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1.
A dramatic rise in the number of resistant Campylobacter to quinolones has been documented in human patients and domestic animals. In this study, the mechanism of acquisition of quinolone resistance was studied by detecting point mutations in the gyrA gene of Campylobacter strains obtained from broilers and strains with in vitro-induced resistance. The minimal inhibitory concentrations (MICs) of norfloxacin (NFLX) and ofloxacin (OFLX) for the strains that had no point mutation were slightly increased from the source strain (Campylobacter jejuni ATCC 33560). The MICs of nalidixic acid (NA), NFLX, and OFLX for the strains that had the point mutation at Thr-86 were 100 or 200 microg/ml, 50 microg/ml, and 25 microg/ml, respectively. The MIC of NA for the strain that had a point mutation at Asp-90 higher than those for the strains that had the point mutation at Thr-86, but the MICs of NFLX and OFLX were relatively lower than those for the strains that had point mutation at Thr-86. These findings suggest that the degree of antimicrobial resistance against NA, NFLX, and OFLX in the in vitro-induced C. jejuni strains was associated with the location of the point mutation in gyrA. On the other hand, a point mutation in all seven resistant strains isolated from broilers was located only at Thr-86, while the MICs of the three quinolones varied in each wild strain. This suggests that another mechanism might also be involved in the acquisition of quinolone resistance in C. jejuni wild strains.  相似文献   

2.
The aim of this study was to evaluate the incidence and the distribution of antimicrobial resistance, and the presence of genetic determinants of resistance, in Campylobacter recovered from swine, poultry, and human populations in Quebec. Minimum inhibitory concentrations (MICs) of 10 antimicrobial agents were determined by the agar dilution technique. Polymerase chain reaction (PCR) was used to detect the tetO determinant, and mutations in gyrA were analyzed by sequencing and by mismatch amplification mutation assay (MAMA) PCR. Among C. coli isolates from pigs, the rates of resistance were high, at 59% for clindamycin, 61% for erythromycin, 67% for streptomycin, and 68% for tetracycline; isolates from chicken broilers were mainly resistant to streptomycin and tetracycline, with a rate of 50% for each; and 56% of the isolates from humans were resistant to tetracycline. The rates of resistance among C. jejuni isolates were low except for tetracycline (39% and 67% in humans and broilers, respectively). The tetO determinant was identified among both tetracycline-resistant and tetracycline-susceptible Campylobacter isolates from swine. Sequencing analysis showed that 64% and 100% of ciprofloxacin-resistant C. coli isolates from swine and humans, respectively, had the mutation Thr-86-->Ile, which is associated with quinolone resistance. The MAMA PCR gave identical results. Further analyses need to be done in order to detect other genetic determinants of tetracycline resistance.  相似文献   

3.
Anti‐microbial resistance is an emerging public health issue. Farmed animals may act as reservoirs and potential sources of anti‐microbial resistant Campylobacters. The aim of this study was to investigate the anti‐microbial resistance profile of cattle and environmental Campylobacter isolates from normal untreated feedlot cattle, the role of the gyrA Thr‐86‐Ile mutation in ciprofloxacin‐resistant Campylobacter jejuni isolates and the involvement of the tripartite CmeABC efflux system for multi‐resistant C. jejuni isolates. The phenotypic anti‐microbial resistance testing was carried out on 500 Campylobacter isolates (445 cattle isolates and 55 environmental isolates). In general, there was a higher level of anti‐microbial resistance for the environmental isolates compared with the animal isolates, 45% of the animal isolates were resistant to one or more of the seven anti‐microbials compared with 84% of the environmental isolates. The combined cattle and environmental Campylobacters had 34 (6.8%) isolates resistant to three or more of the seven anti‐microbials tested on all isolates and 11 (2.2%) isolates were resistant to the seven anti‐microbials. There was a substantial level of ciprofloxacin‐resistant Campylobacters in both animal (8.5%) and environmental (21.8%) isolates. The gyrA Thr‐86‐Ile mutation was only present in five of 22 ciprofloxacin‐resistant C. jejuni isolates investigated. No multi‐drug‐resistant associated mutation was detected in the CmeB or the CmeR regions investigated. In conclusion, our study observed a substantial level of Campylobacter anti‐microbial resistance, highlighting the need for an active anti‐microbial surveillance program for food animals in Ireland and the importance of the chosen sampling point can have on the findings of such a program.  相似文献   

4.
Thermotolerant Campylobacter spp., in particular Campylobacter jejuni, are among the most frequently identified pathogens, found to be causing human gastrointestinal infections in Europe, with the Czech Republic being no exception. The presented work aimed at assessing results of the first nationwide monitoring of prevalence and antibiotic resistance of Campylobacter spp. in broiler flocks in the Czech Republic, including a comparison of antibiotic resistance of C. jejuni isolates collected from poultry and the human community. The monitoring was carried out in poultry slaughterhouses in 2006 and 2007. From broilers, cloacal swabs were collected and examined. The human isolates of C. jejuni were acquired from rectal swabs in community patients with diarrhoeal diseases. Suspected isolates of both animal and human origin were confirmed by the PCR methods. Antibiotic resistance to selected anti-microbial agents was tested by the microdilution method. In the monitored period, the prevalence of thermotolerant Campylobacter spp. in broilers in the Czech Republic reached almost 50%. In 2006, C. jejuni was detected in 46% and Campylobacter coli in 3% of the tested samples. In 2007, C. jejuni was found in 43% and C. coli in 2% of the samples. The results of anti-microbial susceptibility testing of C. jejuni showed higher resistance in animals when compared with humans. The only exception was tetracycline with higher resistance in isolates of human origin. The highest resistance detected was to quinolone antibiotics. Resistance to oxolinic acid was 77% in animal and 60% in human isolates, to ciprofloxacin 72% in isolates from poultry and 55% in those from humans. In ampicillin, 26% of poultry isolates and 16% of human isolates were resistant. Moreover, 9% of animal isolates demonstrated resistance to streptomycin, undetected in human isolates. In erythromycin, resistance was found in 6% of poultry and 1% of human isolates.  相似文献   

5.
Measurements were made of the susceptibility to six commonly prescribed antibiotics, including erythromycin, tetracycline and ciprofloxacin, of 130 isolates of Campylobacterjejuni and 15 isolates of Campylobacter coli cultured from human and poultry sources during 2000. The results were compared with the results from a collection of strains isolated between 1996 and 1998. The levels of resistance to erythromycin remained low, 2 per cent and 4.4 per cent for the human and poultry isolates, respectively. Resistance to tetracycline had increased to 31 per cent and 24.4 per cent from 13.9 per cent and 18.8 per cent for the human and poultry isolates, respectively. However, the resistance to ciprofloxacin of the strains isolated during 2000 had increased to 30 per cent, whereas between 1996 and 1998 there had been no resistance to this agent among human isolates, and only 3.1 per cent resistance among poultry isolates. The molecular basis for this resistance has been shown to be the result of a single amino acid substitution, Thr-86-Ile, in the gyrA subunit of DNA gyrase in Cjejuni. A subset of 59 isolates was tested by molecular methods and all of the 25 phenotypically resistant isolates possessed this substitution. None of the human isolates had been treated with ciprofloxacin before their laboratory isolation.  相似文献   

6.
The purpose of this study was to investigate the genetic similarity of Campylobacter jejuni and Campylobacter coli with similar antimicrobial resistance phenotypes, isolated from cattle on different farms and at different times, in order to evaluate the possible existence of disseminated antimicrobial resistant clones. PFGE after SmaI and KpnI restriction identified 23 and 16 distinct PFGE patterns among 29 C. jejuni and 66 C. coli isolates, respectively. In C. coli, 51 (77%) of the resistant isolates demonstrated one of the four indistinguishable PFGE patterns, whereas only 24% doxycycline resistant C. jejuni shared one of the two indistinguishable PFGE patterns. The genetic mechanisms of resistance were homogeneous within and between these clonal types. Genetically indistinguishable (clonal) groups of C. coli accounted for most Campylobacter sp. with multiple antimicrobial resistance observed in this study, consistent with a role for clonal dissemination in the epidemiology of resistance in this species.  相似文献   

7.
The objective of the present study was to determine whether selection of fluoroquinolone resistance could be easily induced in Campylobacter jejuni-colonized chickens by treatment with enrofloxacin of representative fluoroquinolones at the inherent dosage licensed in Japan (50 ppm in drinking water for 3 days). In the case of isolates from chickens of study 1, an increase in the population of susceptible isolates appeared after the cessation of treatment and maintained throughout the experiments. On the contrary, our results of study 2 demonstrated that administration of enrofloxacin generated a rapid increase of fluoroquinolone resistance in C. jejuni showing the mutation of Asp-90-Asn in the gyrA gene. Present results indicate that the enrofloxacin treatment for broilers at the inherent dosage is able to select fluoroquinolone resistance in C. jejuni. We conclude that whatever enrofloxacin dosage is used, an emergence of fluoroquinolone resistant of C. jejuni occurs.  相似文献   

8.
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.  相似文献   

9.
Thermophilic Campylobacter species, including Campylobacter jejuni and Campylobacter coli, are responsible for foodborne campylobacteriosis in humans and are increasingly resistant to fluoroquinolone (FQ) antimicrobials. The therapeutic use of FQ antimicrobial agents in food animal production, particularly in poultry, has become a concern for public health, because the practice may promote the emergence of FQ-resistant Campylobacter that can be transmitted to humans through the food chain. Recent studies have indicated that Campylobacter displays a hypermutable phenotype in response to in vivo treatment with FQ antimicrobials, resulting in the rapid emergence of resistant mutants. Distinct from other Gram-negative bacteria, the acquisition of FQ resistance in Campylobacter does not require stepwise accumulation of gyrA mutations and overexpression of efflux pumps, and is mainly mediated by single-step point mutations in gyrA in the presence of a constitutively expressed multidrug efflux pump, CmeABC. The simplicity of the resistance mechanisms may facilitate the rapid adaptation of Campylobacter to FQ treatment. The FQ-resistant Campylobacter mutants derived from chickens do not show a fitness cost in vivo and are ecologically competitive in the colonization of chickens even in the absence of antimicrobial selection pressure. These findings suggest that FQ-resistant Campylobacter may continue to persist regardless of antimicrobial usage, and highlight the need for extra effort to prevent the occurrence and spread of FQ-resistant Campylobacter in animal reservoirs.  相似文献   

10.
The current study aimed at determining the prevalence and the antimicrobial resistance profiles of thermophilic Campylobacter spp. infecting broiler chickens. A total of 240 caecal samples from six slaughterhouses were examined for the presence of Campylobacter spp. C. jejuni was detected in 40.4% (97/240) of the samples and C. coli in 12.1% (29/240). The agar disc diffusion method and the E-test were used for testing the antimicrobial susceptibility of C. jejuni and C. coli isolates. C. jejuni isolates were most resistant to nalidixic acid (79.4%) followed by tetracycline (76.3%), ciprofloxacin (74.2%) and enrofloxacin (15.5%). Among the C. coli isolates, the frequency of resistance to nalidixic acid and ciprofloxacin was the same at 65.5%. The predominant profiles of multidrug resistance to three or more antimicrobials in C. jejuni and C. coli were determined as tetracycline/nalidixic acid/ciprofloxacin resistance (48.5%) and tetracycline/nalidixic acid/ciprofloxacin/enrofloxacin resistance (51.7%), respectively. To prevent the transmission of antimicrobial-resistant bacteria of animal origin to humans, it should be noted that high proportions of multidrug resistance were found in both species.  相似文献   

11.
The aim of this study was to determine antimicrobial resistance of Aeromonas hydrophila isolated from farmed Nile Tilapia. A total of 50 A. hydrophila isolates from clinical cases were screened for the presence of class 1, 2 and 3 integrons and all the strains resistant to enrofloxacin and/or ciprofloxacin (n=19) examined for mutation in the quinolone resistance-determining regions (QRDRs) of gyrA and parC. The intI1 gene was detected in 23 A. hydrophila strains (46%) but no intl2 and intl3 were detected. Among these, 14 isolates (60.8%) carried gene cassettes inserted in variable regions i.e., partial aadA2, aadA2, dfrA1-orfC and dfrA12-aadA2, of which the most common gene cassette array was dfrA12-aadA2 (26.09%). Conjugal transfer of class 1 integrons with resistance gene array was detected. All the A. hydrophila strains resistant to enrofloxacin and/or ciprofloxacin possessed mutations in the QRDRs of gyrA and parC. Only a Ser-83-Ile substitution was identified in GyrA and only a Ser-80-Ile amino change was found in ParC. The data confirms that A. hydrophila from farm-raised Nile Telapia serve as a reservoir for antimicrobial resistance determinants.  相似文献   

12.
The aim of this study was to investigate faecal shedding and transmission of Campylobacter spp. in cohorts of cattle within a feedlot, to assess subsequent contamination of carcasses with this pathogen and to identify risk factors associated with faecal shedding of Campylobacter spp. A cohort of 133 heifers housed in four adjacent pens was examined over a five and a half month period, from entering the feedlot to slaughter. A parallel investigation of individual rectal faecal samples and pen environmental samples were taken at monthly intervals from November to February. The entire outer and inner surfaces of a carcass side of each animal were swabbed immediately following slaughter. Campylobacter spp. were isolated from 322 (54%) of the 600 rectal faecal samples. Campylobacter jejuni and C. coli accounted for 69 and 29.7% of the isolate recovered, respectively. A total of 159 environmental samples were examined, of these Campylobacter spp. was isolated from 46 samples (29%). Campylobacter jejuni and C. coli accounted for 35 and 59% of these isolates, respectively. Campylobacter spp. was not isolated from any of the dressed carcasses. Logistic regression indicated prevalence of Campylobacter spp. faecal shedding within pens was positively correlated to the pen, the month of sampling and the Campylobacter spp. contamination status of the pen dividing bars and the water trough surface. Campylobacter spp. should be considered as a pathogen shed in the faeces of a substantial proportion of feedlot cattle. However, with good hygienic practice during harvest, a very low level of this pathogen can be achieved on dressed carcasses.  相似文献   

13.
从307份鸡盲肠内容物样品中分离到47株空肠弯曲杆菌,并测定这些空肠弯曲杆菌耐药性,结果显示对喹诺酮类药(环丙沙星)耐药性为31.9%;对氨苄青霉素,克林霉素和红霉素耐药性较高,分别达到85.1%、83.0%和83.0%;而对痢特灵和庆大霉素则较为敏感,敏感度分别为85.1%和74.5%。有89.4%的菌株显示多重耐药性。利用MAMAPCR技术,对获得的47株空肠弯曲杆菌进行检测,结果显示对环丙沙星耐药的15株空肠弯曲杆菌均检测出其在gyrA基因257位发生点突变,30株对喹诺酮药物敏感的菌株均未检出。另外2株对环丙沙星耐药的菌株,有1株检测出点突变。  相似文献   

14.
沙门氏菌耐药株gyrA基因和parC基因突变特征分析   总被引：3，自引：0，他引：3  
提取沙门氏菌染色体DNA，设计引物扩增gyrA基因和parC基因片段，克隆测序寻找耐药菌株的突变位点，通过系统的比较，分析氟喹诺酮类药物（以环丙沙星为代表）对各沙门氏菌MIC和耐药突变位点之间的关系。通过对耐药突变位点的研究，可以为下一步研究耐药性监测的快速方法提供理论基础。  相似文献   

15.
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.  相似文献   

16.
AIM: To investigate the role of free-living animals such as sparrows, rodents and flies as potential reservoirs of Campylobacter spp on a dairy farm, and to assess the genetic diversity among Campylobacter isolates from the farm and an urban source. METHODS: A total of 290 samples (bovine, passerine and rodent faeces, and whole flies) were collected from a large commercial dairy farm in the Manawatu district in New Zealand, and from faeces from urban sparrows in a nearby city. Other samples collected from the dairy farm included five from silage, two from aprons worn by workers during milking, two from workers' boots and two from water in troughs in a paddock. Isolates of thermophilic Campylobacter spp were identified morphologically and phenotypically and further characterised molecularly using pulsed-field gel electrophoresis (PFGE) and the restriction enzyme SmaI. RESULTS: Campylobacter jejuni was the only Campylobacter species isolated from all samples. The highest prevalence was found in faeces from dairy cows (54%), followed by faeces from sparrows from the urban area (40%) and the farm (38%), and from rodents (11%) and whole flies (9%). Other samples from the farm environment such as silage, trough water, and workers' aprons and boots were also positive for C. jejuni. Of the 22 restriction patterns obtained, seven were common to more than one source. CONCLUSIONS: Cattle, sparrows, rodents and flies are potential reservoirs of C. jejuni on dairy farms. Identical clones of C. jejuni carried by cattle, sparrows, flies and rodents probably indicate a common source of infection. The high level of asymptomatic carriage of C. jejuni by healthy dairy cows could be sufficient to maintain infections within the dairy farm surroundings via environmental contamination.  相似文献   

17.
One hundred and twenty five chickens from Grenada, consisting of 77 broilers and 48 layers were examined for carriage of thermophilic campylobacters in their ceca by culture. Seventy nine percent of chickens were positive for campylobacters, with an isolation rate of 93.5% for broilers and 56.3% for layers, the difference being significant. Sixty-four pure cultures comprising 39 Campylobacter coli, 21 Campylobacter jejuni, and 4 Campyilobacter lari isolates were tested for their resistance against 7 antibiotics using the E-test. None of the isolates were resistant to chloramphenicol and gentamicin. Resistance rates to other drugs were: ampicillin, 9.4%; ciprofloxacin, 12.5%; erythromycin, 3.1%; metronidazole, 9.4%, and tetracycline, 50% with MICs of >or=256 microg/mL for tetracycline. There were no significant differences in resistance rates between C. coli and C. jejuni. Multiple resistance to >or=2 drugs was seen in 15.6% of total isolates. All C. lari isolates were resistant to ciprofloxacin, and 3 of 4 isolates had multiple drug resistance. Overall, erythromycin, which is the drug of choice for treatment of Campylobacter infections in humans, is effective in vitro against 97% of chicken isolates in Grenada.  相似文献   

18.
Thermotolerant Campylobacter spp. are frequent causes of diarrhoea in humans worldwide mostly originating from poultry. It has been suggested that extensive veterinary use of antibiotics is largely responsible for resistance in human isolates. During a 4-month period from January to April 2004, 192 Campylobacter spp. were isolated from fecal samples of 485 healthy food animals. The in vitro susceptibility to 12 antibiotics was determined by the agar disk diffusion method. Among the 192 Campylobacter spp. isolated, 135 (70.3%) were identified to be C. jejuni, 51 (26.6%) were C. coli and 6 (3.1%) were C. lari. C. jejuni was the most prevalent species in chickens (80.8%) versus 16.2% C. coli and 3.0% C. lari. All isolates found in pigs were C. coli. All strains were sensitive to chloramphenicol and ciprofloxacin and all were resistant to cephalothin. More than 90% of the strains were sensitive to clindamycin, erythromycin, gentamicin, nalidixic acid, norfloxacin, streptomycin and tetracycline. Resistance was found against ampicillin in 20% and trimethoprim-sulphamethoxazole in 37.5%. Resistance was not statistically different among C. jejuni, C. coli and C. lari (p>0.05). Multidrug resistance to two or more drugs was detected in 14.5% of strains. In conclusion, the study showed that antimicrobial resistance is found only at relatively low frequencies for most antimicrobial agents tested except for ampicillin and trimethoprim-sulphamethoxazole. The low percentages of resistance to most antimicrobial agents tested in this study may be the result of low/no usage of these agents as a growth promoters or treatment in the Ethiopian animal farm setting. The detection of multidrug resistant isolates may pose a threat to humans and further limits therapeutic options.  相似文献   

19.
ELISA was adapted for the study of antigenic relations among important Campylobacters and for the presence of anti-campylo-bacter antibodies in 394 sheep and 265 cattle. Rabbit anti-C. jejuni, C. coli, G. fetus subsp. fetus and C. laridis heat-stable antigen sera were evaluated against 29 Campylobacter strains and 6 other bacteria. Anti-C. jejuni and G. coli reacted strongly with homologous antigens and weakly with C. fetus subsp. fetus, C. laridis and C. fecalis antigens. C. fetus subsp. fetus serum reacted mainly with its homologous antigen. C. laridis serum showed closer reactivity to C. jejuni than to C. fetus subsp. fetus, C. coli and C. fecalis. Insignificant cross-reactions were observed with Y. enterocolitica, S. dublin and E. aerogenes heat-stable antigens, Ewes vaccinated with C. fetus subsp. fetus bacterin showed higher ELISA titers against C. fetus subsp. fetus antigens than non-vaccinated ewes or rams. Twenty-five percent of the vaccinated animals showed titers as low as 95 % of the non-vaccinated animals. In cattle the lowest antibody titers against C. fetus subsp. fetus, C. jejuni, C. coli and C. laridis antigens were exhibited by the precolostrum sera followed by the postcolostrum and adult sera. These studies demonstrated the applicability of the ELISA test in seroepidemiological investigations concerning the distribution and significance of Campylobacter antibodies in food animal sera.  相似文献   

20.
During 2000-2002 the National Veterinary Reference Laboratory for Salmonella (NRL-Salm) in Germany typed 11,911 isolates from animals, food, feed and the environment. All of them were tested for their susceptibility to 17 anti-microbial agents. Sixty-three per cent of all isolates were resistant and 40% were multiresistant (resistant against more than one anti-microbial). This general resistance level was strongly influenced by those specific serotypes which dominate the Salmonella epidemiology in Germany. Salmonella Typhimurium DT104 isolates from pig and cattle, and their resulting food products, were multiresistant in 98 and 94% of the cases respectively. During the period 2000-2003 an increasing quinolone resistance especially in Salmonella isolates from poultry and poultry meat (to 26%) and in S. Paratyphi B D-tartrate positive isolates (to 64%) could be observed. This increase was accompanied by a shift towards higher minimal inhibitory concentrations for ciprofloxacin.  相似文献   

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