Clonal population structure and specific genotypes of multidrug-resistant Campylobacter coli from Turkeys

Broiler farming practices using new or re-used bedding, inclusive of free-range, have no impact on Campylobacter levels, species diversity, Campylobacter community profiles and Campylobacter bacteriophages

A multi-stage option to address food-safety can be produced by a clearer understanding of Campylobacter's persistence through the broiler production chain, its environmental niche and its interaction with bacteriophages. This study addressed Campylobacter levels, species, genotype, bacteriophage composition/ levels in caeca, litter, soil and carcasses across commercial broiler farming practices to inform on-farm management, including interventions. Broilers were sequentially collected as per company slaughter schedules over two-years from 17 farms, which represented four commercially adopted farming practices, prior to the final bird removal (days 39-53). The practices were conventional full clean-out, conventional litter re-use, free-range-full cleanout and free-range-litter re-use. Caeca, litter and soil collected on-farm, and representative carcases collected at the processing plant, were tested for Campylobacter levels, species dominance and Campylobacter bacteriophages. General community profiling via denaturing gradient gel electrophoresis of the flaA gene was used to establish the population relationships between various farming practices on representative Campylobacter isolates. The farming practice choices did not influence the high caeca Campylobacter levels (log 7.5 to log 8.5 CFU/g), the carcass levels (log 2.5 to log 3.2 CFU/carcass), the C. jejuni/C. coli dominance and the on-farm bacteriophage presence/levels. A principal coordinate analysis of the flaA distribution for farm and litter practices showed strong separation but no obvious farming practice related grouping of Campylobacter. Bacteriophages originated from select farms, were not practice-dependent, and were detected in the environment (litter) only if present in the birds (caeca). This multifaceted study showed no influence of farming practices on on-farm Campylobacter dynamics. The significance of this study means that a unified on-farm risk-management could be adopted irrespective of commercial practice choices to collectively address caeca Campylobacter levels, as well as the potential to include Campylobacter bacteriophage biocontrol. The impact of this study means that there are no constraints in re-using bedding or adopting free-range farming, thus contributing to environmentally sustainable (re-use) and emerging (free-range) broiler farming choices.

Antimicrobial resistance and interspecies gene transfer in Campylobacter coli and Campylobacter jejuni isolated from food animals, poultry processing, and retail meat in North Carolina, 2018-2019

The Center for Disease Control and Prevention identifies antimicrobial resistant (AMR) Campylobacter as a serious threat to U.S. public health due to high community burden, increased transmissibility, and limited treatability. The National Antimicrobial Resistance Monitoring System (NARMS) plays an important role in surveillance of AMR bacterial pathogens in humans, food animals and retail meats. This study investigated C. coli and C. jejuni from live food animals, poultry carcasses at production, and retail meat in North Carolina between January 2018-December 2019. Whole genome sequencing and bioinformatics were used for phenotypic and genotypic characterization to compare AMR profiles, virulence factors associated with Guillain-Barré Syndrome (GBS) (neuABC and cst-II or cst-III), and phylogenic linkage between 541 Campylobacter isolates (C. coli n = 343, C. jejuni n = 198). Overall, 90.4% (489/541) Campylobacter isolates tested positive for AMR genes, while 43% (233/541) carried resistance genes for three or more antibiotic classes and were classified molecularly multidrug resistant. AMR gene frequencies were highest against tetracyclines (64.3%), beta-lactams (63.6%), aminoglycosides (38.6%), macrolides (34.8%), quinolones (24.4%), lincosamides (13.5%), and streptothricins (5%). A total of 57.6% (114/198) C. jejuni carried GBS virulence factors, while three C. coli carried the C. jejuni-like lipooligosaccharide locus, neuABC and cst-II. Further evidence of C. coli and C. jejuni interspecies genomic exchange was observed in identical multilocus sequence typing, shared sequence type (ST) 7818 clonal complex 828, and identical species-indicator genes mapA, ceuE, and hipO. There was a significant increase in novel STs from 2018 to 2019 (2 in 2018 and 21 in 2019, p<0.002), illustrating variable Campylobacter genomes within food animal production. Introgression between C. coli and C. jejuni may aid pathogen adaption, lead to higher AMR and increase Campylobacter persistence in food processing. Future studies should further characterize interspecies gene transfer and evolutionary trends in food animal production to track evolving risks to public health.

Prevalence of thermotolerant Campylobacter species in dogs and cats in Iran

Campylobacter is considered the most common bacterial cause of human gastroenteritis in the world with C. jejuni being regarded as the primary cause of bacterial gastroenteritis. A broad range of other Campylobacter species, including C. coli have also been implicated in human gastroenteritis. This study sought to isolate, characterize and assess the antibiogram of Campylobacter jejuni and C. coli from faecal samples obtained from cats and dogs in Isfahan and Shahrekord cities in Iran. Faecal samples were collected from 100 pets comprising of 50 dogs and 50 cats from March 2015 to March 2016; incorporating the four seasons (spring, summer, autumn and winter). Campylobacter spp. was isolated by culture, characterized by biochemical tests and confirmed by PCR-based assays. Antimicrobial susceptibility test was performed by the Kirby-Bauer disk diffusion method, using Mueller Hinton agar. A total of 19 Campylobacter isolates among them two C. jejuni and one C. coli were recovered from dogs and cats' faecal samples. The prevalence rates of Campylobacter spp. were 16.0% (8 out of 50) in dogs and 22.0% (11 out of 50) in cats. The highest (4 out of 16, 25%) Campylobacter spp. prevalence among dogs was reported in autumn and the lowest (1 out of 11, 9.1%) in spring, while among the cats, the highest (4 out of 12, 33.3%) Campylobacter spp. prevalence was reported in summer and lowest (1 out of 11, 9.09%) in spring. Campylobacter spp. isolated from faecal samples obtained from cats and dogs exhibited the most frequent antimicrobial resistance against tetracycline at 81.8% and 87.5%, respectively, compared to all other antimicrobial agents. These results show a low prevalence of Campylobacter spp. in faecal samples obtained from pet dogs and cats in Shahrekord and Isfahan cities in Iran. Given the relatively low prevalence of the C. jejuni and C. coli in pet dogs and cats in Isfahan and Shahrekord cities, it can be assumed that their importance as reservoirs for infection in humans is likely to be limited to the studied cities, but should not be neglected.

Proximity to Other Commercial Turkey Farms Affects Colonization Onset, Genotypes, and Antimicrobial Resistance Profiles of Campylobacter spp. in Turkeys: Suggestive Evidence from a Paired-Farm Model

Campylobacter is a leading foodborne pathogen, and poultry products are major vehicles for human disease. However, determinants impacting Campylobacter colonization in poultry remain poorly understood, especially with turkeys. Here, we used a paired-farm design to concurrently investigate Campylobacter colonization and strain types in two turkey breeds (Hybrid and Nicholas) at two farms in eastern North Carolina. One farm (the Teaching Animal Unit [TAU]) was a university teaching unit at least 40 km from commercial turkey farms, while the other (SIB) was a commercial farm in an area with a high density of turkey farms. Day-old birds were obtained from the same breeder flock and hatchery and placed at TAU and SIB on the same day. Birds were marked to identify turkey breed and then commingled on each farm. TAU birds became colonized 1 week later than SIB and had lower initial Campylobacter levels in the cecum. Interestingly, Campylobacter genotypes and antimicrobial resistance profiles differed markedly between the farms. Most TAU isolates were resistant only to tetracycline, whereas multidrug-resistant isolates predominated at SIB. Multilocus sequence typing revealed that no Campylobacter genotypes were shared between TAU and SIB. A bovine-associated genotype (sequence type 1068 [ST1068]) predominated in Campylobacter coli from TAU, while SIB isolates had genotypes commonly encountered in commercial turkey production in the region. One multidrug-resistant Campylobacter jejuni strain (ST1839) showed significant association with one of the two turkey breeds. The findings highlight the need to further characterize the impact of farm-specific factors and host genetics on antimicrobial resistance and genotypes of C. jejuni and C. coli that colonize turkeys.IMPORTANCE Colonization of poultry with Campylobacter at the farm level is complex, poorly understood, and critically linked to contamination of poultry products, which is known to constitute a leading risk factor for human campylobacteriosis. Here, we investigated the use of a paired-farm design under standard production conditions and in the absence of experimental inoculations to assess potential impacts of farm and host genetics on prevalence, antimicrobial resistance and genotypes of Campylobacter in commercial turkeys of two different breeds. Data suggest impacts of farm proximity to other commercial turkey farms on the onset of colonization, genotypes, and antimicrobial resistance profiles of Campylobacter colonizing the birds. Furthermore, the significant association of a specific multidrug-resistant Campylobacter jejuni strain with turkeys of one breed suggests colonization partnerships at the Campylobacter strain-turkey breed level. The study design avoids potential pitfalls associated with experimental inoculations, providing novel insights into the dynamics of turkey colonization with Campylobacter in actual farm ecosystems.

Sources of contamination, prevalence, and antimicrobial resistance of thermophilic Campylobacter isolated from turkeys

AIM

Sources of contamination, prevalence, and antimicrobial susceptibility of thermophilic Campylobacter isolated from turkey samples were determined.

MATERIALS AND METHODS

A total of 300 samples were collected from 3 farms (fecal droppings) and 4 poultry slaughterhouses (neck skins and ceca) located in the middle area of Algeria (Algiers, Boumerdès, and Bouira). After detection, an antibiogram was realized only for slaughterhouses samples.

RESULTS

Samples from cecum (90.0%, 90/100; 95% confidence interval (CI)=84.1-95.9%), fecal dropping (68.0%, 68/100; 95% CI=58.9-77.1%), and neck skin (55.0%, 55/100; 95% CI=45.2-64.8%) were positive for thermophilic Campylobacter (p<0.05). Contamination rate of turkey carcasses was higher in modern slaughterhouse (96.7%) than in traditional slaughterhouses (37.1%) (p<0.05). Isolated strains were resistant to nalidixic acid (NA) (87.5%), tetracycline (TE) (81.3%), ciprofloxacin (CIP) (75.0%), ampicillin (AM) (65.6%), and erythromycin (25.0%) (p<0.05). 96.9% (124/128) of the isolates were multiresistant and 18 drug resistance patterns were registered. The predominant one (43.0%) was AM, NA, CIP, and TE.

CONCLUSIONS

Potential sources of contamination of this fastidious bacterium were noticed in farms and slaughterhouses. Modern slaughterhouse allowed contamination of turkey carcasses more than a traditional slaughterhouse. However, the scalding step could not represent a source of contamination. The most tested strains exhibited resistance to erythromycin and/or CIP. It is worrisome because these molecules are considered as first-choice antibiotics for human campylobacteriosis.

Multilocus sequence typing of Campylobacter jejuni and Campylobacter coli to identify potential sources of colonization in commercial turkey farms

Poultry are the main reservoir for thermophilic Campylobacter spp., which is the most common causative agent of human bacterial gastroenteritis. The epidemiology of Campylobacter in poultry, particularly in turkeys, is not completely understood. This study aimed at identifying potential sources and transmission routes of thermophilic Campylobacter spp. in commercial turkey farms. C. jejuni and C. coli isolates from breeders (n = 29, 20 C. jejuni and 9 C. coli) and their progeny (n = 51, 18 C. jejuni and 33 C. coli) reared in two different farms for three sequential production cycles were analysed by multilocus sequence typing (MLST). Strains (n = 88, 42 C. jejuni and 46 C. coli) isolated from environmental (i.e. anteroom and in-house overshoes), water (i.e. drinkers and water line), and pest (i.e. flies, Alphitobius diaperinus, and mice) sources were also examined. MLST of C. jejuni and C. coli isolates resulted in 13 and 12 different sequence types (STs) belonging to six and one previously-described clonal complexes (CCs), respectively. Three novel STs were identified. Genetic similarities were detected between isolates from fattening turkeys and the considered environmental, water, and pest sources, and with the breeders to a lesser extent. Source attribution analysis estimated that environmental and water sources accounted for most (∼75%) of fattening turkey isolates and were therefore identified as the most likely sources of flock colonization, followed by pests (∼20%) and breeders (∼5%). These sources may thus be targeted by control measures to mitigate the risk of Campylobacter colonization in commercial turkeys. RESEARCH HIGHLIGHTS High occurrence of C. jejuni and C. coli in commercial turkey flocks. High genetic diversity of C. jejuni and C. coli in commercial turkey flocks. Horizontal transmission responsible for Campylobacter colonization of commercial turkey flocks. Environmental and water sources involved in Campylobacter colonization of commercial turkey flocks. Strategies for prevention and control of Campylobacter colonization of commercial turkey flocks are needed.

Prevalence and Characteristics of Salmonella and Campylobacter in Retail Poultry Meat in Japan

This study was performed to determine the prevalence, antimicrobial susceptibility, and genetic relatedness of Salmonella enterica subsp. enterica and Campylobacter spp. in poultry meat, and to analyze the association of genetic types of these bacteria with their geographical distribution and antimicrobial resistance profiles. Salmonella and Campylobacter isolates have been detected, respectively, in 54 and 71 samples out of 100 samples tested. Nine Salmonella serotypes were found, including S. enterica subsp. enterica serovar Infantis (33%), Schwarzengrund (12%), Manhattan (9%), and others. Campylobacter jejuni and C. coli were detected in 64 (64%) and 14 (14%) samples, respectively. S. enterica subsp. enterica isolates were very frequently resistant to tetracycline (78.3%) and streptomycin (68.3%). Many C. jejuni and C. coli isolates were resistant to sulfamethoxazole/trimethoprim (90.5%), nalidixic acid (47.3%), ampicillin (45.9%), and ciprofloxacin (40.5%). Cluster analysis was performed for the Salmonella isolates using pulsed-field gel electrophoresis (PFGE) data. For Campylobacter isolates, the cluster analysis was based on both PFGE and comparative genomic fingerprinting. The molecular typing results were compared with the information about antimicrobial resistance and geographical locations in which the poultry meat was produced. This analysis revealed that C. jejuni strains with a particular genotype and antimicrobial resistance profile are spreading in specific areas of Japan.

High genetic similarity of ciprofloxacin-resistant Campylobacter jejuni in central Europe

Campylobacteriosis is the leading zoonosis in the European Union with the majority of cases attributed to Campylobacter jejuni. Although the disease is usually self-limiting, some severe cases need to be treated with antibiotics, primarily macrolides and quinolones. However, the resistance to the latter is reaching alarming levels in most of the EU countries. To shed light on the expansion of antibiotic resistance in central Europe, we have investigated genetic similarity across 178 ciprofloxacin-resistant C. jejuni mostly isolated in Slovenia, Austria and Germany. We performed comparative genetic similarity analyses using allelic types of seven multilocus sequence typing housekeeping genes, and single nucleotide polymorphisms of a quinolone resistance determining region located within the DNA gyrase subunit A gene. This analysis revealed high genetic similarity of isolates from clonal complex ST-21 that carry gyrA allelic type 1 in all three of these central-European countries, suggesting these ciprofloxacin resistant isolates arose from a recent common ancestor and are spread clonally.

Multidrug-resistant pathogens in the food supply

Antimicrobial resistance, including multidrug resistance (MDR), is an increasing problem globally. MDR bacteria are frequently detected in humans and animals from both more- and less-developed countries and pose a serious concern for human health. Infections caused by MDR microbes may increase morbidity and mortality and require use of expensive drugs and prolonged hospitalization. Humans may be exposed to MDR pathogens through exposure to environments at health-care facilities and farms, livestock and companion animals, human food, and exposure to other individuals carrying MDR microbes. The Centers for Disease Control and Prevention classifies drug-resistant foodborne bacteria, including Campylobacter, Salmonella Typhi, nontyphoidal salmonellae, and Shigella, as serious threats. MDR bacteria have been detected in both meat and fresh produce. Salmonellae carrying genes coding for resistance to multiple antibiotics have caused numerous foodborne MDR outbreaks. While there is some level of resistance to antimicrobials in environmental bacteria, the widespread use of antibiotics in medicine and agriculture has driven the selection of a great variety of microbes with resistance to multiple antimicrobials. MDR bacteria on meat may have originated in veterinary health-care settings or on farms where animals are given antibiotics in feed or to treat infections. Fresh produce may be contaminated by irrigation or wash water containing MDR bacteria. Livestock, fruits, and vegetables may also be contaminated by food handlers, farmers, and animal caretakers who carry MDR bacteria. All potential sources of MDR bacteria should be considered and strategies devised to reduce their presence in foods. Surveillance studies have documented increasing trends in MDR in many pathogens, although there are a few reports of the decline of certain multidrug pathogens. Better coordination of surveillance programs and strategies for controlling use of antimicrobials need to be implemented in both human and animal medicine and agriculture and in countries around the world.

Antimicrobial resistance of Campylobacter jejuni and Campylobacter coli from poultry in Italy

This study was aimed at assessing the antimicrobial resistance (AMR) of Campylobacter isolates from broilers and turkeys reared in industrial farms in Northern Italy, given the public health concern represented by resistant campylobacters in food-producing animals and the paucity of data about this topic in our country. Thirty-six Campylobacter jejuni and 24 Campylobacter coli isolated from broilers and 68 C. jejuni and 32 C. coli from turkeys were tested by disk diffusion for their susceptibility to apramycin, gentamicin, streptomycin, cephalothin, cefotaxime, ceftiofur, cefuroxime, ampicillin, amoxicillin+clavulanic acid, nalidixic acid, flumequine, enrofloxacin, ciprofloxacin, erythromycin, tilmicosin, tylosin, tiamulin, clindamycin, tetracycline, sulfamethoxazole+trimethoprim, chloramphenicol. Depending on the drug, breakpoints provided by Comité de l'antibiogramme de la Société Française de Microbiologie, Clinical and Laboratory Standards Institute, and the manufacturer were followed. All broiler strains and 92% turkey strains were multidrug resistant. Very high resistance rates were detected for quinolones, tetracycline, and sulfamethoxazole+trimethoprim, ranging from 65% to 100% in broilers and from 74% to 96% in turkeys. Prevalence of resistance was observed also against ampicillin (97% in broilers, 88% in turkeys) and at least three cephalosporins (93-100% in broilers, 100% in turkeys). Conversely, no isolates showed resistance to chloramphenicol and tiamulin. Susceptibility prevailed for amoxicillin+clavulanic acid and aminoglycosides in both poultry species, and for macrolides and clindamycin among turkey strains and among C. jejuni from broilers, whereas most C. coli strains from broilers (87.5%) were resistant. Other differences between C. jejuni and C. coli were observed markedly in broiler isolates, with the overall predominance of resistance in C. coli compared to C. jejuni. This study provides updates and novel data on the AMR of broiler and turkey campylobacters in Italy, revealing the occurrence of high resistance to several antimicrobials, especially key drugs for the treatment of human campylobacteriosis, representing a potential risk for public health.

Widespread acquisition of antimicrobial resistance among Campylobacter isolates from UK retail poultry and evidence for clonal expansion of resistant lineages

Background

Antimicrobial resistance is increasing among clinical Campylobacter cases and is common among isolates from other sources, specifically retail poultry - a major source of human infection. In this study the antimicrobial susceptibility of isolates from a UK-wide survey of Campylobacter in retail poultry in 2001 and 2004–5 was investigated. The occurrence of phenotypes resistant to tetracycline, quinolones (ciprofloxacin and naladixic acid), erythromycin, chloramphenicol and aminoglycosides was quantified. This was compared with a phylogeny for these isolates based upon Multi Locus Sequence Typing (MLST) to investigate the pattern of antimicrobial resistance acquisition.

Results

Antimicrobial resistance was present in all lineage clusters, but statistical testing showed a non-random distribution. Erythromycin resistance was associated with Campylobacter coli. For all antimicrobials tested, resistant isolates were distributed among relatively distant lineages indicative of widespread acquisition. There was also evidence of clustering of resistance phenotypes within lineages; indicative of local expansion of resistant strains.

Conclusions

These results are consistent with the widespread acquisition of antimicrobial resistance among chicken associated Campylobacter isolates, either through mutation or horizontal gene transfer, and the expansion of these lineages as a proportion of the population. As Campylobacter are not known to multiply outside of the host and long-term carriage in humans is extremely infrequent in industrialized countries, the most likely location for the proliferation of resistant lineages is in farmed chickens.

MLST genotypes and antibiotic resistance of Campylobacter spp. isolated from poultry in Grenada

This study determined whether multilocus sequence types (MLST) of Campylobacter from poultry in 2 farms in Grenada, West Indies, differed by farm, antimicrobial resistance and farm antibiotic use. Farm A used fluoroquinolones in the water and Farm B used tetracyclines. The E-test was used to determine resistance of isolates to seven antibiotics. PCR of the IpxA gene confirmed species and MLST was used to characterize 38 isolates. All isolates were either C. jejuni or C. coli. Farm antibiotic use directly correlated with antimicrobial resistance of Campylobacter isolates. Almost 80% of the isolates from Farm A were fluoroquinolone resistant and 17.9% of the isolates from Farm B were fluoroquinolone resistant. All Campylobacter isolates from Farm A were tetracycline sensitive, whereas 35.7% of isolates from Farm B were tetracycline resistant. Six previously recognized sequence types (STs) and 2 novel STs were identified. Previously recognized STs were those overwhelmingly reported from poultry and humans globally. Isolates with the same ST did not always have the same antibiotic resistance profile. There was little ST overlap between the farms suggesting that within-farm transmission of Campylobacter genotypes may dominate. MLST typing was useful for tracking Campylobacter spp. among poultry units and can help elucidate Campylobacter host-species population structure and its relevance to human health.

Antimicrobial susceptibilities of Campylobacter jejuni and Campylobacter coli strains isolated from two early stages of poultry production

Our aim was to monitor the resistance of Campylobacter isolates from two initial stages of broiler production in 5 grandparent breeder broiler farms (GPBFs) and 12 parent breeder broiler farms (PBFs) in which no antimicrobials were used during the study. Susceptibility tests were carried out for 805 strains (697 Campylobacter jejuni and 108 Campylobacter coli) against nalidixic acid, ciprofloxacin, erythromycin, amoxicillin, amoxicillin plus clavulanic acid, tetracycline, gentamicin, and chloramphenicol using the disk-diffusion method. Quinolone resistance was the most abundant overall (74.9%) and at each stage of production. The second largest resistance was for tetracycline with 48.2%. The resistance against amoxicillin plus clavulanic acid, gentamicin, and chloramphenicol was not found. The percentages of resistance and multidrug-resistant (MDR) isolates were always higher in the PBFs than in the GPBFs. However, pan-susceptible populations (total 10.3%) were isolated in our survey. C. coli isolates were more resistant to tetracycline and erythromycin (96.3% and 23.1%, respectively) than for C. jejuni (40.7% and 0%, respectively) and were more MDR (33.3% vs. 11.9%). In conclusion, as other authors have shown, even in the absence of antibiotic pressure, relatively high rates of quinolone resistance are found in Campylobacter. However, a decrease in quinolone resistance has been observed compared to other studies in Spain [i.e., 99%; Saenz et al. Antimicrob. Agents Chemother. 2000;44(2):267-271]. MDR, fluoroquinolone-, macrolide-, and tetracycline-resistant Campylobacter populations are issues of concern in public health.

Campylobacter spp. as a Foodborne Pathogen: A Review

Campylobacter is well recognized as the leading cause of bacterial foodborne diarrheal disease worldwide. Symptoms can range from mild to serious infections of the children and the elderly and permanent neurological symptoms. The organism is a cytochrome oxidase positive, microaerophilic, curved Gram-negative rod exhibiting corkscrew motility and is carried in the intestine of many wild and domestic animals, particularly avian species including poultry. Intestinal colonization results in healthy animals as carriers. In contrast with the most recent published reviews that cover specific aspects of Campylobacter/campylobacteriosis, this broad review aims at elucidating and discussing the (i) genus Campylobacter, growth and survival characteristics; (ii) detection, isolation and confirmation of Campylobacter; (iii) campylobacteriosis and presence of virulence factors; and (iv) colonization of poultry and control strategies.

Study of the molecular mechanisms involved in high-level macrolide resistance of Spanish Campylobacter jejuni and Campylobacter coli strains

OBJECTIVES

To investigate the molecular mechanisms involved in the high-level erythromycin resistance of clinical Spanish Campylobacter jejuni and Campylobacter coli strains.

METHODS

Overall susceptibilities of 678 C. jejuni and 119 C. coli strains, collected from 10 Spanish provinces during 2006 and 2007, were determined by Etest. In high-level erythromycin-resistant strains, molecular determinants were studied. The analysis was focused on region V of the 23S rRNA gene, the rplD and rplV ribosomal genes, and the regulatory region of the CmeABC efflux pump.

RESULTS

The global resistance rate to erythromycin was 3.8%. Among the resistant strains, 93% were C. coli and 7% were C. jejuni. The A2075G mutation in the 23S rRNA gene was detected in all of the resistant strains except for two, which carried the A2074G mutation. None of the ribosomal rplD and rplV genes harboured the described mutations that confer resistance to macrolides. Different mutations affecting the regulatory region of the CmeABC efflux pump were also found.

CONCLUSIONS

C. coli strains are clearly more resistant to erythromycin than C. jejuni. The mutation A2075G in the 23S rRNA gene was responsible for the resistance in most of the strains; A2074G was only found in two strains. Further studies are required to ascertain the effect of mutations in the regulatory region of cmeABC. Our data indicate that the rate of resistance was similar to that of other European countries.

Host association of Campylobacter genotypes transcends geographic variation

Genetic attribution of bacterial genotypes has become a major tool in the investigation of the epidemiology of campylobacteriosis and has implicated retail chicken meat as the major source of human infection in several countries. To investigate the robustness of this approach to the provenance of the reference data sets used, a collection of 742 Campylobacter jejuni and 261 Campylobacter coli isolates obtained from United Kingdom-sourced chicken meat was established and typed by multilocus sequence typing. Comparative analyses of the data with those from other isolates sourced from a variety of host animals and countries were undertaken by genetic attribution, genealogical, and population genetic approaches. The genotypes from the United Kingdom data set were highly diverse, yet structured into sequence types, clonal complexes, and genealogical groups very similar to those seen in chicken isolates from the Netherlands, the United States, and Senegal, but more distinct from isolates obtained from ruminant, swine, and wild bird sources. Assignment analyses consistently grouped isolates from different host animal sources regardless of geographical source; these associations were more robust than geographic associations across isolates from three continents. We conclude that, notwithstanding the high diversity of these pathogens, there is a strong signal of association of multilocus genotypes with particular hosts, which is greater than the geographic signal. These findings are consistent with local and international transmission of host-associated lineages among food animal species and provide a foundation for further improvements in genetic attribution.

Antimicrobial resistance in Campylobacter coli selected by tylosin treatment at a pig farm

Limited knowledge is available regarding the dynamics of macrolide resistance under farm conditions with natural Campylobacter populations. We examined the dynamics of antimicrobial resistance in Campylobacter coli at a large pig farm. Faeces were sampled from untreated sows and piglets (n=57), weaned pigs treated with tylosin (n=68) and pigs of the same group 3-5 weeks after withdrawal of tylosin (n=15). Additionally, 48 weaned pigs were sampled after tylosin had not been administered for 7 months at the farm. MICs for seven antimicrobials were determined, isolates were genotyped by PFGE and mutations conferring macrolide resistance were identified. Resistance to at least one antimicrobial agent was higher (P<0.001) in the isolates from the treated pigs (30 of 56) than in those from the untreated animals (2 of 40). Resistance to ciprofloxacin, erythromycin, nalidixic acid and streptomycin was higher (P<0.05) in the isolates from the treated pigs than in those from the untreated animals. All 14 erythromycin-resistant isolates studied (MIC ≥ 512 μg/ml) contained mutation A2075G in 23S rRNA. Resistance against at least one antimicrobial was significantly lower (P<0.05) when tylosin had not been administered for 7 months. Resistance to erythromycin and streptomycin also decreased (P<0.05). PFGE analysis revealed a change of genotypes induced by tylosin treatment. In conclusion, tylosin treatment of pigs selected for a high-level of resistance to erythromycin and resistance to ciprofloxacin, nalidixic acid and streptomycin also increased in C. coli isolates within a few days.

Campylobacter genotypes from food animals, environmental sources and clinical disease in Scotland 2005/6

A nationwide multi-locus sequence typing (MLST) survey was implemented to analyze patterns of host association among Campylobacter jejuni and Campylobacter coli isolates from clinical disease in Scotland (July 2005-September 2006), food animals (chickens, cattle, sheep, pigs and turkey), non-food animals (wild birds) and the environment. Sequence types (STs) were determined for 5247 clinical isolates and 999 from potential disease sources (augmented with 2420 published STs). Certain STs were over represented among particular sample sets/host groups. These host-associated STs were identified for all sample groups in both Campylobacter species and host associated clonal complexes (groups of related STs) were characterized for C. jejuni. Some genealogical lineages were present in both human disease and food animal samples. This provided evidence for the relative importance of different infection routes/food animal sources in human disease. These results show robust associations of particular genotypes with potential infection sources supporting the contention that contaminated poultry is a major source of human disease.

Genotyping of Campylobacter coli isolated from humans and retail meats using multilocus sequence typing and pulsed-field gel electrophoresis

AIMS

To determine the antimicrobial resistant profiles and clonality of Campylobacter coli isolated from clinically ill humans and retail meats.

METHODS AND RESULTS

A total of 98 C. coli isolates (20 from humans and 78 from retail meats) were phenotypically characterized. Antimicrobial susceptibility testing was done using agar dilution method for ciprofloxacin, gentamicin, erythromycin and doxycycline. Seventy C. coli isolates including humans (n = 20) and retail meats (n = 50) were genotyped by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). Resistance to ciprofloxacin was found in 29% and 15% of isolates from retail meats and humans. We observed 61 PFGE profiles using two enzymes (SmaI, KpnI) with an Index of discrimination of 0.99, whereas MLST generated 37 sequence types. Two clonal complexes were identified with 58 (82%) C. coli isolates clustered in the ST-828 complex.

CONCLUSIONS

Resistance to ciprofloxacin and erythromycin was identified in C. coli obtained from retail meats and ill humans. PFGE typing of C. coli isolates was more discriminatory than MLST. Grouping of C. coli isolates (82%) by MLST in ST-828 clonal complex indicates a common ancestry.

SIGNIFICANCE AND IMPACT OF THE STUDY

A high frequency of resistance found to ciprofloxacin and erythromycin is concerning from food safety perspective. PFGE using single or double restriction enzymes was found to be more discriminatory than MLST for genotyping C. coli. Overall, the C. coli populations recovered from humans and retail meats were genotypically diverse.

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.

Genomic evidence for interspecies acquisition of chromosomal DNA from Campylobacter jejuni by Campylobacter coli strains of a turkey-associated clonal group (cluster II)

Previous multilocus sequence typing studies of Campylobacter coli from meat animals identified an unusual cluster of strains, primarily from turkeys, termed "cluster II" and characterized by the presence of the C. jejuni aspA103 allele. To characterize the extent of genomic input from C. jejuni in the aspA region of cluster II C. coli, we sequenced the 6.1 kb genomic region upstream of and including aspA from two turkey-derived cluster II strains (C. coli 6979 and C. coli 7474, of ST-1150 and ST-1161, respectively), as well as from a turkey-derived multidrug-resistant strain (C. coli 6818) representing a major sequence type (ST-1101) outside of cluster II. A gene encoding a putative CRP-family transcriptional regulator (CCO0137) was present in C. coli 6818 and the reference strain C. coli RM2228, whose genome has been sequenced, but not in either cluster II strain evaluated. This gene was also absent from C. jejuni NCTC 11168 and C. jejuni RM1221. Moreover, single nucleotide polymorphism (SNP) analysis revealed that in both cluster II strains, genes encoding subunit II of cytochrome d ubiquinol oxidase (cydB) and a putative aspartate racemase (Cj0085c) harbored numerous C. jejuni-specific SNPs. Interestingly, genes encoding subunit I of cytochrome d ubiquinol oxidase (cydA), uracil-DNA glycosylase (ung), and aspartate ammonia-lyase (aspA) harbored C. coli-specific SNPs in certain portions but C. jejuni-specific SNPs in others, suggesting that these were hybrid genes with C. jejuni-derived segments. Analysis of a ung mutant in C. coli 7474 indicated that the putative hybrid ung of this cluster II strain was functional. Our data suggest the occurrence of recombination events that resulted in genomic import of DNA from C. jejuni in the region between cydA and aspA in cluster II strains of C. coli.

Antimicrobial susceptibilities of Vibrio parahaemolyticus and Vibrio vulnificus isolates from Louisiana Gulf and retail raw oysters

The antimicrobial susceptibilities of 168 Vibrio parahaemolyticus and 151 Vibrio vulnificus isolates recovered from 82 Louisiana Gulf and retail oysters in 2005 and 2006 were determined. Overall, the two vibrios remained susceptible to the majority of antimicrobials tested; reduced susceptibility was detected only in V. parahaemolyticus for ampicillin (81%; MIC > or = 16 microg/ml). Additionally, V. parahaemolyticus displayed significantly higher MICs for cefotaxime, ciprofloxacin, and tetracycline than V. vulnificus.