Prevalence and antimicrobial resistance of Campylobacter coli isolated from fattening pigs in France

Campylobacter are a leading cause of human diarrhea. The usual source of infection is contaminated food, particularly poultry but pork has also been described. The veterinary use of antimicrobial drugs has been suggested to be largely responsible for resistance in human isolates of this zoonotic pathogen. A study was carried out to investigate the occurrence and antimicrobial resistance of Campylobacter isolated from French fattening pigs. From March 1998 to June 1999, stomach samples were collected at slaughter from 240 fattening pigs originating from 24 different farms. Half of the pigs were found to be positive for Campylobacter but considerable variation was observed between farms. Isolates all belong to the Campylobacter coli species. Susceptibilities of the strains were determined for five antimicrobial drugs using agar dilution. Resistance to tetracycline and erythromycin was high (79 and 55%, respectively). For nalidixic acid, enrofloxacin and ampicillin, resistance was observed in 34, 15 and 20% of the isolates, respectively. More than one-third of the strains was resistant to at least three antimicrobial drugs. A Thr86Ile modification in GyrA was observed in the enrofloxacin-resistant strains studied. The multiresistant strains analyzed expressed the multidrug transporter CmeB at a high level. Results indicated a high prevalence of C. coli in the stomach of the French pigs examined. In addition, a high proportion of the strains was resistant to antimicrobial drugs, particularly to tetracycline and erythromycin, or were multiresistant.     

Associations of antimicrobial uses with antimicrobial resistance of fecal Escherichia coli from pigs on 47 farrow-to-finish farms in Ontario and British Columbia

This study assessed the associations between antimicrobial use and other management practices in pigs and antimicrobial resistance in generic Escherichia coli recovered from feces of weaner and finisher pigs on 39 purposefully selected farrow-to-finish farms in Ontario and 8 in British Columbia. Antimicrobials (n = 13), most frequently penicillins and tetracycline, wer dministered to different age groups of pigs on study farms through various routes of administration. Logistic regression was used to model risk factors to antimicrobial resistance in fecal E. coli of pigs for the following antimicrobials: ampicillin, apramycin, carbadox, cephalothin, chloramphenicol, kanamycin, neomycin, nitrofurantoin, spectinomycin, streptomycin, sulfamethoxazole tetracycline, and cotrimoxazole (trimethoprim and sulfamethoxazole). Use of antimicrobials in weaner pigs compared with use in finisher pigs was associated with resistance in most models. There was phenotypic evidence of different mechanisms of resistance selection, including direct selection [use of carbadox was associated with carbadox resistance (OR = 6.48)]; cross-resistance [use of spectinomycin was associated with streptomycin resistance (OR = 2.29)]; and possible co-selection [ceftiofu use was associated with tetracycline resistance (OR = 6.12)]. These results provide further evidence that use of antimicrobials in pigs selects for resistance among fecal E. coli within and between classes of antimicrobials.     

Antimicrobial resistance of fecal Escherichia coli isolated from grow-finish pigs in 20 herds in Alberta and Saskatchewan.

Escherichia coli (n = 1439), isolated from the feces of apparently healthy grow-finish pigs in 20 herds in Alberta and Saskatchewan, were tested for susceptibility to 16 antimicrobials. All isolates were susceptible to amikacin, ceftriaxone, and ciprofloxacin and less than 1% was resistant to amoxicillin-clavulanic acid, cefoxitin, ceftiofur, gentamicin, and nalidixic acid. Resistance was most common to tetracycline (66.8%), sulfamethoxazole (46.0%) and streptomycin (33.4%). Twenty-one percent of the isolates were susceptible to all drugs, while 57% were resistant to 2 or more antimicrobials. Unconditional associations between resistances provided insight into the potential for co-selection. Every resistance-outcome was associated with at least 2 other drug-resistances. These associations illustrate the propensity for resistance phenotypes to occur together and the importance of considering co-selection in antimicrobial use decisions. A 2nd analysis explored the associations between resistance phenotypes in E. coli and Salmonella spp. from the same herd. Only 2 resistances in Salmonella were associated with herd-level E. coli resistance, indicating that E. coli is a poor sentinel for Salmonella AMR within herds. Herd-level management, including antimicrobial use, could affect antimicrobial resistance. The intra-class correlation between isolates within herds ranged from 0.1 to 0.46, which confirmed resistance clustered within herds. This suggests herd-level interventions might mitigate antimicrobial resistance. Overall, these results reflect the on-farm selection pressure for resistance and the potential food-safety risk from near-market animals. These data provide a baseline for comparisons with future on-farm monitoring of antimicrobial resistance in E. coli.     

Associations between antimicrobial use and the prevalence of antimicrobial resistance in fecal Escherichia coli from feedlot cattle in western Canada

A randomized, controlled, blinded clinical trial was performed at a research feedlot in western Canada. Auction-market-derived steers (n = 288) were randomly assigned to 1 of 3 treatments: 1) no antimicrobials on arrival; 2) oxytetracycline in the starter ration for 14 d; and 3) long-acting oxytetracycline subcutaneously on day 0. Minimal inhibitory concentrations of 7 antimicrobials were determined for 3 generic fecal E. coli isolates per animal on arrival and throughout the feeding period. There was a low prevalence of antimicrobial resistance in generic E. coli isolates from calves on arrival. There were increased proportions of cattle with resistant E. coli isolates early in the feeding period among calves in groups 2 and 3. Individual animal treatments were not associated with increased proportions of cattle with resistant E. coli isolates preslaughter. There was no difference in the proportion of animals with E. coli isolates resistant to tetracycline between the treatment groups preslaughter. However, there were significantly more animals with tetracycline resistant isolates of E. coli preslaughter than at arrival.     

Antimicrobial resistance in Campylobacter from broilers: association with production type and antimicrobial use

The isolation and antimicrobial resistance of Campylobacter jejuni and Campylobacter coli strains from broilers arriving in French slaughterhouses, were analysed according to production types (i.e. standard, export or free-range) and antimicrobial (i.e. coccidiostats, growth promoters or therapeutic agents) administration in flocks. Prevalence was 56.6% in standard, 51.3% in export and 80.0% in free-range broilers. Three hundred and ninety-three strains were identified. Two-thirds of the strains belonged to the species C. jejuni. The others were C. coli. Antimicrobial susceptibility testing was carried out for ampicillin, nalidixic acid, enrofloxacin, tetracycline, erythromycin and gentamicin according to a dilution method. The percentages of resistant strains were, 23, 25, 17, 57, 0.3 and 0% for C. jejuni and 29, 43, 40, 70, 31 and 0% for C. coli. Statistical analysis revealed significant difference in distribution of C. jejuni and C. coli and antimicrobial resistance according to production type or antimicrobial administration.     

Genotypes and antibiotic resistance of Campylobacter coli in fattening pigs

Campylobacter coli is a food-borne zoonotic pathogen causing human gastroenteritis worldwide. The organism is a commensal in the intestine of many food production animals including fattening pigs. The role of the pig as a potential reservoir for C. coli affecting human either directly or via poultry has hardly been investigated and genetic characterization of porcine strains is needed to address this question. For this aim multilocus sequence typing (MLST) and flaB typing was applied to 256 C. coli isolates from faeces of fattening pig collected during 2009 at different slaughterhouses in Switzerland. In addition genotypic resistances towards macrolides and quinolones based on point mutations in the 23S rRNA and gyrA genes, respectively, were determined. Of the 67 sequence types (STs) obtained by MLST, 37 were found for the first time. flaB typing revealed 46 different types with 14 of them being novel and was useful to further differentiate strains with an identical ST. Quinolone resistance was detected in 33.6% and macrolide resistance was found in 10.6% of isolates. Comparison with 99 C. coli pig isolates from 2001 revealed a significant decrease in antibiotic resistance towards both groups of antibiotics and there was high overlap between genotypes of 2001 and 2009. Little overlap of porcine genotypes was found with 97 C. coli isolates from poultry collected 2008, however, macrolide resistance was significantly higher in pig isolates. In conclusion, C. coli from Swiss pig are heterogeneous containing many novel STs, findings that could reflect the partitioned Swiss pig production with almost no international breed exchange. The antibiotic resistance echoes the use of corresponding drugs in the Swiss livestock production and indicates the efficacy of restrictive application of antibiotics in order to reduce resistances.     

Longitudinal on-farm study of the development of antimicrobial resistance in Campylobacter coli from pigs before and after danofloxacin and tylosin treatments

Effects of danofloxacin or consecutive fluoroquinolone and macrolide treatments on resistance development in Campylobacter have remained uncharacterised. Therefore we analysed the development of resistance in porcine Campylobacter coli before and after danofloxacin and tylosin treatments at a farrowing farm. Danofloxacin-treated (n=12, group A) and control pigs (n=15, group B) were subsequently treated with tylosin and sampled longitudinally. C. coli were isolated and susceptibilities to ciprofloxacin and erythromycin were assessed, isolates were genotyped with PFGE and resistance-related mutations were identified. Isolates from the danofloxacin-treated pigs had more frequently non-wild type MICs (above the epidemiological cut-off value (ECOFF)) for ciprofloxacin (P<0.001) and erythromycin (P<0.05) than those isolated before danofloxacin or those from the controls. Subsequent tylosin treatment increased proportion of isolates with non-wild type MICs for erythromycin in both groups A and B (P<0.01) and, interestingly, proportion of isolates with non-wild type MICs for ciprofloxacin in group B (P<0.001) with high MICs (128 μg/ml). PFGE analysis revealed treatments selecting predominant genotypes with variable resistance patterns and decreasing initial diversity of genotypes. The most common genotype had mainly high MICs for ciprofloxacin among danofloxacin-treated pigs but wild type MICs (below the ECOFF) among the controls housed in the same pens. This suggests that the non-wild type isolate was rarely transmitted or outcompeting wild type genotype in the control pigs without selection pressure. Isolates exhibiting non-wild type MICs for ciprofloxacin harboured the C257T (Thr-86-Ile) mutation in the gyrA gene. In conclusion, a high dose of danofloxacin used at the farm did not prevent emergence of isolates with high MICs for ciprofloxacin. After subsequent tylosin treatment isolates had even higher MICs for ciprofloxacin and erythromycin than before the treatment. Therefore, controlled use of antimicrobials in food animal production is essential.     

Antimicrobial resistance in Campylobacter spp. isolated from Ontario sheep flocks and associations between antimicrobial use and antimicrobial resistance

The objectives of this study were to determine the prevalence of antimicrobial resistance (AMR) in faecal Campylobacter spp. from lambs and adult sheep and associations between antimicrobial use (AMU) and AMR. A total of 275 faecal samples collected during initial and final visits from 51 sheep flocks, including one feedlot, across southern Ontario were tested for the presence of Campylobacter spp. Campylobacter jejuni was detected in 52% (143/275) of the faecal samples, Campylobacter coli in 7% (19/275), Campylobacter lari in 1% (2/275) and 2% (4/275) were non-speciated Campylobacter. Broth microdilution was used to test antimicrobial susceptibility of 162 isolates to nine antimicrobials. Campylobacter jejuni isolates (n = 142) were resistant to tetracycline (39%), ciprofloxacin (4%), nalidixic acid (4%) and telithromycin (1%). C. coli isolates (n = 19) were resistant to tetracycline (74%), and azithromycin, clindamycin, erythromycin, and telithromycin (5%). The C. lari isolate displayed resistance to nalidixic acid. No statistically significant associations were found between AMU and AMR during multivariate modelling in this study.     

Campylobacter spp in human,chickens, pigs and their antimicrobial resistance

Campylobacter spp. have been identified as etiologic agents in outbreaks and sporadic cases of gastroenteritis in developed countries. In developing countries, most reported Campylobacter infections are in children. Previously reported prevalences of Campylobacter spp. in children in Southeast Asia range from 2.9% to 15%. The frequency and pattern of occurrence of Campylobacter spp. differ between developed and developing countries, especially in the number of cases reported in adults and the presence of any seasonal patterns in occurrence. Although the severity of Campylobacter infection in adults was different between developed and developing countries, the clinical symptoms of infection in adults resulting from infection in developing countries was similar to those in developed countries. Many different animal species maintain Campylobacter spp. with no clinical signs. There do not appear to be significantly different colonization rates of Campylobacter in food animals between developed and developing countries. The role of C. jejuni as a primary pathogen in farm animals is uncertain. C. jejuni can be found in feces of diarrheic and healthy calves and piglets. Campylobacter with resistance to antimicrobial agents have been reported in both developed and developing countries, and the situation seems to deteriorate more rapidly in developing countries, where there is widespread and uncontrolled use of antibiotics resistance was observed at high levels in food animals in both developed and developing countries. Studies suggested an association between antimicrobial use in food animals and the development of resistance in human isolates in developed countries.     

弯曲菌耐药性的研究进展

弯曲菌耐药性已经成为全球关注的重点,尤其是对氟喹诺酮类和大环内酯类的耐药性,在人和动物表现更为严重。本文对人和动物弯曲菌临床耐药性的状况、生物杀菌剂耐药性和环境因素在弯曲菌耐药性的获得与传播中的作用等方面进行综述。     

Antimicrobial resistance in Campylobacter spp., Escherichia coli and enterococci associated with pigs in Australia

The major influences on the amplification and spread of antibiotic-resistant bacteria are the therapeutic use of antibiotics in human medicine and their use in livestock for therapy, prophylaxis and growth promotion. The use of veterinary antibiotics has many benefits to the livestock industries ensuring animal health and welfare, but use at subtherapeutic levels also exerts great selective pressure on emergence of resistant bacteria. The possible effect on human health is a problem of current debate. This study involved sampling pig carcasses, pig meat and assessing the level of resistance in zoonotic enteric bacteria of concern to human health. In South Australian pigs, thermophilic Campylobacter species showed widespread resistance (60-100%) to tylosin, erythromycin, lincomycin, ampicillin and tetracycline. No resistance was seen to ciprofloxacin. The enterococci demonstrated little resistance (0-30%) to vancomycin or virginiamycin, but the overall results from the antibiotic sensitivity testing of the enterococci have demonstrated how widespread their resistance has become. Escherichia coli strains showed widespread resistance to tetracycline and moderately common resistance (30-60%) to ampicillin and sulphadiazine. Resistance to more than one antibiotic was common. Pigs from New South Wales were also sampled and differences in resistance patterns were noted, perhaps reflecting different antibiotic use regimens in that state.     

Genetic diversity in fluoroquinolone and macrolide-resistant Campylobacter coli from pigs

The genetic diversity of 115 Campylobacter coli strains, isolated from pigs of 59 geographical distant farms in Switzerland, were characterized on the basis of their DNA fingerprints and resistance to macrolides and fluoroquinolones. Sequence analysis showed that the macrolide-resistant isolates had a point mutation in the 23S ribosomal RNA (rRNA) genes (A2075G) and that the fluoroquinolone-resistant isolates had a point mutation in the gyrase gene gyrA (C257T). One fluoroquinolone-resistant strain had an additional transition mutation in the gyrB gene (A1471C). The flaA restriction fragment length polymorphism (RFLP) genotyping revealed that 57% of the isolates were genetically different. Point mutations in the 23S rRNA and gyrA genes could be found in both genetically distant and genetically related isolates. Additionally, isolates with and without point mutations were found within individual farms and on different farms. This study showed that the ciprofloxacin and erythromycin-resistant C. coli population present on the pig farms is not issued from a common ancestral clone, but individual Campylobacter strains have most likely mutated independently to acquire resistances under the selective pressure of an antibiotic.     

Prevalence and antimicrobial resistance of Campylobacter and Salmonella in layer flocks in Honshu,Japan

Campylobacter and non-typhoidal Salmonella are the major causes of bacterial gastrointestinal infections in humans. Although antimicrobial therapy is typically not recommended in many cases of these infections, it may be life-saving in patients with severe symptoms. Since chicken eggs and meat derived from layers are destined for human consumption, we investigated the prevalence and antimicrobial resistance of these two bacterial genera in 82 layer flocks at chicken processing plants in Honshu, Japan. Campylobacter was isolated from 77 flocks (93.9%). Resistance to ampicillin, tetracycline, and ciprofloxacin was documented in 42.3 (30/71), 16.9 (12/71), and 14.1% (10/71) of Campylobacter jejuni, respectively. Multilocus-sequence typing identified ST4389 and ST5262 as the most frequent C. jejuni sequence types. In C. coli, resistance to ampicillin, tetracycline, and ciprofloxacin was found in 20.0 (7/35), 20.0 (7/35), and 25.7% (9/35), respectively. The most frequent sequence type in C. coli was ST8292. Erythromycin resistance was not observed among Campylobacter species. Salmonella was isolated from 14 flocks (17.1%). The two most frequent serovars were Salmonella Corvallis and S. Braenderup. Neither S. Enteritidis nor S. Infantis were isolated. Streptomycin resistance was observed in six isolates (26.1%), and all isolates were susceptible to cefotaxime and ciprofloxacin. Thus, chicken eggs and meat derived from layers are possible sources of these bacterial infections in humans. The antimicrobial susceptibility of these isolates was maintained, reflecting restrictions on the use of antimicrobial agents on layers.     

猪致病性大肠杆菌耐药性与整合子-基因盒的相关性

为了解猪致病性大肠杆菌耐药性与整合子-基因盒的相关性,本研究采用腹腔注射法测定52株大肠杆菌对昆明小鼠的致病性;采用K-B法测定致病性大肠杆菌对15种抗菌药物的敏感性;对致病性大肠杆菌Ⅰ、Ⅱ和Ⅲ型整合子及其基因盒进行PCR检测及测序分析,并分析其整合子-基因盒与耐药性的相关性。结果显示,52株大肠杆菌对小鼠均具有较强致病性,96.15%分离株对15种抗菌药物表现为多重耐药性,61.54%分离株耐药性均在八重耐药以上。Ⅰ、Ⅱ和Ⅲ型整合子阳性率分别为84.62%,15.38%和3.85%。Ⅰ型整合子检测到dfrA17-aadA5(18.18%)、dfrA12-orfF-aadA2(4.55%)和dfrA1-catB3-aacA4(4.55%)基因盒,Ⅱ型整合子检测到dfrA1-sat2-aadA1(50.00%)基因盒,Ⅲ型整合子未检测到基因盒,基因盒阳性率与细菌耐药性不存在相关性。     

Molecular typing and antimicrobial resistance of Salmonella enterica subspecies enterica serovar Choleraesuis isolates from diseased pigs in Japan

Salmonella enterica serovar Choleraesuis (S. Choleraesuis) isolates derived from diseased pigs in Japan during 2001 and 2005 were analyzed for biotype, based on H(2)S production and dulcitol fermentation, pulsed-field gel electrophoresis (PFGE) profile, and antimicrobial resistance profile. S. Choleraesuis biotype Choleraesuis (biotype Choleraesuis) was classified into one genotype, while varietas Kunzendorf (var. Kunzendorf) was classified into two genotypes. The isolates of var. Kunzendorf belonging to one genotype were isolated in a limited area of Japan. Variation in the antimicrobial resistance pattern was observed in isolates of both biotypes Choleraesuis and var. Kunzendorf. We have also shown that the PFGE profile was associated with the biotype and isolation region of each isolate.     

Fecal shedding of Campylobacter jejuni and Campylobacter coli among feral pigs in Texas

The population and range of feral pigs in the United States are rapidly expanding, yet key knowledge gaps exist regarding their role in the ecology and transmission of foodborne pathogens. Our objectives were to estimate the prevalence of Campylobacter jejuni and Campylobacter coli shedding among feral pigs throughout Texas and to identify risk factors for positive status. Faecal samples were collected from feral pigs in Texas from February 2014 through May 2015, and target organisms were detected using PCR assays. The prevalence of C. jejuni shedding was 1.6% (6/370), and the prevalence of C. coli shedding was 3.5% (13/370). C. coli shedding was significantly more common (p = .008) among female pigs than among male pigs. Feral pigs may represent a source of human campylobacteriosis.     

Prevalence and antimicrobial resistance of Campylobacter from wild birds of prey in Spain

Wild birds have been identified as a relevant reservoir of Campylobacter spp., therefore, a potential source of infection in humans and domestic animals. The objective of this study was to determine the occurrence of Campylobacter spp. on birds of prey in Spain. In addition, antibiotic resistance profiles of the isolates were evaluated. A total of 689 specimens of 28 raptor species were analyzed, with a resulting individual prevalence of 7.5%. C. jejuni was the most frequently isolated species (88.5%), followed by C. coli and C. lari (3.8% each). The occurrence of Campylobacter was significantly higher (p < 0.05) in nocturnal birds of prey (15.3%), in spring season (12.2%) and in carnivorous species (9.4%). Isolates displayed a remarkable resistance to nalidixic acid (69.9%), ciprofloxacin (69.9%), and tetracycline (55.6%), and a low resistance to streptomycin (6.7%).Our findings highlight the importance of birds of prey as reservoirs of Campylobacter strains and their significant role as carriers of antimicrobial resistance.