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1.
Approximately 46% (75/162) or poultry enterococci collected between 1999 and 2000 exhibited high-level resistance to gentamicin (minimum inhibitory concentration [MIC] > or = 500 microg/ml), kanamycin (MIC > or = 500 microg/ml), or streptomycin (MIC > or = 1000 microg/ml). Forty-one percent of the isolates were resistant to kanamycin (n = 67), whereas 23% and 19% were resistant to genramicin (n = 37) and streptomycin (n = 31), respectively. The predominant species identified was Enterococcus faecium (n = 105), followed by Enterococcus faecalis (n = 40) and Enterococcus durans (n = 8). Using polymerase chain reaction, the isolates were examined for the presence of 10 aminoglycoside resistance genes [ant(6)-Ia, ant(9)-Ia, ant(4')-Ia, aph(3')-IIIa, aph(2")-Ib, aph(2")-Ic, aph(2")-Id, aac(6')-Ie-aph(2")-Ia, and aac(6')-Ii]. Five aminoglycoside resistance genes were detected, most frequently aac(6')-Ii and ant(6)-Ia from E. faecium. Seven E. faecalis isolates resistant to gentamicin, kanamycin, or streptomycin were negative for all genes tested, indicating that additional resistance genes may exist. Phylogenetic analysis revealed that the isolates were genetically different with little clonality. These data indicate that enterococci from poultry are diverse and contain potentially unidentified aminoglycoside resistance genes. 相似文献
2.
Although methicillin-resistant Staphylococcus aureus (MRSA) were generally isolated from human beings; these agents were recently isolated from various animal species. It has
been shown that MRSA isolates are not only resistant to beta-lactam antibiotics, but can also be resistant to the other commonly
used antibiotics. In this study, 18 phenotypic methicillin resistant S. aureus isolates from bovine mastitis cases were analyzed by PCR for the presence of mecA gene encoding methicillin resistance and aac(6′)/aph(2″), aph(3′)-IIIa and ant(4′)-Ia genes encoding aminoglycoside resistance. Out of 18 S. aureus isolates (oxacillin MICs, ≥4 μg/ml), 3 were positive for mecA gene. Only one from 3 mecA positive isolates was positive for genes encoding aminoglycoside-modifying enzymes and this isolate carried aac(6′)/aph(2″) in combination with aph(3′)-IIIa gene. The aph(3′)-IIIa gene was detected in 3 isolates. These three isolates carrying the aminoglycoside-modifying enzyme genes were resistant to
gentamicin, kanamycin and neomycin. The mecA gene of 3 MRSA isolates was sequenced. All three mecA genes of these isolates were identical to that found in human MRSA strains, except a one-base substitution at nucleotide
position 757. From the data presented in this study, it can be concluded that MRSA isolated from bovine mastitis may be originated
from human beings, but further studies are needed to investigate the possibility of zoonotic transfer of MRSA. 相似文献
3.
为检测7株鱼源维氏气单胞菌(Aeromonas veronii)的耐药基因和耐药表型的分布情况,试验采用PCR法检测分离株中氨基糖苷类耐药基因(aac(3)-Ⅱa、aac(6')-Ⅰb、ant(3")-Ⅰa和aph(3')-Ⅱa),磺胺类耐药基因(Sul1、Sul2和Sul3)和四环素类耐药基因(tetA、tetC和tetM),运用Kirby-Bauer纸片扩散法检测7株鱼源维氏气单胞菌分离株对22种常用抗生素的敏感性。结果表明,可检出耐药基因aac(3)-Ⅱa(71.4%)、aac(6')-Ⅰb(85.7%)、Sul2(85.7%)和tetA(28.5%);未检出ant(3")-Ⅰa、aph(3')-Ⅱa、Sul1、Sul3、tetC和tetM基因。7株维氏气单胞菌对磷霉素(100%)、多黏霉素B(100%)、痢特灵(85.7%)、奥复星(71.4%)较敏感;对氨苄西林(100%)、乙酰螺旋霉素(100%)、复方新诺明(85.7%)、磺胺异恶唑(85.7%)、四环素(85.7%)等耐药。这说明耐药基因和耐药表型之间存在一定的相关性。 相似文献
4.
为探究温和气单胞菌对氨基糖苷类和四环素类抗生素的耐药性,试验采用PCR法检测10株来源不同的鱼源温和气单胞菌对氨基糖苷类抗生素的4种耐药基因（aph（3'）-Ⅱa、ant（3″）-Ⅰa、aac（6'）-Ⅰb、aac（3）-Ⅱa）及四环素类抗生素的3种耐药基因（tetA、tetC、tetM）的表达情况,并利用K-B纸片扩散法对6种抗生素进行耐药表型分析。结果显示,10株温和气单胞菌对氨基糖苷类耐药基因aph（3'）-Ⅱa、ant（3″）-Ⅰa、aac（6'）-Ⅰb的检出率分别为20%、30%、20%,未检测出aac（3）-Ⅱa基因;对四环素类的耐药基因tetA、tetC、tetM的检出率分别为70%、20%、60%。K-B纸片扩散法结果显示,10株菌对四环素耐药率最高,对链霉素敏感,对庆大霉素、卡那霉素、多西环素、米诺环素高度敏感。结果表明,本次分离的温和气单胞菌对氨基糖苷类和四环素类抗生素具有一定的耐药性,为深入了解温和气单胞菌的耐药机制提供参考。 相似文献
5.
ABSTRACT1. The aim of the experiment was to determine the occurrence of genes encoding aminoglycoside-modifying enzymes (AMEs) in Escherichia coli isolates recovered from chicken meat.2. Antibiotic sensitivity was tested using the disc diffusion test. AMEs and virulence profile were determined by PCR/sequencing.3. Out of 195 meat samples collected, 185 (95%) isolates were identified as E. coli. Disc diffusion showed a resistance value of 22% (n = 42) for at least one of the antibiotic aminoglycosides (AGs) tested (tobramycin, gentamycin, amikacin and kanamycin). PCR screening showed the presence of three classes of AMEs, namely, aac(3)-II (12%), aac(6?)-Ib (7%) and aac(2?)-Ia (5%). Eight of the 42 isolates were positive for the stx1 and sxt2 genes and were defined as Shiga toxin-producing E coli., while the eae gene was positive in one strain. Among the 42 isolates, group A was the predominant phylogenetic identified (76%), followed by group D (21%). One isolate belonged to subgroup B23.4. The results suggested that chicken meat could be an important reservoir of AMEs, and pose a potential risk by dissemination of resistance to humans through the food chain. 相似文献
6.
为了解鸡源致病性大肠埃希菌对氨基糖苷类抗生素的耐药性变化和钝化酶耐药基因的携带情况及耐药基因与耐药性的相关性,从陕西、河南、河北、山西、宁夏和甘肃6省(区)的部分规模化养鸡场的病、死鸡中分离鉴定320株致病性大肠埃希菌。采用K-B药敏纸片法检测分离菌对6种氨基糖苷类药物的敏感性,PCR方法检测6种氨基糖苷类钝化酶耐药基因,用DNA Star软件对获得的耐药基因序列与GenBank中的相关序列进行比对。结果显示,鸡源致病性大肠埃希菌分离株对庆大霉素、链霉素、妥布霉素、卡那霉素、新霉素和阿米卡星的耐药率分别为53.4%、49.3%、37.5%、34.7%、22.8%和5.3%,对妥布霉素和卡那霉素耐药率呈上升趋势,而对庆大霉素的耐药率虽呈下降趋势,但仍维持在40%以上。3重以上耐药菌株占80%(256/320)。氨基糖苷类钝化酶基因aac(3)-Ⅱ、aph(3′)-Ⅰ和aac(6′)-Ⅰ的检出率分别为50.9%、25.9%和3.1%,未检测到aac(3)-Ⅳ、ant(3′′)-Ⅰ和aph(3′)-Ⅱ基因。研究表明,分离的鸡源致病性大肠埃希菌对氨基糖苷类抗生素的耐药性普遍存在,以多重耐药为主,且对妥布霉素和卡那霉素的耐药性不断上升。耐药基因aac(3)-Ⅱ和aph(3′)-Ⅰ的检出率与其耐药性呈正相关。 相似文献
7.
The aminoglycoside apramycin has been used widely in animal production in China since 1999. This study was aimed to investigate the resistance pattern of apramycin-resistant Escherichia coli isolated from farm animals and farm workers in northeastern of China during 2004–2007 and to determine whether resistance to apramycin was mediated by plasmid containing the aac(3)-IV gene and the mode for the transfer of genetic information between bacteria of farm animals and farm workers. Thirty six E. coli isolates of swine, chicken, and human origins, chosen randomly from 318 apramycin-resistant E. coli isolates of six farms in northeastern of China during 2004–2007, were multi-resistant and carried the aac(3)-IV gene encoding resistance to apramycin. Conjugation experiments demonstrated that in all 36 cases, the gene encoding resistance to apramycin was borne on a mobilisable plasmid. Homology analysis of the cloned aac(3)-IV gene with the sequence (accession no. X01385) in GenBank showed 99.3% identity at a nucleotide level, but only with a deletion of guanosine in position 813 of the gene in all 36 cases. The results indicted that resistance to apramycin in these isolates was closely related to aac(3)-IV gene. Therefore, the multi-resistance of E. coli could complicate therapeutic practices for enteric infections in both farm animals and human. 相似文献
8.
Mastitis is one of the most important diseases in dairy cows throughout the world and is responsible for significant economic losses to the dairy industry. This study was performed to characterize the genetic basis of drug resistance in Escherichia coli isolated from cases of clinical and sub-clinical bovine mastitis. A total of 224 California mastitis test (CMT)-positive milk samples were collected from December 2015 to April 2016 to characterize the phenotypic and genetic basis of antimicrobial resistance in E. coli isolated from raw milk from dairy farms found in Burayu, Sebeta, and Holeta areas of Ethiopia. The prevalence of E. coli was 7.1% (16) and both phenotypic and molecular techniques were used to identify E. coli antimicrobial susceptibility trait. The most commonly observed phenotypic resistance was against ampicillin (68.7%), sulphamethazole-trimethoprim (50%), and streptomycin (25%). Multidrug resistance phenotypes were found in 11 of 16 (68.7%) of E. coli isolates. Tetracycline (tet (A)) and chloramphenicol (cml (A)) genes were the most predominant encoding resistance genes identified (50%) each, followed by gentamycin resistance encoding gene (aac (3)-IV) (37.5%). Overall, 11 (68.7%) of the isolates had multidrug resistance genes responsible to two or more classes of antibiotics. The most common pattern detected was cml (A) and tet (A) together 37.5% followed by aac (3)-IV and tet (A) 25%. The current study indicated that raw milk could be regarded as critical source of antibiotic-resistant pathogenic E. coli. 相似文献
9.
为了解新疆北疆地区猪源粪肠球菌的耐药性及相关耐药基因型的分布情况,本试验采用K-B（Kirby-Baller）琼脂扩散法检测了49株猪源粪肠球菌对8种抗菌药物的敏感性,并采用PCR法对9种相关耐药基因进行检测并测序,测序结果与GenBank中的相应基因序列比对。药敏试验结果显示,分离菌对链霉素耐药率最高,其次为青霉素和红霉素,对呋喃妥因、氨苄西林高度敏感。PCR检测结果显示,β-内酰胺类耐药基因tem的检出率最高,为93.88%,其次是四环素类耐药基因tetM,为85.71%,喹诺酮类基因gyrA和parC检出率均为42.86%,氨基糖苷类耐药基因aph（3'）-Ⅲ、aac（6'）/aph2″和ant（6'）-Ⅰ的检出率分别为36.73%、16.33%和16.33%,未检出mefA和ermB基因。本试验从表型与基因型分析发现,北疆地区猪源粪肠球菌的多重耐药现象非常严重,且其耐药表型与基因型并不完全一致。 相似文献
10.
Forty-two enrofloxacin-resistant Escherichia coli strains isolated from eggs and first-week mortality associated with yolk sac infection of two vertically integrated poultry companies of Central Mexico in 1997 and 2005 were characterised. E. coli resistance to 19 antibiotics was determined, as well as the minimum inhibitory concentrations (broth dilution) for ciprofloxacin. The presence of gyrA,B, parC,E chromosomal point mutations, qnrA,B,S plasmid genes and the aminoglycoside acetyltransferase aac(6?)-Ib-cr were determined by PCR and sequencing. Resistance to ampicillin (95%), piperacillin (95%), gatifloxacin (95%), levofloxacin (95%), ampicillin/sulbactam (90%), cefazolin (85%), trimethoprim/sulfamethoxazole (80%), amoxicillin/clavulanic acid (80%), aztreonam (80%), cefepime (80%), cefotaxime (80%), ceftazidime (80%), ceftriaxone (80%) and cefoxitin (75%) was high in the 2005 strains and 19 (95%) strains were resistant to 7 or more antimicrobials. The strains from 1997 expressed high rates of resistance only to the fluoroquinolones and 4 strains (18%) expressed resistance to 7 or more antimicrobials. All strains had a gyrA mutation (Ser83Leu) and a parC mutation (Ser80Ile or Ser80Arg) and 41 (97.6%) strains had a second gyrA mutation (Asp87Asn, Asp87Tyr or Asp87Gly). Only two (4.7%) strains had a parE mutation (Ser458Ala). A total of 10 strains were positive for the aac(6?)-Ib wild-type gene, 6 strains for the aac(6?)-Ib-cr variant and 6 strains possessed both the wild type and the variant. No gyrB mutations or qnrA,B,S genes were detected. This is the first report in Latin America of chromosomal and plasmid quinolone resistance genes in E. coli strains recovered from poultry.
相似文献
11.
为探讨肉牛运输应激综合征的潜在致病菌,本试验采集肉牛运输前后的粪便和血液,针对牛源肠球菌进行分离鉴定、药敏试验和耐药基因检测。结果检出45株肠球菌（粪便中34株,血液中11株）,且对克林霉素等不敏感,其中携带耐药基因aac（6’）／aph（2＂）阳性菌株14株（阳性率31.1%）和ant（6）-Ⅰ的阳性菌株9株（阳性率20%）。表明肉牛经过长途运输后易被携带耐药基因的肠球菌侵入。 相似文献
12.
ABSTRACT1. The real burden of Campylobacter spp. in Lebanon is still unknown. The aims of this study were to unravel the epidemiology of Campylobacter spp. in broilers at slaughterhouses in Tripoli, North of Lebanon and to characterise their antibiotic resistance profiles.2. From May to November 2015, sampling was performed through five repeated surveys from 15 slaughterhouses that sold chicken directly to Lebanese customers. Isolates were subjected to pulsed field gel electrophoresis (PFGE) and flaA-restriction fragment length polymorphism ( flaA-RFLP).3. All investigated slaughterhouses were found to be positive for Campylobacter spp. Campylobacter coli was the predominant species (38 isolates) followed by C. jejuni (eight isolates). A noticeable level of resistance was detected among isolates against ciprofloxacin (97% of C. coli and 87.5% of C. jejuni), amoxicillin (89% of C. coli and 75% of C. jejuni), gentamicin (79% of C. coli and 50% of C. jejuni), and co-amoxiclav (24% of C. coli and 25% of C. jejuni). Erythromycin and ertapenem resistance were observed only in C. coli with the following percentages 74% and 13% respectively, but not in C. jejuni. PFGE and flaA-RFLP using DdeI as restriction enzyme divided the strains into 27 and 25 types respectively.4. The high observed genetic diversity of Campylobacter spp. revealed the complexity of the spread of this genus in broilers. This study highlighted the pressing need to monitor antibiotic resistance and to ensure food safety from ‘farm to fork’ in Lebanon. 相似文献
13.
为确定内蒙古地区羊源大肠杆菌的耐药表型及其耐药基因的流行情况,本研究采用微量稀释法测定了内蒙古地区108株羊源大肠杆菌对13种临床常用抗菌药物的最小抑菌浓度。结果显示,分离菌株对阿莫西林、头孢噻吩、磺胺甲唑、黏菌素的耐药率最高,均达100.0%,对阿莫西林/克拉维酸、四环素、环丙沙星的耐药率在50%~80%之间,对头孢噻肟、美洛培南、新霉素的耐药率均低于10%,较为敏感。108株羊源大肠杆菌中耐7种以上药物的菌株占94.4%,其中15.6%菌株对13种抗菌药物耐药,只有1株菌对所有抗菌药物敏感。采用PCR方法对羊源大肠杆菌分离株所携带的6种相关耐药基因进行检测,结果显示,6种耐药基因中的4种耐药基因bla TEM、proP-2、sul-Ⅰ、ampG检出率超过50%,耐药基因aph（3'）-Ⅰ携带率达40%,只有耐药基因aac（3）-Ⅱ检出率仅为5.5%。由此可见,内蒙古地区羊源大肠杆菌对13种抗菌药物产生了不同程度的耐药性,且存在严重的多重耐药情况,羊源大肠杆菌分离株携带aph（3'）-Ⅰ、sul-Ⅰ、ampG、bla TEM、proP-2、aac（3）-Ⅱ耐药基因。 相似文献
14.
1. Tetracycline resistance determinants are widespread among bacterial species. Resistance to tetracycline occurs by different mechanisms regulated by various genes. 2. The study was conducted to determine the tetracycline resistance and prevalence of tetracycline resistance determinants among Escherichia coli strains isolated from broilers in northern Iran. 3. Minimum inhibitory concentration (MIC) of tetracycline and susceptibility pattern of the isolates were screened using micro-dilution and disk diffusion methods, respectively. The presence of 7 tetracycline resistance genes including tetA, tetB, tetC, tetD, tetE, tetG and tetM was tested using the polymerase chain reaction. 4. Among 100 strains isolated from broilers, 73% were identified as tetracycline resistant. All isolates showed the presence of tetracycline-associated genes. The most prevalent genes were tetA (46%) and tetB (41%) and totally, 17 different genotypes were recognised according to the presence of tetracycline resistance genes. Statistical analysis revealed that concomitant presence of the resistance genes significantly increased the tetracycline MIC and effectiveness of phenotypic characterisation. 5. The results demonstrated a high occurrence of tetracycline-resistant E. coli and related genes among broilers which presents a risk of increasing these strains in human infections associated with food animals. 相似文献
15.
The aminoglycoside apramycin has been used widely in animal production in China since 1999. This study was aimed to investigate the resistance pattern of apramycin-resistant Escherichia coli isolated from farm animals and farm workers in northeastern of China during 2004–2007 and to determine whether resistance to apramycin was mediated by plasmid containing the aac(3)-IV gene and the mode for the transfer of genetic information between bacteria of farm animals and farm workers. Thirty six E. coli isolates of swine, chicken, and human origins, chosen randomly from 318 apramycin-resistant E. coli isolates of six farms in northeastern of China during 2004–2007, were multi-resistant and carried the aac(3)-IV gene encoding resistance to apramycin. Conjugation experiments demonstrated that in all 36 cases, the gene encoding resistance to apramycin was borne on a mobilisable plasmid. Homology analysis of the cloned aac(3)-IV gene with the sequence (accession no. X01385) in GenBank showed 99.3% identity at a nucleotide level, but only with a deletion of guanosine in position 813 of the gene in all 36 cases. The results indicted that resistance to apramycin in these isolates was closely related to aac(3)-IV gene. Therefore, the multi-resistance of E. coli could complicate therapeutic practices for enteric infections in both farm animals and human. 相似文献
16.
In order to provide therapeutical guidance for drug admistration, the bacteria of three sick minks suffering from typical diarrhea symptoms provided by mink farms in Jilin province were isolated and identified, and the drug sensitivity was tested. The bacteria were isolated with TSA plates, and identified using biochemical methods and PCR assay. The virulence of the isolates was determined by infecting BALB/c mice. The antimicrobial susceptibility of the isolates to antimicrobial agents was investigated using the K-B method. PCR was used to detect the resistance genes and Ⅰ integrons. A total of 3 Shigella isolates were obtained from sick minks. The virulent determination showed that all isolates could cause mice diarrhea. The drug sensitivity results showed that 3 strains were sensitive to fluoroquinolone, cephalosporin, florfenicol and polymyxin, but they were resistant to aminoglycoside, tetracycline, chloramphenicol, penicillin and ampicillin. There were seven resistance genes were detected,bla TEM-1,aadA1, aac(3')-Ⅱc, aac(6')-Ⅰb, aph(3')-Ⅶ, tet(M), cat2 and three class Ⅰ integrons carrying aadA 1 gene cassette. All of the isolates were virulent and caused the mice diarrhea. The resistance of the 3 strains were very serious and mainly for multiple drug resistance phenomenon. The resistance genes detected in the mink were various, and could bring enormous implications for clinical treatment. 相似文献
17.
The aims of the present study were to investigate the prevalence of some virulence genes and also determine the antimicrobial resistance pattern of E. coli isolated from bovine with subclinical mastitis. The milk of 502 cows was collected from 8 dairy herds in the southwest of Iran. Conventional biochemical tests were used for identification of E. coli at the species level. Antimicrobial susceptibility patterns of E. coli isolates were determined by disc agar diffusion method and polymerase chain reaction (PCR) was used for detection of seven virulence genes including f17A, afaE-8, afaD-8, eaeA, cnf1, cnf2, and iucD. Seventy (13.94%) isolates of E. coli were identified in 502 milk samples. The highest rate of resistance was observed against tetracycline (18.6%), while none of the isolates were resistant to streptomycin. Eight (11.5%) out of 70 E. coli isolates carried at least one of the virulence genes. The afaD-8 was the most prevalent gene detected in 5 (7.1%) isolates. The afaE-8, iucD, and eaeA were detected in 3, 3, and 2 isolates respectively. Low prevalence of virulence factors may be indicating that most of the E. coli isolates originated from the commensal flora of cows and enter to the udders via environment contamination with feces. 相似文献
18.
1. The aim of this study was to analyse the association between Escherichia coli isolates recovered from turkeys and the expression of beta-lactamase genes, such as extended spectrum beta-lactamase (ESBL) and ampicillin class C (AmpC). The phenotype of the resistance profile was examined using the association between amoxicillin and ceftiofur resistance. 2. Results showed that 84% from the turkey isolates harboured 4 or 5 genes associated with the CoIV plasmid. In an antibiogram test, 82% of the isolates were multidrug-resistant, the highest levels of resistance being against erythromycin (99%) and amoxicillin (76.1%). ESBL-positive groups were 31% positive for the ctx-m-2 gene, 6.8% were positive for ctx-m-8 and 70% harboured the tem wild gene. 3. All positive isolates from the AmpC beta-lactamase-positive group harboured the cmy-2 gene. The presence of the cmy-2 gene was associated with both the CTX-group genes and resistance to ceftiofur. 4. There was a high prevalence of avian pathogenic E. coli in suspected cases of colibacillosis in turkeys and a high antimicrobial resistance index. The results highlighted the risk of ceftiofur resistance and the presence of both ESBL and AmpC beta-lactamase E. coli in the turkey production chain. 相似文献
19.
为了分析四川地区牦牛源肺炎克雷伯氏菌耐药性并确定其耐药基因的携带情况，本试验采集了四川地区不同养殖场患呼吸道疾病牦牛肺脏、咽拭子、鼻拭子共127份病料组织，分离得到了43株肺炎克雷伯氏菌，并采用微量肉汤稀释法结合PCR扩增法检测43株肺炎克雷伯氏菌的耐药性和耐药基因携带情况。结果表明：43株肺炎克雷伯氏菌对氨苄西林、阿莫西林、多西环素、磺胺间甲氧嘧啶4种药物耐药率较高，为65.12%~90.70%；对阿米卡星、氟苯尼考、多黏菌素B、大观霉素4种药物的耐药率在20.93%~48.84%之间；对头孢噻呋、恩诺沙星、环丙沙星3药物的耐药率在18.60%~25.58%之间；多数筛选分离得到的菌株均呈现出多重耐药性，耐9、10种药物的菌株最多，分别占分离菌株的23.3%和20.9%。通过使用PCR扩增法检测分离菌携带的耐药基因情况，结果表明：bla TEM、bla SHV、sul2、sul3、floR 5种耐药基因检出率较高，检出率在62.8%~69.8%之间；ant （3″）-Ⅰa、aph （3'）-Ⅱa、aac （6'）-Ⅰb、aacC2 4种耐药基因检出率较低，检出率在7.0%~20.9%；bla CTX-M、Mcr-1、qnrA、qnrS、rmtB 5种耐药基因未检出。综上所述，本试验中分离得到肺炎克雷伯氏菌具有较强的耐药性并携带有较多的耐药基因，为了更好的促进四川省牦牛养殖产业的发展，应注意避免滥用抗生素并通过药敏试验对症下药。 相似文献
20.
Abstract AIM: To provide baseline data on the levels and patterns of antibacterial drug resistance expressed by Gram-negative bacteria isolated from poultry carcasses in New Zealand. METHODS: Between July and December 2006, isolates of Escherichia coli (n=407) and Salmonella spp. (n=3) originating from carcass-rinse samples were submitted by testing laboratories affiliated to five major poultry processing plants. Isolates of Campylobacter jejuni (n=193) originating from retail poultry carcasses in 2005–2006 were retrieved from the Massey University archives. All isolates underwent disc diffusion susceptibility testing against panels of 12 (Enterobacteriaceae) and six ( Campylobacter spp.) antibacterial drugs. Cephalothin-resistance in isolates of E. coli was confirmed using ETest strips, and confirmation of the resistance phenotypes for a subset of C. jejuni isolates used microbroth dilution assays. Patterns within the resistance phenotypes of the isolates were investigated using hierarchical clustering, and logistic regression modelling. RESULTS: The majority of isolates (71.5% E. coli, 99% C. jejuni, and all three Salmonella spp. isolates) were fully susceptible to the drugs that were tested. Four (1%) E. coli isolates showed resistance to three or more drugs. The proportions of susceptible E. coli differed between the five processing plants. Resistances were detected in E. coli isolates, using disc diffusion to cephalothin (18.2%), ampicillin (4.4%), tetracycline (4.4%) and gentamicin (1.5%). There was an association between cephalothin-resistant isolates of E. coli and decreased susceptibility to gentamicin. Using ETests to ascertain the minimum inhibitory concentrations (MIC) of E. coli for cephalothin gave inconsistent results. One of 193 C. jejuni isolates was resistant to erythromycin, and microbroth dilution assays confirmed that this panel of C. jejuni was generally susceptible to antibacterial drugs. CONCLUSIONS: The levels of resistance shown by Gram-negative bacteria isolated from chicken carcasses in New Zealand are among the lowest reported around the world. No resistance to extended-spectrum cephalosporin drugs was detected in E. coli, suggesting that CTX-M and AmpC beta-lactamases are rare or absent. Salmonella spp. are rarely isolated from poultry carcasses during routine testing in New Zealand, and the isolates identified during this study were fully susceptible to the drugs tested. A panel of C. jejuni isolates originating from retail poultry carcasses were susceptible to first-line and second-line antibacterial drugs. The use of cephalothin as a marker of resistance to first-generation cephalosporins may not be appropriate for non-type-specific E. coli of animal origin. 相似文献
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