Antimicrobial resistance and plasmid profiles of Campylobacter jejuni and Campylobacter coli from human and animal sources

AIMS: The purpose of this study was to determine the susceptibility of Campylobacter jejuni and Campylobacter coli isolates to antimicrobial agents and to investigate the presence of plasmid DNA. METHODS AND RESULTS: A total of 15 clinical isolates from children faeces, and 29 animal isolates of Campylobacter jejuni (n=22) and Campylobacter coli (n=22) were tested for susceptibility to 9 antimicrobial agents using a disc diffusion method, and screened for the presence of plasmid DNA by agarose gel electrophoresis. Of the 44 isolates, 56.8% were resistant to sulphonamide, 25% to norfloxacin, 18.2% to erythromicin, ciprofloxacin and ampicillin, and 13.6% to tetracycline. All isolates were susceptible to gentamicin, chloramphenicol and cefotaxime. Plasmids were detected in one Camp. jejuni (4.54%) strain isolated from sheep and in six (27.27%) Camp. coli strains isolated from rhesus monkey(3), swine(2), and poultry(1) with sizes ranging from 3.4 to 50 kb. CONCLUSIONS: The majority of the human isolates were susceptible to antibiotics commonly used for the treatment of campylobacteriosis. SIGNIFICANCE AND IMPACT OF THE STUDY: The origin and spread of Campylobacter resistance to antibiotics are discussed, with particular respect to the current situation in Brazil.     

Antimicrobial resistance profiling and DNA Amplification Fingerprinting (DAF) of thermophilic Campylobacter spp. in human, poultry and porcine samples from the Cork region of Ireland

Antimicrobial resistance (R) typing and DNA Amplification Fingerprinting (DAF) of a random collection of 84 Irish thermophilic Campylobacter isolates is described. The collection included human, veterinary (porcine) and poultry isolates cultured between 1996 and 1998 in the Cork region of Ireland. Biochemical and molecular methods were used to identify Campylobacter jejuni and Camp. coli. Many of these isolates were simultaneously resistant to several common antimicrobial agents. In particular, resistance to ampicillin, spectinomycin, sulphafurazole and tetracycline was common. A total of 74 DAF profiles was identified among the study collection, showing a high degree of diversity. Dendrogram analysis of the DNA patterns identified three main clusters at the 50% similarity level, which included two clusters of Camp. coli and a third containing a mixture of Camp. jejuni and Camp. coli.     

Resistance to quinolones in Campylobacter jejuni and Campylobacter coli from Danish broilers at farm level

AIMS: To investigate the prevalence of quinolone resistance among Campylobacter jejuni and Camp. coli isolates from Danish poultry at the farm level, as well as for the whole country. METHODS AND RESULTS: Data and isolates were collected from a national surveillance of Campylobacter in poultry. Quinolone resistance was investigated by determination of minimum inhibitory concentration (MIC) to nalidixic acid and enrofloxacin. Among Camp. jejuni and Camp. coli combined, 7.5% were resistant to nalidixic acid. Quinolone resistance varied considerably from farm to farm, with 0% on some farms and almost 100% on others, but the resistance was evenly distributed geographically. With respect to isolates from farms where resistance was detected, quinolone resistance was higher among Camp. coli (28.7%) than among Camp. jejuni (11.3%). PFGE typing of quinolone-resistant and quinolone-susceptible isolates from four farms indicated that certain resistant isolates belonged to specific clones that were able to persist on the farms during several rotations, even in the absence of selective pressure. Some clones were present and repeatedly isolated in both a quinolone-susceptible and quinolone-resistant variant. CONCLUSIONS: Overall, quinolone resistance among Campylobacter isolates from Danish broilers was 7.5% in 1998 and 1999; it was higher among Camp. coli than Camp. jejuni. Genetic diversity among resistant isolates was lower than among susceptible isolates, and certain clones existed in both a resistant and a susceptible variant. Some resistant clones appeared to persist on the farms and were repeatedly isolated from poultry flocks. SIGNIFICANCE AND IMPACT OF THE STUDY: The study is important for the understanding of persistence and dynamics of Campylobacter in broiler houses. It also highlights the extent, farm-to-farm variation and persistence of quinolone-resistant Campylobacter in broiler houses.     

Prevalence and antimicrobial resistance of Campylobacter in US dairy cattle

AIMS: To obtain an overview of the prevalence and antimicrobial resistance of Campylobacter in faeces of US dairy cows in 2002. METHODS AND RESULTS: Faeces from 1435 cows, representing 96 dairy operations in 21 US states, were collected for the culture of Campylobacter. A total of 735 Campylobacter strains were isolated (51.2% positive samples) with 94 operations positive (97.9%) for Campylobacter. From this collection, 532 isolates (473 Campylobacter jejuni and 59 Campylobacter coli) were randomly selected for susceptibility testing to eight antimicrobials: azithromycin, chloramphenicol, ciprofloxacin, clindamycin, erythromycin, gentamicin, nalidixic acid and tetracycline. The C. jejuni isolates exhibited resistance to tetracycline (47.4%), nalidixic acid (4.0%) and ciprofloxacin (2.5%), while the C. coli strains exhibited some resistance to all antimicrobials except chloramphenicol and ciprofloxacin. Only 3.6% of the C. jejuni isolates were resistant to two or more antimicrobials but 20.3% of the C. coli strains were multiresistant. CONCLUSIONS: On most operations, at least one cow was positive for Campylobacter and more than half of the cows sampled were shedding Campylobacter. The C. coli isolates had significantly higher levels of resistance to macrolides and to tetracycline compared with the C. jejuni strains, but were susceptible to ciprofloxacin. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrated a high prevalence of Campylobacter on US dairy operations; however, US dairy cattle have not been recognized as a major source of human infection compared with poultry. Campylobacter coli appears to develop antimicrobial resistance more readily than C. jejuni from the same environment.     

The isolation and characterization of Campylobacter jejuni subsp. jejuni from domestic geese (Anser anser)

AIMS: The objectives of this study were to determine the presence of thermophilic Campylobacter spp. in free range domestic geese, and to characterize isolated strains using phenotyping criteria and SDS-PAGE of whole-cell proteins. METHODS AND RESULTS: Forty cloacal swabs from two different flocks of domestic geese were examined. All Camp. jejuni strains isolated from geese were biotyped using the Lior biotyping scheme. Twelve Camp. jejuni isolates were also tested for their susceptibility to 17 different antibacterial agents by a disc diffusion METHOD: Fourteen of the isolates were also subjected to SDS-PAGE. All of the geese examined were found to harbour Camp. jejuni. Six geese carried more than one species of Campylobacter. All strains examined were susceptible to various antibiotics but resistant to penicillin G and cephalothin. Eleven strains (92%) were resistant to sodium cefuroxime, and eight (67%) were resistant to cloxacillin, ampicillin and colistin sulphate. Three strains (25%) were resistant to tetracycline, and one strain was resistant to sulfamethoxazole/trimethoprim and kanamycin. Nine strains were subtyped as Camp. jejuni subsp. jejuni biotype II and the remaining ones as biotype I. There were 96% and 100% similarities between all the strains examined by SDS-PAGE. CONCLUSION: This study showed that Camp. jejuni were common in the intestinal tract of domestic geese. SIGNIFICANCE AND IMPACT OF THE STUDY: Geese should be considered as potential reservoirs for human and animal campylobacteriosis. The antibiotic resistance data from this study also showed that fluoroquinolone resistance, which appears to be a problem in poultry isolates in some countries, is not yet a problem in these geese.     

Antimicrobial susceptibilities of Campylobacter sp strains isolated from humans in 2005 to 2006 in Bielsko-Biala Region, Poland

Campylobacter jejuni and Campylobacter coli are frequent causes of bacterial gastroeneritis in humans worldwide. Campylobacteriois is usually a self-limiting disease and therapy with antibiotics is required in severe clinical infections. The objective [corrected] of this study was to determine the antibiotic resistance of C. jejuni and C. coli isolated from humans with diarrhea during 2005-2006 in Bielsko-Biala region in Poland. The MICs of ciprofloxacin, tetracycline, erythromycin, gentamicin and ampicillin were determined by the E-test method. It was observed that 23 % and 6% C. jejuni isolates were resistant to two and three antibiotics, respectively. All isolates of Campylobacter sp. were sensitive to erythromycin and gentamicin. From the 69 C. jejuni strains 58% were resistant to ciprofloxacin, 23% to tetracycline and 17% to ampicillin. From the 8 C. coli strains all were resistant to ciprofloxacin, 62,5% to ampicillin and 12,5% to tetracycline.     

Effects of orally administered tetracycline on the intestinal community structure of chickens and on tet determinant carriage by commensal bacteria and Campylobacter jejuni

There is a growing concern that antibiotic usage in animal production has selected for resistant food-borne bacteria. Since tetracyclines are common therapeutic antibiotics used in poultry production, we sought to evaluate the effects of oral administration on the resistance of poultry commensal bacteria and the intestinal bacterial community structure. The diversity indices calculated from terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA amplicons did not indicate significant changes in the cecal bacterial community in response to oxytetracycline. To evaluate its effects on cultivable commensals, Enterococcus spp., Escherichia coli, and Campylobacter spp. were isolated from the cecal droppings of broiler chickens. Enterococcus spp. and E. coli expressed tetracycline MICs of >8 microg/ml and harbored a variety of tet resistance determinants regardless of the tetracycline exposure history of the birds. The enterococcal isolates possessed tetM (61%), tetL (25.4%), and tetK (1.3%), as well as tetO (52.5%), the determinant known to confer a tetracycline resistance phenotype in Campylobacter jejuni. E. coli isolates harbored tetA (32.2%) or tetB (30.5%). Tetracycline MICs remained at <2 microg/ml for Campylobacter isolates before and after tetracycline treatment of the chickens, even though isolates expressing MICs of >16 mug/ml were commonly cultured from flocks that did not receive oxytetracycline. The results imply that complex ecological and genetic factors contribute to the prevalence of antibiotic resistance arising from resistance gene transfer in the production environment.     

Antimicrobial resistance profiling and fla-typing of Irish thermophillic Campylobacter spp. of human and poultry origin

AIMS: To determine the genetic relationship between a random collection of Irish human and poultry Campylobacter isolates and to determine the frequency of antibiotic resistance. METHODS AND RESULTS: Sixty-six Campylobacter isolates (34 human and 32 poultry) were typed by restriction fragment length polymorphism of flagellin-A (flaA) PCR products (flaA-RFLP) and by sequencing of the short variable region of flaA (flaA-SVR). FlaA-RFLP identified 58 distinct profiles, while flaA-SVR identified 28 different alleles. The highest level of antibiotic resistance was found for ampicillin (48.5%) followed by nalidixic acid (42.2%) and ciprofloxacin (31.8%). In general, poultry isolates displayed a higher incidence of resistance to the antimicrobials tested than the human isolates. CONCLUSIONS: A high level of genetic diversity existed among the Campylobacter strains confirming the weak clonality of this species. There was no relationship between antimicrobial resistance and specific genotypes determined by flaA typing suggesting that resistance was due to pressures of antimicrobial therapy. SIGNIFICANCE AND IMPACT OF THE STUDY: This study emphasizes the need for increased surveillance of antimicrobial susceptibility among Campylobacter isolates in Ireland and the implementation of more stringent control policies relating to the use of antimicrobials in the poultry industry.     

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.     

139株空肠弯曲菌耐药性分析

空肠弯曲菌(Campylobacter jejuni)是最常见的食源性病原菌之一。本研究采用微量肉汤稀释法对分离得到的139株空肠弯曲菌(117株为禽源样本分离株,22株为人源样本分离株)进行耐药性检测。通过对最小抑菌浓度(MIC)的判定结果得出:120株(86. 33%)空肠弯曲菌分离株对6类9组临床常用的抗生素表现出不同程度的耐药,其中禽源空肠弯曲菌耐药率为83. 76%,22株人源空肠弯曲菌均表现出耐药性。对喹诺酮类抗生素表现出高度耐药(环丙沙星80. 58%,萘啶酸77. 70%);对四环素类表现为中等耐药(四环素53. 24%);对部分大环内酯类、氨基糖苷类、林可酰胺类表现为低耐药(庆大霉素7. 19%,阿奇霉素5. 76%,克林霉素6. 47%);对酰胺醇类、部分大环内酯类表现为敏感(氟苯尼考0%,红霉素0%、泰利霉素0%)。139株空肠弯曲菌共产生14种耐药谱型,以TET-CIP-NAL谱型最多,占比38. 13%,耐三重及以上抗生素的多重耐药菌株占比53. 24%。禽源菌株中多重耐药占比46. 15%,人源菌株中多重耐药占比90. 91%。研究结果显示空肠弯曲菌耐药现状不容乐观,尤其对喹诺酮类与四环素类抗生素耐药性较为突出,且过半数菌株为多重耐药。本研究为食源性空肠弯曲菌的防控及临床用药提供参考。     

Effect of conventional and organic production practices on the prevalence and antimicrobial resistance of Campylobacter spp. in poultry

Intestinal tracts of broilers and turkeys from 10 conventional broiler farms and 10 conventional turkey farms, where antimicrobials were routinely used, and from 5 organic broiler farms and 5 organic turkey farms, where antimicrobials had never been used, were collected and cultured for Campylobacter species. A total of 694 Campylobacter isolates from the conventional and organic poultry operations were tested for antimicrobial resistance to nine antimicrobial agents by the agar dilution method. Although Campylobacter species were highly prevalent in both the conventional and organic poultry operations, the antimicrobial resistance rates were significantly different between the organic operations and the conventional operations. Less than 2% of Campylobacter strains isolated from organically raised poultry were resistant to fluoroquinolones, while 46% and 67% of Campylobacter isolates from conventionally raised broilers and conventionally raised turkeys, respectively, were resistant to these antimicrobials. In addition, a high frequency of resistance to erythromycin (80%), clindamycin (64%), kanamycin (76%), and ampicillin (31%) was observed among Campylobacter isolates from conventionally raised turkeys. None of the Campylobacter isolates obtained in this study was resistant to gentamicin, while a large number of the isolates from both conventional and organic poultry operations were resistant to tetracycline. Multidrug resistance was observed mainly among Campylobacter strains isolated from the conventional turkey operation (81%). Findings from this study clearly indicate the influence of conventional and organic poultry production practices on antimicrobial resistance of Campylobacter on poultry farms.     

Comparison of genotypes and antibiotic resistance of Campylobacter jejuni isolated from humans and slaughtered chickens in Switzerland

Aims: To get an overview of genotypes and antibiotic resistances in Swiss Campylobacter jejuni implicated in human gastroenteritis and to examine the association with isolates from chickens. Methods and Results: Multilocus sequence typing (MLST) and flaB typing were applied to 136 human clinical isolates. Phenotypic resistance to 12 antimicrobials and genotypic resistance to macrolides and quinolones were determined. MLST resulted in 35 known and six new sequence types (ST). The flaB analysis revealed 35 different types, which – in combination with MLST – increased the resolution of the typing approach. Resistance to quinolones, tetracycline and ampicillin was found in 37·5, 33·1 and 8·1% of the isolates, respectively, whereas macrolide resistance was found only once. Genotypic and phenotypic resistance correlated in all cases. A comparison to Camp. jejuni isolated from slaughtered chickens was performed. While 86% of the quinolone‐sensitive human isolates showed overlapping MLST‐flaB types with those of chicken origin, resistant strains showed only 39% of matching types. Conclusion: Mainly quinolone‐sensitive Camp. jejuni strains implicated in human campylobacteriosis showed matching genotypes with isolates originating from chickens. Significance and Impact of the Study: A large proportion of human cases in Switzerland are likely to originate from domestic chickens, confirming that prevention measures in the poultry production are important.     

Evidence for natural horizontal transfer of tetO gene between Campylobacter jejuni strains in chickens

AIMS: The transfer of tetO gene conferring resistance to tetracycline was studied between Campylobacter jejuni strains, in the digestive tract of chickens. METHODS AND RESULTS: In vitro conjugation experiments were first performed in order to select donor/recipient couples for further in vivo assay. Then, chickens were inoculated with a donor/recipient couple of C. jejuni strains displaying spontaneous in vitro tetracycline resistance gene transfer. The donor was a tetracycline-resistant ampicillin-susceptible strain, and the recipient was a tetracycline-susceptible ampicillin-resistant strain. Chicken droppings were streaked on antimicrobial selective media and bi-resistant Campylobacter isolates were further characterized according to their donor or recipient flaA gene RFLP profile. The acquisition of tetracycline-resistance gene by the recipient C. jejuni strain from the donor C. jejuni strain was confirmed by tetO PCR. CONCLUSIONS: The study showed that transfer of tetO gene occurs rapidly and without antimicrobial selection pressure between C. jejuni strains in the digestive tract of chickens. SIGNIFICANCE AND IMPACT OF THE STUDY: The rapid and spontaneous transfer of tetO gene may explain the high prevalence of tetracycline resistance in chicken Campylobacter strains.     

Genotyping of Campylobacter jejuni strains from Danish broiler chickens by restriction fragment length polymorphism of the LPS gene cluster

AIMS: To apply and evaluate LG (LPS genes) genotyping, which is a genotyping method based on a cluster of genes involved in the synthesis of surface lipopolysaccharides (LPS) in Campylobacter species, for typing of Campylobacter jejuni isolates obtained from Danish broiler chickens. Furthermore, the LG genotyping method was used to study the genetic stability of four C. jejuni strains after gastrointestinal passage through experimentally infected chickens. METHODS AND RESULTS: In the present study, the LG genotyping method was modified with respect to the restriction enzymes used. To validate the method, 63 Penner serotype reference strains and 107 C. jejuni chicken isolates, representing the most common Penner serotypes of C. jejuni in Danish poultry, were selected for typing. The method was successfully used for typing all isolates and the LG genotype profiles were reproducible. There were no changes in the LG genotype of the C. jejuni strains obtained after experimental passage through chickens. CONCLUSIONS: All C. jejuni strains obtained from broiler chickens were typeable by the LG genotyping method. Application of the RsaI restriction enzyme improved the method in terms of ease and consistency of analyses and increase of discriminatory power. SIGNIFICANCE AND IMPACT OF THE STUDY: The LG genotyping method is a valuable tool for typing C. jejuni isolates obtained from poultry. However, the association between Penner serotyping based on passive haemagglutination of heat-stable antigens and LG genotyping was low when applied to poultry isolates. This is in contrast to previous studies on isolates of human origin that reported a high correlation between results obtained by the two typing methods (Shi et al. 2002).     

Effects of subtherapeutic administration of antimicrobial agents to beef cattle on the prevalence of antimicrobial resistance in Campylobacter jejuni and Campylobacter hyointestinalis

The influence of antimicrobial agents on the development of antimicrobial resistance (AMR) in Campylobacter isolates recovered from 300 beef cattle maintained in an experimental feedlot was monitored over a 315-day period (11 sample times). Groups of calves were assigned to one of the following antimicrobial treatments: chlortetracycline and sulfamethazine (CS), chlortetracycline alone (Ct), virginiamycin, monensin, tylosin phosphate, and no antimicrobial agent (i.e., control treatment). In total, 3,283 fecal samples were processed for campylobacters over the course of the experiment. Of the 2,052 bacterial isolates recovered, 92% were Campylobacter (1,518 were Campylobacter hyointestinalis and 380 were C. jejuni). None of the antimicrobial treatments decreased the isolation frequency of C. jejuni relative to the control treatment. In contrast, C. hyointestinalis was isolated less frequently from animals treated with CS and to a lesser extent from animals treated with Ct. The majority (> or =94%) of C. jejuni isolates were sensitive to ampicillin, erythromycin, and ciprofloxacin, but more isolates with resistance to tetracycline were recovered from animals fed Ct. All of the 1,500 isolates of C. hyointestinalis examined were sensitive to ciprofloxacin. In contrast, 11%, 10%, and 1% of these isolates were resistant to tetracycline, erythromycin, and ampicillin, respectively. The number of animals from which C. hyointestinalis isolates with resistance to erythromycin and tetracycline were recovered differed among the antimicrobial treatments. Only Ct administration increased the carriage rates of erythromycin-resistant isolates of C. hyointestinalis, and the inclusion of CS in the diet increased the number of animals from which tetracycline-resistant isolates were recovered. The majority of C. hyointestinalis isolates with resistance to tetracycline were obtained from cohorts within a single pen, and most of these isolates were recovered from cattle during feeding of a forage-based diet as opposed to a grain-based diet. The findings of this study show that the subtherapeutic administration of tetracycline, alone and in combination with sulfamethazine, to feedlot cattle can select for the carriage of resistant strains of Campylobacter species. Considering the widespread use of in-feed antimicrobial agents and the high frequency of beef cattle that shed campylobacters, the development of AMR should be monitored as part of an on-going surveillance program.     

Restriction endonuclease analysis, DNA relatedness and phenotypic characterization of Campylobacter jejuni and Camp. coli isolates involved in food-borne disease

Seven cases of Campylobacter infection, each of them involving two isolates, were analysed. Study of their biochemical profiles and susceptibility patterns allowed the identification of Camp. jejuni and Camp. coli isolates and the effective typing of Camp. jejuni strains into biotypes. Genotyping was carried out by comparing chromosomal DNA restriction patterns obtained by cleavage with Bgl II and Eco RV and by Southern hybridization experiments. These studies revealed clonal homogeneity between both isolates in five of the seven cases studied, indicating that in these cases Campylobacter infection was caused by a single strain. Infection with two different strains was characterized in only two of the seven cases studied, two different species belonging to Camp. coli and Camp. jejuni ssp. jejuni biotype 1 being identified. Genetic analysis proved to be the most reliable technique to achieve precise identification of strains and to elucidate clonal heterogeneity among Campylobacter isolates obtained from a single patient.     

Dissemination of fluoroquinolone-resistant Campylobacter spp. within an integrated commercial poultry production system

While characterizing the intestinal bacterial community of broiler chickens, we detected epsilon-proteobacterial DNA in the ilea of 3-day-old commercial broiler chicks (J. Lu, U. Idris, B. Harmon, C. Hofacre, J. J. Maurer, and M. D. Lee, Appl. Environ. Microbiol. 69:6816-6824, 2003). The sequences exhibited high levels of similarity to Campylobacter jejuni and Campylobacter coli sequences, suggesting that chickens can carry Campylobacter at a very young age. Campylobacter sp. was detected by PCR in all samples collected from the ilea of chicks that were 3 to 49 days old; however, it was detected only in the cecal contents of chickens that were at least 21 days old. In order to determine whether the presence of Campylobacter DNA in young chicks was due to ingestion of the bacteria in food or water, we obtained commercial broiler hatching eggs, which were incubated in a research facility until the chicks hatched. DNA sequencing of the amplicons resulting from Campylobacter-specific 16S PCR performed with the ileal, cecal, and yolk contents of the day-of-hatching chicks revealed that Campylobacter DNA was present before the chicks consumed food or water. The 16S rRNA sequences exhibited 99% similarity to C. jejuni and C. coli sequences and 95 to 98% similarity to sequences of other thermophilic Campylobacter species, such as C. lari and C. upsaliensis. The presence of C. coli DNA was detected by specific PCR in the samples from chicks obtained from a commercial hatchery; however, no Campylobacter was detected by culturing. In order to determine whether the same strains of bacteria were present in multiple levels of the integrator, we cultured Campylobacter sp. from a flock of broiler breeders and their 6-week-old progeny that resided on a commercial broiler farm. The broiler breeders had been given fluoroquinolone antibiotics, and we sought to determine whether the same fluoroquinolone-resistant strain was present in their progeny. The isolates were typed by pulsed-field gel electrophoresis, which confirmed that the parental and progeny flocks contained the same strain of fluoroquinolone-resistant C. coli. These data indicate that resistant C. coli can be present in multiple levels of an integrated poultry system and demonstrated that molecular techniques or more sensitive culture methods may be necessary to detect early colonization by Campylobacter in broiler chicks.     

Antimicrobial-resistant Campylobacter species from retail raw meats

The antimicrobial susceptibilities of 378 Campylobacter isolates were determined. Resistance to tetracycline was the most common (82%), followed by resistance to doxycycline (77%), erythromycin (54%), nalidixic acid (41%), and ciprofloxacin (35%). Campylobacter coli displayed significantly higher rates of resistance to ciprofloxacin and erythromycin than Campylobacter jejuni, and Campylobacter isolates from turkey meat showed a greater resistance than those from chicken meat.     

Prevalence, development, and molecular mechanisms of bacteriocin resistance in Campylobacter

Bacteriocins (BCNs) are antimicrobial peptides produced by bacteria with narrow or broad spectra of antimicrobial activity. Recently, several unique anti-Campylobacter BCNs have been identified from commensal bacteria isolated from chicken intestines. These BCNs dramatically reduced C. jejuni colonization in poultry and are being directed toward on-farm control of Campylobacter. However, no information concerning prevalence, development, and mechanisms of BCN resistance in Campylobacter exists. In this study, susceptibilities of 137 C. jejuni isolates and 20 C. coli isolates to the anti-Campylobacter BCNs OR-7 and E-760 were examined. Only one C. coli strain displayed resistance to the BCNs (MIC, 64 μg/ml), while others were susceptible, with MICs ranging from 0.25 to 4 μg/ml. The C. coli mutants resistant to BCN OR-7 also were obtained by in vitro selection, but all displayed only low-level resistance to OR-7 (MIC, 8 to 16 μg/ml). The acquired BCN resistance in C. coli could be transferred at intra- and interspecies levels among Campylobacter strains by biphasic natural transformation. Genomic examination of the OR-7-resistant mutants by using DNA microarray and random transposon mutagenesis revealed that the multidrug efflux pump CmeABC contributes to both intrinsic resistance and acquired resistance to the BCNs. Altogether, this study represents the first report of and a major step forward in understanding BCN resistance in Campylobacter, which will facilitate the development of effective BCN-based strategies to reduce the Campylobacter loads in poultry.     

Genomic diversity of Campylobacter coli and Campylobacter jejuni isolates recovered from free-range broiler farms and comparison with isolates of various origins

In many industrialized countries, the incidence of campylobacteriosis exceeds that of salmonellosis. Campylobacter bacteria are transmitted to humans mainly in food, especially poultry meat products. Total prevention of Campylobacter colonization in broiler flocks is the best way to reduce (or eliminate) the contamination of poultry products. The aim of this study was to establish the sources and routes of contamination of broilers at the farm level. Molecular typing methods (DNA macrorestriction pulsed-field gel electrophoresis and analysis of gene polymorphism by PCR-restriction fragment length polymorphism) were used to characterize isolates collected from seven broiler farms. The relative genomic diversity of Campylobacter coli and Campylobacter jejuni was determined. Analysis of the similarity among 116 defined genotypes was used to determine clusters within the two species. Furthermore, evidence of recombination suggested that there were genomic rearrangements within the Campylobacter populations. Recovery of related clusters from different broiler farms showed that some Campylobacter strains might be specifically adapted to poultry. Analysis of the Campylobacter cluster distribution on three broiler farms showed that soil in the area around the poultry house was a potential source of Campylobacter contamination. The broilers were infected by Campylobacter spp. between days 15 and 36 during rearing, and the type of contamination changed during the rearing period. A study of the effect of sanitary barriers showed that the chickens stayed Campylobacter spp. free until they had access to the open area. They were then rapidly colonized by the Campylobacter strains isolated from the soil.