public health. Although ruminant animals serve as a significant reservoir for Campylobacter, limited information is available on antibiotic-resistant Campylobacter of bovine origin. Here, we analyzed the antimicrobial susceptibilities of 320 C. jejuni and 115 C. coli isolates obtained from feedlot cattle farms in multiple states in the U.S. The results indicate that fluoroquinolone resistance reached to 35.4% in C. jejuni and 74.4% in C. coli, which are significantly higher than those previously reported in the U.S. While all fluoroquinolone resistant (FQ^R) C. coli isolates examined in this study harbored the single Thr-86-Ile mutation in GyrA, FQ^RC. jejuni isolates had other mutations in GyrA in addition to the Thr-86-Ile change. Notably, most of the analyzed FQ^RC. coli isolates had similar PFGE (pulsed field gel electrophoresis) patterns and the same MLST (multilocus sequence typing) sequence type (ST-1068) regardless of their geographic sources and time of isolation, while the analyzed C. jejuni isolates were genetically diverse, suggesting that clonal expansion is involved in dissemination of FQ^RC. coli but not C. jejuni. These findings reveal the rising prevalence of FQ^RCampylobacter in the U.S. and provide novel information on the epidemiology of antibiotic-resistant Campylobacter in the ruminant reservoir.

High-Level Ciprofloxacin-Resistant Campylobacter jejuni Isolates Circulating in Humans and Animals in Incheon, Republic of Korea

Campylobacter jejuni is one of the major causative pathogens of outbreaks or sporadic cases of diarrhoeal diseases worldwide. In this study, we compared the phenotypic and genetic characteristics of C. jejuni isolates of human and food-producing animal origins in Korea and examined the genetic relatedness between these two groups of isolates. Regardless of isolation source, all C. jejuni isolates harboured four virulence genes, cadF, cdtB, ciaB and racR, whereas the wlaN and virB11 genes were more frequently observed in human isolates. Antimicrobial susceptibility testing showed that the majority of C. jejuni isolates displayed high-level resistance to fluoroquinolone (95.2%) or tetracycline (76.2%) antibiotics, and 12.4% of isolates exhibited multidrug resistance (more than three classes of antibiotics tested). Pulsed-field gel electrophoresis (PFGE) of all Campylobacter isolates revealed 51 different SmaI-PFGE patterns and six major clusters containing both human and animal isolates. These results indicate that genetically diverse strains of C. jejuni with antimicrobial drug-resistance and virulence properties have prevailed in Incheon. Nevertheless, some particular populations continue to circulate within the community, providing the evidence for an epidemiological link of C. jejuni infections between humans and food-producing animals. Therefore, the continued monitoring and surveillance of C. jejuni isolates of human and food-producing animal origins are required for public health and food safety.

Comparison of Antimicrobial Susceptibility of Campylobacter Strains Isolated from Food Samples and Patients with Diarrhea

BACKGROUND

Campylobacter infections may lead to serious conditions, including septicemia or other invasive forms of the disease, which require rapid and accurate laboratory diagnosis and subsequently appropriate antimicrobial therapy. The aim of this study was to compare the species distribution and antimicrobial susceptibility pattern of Campylobacter spp. strains isolated from patients and food samples.

METHODS

Biochemical identification was performed on 15 clinical and 30 food isolates of Campylobacter recovered onto Brucella agar containing 5% sheep blood. PCR was carried out to confirm the identity of Campylobacter spp. using primers for cadF, hipO, and asp genes of Campylobacter. To determine antibiotic sensitivity of isolates, Kirby-Bauer assay was carried out using 16 different antibiotic discs.

RESULTS

PCR assay and biochemical tests confirmed all 45 isolates as Campylobacter: 20 (44.44%) as C. jujeni, 10 (22.22%) as C. coli, and 15 (33.34%) as other Campylobacter strains. The maximum resistance was observed to cefotaxime and imipenem (each 86.49%) and the maximum sensitivity to erythromycin (48.65%).

CONCLUSION

C. jujeni is dominant among isolates from clinical and food samples. In addition, tetracycline remains the first-line therapeutic agent against Campylobacter infections in Iran.

Genetic Characterization of Campylobacter Jejuni and C. coli Isolated From Broilers Using flaA PCR-Restriction Fragment Length Polymorphism Method in Shiraz, Southern Iran

Background:

Thermophilic campylobacters, particularly Campylobacter jejuni and C. coli are the main agents of human campylobacteriosis. Campylobacter contaminated chicken products is the most important source of foodborne gastroenteritis. Evaluation of genetic diversity among Campylobacter population is critical for understanding the epidemiology of this bacterium and developing effective control strategies against Campylobacter infections and other related disorders.

Objectives:

The aim of this study was to investigate the polymorphism of thermophilic Campylobacter isolated from broiler fecal samples in Shiraz, southern Iran.

Materials and Methods:

Ninety Campylobacter isolates were recovered from broiler feces using enrichment process followed by cultivation method. The isolates were species typing on the basis of polymerase chain reaction (PCR) detection of 16SrRNA and multiplex PCR for determining two thermophilic species. To evaluate strain diversity of thermophilic Campylobacter isolates, flaA PCR-Restriction Fragment Length Polymorphism (RFLP) was performed using DdeI restriction enzyme.

Results:

All 90 Campylobacter isolates confirmed by m-PCR were successfully typed using flaA-PCR-RFLP. Eleven different types were defined according to flaA-typing method and the RFLP patterns were located at three separate clusters in RFLP image analysis dendrogram.

Conclusions:

Campylobacter jejuni isolates significantly showed more variety than C. coli isolates. A relatively low genetic diversity existed among C. jejuni and C. coli isolated from broilers in Shiraz, southern Iran. In our knowledge, this was the first report of genetic diversity among broiler originated human pathogen thermophilic campylobacters in Shiraz, southern Iran.

Comparison of Campylobacter jejuni pulsotypes isolated from humans and poultry in Split and Dalmatia County, Croatia

Consumption of poultry is considered to be an important source of human infection with Campylobacter. In the period from 2008 to 2010, 50 isolates of Campylobacter jejuni from human faeces were analysed and compared with 61 isolates from poultry by pulsed field gel electrophoresis using SmaI and KpnI. Based on the analysis of SmaI macrorestriction profiles, 86 isolates (77.5 %) were assigned to 15 S clusters: 31 (62 %) from humans and 55 from poultry (90.2 %). Altogether 21 isolates (19 %) exhibited macrorestriction profiles common to both humans and poultry after restriction with SmaI and KpnI. A total of five identical pulsotypes were isolated from both poultry and patients and one of them appeared in eight different locations in the time interval of one year. These results indicate that poultry could be an important source of Campylobacter infection in Split and Dalmatia County which is the biggest County in Croatia and the most important tourist destination.

Prevalence, quantitative load and genetic diversity of Campylobacter spp. in dairy cattle herds in Lithuania

BACKGROUND

Campylobacteriosis is a zoonotic disease, and animals such as poultry, pigs and cattle may act as reservoirs for Campylobacter spp. Cattle shed Campylobacter spp. into the environment and they can act as a reservoir for human infection directly via contact with cattle or their faeces or indirectly by consumption of contaminated food. The aim of this study was to determine the prevalence, the quantitative load and the genetic strain diversity of Campylobacter spp. in dairy cattle of different age groups.

RESULTS

Faecal samples of 200 dairy cattle from three farms in the central part of Lithuania were collected and examined for Campylobacter. Cattle herds of all three farms were Campylobacter spp. positive, with a prevalence ranging from 75% (farm I), 77.5% (farm II) to 83.3% (farm III). Overall, the highest prevalence was detected in calves (86.5%) and heifers (86.2%). In contrast, the lowest Campylobacter prevalence was detectable in dairy cows (60.6%). C. jejuni, C. coli, C. lari and C. fetus subsp. fetus were identified in faecal samples of dairy cattle. C. upsaliensis was not detectable in any sample. The high counts of Campylobacter spp. were observed in faecal material of dairy cattle (average 4.5 log10 cfu/g). The highest numbers of Campylobacter spp. were found in faecal samples from calves (average 5.3 log10 cfu/g), whereas, faecal samples from cows harboured the lowest number of Campylobacter spp. (average 3.7 log10 cfu/g). Genotyping by flaA PCR-RFLP analysis of selected C. jejuni isolates showed that some genotypes were present in all farms and all age groups. However, farm or age specific genotypes were also identified.

CONCLUSIONS

Future studies are needed to investigate risk factors related to the degree of colonisation in cattle. Based on that, possible measures to reduce the colonisation and subsequent shedding of Campylobacter in cattle could be established. It is important to further investigate the epidemiology of Campylobacter in the cattle population in order to assess associated risks to public health.

The role of environmental reservoirs in human campylobacteriosis

Campylobacteriosis is infection caused by the bacteria Campylobacter spp. and is considered a major public health concern. Campylobacter spp. have been identified as one of the most common causative agents of bacterial gastroenteritis. They are typically considered a foodborne pathogen and have been shown to colonise the intestinal mucosa of all food-producing animals. Much emphasis has been placed on controlling the foodborne pathway of exposure, particularly within the poultry industry, however, other environmental sources have been identified as important contributors to human infection. This paper aims to review the current literature on the sources of human exposure to Campylobacter spp. and will cover contaminated poultry, red meat, unpasteurised milk, unwashed fruit and vegetables, compost, wild bird faeces, sewage, surface water, ground water and drinking water. A comparison of current Campylobacter spp. identification methods from environmental samples is also presented. The review of literature suggests that there are multiple and diverse sources for Campylobacter infection. Many environmental sources result in direct human exposure but also in contamination of the food processing industry. This review provides useful information for risk assessment.

Risk factors for campylobacteriosis in two washington state counties with high numbers of dairy farms

Campylobacteriosis is a frequently reported, food-borne, human bacterial disease that can be associated with ruminant reservoirs, although public health messages primarily focus on poultry. In Washington State, the two counties with the highest concentrations of dairy cattle also report the highest incidences of campylobacteriosis. Conditional logistic regression analysis of case-control data from both counties found living or working on a dairy farm (odds ratio [OR], 6.7 [95% confidence interval [CI], 1.7 to 26.4]) and Hispanic ethnicity (OR, 6.4 [95% CI, 3.1 to 13.1]) to have the strongest significant positive associations with campylobacteriosis. When the analysis was restricted to residents of one county, Hispanic ethnicity (OR, 9.3 [95% CI, 3.9 to 22.2]), contact with cattle (OR, 5.0 [95% CI, 1.3 to 19.5]), and pet ownership (OR, 2.6 [95% CI, 1.1 to 6.3]) were found to be independent risk factors for disease. Campylobacter jejuni isolates from human (n = 65), bovine (n = 28), and retail poultry (n = 27) sources from the same counties were compared using multilocus sequence typing. These results indicated that sequence types commonly found in human isolates were also commonly found in bovine isolates. These findings suggest that, in areas with high concentrations of dairy cattle, exposure to dairy cattle may be more important than food-borne exposure to poultry products as a risk for campylobacteriosis.

Antibiotic resistance in bacterial pathogens from retail raw meats and food-producing animals in Japan

To determine the prevalence and antimicrobial susceptibility profiles of Campylobacter, Salmonella, Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), and vancomycin-resistant enterococci (VRE) in food-producing animals and retail raw meats in Japan, raw meat samples as well as food-producing animal feces, cutaneous swabs, and nasal swabs collected from 2004 to 2006 were analyzed. Isolation rates of Campylobacter jejuni and Campylobacter coli, Salmonella, and S. aureus were 34.6% (363 of 1,050), 2.7% (28 of 1,050), and 32.8% (238 of 725), respectively. MRSA was isolated from 3% (9 of 300) of meat samples. No VRE were isolated in this study. Antibiotic resistance in C. coli was higher than that in C. jejuni. Three C. jejuni isolates from a patient with diarrhea in a hospital of Shizuoka Prefecture and two chicken samples that exhibited resistance to ciprofloxacin had identical pulsed-field gel electrophoresis patterns, suggesting that ciprofloxacin-resistant C. jejuni could have been distributed in meat. S. aureus isolates showed the highest level of resistance to ampicillin and tetracycline. Resistance to tetracycline in S. aureus isolates from beef was lower than that seen in isolates from chicken and pork (P < 0.01). This study revealed that the prevalence of MRSA and VRE were low in food-producing animals and retail domestic meats in Japan, although Campylobacter isolates resistant to fluoroquinolone and erythromycin were detected. The occurrence of antimicrobial-resistant pathogens should be monitored continuously to improve the management of the risks associated with antimicrobial drug resistance transferred from food-producing animals to humans.

Phenotypic and genotypic methods for typing Campylobacter jejuni and Campylobacter coli in poultry

Human campylobacteriosis, an infection caused by the bacterium Campylobacter, is a major issue in the United States food system, especially for poultry products. According to the Center for Disease Control, campylobacterosis is estimated to affect over 2.4 million people annually. Campylobacter jejuni and Campylobacter coli are 2 species responsible for the majority of campylobacterosis infections. Phenotypic and genotypic typing methods are often used to discriminate between bacteria at the species and subspecies level and are often used to identify pathogenic organisms, such as C. jejuni and C. coli. This review describes the design as well as advantages and disadvantages for 3 current phenotypic techniques (biotyping, serotyping, and multilocus enzyme electrophoresis) and 6 genotypic techniques (multilocus sequence typing, PCR, pulse-field gel electrophoresis, ribotyping, flagellin typing, and amplified fragment length polymorphisms) for typing pathogenic Campylobacter spp.

Comparison of molecular typing methods useful for detecting clusters of Campylobacter jejuni and C. coli isolates through routine surveillance

Campylobacter spp. may be responsible for unreported outbreaks of food-borne disease. The detection of these outbreaks is made more difficult by the fact that appropriate methods for detecting clusters of Campylobacter have not been well defined. We have compared the characteristics of five molecular typing methods on Campylobacter jejuni and C. coli isolates obtained from human and nonhuman sources during sentinel site surveillance during a 3-year period. Comparative genomic fingerprinting (CGF) appears to be one of the optimal methods for the detection of clusters of cases, and it could be supplemented by the sequencing of the flaA gene short variable region (flaA SVR sequence typing), with or without subsequent multilocus sequence typing (MLST). Different methods may be optimal for uncovering different aspects of source attribution. Finally, the use of several different molecular typing or analysis methods for comparing individuals within a population reveals much more about that population than a single method. Similarly, comparing several different typing methods reveals a great deal about differences in how the methods group individuals within the population.

Antimicrobial resistance and molecular subtyping of Campylobacter jejuni and Campylobacter coli from retail meats

Campylobacter isolates (n = 297; 202 C. jejuni and 95 C. coli isolates) recovered from 2,513 retail meat samples (chicken breasts, ground turkey, ground beef, and pork chops) were examined for antimicrobial susceptibility. The isolates were further analyzed for genetic relatedness by pulsed-field gel electrophoresis (PFGE) using SmaI and KpnI restriction enzymes, and a subset of isolates (n = 174) were subtyped by multilocus sequence typing (MLST). The resistance most frequently observed was that to doxycycline (27.6%), followed by ciprofloxacin (13.8%) and erythromycin (6.4%). All isolates were susceptible to gentamicin and meropenem. C. coli showed higher resistance to doxycycline than did C. jejuni (42.1 versus 20.8%) and lower resistance to ciprofloxacin than did C. jejuni (10.5 versus 15.3%). Erythromycin resistance was only observed in C. coli. PFGE using SmaI plus KpnI digestion generated 168 clusters from 297 isolates: 115 from C. jejuni and 53 from C. coli. MLST revealed 44 sequence types (STs) under 10 clonal complexes from 120 C. jejuni and 27 STs under two clonal complexes from 54 C. coli. There was a positive association between PFGE and STs; however, PFGE showed greater discriminatory power than MLST. Subtyping data did not correlate with antimicrobial resistance phenotypes.

PFGE, Lior serotype, and antimicrobial resistance patterns among Campylobacter jejuni isolated from travelers and US military personnel with acute diarrhea in Thailand, 1998-2003

Background

Campylobacter jejuni is a major cause of gastroenteritis worldwide. In Thailand, several strains of C. jejuni have been isolated and identified as major diarrheal pathogens among adult travelers. To study the epidemiology of C. jejuni in adult travelers and U.S. military personnel with acute diarrhea in Thailand from 1998-2003, strains of C. jejuni were isolated and phenotypically identified, serotyped, tested for antimicrobial susceptibility, and characterized using pulsed-field gel electrophoresis (PFGE).

Results

A total of 312 C. jejuni isolates were obtained from travelers (n = 46) and U.S. military personnel (n = 266) in Thailand who were experiencing acute diarrhea. Nalidixic acid and ciprofloxacin resistance was observed in 94.9% and 93.0% of the isolates, respectively. From 2001-2003, resistance to tetracycline (81.9%), trimethoprim-sulfamethoxazole (57.9%), ampicillin (28.9%), kanamycin (5.9%), sulfisoxazole (3.9%), neomycin (2.0%), and streptomycin (0.7%) was observed. Combined PFGE analysis showed considerable genetic diversity among the C. jejuni isolates; however, four PFGE clusters included isolates from the major Lior serotypes (HL: 36, HL: 11, HL: 5, and HL: 28). The PFGE analysis linked individual C. jejuni clones that were obtained at U.S. military exercises with specific antimicrobial resistance patterns.

Conclusions

In summary, most human C. jejuni isolates from Thailand were multi-resistant to quinolones and tetracycline. PFGE detected spatial and temporal C. jejuni clonality responsible for the common sources of Campylobacter gastroenteritis.

Antimicrobial resistance profiling and molecular subtyping of Campylobacter spp. from processed turkey

BACKGROUND

Campylobacter is a major cause of human disease worldwide and poultry are identified as a significant source of this pathogen. Most disease in humans is associated with the consumption of contaminated poultry or cross-contamination with other foods. The primary drugs of choice for treatment of human campylobacteriosis include erythromycin and ciprofloxacin. In this study, we investigated the prevalence of resistance to erythromycin and ciprofloxacin in Campylobacter isolates recovered from turkey carcasses at two processing plants in the Upper Midwest US. Further analysis of a subset of isolates was carried out to assess resistance and genotype profiles.

RESULTS

Campylobacter isolates from plant A (n = 439; including 196 C. coli and 217 C. jejuni) and plant B (n = 362, including 281 C. coli and 62 C. jejuni) were tested for susceptibility to ciprofloxacin and erythromycin using agar dilution. C. coli were more frequently resistant than C. jejuni in both plants, including resistance to ciprofloxacin (28% of C. jejuni and 63% of C. coli, plant B; and 11% of C. coli, plant A). Erythromycin resistance was low among C. jejuni (0% plant A and 0.3% plant B) compared to C. coli (41%, plant A and 17%, plant B). One hundred resistant and susceptible isolates were selected for additional antimicrobial susceptibility testing, restriction fragment length polymorphism analysis of the flaA gene (fla typing), and pulsed-field gel electrophoresis (PFGE). Fla-PFGE types obtained (n = 37) were associated with a specific plant with the exception of one type that was isolated from both plants. C. coli isolates (n = 65) were grouped into 20 types, while C. jejuni isolates (n = 35) were grouped into 17 types. Most isolates with identical fla-PFGE patterns shared identical or very similar antimicrobial resistance profiles. PFGE alone and composite analysis using fla-PFGE with resistance profiles separated C. jejuni and C. coli into distinct groups.

CONCLUSION

Ciprofloxacin and erythromycin resistance in Campylobacter recovered from processed turkey occurred more frequently among C. coli than C. jejuni. Fla-PFGE types were associated with a particular species, antimicrobial resistance profiles, and a specific plant. Molecular subtyping in this study provided more information about the relationships among antimicrobial-resistant Campylobacter at the processing level.

Genetic and Epidemiological Relationships among Campylobacter Isolates from Humans

84 Campylobacter jejuni isolates from Swedish patients with domestic infection were characterized with pulsed-field gel electrophoresis (PFGE), and the subtype information considered in relation to epidemiological data. Based on pattern combinations from restriction cleavage with SmaI and SalI, 52 different PFGE types were identified. Types with an average pattern similarity of at least 82% and 63% were assembled in groups and clusters, respectively. The 2 largest clusters included 71% of the isolates. The distribution in time varied between different groups and clusters, where some were isolated sporadically during the whole period and others appeared more concentrated in time. Types in 1 cluster were significantly more often isolated in summer than other types in the study. Isolates from children showed lower pattern similarity to other isolates than isolates from adults. Sets of type and time related cases, possibly representing small outbreaks, were identified when indistinguishable PFGE patterns were found in isolates from temporally related cases. Our results indicate that although a large number of genotypes may be found among C. jejuni strains infecting humans, a large proportion of these may be genetically related, and that different genotypes may appear during different seasons and infect individuals of different ages.

Chickens and cattle as sources of sporadic domestically acquired Campylobacter jejuni infections in Finland

A substantial sampling among domestic human campylobacter cases, chicken process lots, and cattle at slaughter was performed during the seasonal peak of human infections. Campylobacter jejuni isolates (n = 419) were subtyped using pulsed-field gel electrophoresis with SmaI, and isolates representing overlapping types (n = 212) were further subtyped using KpnI for restriction. The SmaI/KpnI profiles of 55.4% (97/175) of the human isolates were indistinguishable from those of the chicken or cattle isolates. The overlapping SmaI/KpnI subtypes accounted for 69.8% (30/43) and 15.9% (32/201) of the chicken and cattle isolates, respectively. The occurrence of identical SmaI/KpnI subtypes with human C. jejuni isolates was significantly associated with animal host species (P < 0.001). A temporal association of isolates from chickens and patients was possible in 31.4% (55/175) of the human infections. Besides chickens as sources of C. jejuni in the sporadic infections, the role of cattle appears notable. New approaches to restrict the occurrence of campylobacters in other farm animals may be needed in addition to hygienic measures in chicken production. However, only about half of the human infections were attributable to these sources.

Antimicrobial susceptibility profiles and strain type diversity of Campylobacter jejuni isolates from turkeys in eastern North Carolina

Campylobacter jejuni is one of the most common bacterial causes of human gastroenteritis, and recent findings suggest that turkeys are an important reservoir for this organism. In this study, 80 C. jejuni isolates from eastern North Carolina were characterized for resistance to nine antimicrobials, and strain types were determined by fla typing, pulsed-field gel electrophoresis (PFGE) with SmaI and KpnI, and (for 41 isolates) multilocus sequence typing (MLST). PFGE analysis suggested that many of the isolates (37/40 [ca. 93%]) in a major genomic cluster had DNA that was partially methylated at SmaI sites. Furthermore, 12/40 (30%) of the isolates in this cluster were completely resistant to digestion by KpnI, suggesting methylation at KpnI sites. MLST of 41 isolates identified 10 sequence types (STs), of which 4 were new. Three STs (ST-1839, ST-2132 and the new ST-2934) were predominant and were detected among isolates from different farms. The majority of the isolates (74%) were resistant to three or more antimicrobials, and resistance to ciprofloxacin was common (64%), whereas resistance to the other drug of choice for treatment of human campylobacteriosis, erythromycin, was never encountered. Most (33/34) of the kanamycin-resistant isolates were also resistant to tetracycline; however, only ca. 50% of the tetracycline-resistant isolates were also kanamycin resistant. Isolates with certain antimicrobial resistance profiles had identical or closely related strain types. Overall, the findings suggest dissemination of certain clonal groups of C. jejuni isolates in the turkey production industry of this region.

Use of Antimicrobial Agents in Veterinary Medicine and Implications for Human Health

This review discusses why veterinary usage of antimicrobial agents is wrongly accused of causing a substantial part of the problem of resistant human pathogens. Without doubt, resistant organisms in animals are selected by veterinary antimicrobials. However, these are not a major human health risk either because the role of veterinary usage in selection or propagation is insignificant, or because resistant populations selected by veterinary usage do not pose a substantial risk to human health. Indeed, resistant bacterial infections in humans causing serious quantitative and qualitative health consequences are rarely food-borne and are not the same as those selected by veterinary usage of antimicrobial agents. The available evidence for veterinary selection of resistance, transmission to humans, and subsequent health consequences are reviewed for food-borne zoonotic pathogens. A risk assessment strategy is proposed to quantify potential hazards in order to decide on the most effective risk management strategy.

Comparison of Campylobacter jejuni genotypes from dairy cattle and human sources from the Matamata-Piako District of New Zealand

AIMS

To identify the prevalence and types of Campylobacter jejuni carried by dairy cattle and the extent of overlap of these types with those causing disease in humans.

METHODS AND RESULTS

Faecal samples from 410 dairy cattle were collected from 36 farms in the Matamata-Piako district in New Zealand. Campylobacter jejuni was isolated on all 36 farms, with a prevalence of 51% (95% CI 45-57) in dairy cattle and 65% (95% CI 58-72) in calves. Eighty-nine of these isolates were typed using Penner serotyping and pulsed field gel electrophoresis and were compared with 58 human C. jejuni isolates from people resident within this study area.

CONCLUSIONS

Campylobacter jejuni were found in the faeces of over half of the dairy cows and calves examined. Twenty-one per cent of the bovine isolates and 43% of the human isolates formed indistinguishable clusters of at least one bovine and one human isolate.

SIGNIFICANCE AND IMPACT OF THE STUDY

While a direct link between bovine isolates and human cases was not demonstrated, the finding of indistinguishable genotypes among C. jejuni isolates from bovine and human sources confirms that dairy cows and calves are a potential source of human campylobacteriosis. Barriers to separate bovine faecal material from the general public are therefore important public health measures.

Longitudinal study of the molecular epidemiology of Campylobacter jejuni in cattle on dairy farms

Multilocus sequence typing (MLST), an accurate and phylogenetically robust characterization method for population studies of Campylobacter, was applied to Campylobacter jejuni isolates (n = 297) from the fecal samples of cattle from five dairy farms in Cheshire, United Kingdom, collected throughout 2003. The population dynamics of the C. jejuni strains, as identified by the occurrence of sequence types and clonal complexes, demonstrated variations within and between cattle populations over time. Three clonal lineages have emerged to predominate among the cattle isolates, namely, the ST-61 complex (24.2%), ST-21 complex (23.6%), and ST-42 complex (20.5%). This provided further evidence that the ST-61 clonal complex may present a cattle-adapted C. jejuni genotype. In addition, the ST-42 clonal complex may also represent an important cattle-associated genotype. Strong geographical associations for these genotypes were also found among the farms. This is the first longitudinal study and the largest study to date for C. jejuni involving cattle populations using MLST for accurate strain characterization. This study shows the important associations between cattle and C. jejuni clonal complexes ST-61, ST-21, and ST-42, and it suggests that cattle and/or dairy products are likely to be a source of the human Campylobacter gastroenteritis caused by such genotypes. The reported findings have significant implications for the design of effective intervention strategies for disease control and prevention.

Risk factors for infection with Campylobacter jejuni flaA genotypes

We aimed to explore Campylobacter genotype-specific risk factors in Australia. Isolates collected prospectively from cases recruited into a case-control study were genotyped using flaA restriction fragment-length polymorphism typing (flaA genotyping). Exposure information for cases and controls was collected by telephone interview. Risk factors were examined for major flaA genotypes using logistic and multinomial regression. Five flaA genotypes accounted for 325 of 590 (55%) cases - flaA-6b (n=129), flaA-6 (n=70), flaA-10 (n=48), flaA-2 (n=43), flaA-131 (n=35). In Australia, infections due to flaA-10 and flaA-2 were found to be significantly associated with eating non-poultry meat (beef and ham, respectively) in both case-control and inter-genotype comparisons. All major genotypes apart from flaA-10 were associated with chicken consumption in the case-control comparisons. Based on several clinical criteria, infections due to flaA-2 were more severe than those due to other genotypes. Thus genotype analysis may reveal genotype-specific niches and differences in virulence and transmission routes.

Prevalence and strain diversity of thermophilic campylobacters in cattle, sheep and swine farms

AIMS

To determine prevalence and strain diversity of thermophilic campylobacters in healthy ruminants and swine.

METHODS AND RESULTS

Faecal samples collected from 343 herds (120 sheep, 124 beef cattle, 82 dairy cattle and 17 swine) in the Basque Country were screened in pools for thermophilic campylobacters. Two hundred and three herds were positive (67.1% dairy cattle, 58.9% beef cattle, 55.0% sheep and 52.9% pig), and species-specific PCR identified Campylobacter jejuni in 20.7% of the herds and Campylobacter coli in 6.4%. Campylobacter coli was isolated from the four production systems and was the most prevalent species in swine, where C. jejuni was not found. Other thermophilic campylobacters were found in all production systems. Four hundred and ninety-three animals from 11 positive herds were individually analysed, detecting significantly higher within-herd prevalences in dairy cattle (66.7%) and swine (57.8%) than in sheep (8.8%) or beef cattle (5.4%). flaA PCR-RFLP and pulsed-field gel electrophoresis analysis of a selection of isolates showed high genetic diversity.

CONCLUSIONS

Healthy swine, cattle and sheep are important reservoirs of thermophilic campylobacters of different species and high genetic diversity.

SIGNIFICANCE AND IMPACT OF THE STUDY

Efficient farm-based intervention measures are needed to reduce risk of infection. Non-C. jejuni/C. coli species should be monitored to investigate their significance for infection.

Comparison of virulence-associated in vitro properties of typed strains of Campylobacter jejuni from different sources

Campylobacter jejuni is a major cause of human diarrhoeal disease, but specific virulence mechanisms have not been well defined. This blinded study was undertaken with 40 C. jejuni isolates from different sources to determine their haemolytic, cytotoxic and adhesion and invasion activities towards mammalian cells. The results were correlated with source of isolation and genetic makeup by amplified fragment length polymorphism (AFLP) typing. The isolates had variable degrees of haemolytic activity against rabbit erythrocytes and cytotoxicity towards CaCo-2, HeLa and Vero cells. The data indicated that the haemolytic and cytotoxic activities were due to separate factors. A range of cytotoxicity was exhibited, whereby some strains had no activity against the target cells and others had activity against all three cell lines. Certain strains had activity against CaCo-2 cells but little or no activity against the other cells, while others exhibited the opposite phenotype. The data suggested that the cytotoxicity assay with the different cell lines may have detected more than one cytotoxin. A wide variation between isolates was observed for both adherence and invasion with all three cell lines, yet, overall, the strains showed a significantly greater invasion capacity for CaCo-2. There was no clear relationship between source of isolation or disease manifestation and possession of statistically significantly higher levels of particular virulence-associated factors although, in some cases, a correlation between cytotoxicity and cell invasion was evident. Five AFLP clusters, each representing two to eleven isolates with similar profiles, were observed at the 90 % similarity level. Some AFLP groups contained isolates with a common serotype, but each group had C. jejuni isolates from more than one source with the exception of group IV, which contained only human isolates. Isolates with high cytotoxic activity against CaCo-2 cells were confined to groups I, III and IV and a group of unrelated strains (U). Group II isolates had uniformly low cytotoxicity. Isolates in groups I, V and U were more invasive for CaCo-2 cells than isolates in groups II, III and IV. The strain differences in cytotoxicity or invasion did not correlate with source of isolation.

Characterization of genetically matched isolates of Campylobacter jejuni reveals that mutations in genes involved in flagellar biosynthesis alter the organism's virulence potential

Phenotypic and genotypic evidence suggests that not all Campylobacter jejuni isolates are pathogenic for humans. We hypothesized that differences in gene content or gene expression alter the degree of pathogenicity of C. jejuni isolates. A C. jejuni isolate (Turkey) recovered from a turkey and a second C. jejuni isolate (CS) recovered from a chicken differed in their degrees of in vitro and in vivo virulence. The C. jejuni Turkey isolate invaded INT 407 human epithelial cells and secreted the Cia (Campylobacter invasion antigen) proteins, while the C. jejuni CS isolate was noninvasive for human epithelial cells and did not secrete the Cia proteins. Newborn piglets inoculated with the C. jejuni Turkey isolate developed more severe clinical signs of campylobacteriosis than piglets inoculated with the C. jejuni CS isolate. Additional work revealed that flagellin was not expressed in the C. jejuni CS isolate. Microarray and real-time reverse transcription-PCR analyses revealed that all flagellar class II genes were significantly downregulated in the C. jejuni CS isolate compared to the C. jejuni Turkey isolate. Finally, nucleotide sequencing of the flgR gene revealed the presence of a single residue that was different in the FlgR proteins of the C. jejuni Turkey and CS isolates. Complementation of the C. jejuni CS isolate with a wild-type copy of the flgR gene restored the isolate's motility. Collectively, these findings support the hypothesis that critical differences in gene content or gene expression can alter the pathogenic potential of C. jejuni isolates.

Prevalence of Campylobacter spp. in cattle in Finland and antimicrobial susceptibilities of bovine Campylobacter jejuni strains

The study investigated the prevalence of Campylobacter spp. in Finnish cattle at slaughter and carcass contamination after slaughter. During the period January to December 2003, bovine rectal fecal samples (n=952) and carcass surface samples (n=948) from 12 out of 15 Finnish slaughterhouses were examined. In total, campylobacters were detected in 31.1% of fecal samples and in 3.5% of carcass surface samples. Campylobacter jejuni was isolated from 19.5%, Campylobacter coli from 2.2%, and presumptive Campylobacter hyointestinalis from 10.8% of fecal samples. Campylobacters were detected in 4.4% and 37.4% of the fecal samples examined both by direct culture and by enrichment (n=730), respectively, suggesting a low level of campylobacters in the intestinal content. A slightly increasing trend was observed in the overall prevalence of campylobacters towards the end of summer and autumn. Seventeen different serotypes were detected among the fecal C. jejuni isolates using a set of 25 commercial antisera for serotyping heat-stable antigens (Penner) of C. jejuni by passive hemagglutination. The predominant serotypes, Pen2 and Pen4-complex, were isolated from 52% of the fecal samples. Subtyping by pulsed-field gel electrophoresis (SmaI) yielded 56 and 20 subtypes out of 330 fecal and 70 carcass C. jejuni isolates, respectively. MICs of ampicillin, enrofloxacin, erythromycin, gentamicin, nalidixic acid, and oxytetracycline for 187 C. jejuni isolates were determined using a commercial broth microdilution method. Sixteen (9%) of the isolates were resistant to at least one of the antimicrobials tested. Resistance to nalidixic acid was most commonly detected (6%). No multiresistance was observed.

Dissemination of antimicrobial resistant strains of Campylobacter coli and Campylobacter jejuni among cattle in Washington State and California

The purpose of this study was to investigate the genetic similarity of Campylobacter jejuni and Campylobacter coli with similar antimicrobial resistance phenotypes, isolated from cattle on different farms and at different times, in order to evaluate the possible existence of disseminated antimicrobial resistant clones. PFGE after SmaI and KpnI restriction identified 23 and 16 distinct PFGE patterns among 29 C. jejuni and 66 C. coli isolates, respectively. In C. coli, 51 (77%) of the resistant isolates demonstrated one of the four indistinguishable PFGE patterns, whereas only 24% doxycycline resistant C. jejuni shared one of the two indistinguishable PFGE patterns. The genetic mechanisms of resistance were homogeneous within and between these clonal types. Genetically indistinguishable (clonal) groups of C. coli accounted for most Campylobacter sp. with multiple antimicrobial resistance observed in this study, consistent with a role for clonal dissemination in the epidemiology of resistance in this species.

Clonal complexes of Campylobacter jejuni identified by multilocus sequence typing are reliably predicted by restriction fragment length polymorphism analyses of the flaA gene

Multilocus sequence typing (MLST) has provided important new insights into the population structure of Campylobacter jejuni and is rapidly becoming the gold standard for typing this species. However, the methodology is comparatively costly and slow to perform for the routine surveillance testing of large numbers of isolates required by public health laboratories. Restriction fragment length polymorphism analysis of the flaA gene (RFLP-flaA) and sequencing of the variable region in the fla locus (SVR-fla) were compared to MLST to determine if a low cost alternative could be found that reliably predicts clonal lineage (as determined by MLST). An isolate of C. jejuni from each of 153 patients from New South Wales, Australia, collected sequentially over a period of 30 months from 1999 to 2001 and comprising 40 sequence types (ST) from 15 clonal complexes (CC) was examined. Of 15 CC, 12 were represented by more than one isolate and a predominant RFLP-flaA type was found for 10 (83%). Of these, seven (70%) correctly predicted the predominant MLST CC with a probability of >0.8. Of 40 STs detected, 19 were reported for the first time, 9 of which were represented by more than one isolate. Eight of these were represented by a single RFLP-flaA type. Only two of eight major SVR-fla types were able to predict CC with a probability of >0.8, indicating that flaA-RFLP is a more reliable predictor of CC than SVR-fla and thus offers an alternative to MLST for use in routine surveillance.

Genetic characterization and antibiotic resistance of Campylobacter spp. isolated from poultry and humans in Senegal

AIMS

The main objectives of this study were to investigate the diversity of Campylobacter genotypes circulating in Senegal and to determine the frequency of antibiotic resistance.

METHODS AND RESULTS

Strains of Campylobacter jejuni isolated from poultry (n = 99) and from patients (n = 10) and Campylobacter coli isolated from poultry (n = 72) were subtyped by pulsed-field gel electrophoresis (PFGE). The pulsotypes obtained after digestion by SmaI and KpnI revealed a significant genetic diversity in both species, but without any predominant pulsotypes. However, farm-specific clones were identified in the majority of poultry houses (76.5%). Human and poultry isolates of C. jejuni had common PFGE patterns. High quinolone-resistance rates were observed for C. jejuni (43.4%) and C. coli (48.6%) isolates obtained from poultry.

CONCLUSIONS

The results showed a genetic diversity of Campylobacter between farms indicating multiple sources of infection; but specific clones had the ability to colonize the broiler farms. The antimicrobial resistance patterns were not related to any specific PFGE pattern suggesting that resistance was due to the selective pressure of antibiotic usage. Campylobacter with similar genotypes were circulating in both human and poultry.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study is important for the understanding of the epidemiology of Campylobacter in broiler farms in Senegal. It also emphasizes the need for a more stringent policy in the use of antimicrobial agents in food animals.

PCR-based restriction fragment length polymorphism (RFLP) analysis of Campylobacter jejuni isolates from humans, chickens and dogs in northern Taiwan

Two hundred and twenty strains of Campylobacter jejuni (70 human, 51 canine and 99 chicken strains) were isolated from September 2003 to September 2004 in northern Taiwan. These strains were subtyped by PCR-RFLP analysis of the flagellin (FlaA) gene. On the basis of restrictive digest, six types were identified with AfaI, seven types with MboI and five types with HaeIII. With the combination of these three enzymes, 47 distinct PCR-RFLP patterns were observed-25 each from human and chicken isolates, and 9 from canine isolates. In human strains, the most frequently occurring types were Cj-28 (14.3%), Cj-17 (10%), Cj-16 (8.6%), Cj-37 (7.1%) and Cj-46 (7.1%). In canine strains, the most prevalent types were Cj-1 (33.3%), Cj-26 (19.6%), Cj-3 (15.7%), Cj-2 (9.8%) and Cj-10 (9.8%). In chicken strains, the most frequently occurring types were Cj-46 (40.4%), Cj-29 (9.1%), Cj-45 (7.1%) and Cj-41 (5.1%). The results suggest that poultry is a source, but not the sole source, of C. jejuni infection in humans. Two RFLP types, Cj-17 and Cj-37, frequently occurring in human isolates in this study have also been found to be prevalent in human isolates in Japan, China and the Czech Republic, indicating a possible international clonal spread.

In vitro antimicrobial susceptibility, genetic diversity and prevalence of UDP-glucose 4-epimerase (galE) gene in Campylobacter coli and Campylobacter jejuni from Turkey production facilities

This study evaluated the genetic diversity of multi-drug resistant Campylobacter jejuni (n=44) and C. coli (n=30) isolated from 18 turkey houses. Antimicrobial resistances to ampicillin, ciprofloxacin and nalidixic acid were higher (P<0.05) in C. coli than in C. jejuni strains. PCR analysis indicated that 82% of total isolates tested, including 91% of C. jejuni and 70% of C. coli tested positive for a 496-bp UDP-glucose 4-epimerase (galE) gene. The diversity of isolates was mapped by antibiogram, SmaI-PFGE and flaA-RFLP typing methods using the discriminatory index (DI). RFLP was more suitable in discriminating C. coli (DI=0.895) than PFGE (DI=0.816) or antibiogram profile (DI=0.552), while either PFGE (DI=0.941) or RFLP (DI=0.942) could be used in discriminating C. jejuni strains. The combined PFGE and antibiogram dendrogram had the highest DI for both C. coli (0.910) and C. jejuni (0.968), suggesting that a combination of typing methods is more useful in examining the diverse Campylobacter population on turkey farms.

Colonizing capability of Campylobacter jejuni genotypes from low-prevalence avian species in broiler chickens

Genetic variations in Campylobacter jejuni or host factors result in low prevalence rates among nonchicken poultry species. The objective of this study was to determine the colonizing potential, in broiler chickens, of C. jejuni that was recovered from low-prevalence avian species. Twenty-day-old Campylobacter-negative broiler chicks were inoculated by oral gavage with genetically different primary isolates of C. jejuni recovered from squab, duck, or chicken. Serial sampling and microbiologic testing of ceca were used to determine the level of colonization and the prevalence of positive chickens. All isolates were recovered from chickens by 10 days postinoculation. The C. jejuni strains recovered from challenged birds were genetically identical to the inoculated strains. By 10 days postinoculation, treatment groups inoculated with duck or control chicken isolates were 100% positive. The level of colonization by the squab isolate on day 2 postinoculation was significantly less than the duck or chicken isolates and had not colonized all birds by day 10 postinoculation.

Diversity of flaA genotypes among Campylobacter jejuni isolated from six niche-market poultry species at farm and processing

PCR-restriction fragment length polymorphism of the flagellin (flaA) gene in Campylobacter jejuni was used to determine the relationships of isolates collected at the farm and throughout processing for six niche-market poultry species. This study focused on two specialty chicken products, poussin and free range, and four other specialty products, squab, duck, guinea fowl, and quail. Cloacal and carcass samples were collected from three flocks from each of the six niche species. Three processing plants in California participated in a 2-year investigation. A total of 773 isolates from farm, posttransport, and the processing plants were genotyped, yielding a total of 72 distinct flaA profiles for the six commodities. Genetic diversity of C. jejuni at the farm was greatest for ducks with up to 12 distinct flaA types in two flocks and least for squab 1 flaA type between two farms. For two of the guinea fowl flocks, one free-range flock, two squab flocks, and all three poussin flocks, the flaA types recovered at the prepackage station matched those from the farm. Cross-contamination of poultry carcasses was supported by the observation of flaA types during processing that were not present at the farm level. New C. jejuni strains were detected after transport in ducks, guinea fowl, and free-range chickens. Postpicker, postevisceration, and prewash sampling points in the processing plant yield novel isolates. Duck and free-range chickens were the only species for which strains recovered within the processing plant were also found on the final product. Isolates recovered from squab had 56 to 93% similarity based on the flaA types defined by PCR-restriction fragment length polymorphism profiles. The 26 duck isolates had genetic similarities that ranged from 20 to 90%. Guinea fowl and free-range chickens each had 40 to 65% similarity between isolates. Poussin isolates were 33 to 55% similar to each other, and quail isolates were 46 to 100% similar. Our results continue to emphasize the need to clean processing equipment and posttransport crates in order to decrease cross contamination between flocks. This study also determined that several strains of C. jejuni had unique flaA types that could only be recovered in their host species.

Comparison of Campylobacter isolated from humans and food-producing animals in Japan

AIMS

To compare the antimicrobial resistance, serotypes and flagellin gene types of Campylobacter isolated from humans and food-producing animals and thereby facilitate elucidation of the origin of Campylobacter causing human infection in Japan.

METHODS AND RESULTS

The MIC values of ampicillin, dihydrostreptomycin, gentamicin, erythromycin, oxytetracycline, nalidixic acid and enrofloxacin for Campylobacter isolated from humans (134 isolates), cattle (38 isolates), pigs (69 isolates), layers (84 isolates) and broilers (51 isolates) were compared. The MIC(90) values of ampicillin for Campylobacter jejuni isolates from poultry were higher than those from humans and cattle. Campylobacter coli that was resistant to dihydrostreptomycin and erythromycin was observed at a higher frequency in humans and pigs than in poultry. The restriction fragment profiles of flaA of human, bovine and broiler isolates were analysed by clustering, and the isolates were classified into five clusters. Cluster I contained only human and bovine isolates. Clusters III, IV and V contained human, bovine and broiler isolates.

CONCLUSIONS

Campylobacter isolates from humans included isolates that exhibited characteristics identical to those of the bovine, porcine and poultry isolates.

SIGNIFICANCE AND IMPACT OF THE STUDY

In addition to poultry, cattle and pigs are believed to be sources of campylobacteriosis in Japan.

Genotyping of Campylobacter spp. from retail meats by pulsed-field gel electrophoresis and ribotyping

AIMS

To determine the genetic relatedness of Campylobacter spp. from retail meat products, and compare the discriminatory power of pulsed-field gel electrophoresis (PFGE) and automatic ribotyping.

METHODS AND RESULTS

A total of 378 Campylobacter isolates recovered from 159 raw meats (130 chicken, 25 turkey, three pork and one beef) sampled from 50 retail grocery stores of four supermarket chains in the Maryland suburban area from August 1999 to July 2000 were analysed by PFGE with SmaI, 120 isolates of which were also characterized by ribotyping with PstI using RiboPrinter system. A total of 148 unique PFGE patterns were identified, 91 of which were present in multiple Campylobacter isolates and 24 in multiple meat samples. Nineteen Campylobacter clones with identical PFGE patterns recurred frequently (up to nine times) throughout the sampling period. Comparing ribotyping with PFGE, we identified 44 PFGE patterns and 22 RiboGroups among the 120 isolates tested. Multiple PFGE patterns within one RiboGroup were commonly observed, as well as multiple RiboGroups within one PFGE pattern.

CONCLUSIONS

Although Campylobacter present in retail meats were genetically diverse, certain clones persisted in poultry meats. PFGE had a greater discriminatory power than ribotyping, and the two methods were complementary in genotyping Campylobacter.

SIGNIFICANCE AND IMPACT OF THE STUDY

Genomic DNA fingerprinting of Campylobacter confirmed diverse and recurrent Campylobacter clones in the retail meats, which provides additional data for a better understanding of the epidemiological aspect of Campylobacter infection.

Increasing prevalence of Campylobacter jejuni in feedlot cattle through the feeding period

The prevalence of Campylobacter jejuni in commercial feedlot cattle was monitored throughout the feeding period by repeated bacteriologic culture of feces. Fecal pats (n = 10) in 20 feedlot pens were sampled at 2-weeks interval beginning at entry into the feedlot and continuing until slaughter. The least-squares mean C. jejuni prevalence increased from 1.6% at the first sampling to 61.3% at the final sampling just prior to slaughter. Diverse C. jejuni pulsed-field gel electrophoresis macrorestriction profiles (MRP) were identified among the cattle isolates, but five prevalent MRP and minor variants accounted for >80% of all typed isolates. Chlorination of the water supplied to the water troughs of half of the pens did not affect C. jejuni prevalence in the cattle. Overall, the least-squares mean C. jejuni prevalences were 45.6 and 43.6% in chlorinated and nonchlorinated feedlot pens, respectively. The results of this study demonstrate apparent transmission of C. jejuni among feedlot cattle during the feeding period, unaffected by water chlorination, resulting in a high prevalence of C. jejuni excretion by cattle approaching slaughter.