肉鸡屠宰加工过程中沙门氏菌的污染情况及其耐药性分析

目的：了解四川某肉鸡屠宰加工过程不同环节沙门氏菌的污染情况、耐药性和耐药谱,为食品安全和临床用药提供理论依据。方法：根据GB 4789.4-2010《食品安全国家标准 食品微生物学检验 沙门氏菌检验》、沙门氏菌科玛嘉显色培养基筛选疑似沙门氏菌,并针对沙门氏菌invA和hut基因的二重PCR方法对疑似沙门氏菌鉴定,再用纸片扩散法对其分离株进行10 种抗菌药物（组合）的药敏实验,参考临床和实验室标准化研究所（Clinical andLaboratory Standards Institute,CLSI）标准（2010）判定药敏结果。结果：从1 350 份样品中,分离鉴定出156 株沙门氏菌;肉鸡屠宰前沙门氏菌的污染率为13.53%;烫毛脱毛、开肛、净膛、冲淋4 个环节鸡胴体和分割鸡肉、冷冻鸡肉沙门氏菌的污染率分别为0、7.23%、9.80%、11.54%、14.50%、9.33%。沙门氏菌分离株对萘啶酸（100.00%）和氨苄西林（85.90%）的耐药率最高,对甲氧苄啶/磺胺甲噁唑（44.23%）、庆大霉素（39.10%）、四环素（35.26%）的耐药率较高,对头孢曲松敏感,多重耐药率为53.85%,共有39 种耐药谱,从肉鸡屠宰前到分割鸡肉沙门氏菌分离株的耐药谱型先下降再上升。结论：四川某肉鸡屠宰生产链中沙门氏菌的污染率及其耐药情况比较严重,且可能存在从上游向下游生产链传播的情况,需要加强卫生和抗菌药物使用监督。     

北京市顺义区零售鸡胴体中弯曲菌分布与分子特征研究

目的研究北京市顺义区鸡胴体中弯曲菌分布和分子特征,为顺义区弯曲菌防控提供科学依据。方法采集批发市场和零售店鸡胴体60份,采用滤膜法分离培养弯曲菌,对分离菌株进行多位点序列分型分析并构建最小生成树。结果鸡胴体中弯曲菌检出率为75.0%(45/60),空肠弯曲菌与结肠弯曲菌占比分别为38.0%(19/50)和62.0%(31/50)。批发市场和零售店弯曲菌检出率分别为86.0%(37/43)和47.1%(8/17),差异有统计学意义(χ~2=9.877,P0.05);5～7月空肠弯曲菌检出率分别为10.0%(2/20)、40.0%(8/20)和45.0%(9/20),差异有统计学意义(χ~2=6.624,P0.05)。19株空肠弯曲菌共分为13个ST型;28株结肠弯曲菌共分为16个ST型。空肠弯曲菌耐药率前五位由高至低依次为四环素(100.0%,19/19)、萘啶酸(100.0%,19/19)、环丙沙星(94.7%,18/19)、氟苯尼考(57.9%,11/19)、庆大霉素(36.8%,7/19);结肠弯曲菌耐药率前五位由高至低依次为萘啶酸(100.0%,31/31)、环丙沙星(100.0%,31/31)、四环素(93.5%, 29/31)、链霉素(93.5%, 29/31)、庆大霉素(83.9%,26/31)。空肠弯曲菌和结肠弯曲菌多重耐药率分别为68.4%(13/19)和93.5%(29/31)。结论北京市顺义区市场零售鸡胴体中弯曲菌污染水平较高,结肠弯曲菌为污染的优势菌种。批发市场鸡胴体污染弯曲菌的情况比零售店严重。     

辽宁省鸡源空肠弯曲菌耐药性监测与分析

目的了解辽宁省内鸡源空肠弯曲杆菌耐药性情况。方法采用特异性选择培养基分离出空肠弯曲菌,并使用生化反应和分子生物学方法双重方法进行鉴定,并进行耐药性分析。结果采集的辽宁省某屠宰场的鸡盲肠共198份样品,分离鉴定得到60株空肠弯曲菌,分离率为30.3%。同时对60株空肠弯曲菌进行了药物敏感性检测。结论 60株空肠弯曲菌几乎均对红霉素、庆大霉素、克林霉素和萘啶酸耐药,其MIC90值均高于所测试的最高药物浓度。空肠弯曲杆菌氟苯尼考和泰利霉素的敏感性最强。     

青岛市屠宰场整鸡中沙门菌污染水平定量检测及耐药性分析

目的调查青岛市规模化肉鸡屠宰场屠宰后整鸡样品中沙门菌的污染及抗生素耐药谱分布状况。方法2014年10~12月在青岛市选择2家规模化肉鸡屠宰场,采用胴体漂洗法定量检测3次共采集的141份屠宰后整鸡样品中沙门菌,根据Kauffmann-White表对沙门菌菌株进行血清学鉴定,应用微量肉汤稀释法检测菌株对11种抗生素的耐药性。结果整鸡样品沙门菌总体污染率为74.5%(105/141),污染水平3.6~1 100 MPN/100 g,中位数为43 MPN/100 g;共分离355株沙门菌,血清型分布为肠炎沙门菌220株,印第安纳沙门菌88株和阿贡纳沙门菌19株,以及其他型28株。355株沙门菌分离株的总体耐药率为90.4%(321/355),萘啶酸(NAL)耐药率最高(88.7%,315/355)。220株肠炎沙门菌中219株(99.5%)耐药,6株(2.7%)为多重耐药株,优势耐药谱为奈啶酸(156株)。88株印第安纳沙门菌均耐药,85株为多重耐药株,优势耐药谱为庆大霉素-氯霉素-环丙沙星-萘啶酸-氨苄西林-青霉烷砜/氨苄西林-头孢他啶-头孢噻肟-复方新诺明。19株阿贡纳沙门菌除1株对奈啶酸耐药外,其余18株对所测试11种抗生素均敏感。结论青岛市肉鸡屠宰场沙门菌污染率较高,血清型以肠炎沙门菌、印第安纳沙门菌和阿贡纳沙门菌为主。沙门菌总体耐药率较高,并呈现多重耐药性趋势。     

2016—2018年北京市腹泻患者弯曲菌耐药性与脉冲场凝胶电泳分子分型的研究

目的分析北京市腹泻患者弯曲菌(Campylobacter spp.)分离株的抗生素敏感性和脉冲场凝胶电泳(pulsed field gel electrophoresis,PFGE)分子分型特征。方法2016—2018年,对北京市19家医院肠道门诊分离的弯曲菌采用琼脂稀释法进行抗生素敏感性检测,按照PulseNet的方法进行PFGE实验和聚类分析。结果所有空肠弯曲菌至少对一种抗生素有耐药性。空肠弯曲菌对环丙沙星(95.30%)的耐药率最高,其次为四环素(94.02%)和萘啶酸(92.31%),结肠弯曲菌对环丙沙星(95.00%)、四环素(95.00%)的耐药率最高,其次为萘啶酸(90.00%)。空肠弯曲菌菌株和结肠弯曲菌菌株的多耐药率分别是55.56%和75.00%。228株空肠弯曲菌共产生135种PFGE带型,40株结肠弯曲菌共产生34种PFGE带型,带型分布较为分散。结论2016—2018年北京市腹泻患者弯曲菌分离株的耐药率较为严重,耐药模式复杂,PFGE带型呈多态性分布。     

市售鸡肉中沙门菌分离株多重耐药谱测定

为了解我国市售鸡肉中沙门菌多重耐药状况及耐药程度，对国家食源性疾病监测网从市售鸡肉中分离到的51株沙门菌进行耐药检测，并对多重耐药谱进行分析。利用NccLs(National Committee of Clinical Labaratory Standard)推荐的纸片法进行耐药检测，51株分离菌株全部对至少3种以上的抗生素耐药，属多重耐药株，耐5种抗生素的9株(17.6％)，耐6～9种抗生素的12株(23．5％)，耐10种以上抗生素的9株(17．6％)。51株沙门菌对万古霉素、红霉素、苯唑西林都具有耐药性(100％)，对其它抗生素的耐药情况是：萘啶酮酸(52.9％)、磺胺(35．3％)、链霉素(33．3％)、四环素(29.4％)、氨苄青霉素(23．5％)、羧苄西林(21.6％)、阿莫西林(19．6％)、吡拉西林(19．6％)、美唑西林(17．6％)、强力霉素(17．6％)、氯霉素(13．7)和头孢噻吩(9．8％)。有3株菌对庆大霉素耐药，有2株菌对丁胺卡那霉素和甲氧苄胺嘧啶耐药，有1株菌对复方新诺明耐药。分离出1株耐15种抗生素的鼠伤寒沙门菌，其耐药谱与超级耐药鼠伤寒沙门菌DTl04的耐药谱类似。从8省市市售鸡肉中分离的51株沙门菌均为多重耐药株，提示我国畜牧养殖业在使用抗生素方面存在严重问题，应加强对饲料添加剂使用的安全性管理，合理使用抗生素。     

2018年贝类来源副溶血性弧菌毒力基因及耐药性分析

目的 对2018年从产地和市售贝类样品中分离的140株副溶血性弧菌的毒力基因和耐药性进行分析。方法 采用聚合酶链式反应(PCR)扩增法检测毒力基因和耐药基因,采用药敏纸片法测试菌株的耐药性。结果 140株副溶血性弧菌均不含有tdh基因,1株菌含有trh基因;所有菌株对氨苄西林耐药,部分菌株对头孢唑啉、头孢呋辛钠、链霉素、阿米卡星、复方新诺明、四环素和氟苯尼考耐药,所有菌株对头孢吡肟、庆大霉素、亚胺培南、美罗培南、氧氟沙星和强力霉素敏感,6株菌呈现耐受2类及以上抗菌药的多重耐药性;耐链霉素菌株检出耐药基因strA、strB,耐四环素菌株检出耐药基因tetA,耐复方新诺明菌株检出耐药基因sul2,耐氟苯尼考菌株检出耐药基因floR。结论 大多数副溶血性弧菌不含有毒力基因,菌株呈现不同程度的耐药性,少量菌株含有多个耐药基因,表现出多重耐药性,提示应继续加强水产品中副溶血性弧菌的致病性和耐药性监测。     

2014~2018年北京市人源性肠产毒性大肠埃希菌耐药性与PFGE分子分型研究

目的 分析北京市门诊腹泻病例肠产毒性大肠埃希菌(enterotoxigenic Escherichia coli, ETEC)分离株抗生素敏感性及分子分型特征。方法 采用微量肉汤稀释法对2014~2018年北京市门诊腹泻病例ETEC分离株进行8大类14种抗生素敏感性检测。参照PulseNet中非O157大肠埃希菌脉冲场凝胶电泳(pulsed-field gel electrophoresis, PFGE)分型方法, 对不同区县不同采样时间分离的菌株采用随机抽样原则, 对178株菌基因组经限制性内切酶Xba I酶切后进行分子分型和聚类分析。结果 578株2014~2018年北京市门诊腹泻病例ETEC菌株总耐药率为94.29%, 对萘啶酸、氨苄西林、头孢唑林耐药率较高, 分别为61.58%、60.38%、36.19%。578株菌分为152个耐药谱, 耐3种及3种以上抗生素的菌株数达340株(59.00%), 有1株菌对12种抗生素耐药。常见耐药谱为耐喹诺酮类的萘啶酸, 占20.18%, 其次为耐β-内酰胺类的氨苄西林-头孢唑林-头孢噻肟, 占12.29%, 再次为耐β-内酰胺类的氨苄西林-喹诺酮类的萘啶酸-大环内酯类的阿奇霉素, 占6.79%, 且耐药谱种类逐年缓慢上升。其中178株菌共产生153种PFGE带型, 带型分布较为分散, 无优势带型, 菌株之间的相似系数为31.60%~100.0%。结论 2014~2018年北京市腹泻病例肠产毒性大肠埃希菌耐药情况严重, 耐药谱复杂广泛, 多重耐药菌株占比呈逐年缓慢上升趋势。PFGE带型呈多态性分布。     

2014—2018年北京市人源性肠致病性大肠埃希菌耐药特征及分子特征研究

目的 了解北京市门诊腹泻病例肠致病性大肠埃希菌(enteropathogenic Escherichia coli,EPEC)分离株抗生素敏感性情况及分子分型特征。方法 采用微量肉汤稀释法对2014—2018年北京市门诊腹泻病例EPEC分离株进行8类14种抗生素敏感性检测。参照PulseNet中非O157大肠埃希菌脉冲场凝胶电泳(PFGE)分型方法,对不同区县不同采样时间分离的菌株采用随机抽样原则,对140株菌基因组经限制性内切酶Xba Ⅰ酶切后进行分子分型和聚类分析。结果 2014—2018年北京市门诊腹泻病例EPEC分离株总耐药率为84.8%(391/461),氨苄西林、四环素、甲氧苄啶/磺胺甲噁唑耐药率较高,分别为66.4%(294/443)、54.0%(249/461)、45.6%(210/461)。461株菌分为200种耐药谱,耐3类及3类以上抗生素的菌株数达249株(54.0%),有1株菌对7类12种抗生素耐药。常见耐药谱为萘啶酸耐药,占4.3%(20/461)。环丙沙星、萘啶酸、四环素、亚胺培南耐药率和耐药谱种类呈逐年缓慢上升趋势。其中140株菌共产生136种PFGE带型,带型分布较为分散,无优势带型,菌株之间的相似系数为53.3%～100.0%。结论 2014—2018年北京市腹泻病例EPEC 耐药情况严重,耐药谱复杂广泛,多重耐药菌株及耐药谱种类呈逐年增多趋势。菌株的基因型呈多态性分布。     

2016年上海市市售肉制品中沙门菌耐药谱与分型研究

目的 研究上海市市售肉制品中沙门菌血清型、耐药谱和分子分型特征。方法 2016年1～8月在上海市所辖16个行政区,随机选择1个密集型社区,抽取1家超市或市场作为哨点,定期采集畜、禽类肉制品,按国家食品安全风险评估中心(CFSA)食源性疾病监测方案进行沙门菌分离、血清分型、抗生素定量检测与剂量评估、优势菌的分子分型。结果 606份样品包括猪、鸡、鸭、牛、羊、鹅肉制品,共分离沙门菌158株,总阳性率为26.1%,畜肉和禽肉来源分别占52.5%(83/158)和47.5%(75/158)。前5位沙门菌血清型依次为肠炎沙门菌、鼠伤寒沙门菌、德尔卑沙门菌、罗森沙门菌和印第安纳沙门菌,畜肉和禽肉来源优势菌型间差异有统计学意义(P<0.05);菌株对磺胺异噁唑耐药率最高(79.7%,126/158),对链霉素、萘啶酸、氨苄西林、四环素和氯霉素耐药率在38.0%～77.8%,多重耐药(MDR)菌株(≥3类)占77.8%(123/158),猪肉来源沙门菌对庆大霉素、链霉素、磺胺异噁唑、复方新诺明、氯霉素、四环素耐药率均高于鸡肉来源沙门菌,鸡肉来源沙门菌对头孢噻呋、头孢曲松、萘啶酸耐药率均高于猪肉来源沙门菌,差异均有统计学意义(P<0.05),32.9%(52/158)的菌株对至少6种抗生素超检测限值;肠炎沙门菌有15个分型,以1型和3型为优势型;鼠伤寒沙门菌有23个分型,具有遗传多样性特征。结论 上海市市售肉制品沙门菌暴露以猪肉和鸡肉来源为主,肉制品中多重耐药沙门菌污染严重。猪肉来源的罗森沙门菌和鸡肉来源的吉韦沙门菌是新输入性的血清型。     

Antibiotic resistance of Campylobacter jejuni and Campylobacter coli isolated from hog, beef, and chicken carcass samples from provincially inspected abattoirs in Ontario

Campylobacterjejuni is one of the most common causes of bacterial foodborne infection in the United States, and there are reports of resistance of Campylobacter spp. to antimicrobial agents used for the treatment of gastroenteritis. The purpose of this study was to determine the antimicrobial resistance patterns of Campylobacter spp. isolated from hog, beef, and chicken carcasses from provincially inspected abattoirs in Ontario. The agar dilution method was performed to measure antimicrobial resistance of the isolates. Antimicrobial resistance of Campylobacter isolates from hogs (n = 401), beef (n = 21), and chicken (n = 435) to ampicillin, azithromycin, chloramphenicol, ciprofloxacin, clindamycin, erythromycin, gentamicin, nalidixic acid, streptomycin, and tetracycline was determined. Resistance of chicken, hog, and beef isolates was 14.3, 18.2, and 9.5% to ampicillin; 17.9, 67.3, and 38.1% to azithromycin; 0, 0.5, and 0% to chloramphenicol; 3.7, 1.2, and 0% to ciprofloxacin; 2.3, 46.6, and 4.8% to clindamycin; 6.7, 43.6, and 4.8% to erythromycin; 0.2, 0, and 0% to gentamicin; 5.1, 10.7, and 0% to nalidixic acid; 13.6, 57.4, and 4.8% to streptomycin; and 52.6, 44.1, 42.9% to tetracycline, respectively. The hog isolates had the greatest resistance to seven of the ten antimicrobials tested. Results of this study confirm the existence of antimicrobial resistance of Campylobacter to various antimicrobial agents,especially ciprofloxacin and erythromycin, commonly used for treatment of campylobacteriosis in humans.     

PFGE genotyping and antimicrobial susceptibility of Campylobacter in retail poultry meat in Estonia

In the present study, the Campylobacter isolates from retail poultry meat in Estonia were sero- and genotyped, and the antimicrobial susceptibility was determined. Forty-eight chicken (36 Estonian, 12 imported) and 22 turkey (imported) Campylobacter isolates from 580 raw broiler chicken (396 Estonian, 184 imported) and 30 turkey (imported) meat samples were studied. Of the isolates, 64 were C. jejuni, 4 C. coli, and 2 Campylobacter spp. Penner serotyping of 54 C. jejuni isolates revealed 11 different serotypes, and 22% of the isolates were nontypeable by the commercial antisera. The most common serotypes O:1,44; O:21, and O:55 accounted for 28%, 13%, and 13% of the isolates, respectively. Differences in serotype distribution were seen for chicken and turkey isolates. Genotypic characterization of all Campylobacter isolates (n=70) was performed by pulsed-field gel electrophoresis (PFGE). SmaI and KpnI yielded 29 and 34 PFGE types, respectively, revealing high diversity among isolates. The serotype distribution did not show an association with the origin of the sample, but the majority of the isolates sharing a similar PFGE genotype originated from one country. High levels of resistance to ciprofloxacin (66%), nalidixic acid (66%), tetracycline (44%), ampicillin (34%), and erythromycin (14%) were detected among the 70 Campylobacter isolates. The simultaneous resistance to two or three antimicrobial agents occurred in 60% of the isolates. The Campylobacter isolates from turkey meat had higher resistance to ampicillin, ciprofloxacin, nalidixic acid, and tetracycline than those from chicken meat. None of the chicken isolates were resistant to gentamicin, and no turkey isolates to erythromycin or gentamicin.     

Prevalence, genetic diversity, and antibiotic resistance patterns of Campylobacter jejuni from retail raw chickens in Korea

Campylobacter jejuni is a frequently detected food-borne pathogenic bacterium. Clinical cases are mostly sporadic but campylobacteriosis can have serious consequences, such as the development of Guillain-Barré syndrome as well as diarrheal diseases. We examined 265 retail raw chickens from Korean markets for the presence of C. jejuni using the US Food and Drug Administration standard cultural method and multiplex polymerase chain reaction (mPCR). The mPCR-confirmed C. jejuni isolates were subtyped by pulsed field gel electrophoresis (PFGE) and flaA-typing for investigating the genetic diversity of the microorganism in retail raw chickens. Restriction enzymes SmaI and DdeI were used for PFGE and flaA-typing, respectively. Campylobacter spp. were found in 181 samples (68.3%) and C. jejuni in 100 samples (37.74%). For C. jejuni, 73 pulsotypes and 30 flaA types were detected. Antibiotic resistance tests performed by disk diffusion assay indicated that most C. jejuni isolates were resistant to tetracycline, nalidixic acid, and ciprofloxacin, and 87 composite types were revealed by PFGE, flaA-typing, and the antibiotic resistance tests. Our results show that the genetic diversity of C. jejuni isolates is very high and the correlation between genotype and antibiotic resistance was low even though many bacteria showed multi-drug resistance.     

Genetic mechanisms contributing to reduced tetracycline susceptibility of Campylobacter isolated from organic and conventional dairy farms in the midwestern and northeastern United States

Campylobacter is one of the most common causes of gastroenteritis and can be acquired through contact with farm animals or the consumption of raw milk. Because of concerns over the role of food-producing animals in the dissemination of antimicrobial resistance to humans, we evaluated the prevalence of antimicrobial resistance in Campylobacter isolates from dairy farms and the genetic mechanism conferring the observed resistance. Evaluation of antimicrobial resistance was completed on 912 isolates from conventional and 304 isolates from organic dairy farms to eight drugs (azithromycin, chloramphenicol, ciprofloxacin, clindamycin, erythromycin, gentamicin, nalidixic acid, and tetracycline) with microbroth dilution. Resistance to seven of eight drugs was very low and did not differ by farm type. However, tetracycline resistance was common in Campylobacter isolated from both organic and conventional dairy farms, with 48 and 58% of isolates affected, respectively. By multiplex PCR, we determined that tetracycline resistance was highly associated with the carriage of tetO in Campylobacter isolates (X2 = 124, P < 0.01, kappa = 0.86).     

Prevalence and antimicrobial resistance of Campylobacter isolated from retail raw chicken and beef meat, Tehran, Iran

Campylobacter spp. is a leading cause of human diarrhea. The common source of infection is contaminated food, particularly poultry. The veterinary use of antimicrobial drugs has been suggested to be largely responsible for resistance in human isolates of this zoonotic pathogen. From April to October 2004, 241 samples of chicken and beef meat for sale in retail outlets in Tehran (Iran) were analyzed for the presence of Campylobacter. Totally, 88 (36.5%) Campylobacter strains were isolated. Campylobacter was isolated from a significantly larger number of chicken (63%) than beef (10%) meat (P < 0.0001). Susceptibilities of 72 strains were determined for eight antimicrobial drugs using the disk diffusion assay. Resistance to nalidixic acid was the most common finding (75%), followed by resistance to ciprofloxacin (69.4%), tetracycline (45.8%), amoxicillin (11.1%), streptomycin (4.2%), chloramphenicol (2.8%) and gentamicin (1.4%). None of the isolates was resistant to erythromycin. Multidrug resistance was seen in 75% of the Campylobacter strains.     

Prevalence, antibiotic resistance and RAPD typing of Campylobacter species isolated from ducks, their rearing and processing environments in Penang, Malaysia

We report for the first time on the prevalence, antibiotic resistance and RAPD types of Campylobacter species in ducks and duck related environmental samples in Malaysia. Samples were examined by enrichment in Bolton Broth followed by plating onto modified Charcoal Cefoperazone Deoxycholate agar (mCCDA) and/or plating directly onto mCCDA. A total of 643 samples were screened, and the prevalence of Campylobacter spp. in samples from different sources ranged from 0% to 85%. The method of isolation had a significant (P<0.05) effect on the isolation rate. One hundred and sixteen Campylobacter isolates, comprising of 94 Campylobacter jejuni, 19 Campylobacter coli and three Campylobacter lari, were examined for their sensitivity to 13 antibiotics. Majority of the C. jejuni isolates were resistant to cephalothin (99%), tetracycline (96%), suphamethoxazole/trimethoprim (96%), and very few were resistant to gentamicin (5%), chloramphenicol (7%) and erythromycin (1%). All C. coli isolates were resistant to cephalothin, nalidixic acid, norfloxacin and tetracycline but susceptible to chloramphenicol, erythromycin and gentamicin. The three C. lari isolates were resistant to all the antibiotics tested except chloramphenicol and gentamicin (1/3 and 2/3 susceptible, respectively). Genetic diversity of Campylobacter isolates were determined using random amplification of polymorphic DNA (RAPD). C. jejuni and C. coli isolates belong to fifty-eight and twelve RAPD types, respectively.     

Resistance patterns of Campylobacter spp. strains isolated from poultry carcasses in a big Swiss poultry slaughterhouse

The aim of this study was to determine resistance patterns of strains of Campylobacter spp. isolated from poultry carcasses in one of the two big Swiss poultry slaughterhouses. A variety of antibiotics with clinical relevance in human and/or in veterinary medicine was tested. In addition, the results of the disc diffusion method, E-test and microdilution broth methods were compared. Of the 195 Campylobacter jejuni strains isolated from 195 poultry carcasses from 21 flocks, 134 strains were susceptible in vitro to all tested antibiotics. Sixty-one strains (31.3%, from eight flocks) showed resistance. Forty-one strains were resistant to a single antibiotic-34 to streptomycin, 6 to ampicillin and 1 to ciprofloxacin. Eighteen strains (from two flocks) showed combined resistance to erythromycin and streptomycin, two strains to ciprofloxacin and streptomycin. None of the isolates was resistant to tetracycline. The data of this first study in Switzerland show a favourable resistance situation for C. jejuni strains against erythromycin, tetracycline and ciprofloxacin. The disc diffusion method was found to be a reliable and easy tool for monitoring the prevalence of resistant C. jejuni strains. For surveillance of changes in the susceptibility concentration levels to antimicrobial agents, however, a MIC method should be used. Further investigations along the whole poultry production chain (farm, slaughterhouse and retail levels) are now necessary in order to confirm the resistance situation.     

Observational study of the prevalence and antibiotic resistance of Campylobacter spp. from different poultry production systems in KwaZulu-Natal, South Africa

Campylobacter bacteria are important foodborne pathogens that cause acute diarrheal illness, and infection is often associated with contaminated poultry. In a blind observational study, the prevalence and resistance profiles of thermophilic Campylobacter strains collected from different poultry production systems were tested against the clinically used antibiotics ciprofloxacin, tetracycline, erythromycin, gentamicin, and streptomycin. Campylobacter strains were isolated from chickens in rural production systems, a free-range commercial facility, and industrially raised broiler and egg-laying chickens all situated in KwaZulu-Natal, South Africa. Isolates were collected from the chicken cecae and were identified with conventional methods and tested for antibiotic resistance with the Clinical and Laboratory Standards Institute agar dilution method. The prevalence of Campylobacter spp. isolates in chickens was 68% (56 samples) in rural production, 47% (140 samples) in commercial free-range broilers, 47% (133 samples) in industrial broilers, and 94% (34 samples) in industrial layer hens. Isolates from the rurally raised chickens showed significantly (P < 0.01) less resistance against ciprofloxacin (7.9%), erythromycin (0%), and tetracycline (21.6%) than those from commercially produced chickens. Isolates from the commercially raised chickens (free range and industrial) were highly resistant to tetracycline (98.9 to 100%). The incidence of gentamicin and streptomycin resistance was 1.6 and 11.5%, respectively, in commercial free-range broilers, 1.7 and 16.4%, respectively, in industrially raised broilers, and 12.9 and 40%, respectively, in industrially raised layers. It is possible that variations among the poultry production systems, including antimicrobial usage, result in differences in antibiotic resistance profiles in Campylobacter.     

Antimicrobial resistance among Campylobacter jejuni isolated from raw poultry meat at retail level in Denmark

Campylobacter jejuni isolated from raw poultry meat collected at retail shops in Denmark in the period 1996-2003 were tested for susceptibility to seven antimicrobial agents. The food samples consisted of raw chicken meat and other raw poultry meat of domestic or imported origin. The highest levels of resistance among C. jejuni were observed for tetracycline, nalidixic acid and ciprofloxacin, whereas macrolide resistance was rarely detected. C. jejuni originating from other poultry meat (mainly duck and turkey meat) exhibited the highest occurrences of antimicrobial resistance monitored; approximately one third of the isolates were tetracycline resistant (N=100). Among chicken meat isolates, the occurrence of tetracycline resistance was significantly higher (P<0.005) in C. jejuni isolated from imported chicken meat (N=88) than in C. jejuni from Danish chicken meat (N=367). The same tendency was observed for chloramphenicol, nalidixic acid and ciprofloxacin (P<0.05). The trends in resistance in the period 1996-2003 among C. jejuni isolates from chicken meat indicate a decrease in the occurrence of resistance towards fluoroquinolones. This may be due to reduced application of fluoroquinolones for food animals. Monitoring of the occurrence of antimicrobial resistance in C. jejuni isolated from raw uncooked poultry has been performed on a yearly basis since 1996, thus providing useful insight into consumer exposure to antimicrobial-resistant C. jejuni.