四川省鸭和猪源鼠伤寒沙门菌脉冲场凝胶电泳分型与耐药比较分析

目的比较研究四川省鸭和猪源鼠伤寒沙门菌脉冲场凝胶电泳(pulsed field gel electrophoresis,PFGE)分型与耐药特征,为分析鼠伤寒沙门菌食品来源提供支持。方法将鸭和猪源监测中分离的47株鼠伤寒沙门菌进行PFGE分型,并采用最小抑菌浓度法测定9种药物敏感性。结果鸭和猪源中分离的鼠伤寒沙门菌在PFGE分型和耐药上存在差异。鸭源菌株聚集于簇I,而猪源菌株聚集于簇II。簇II菌株对氨苄西林、环丙沙星、氯霉素、庆大霉素、四环素、复方新诺明6种药物的耐药率高于簇I菌株。不同的PFGE分型鼠伤寒沙门菌在监测地区和耐药谱存在差异。SCSTm-10型菌株均分离于绵阳地区,SCSTm-11型主要分离于资阳地区。SCSTm-10型菌株对复方新诺明和环丙沙星的耐药率高于SCSTm-11型菌株。结论 PFGE分型可以获取四川省鼠伤寒沙门菌分离来源、分离地点和耐药的聚类信息,为鼠伤寒沙门菌食物中毒提供流行病学调查支持。     

2016年广西壮族自治区食源性沙门菌的耐药性与耐药谱研究

目的 了解广西壮族自治区食源性沙门菌耐药状况,建立广西壮族自治区食源性沙门菌耐药性数据库。方法 对2016年从广西壮族自治区各市县收集的分离自食品的70株沙门菌和分离自腹泻患者的234株沙门菌采用微量肉汤法对8类14种抗生素进行耐药性试验,开展耐药谱研究。结果 所有沙门菌菌株均对亚胺培南敏感,对其余13种抗生素产生不同程度的耐药。70株食品来源的沙门菌对四环素耐药率最高(45.71%,32/70);234株腹泻患者来源的沙门菌对氨苄西林耐药率最高(70.94%,166/234),其次为四环素(70.09%,164/234)。腹泻患者来源沙门菌对氨苄西林、氨苄西林/舒巴坦、四环素、萘啶酸、头孢噻肟和头孢唑啉的耐药率均高于食品分离株,差异有统计学意义(P<0.05)。2种来源的沙门菌耐药谱广泛,共同耐药谱为ACTT/S(耐氨苄西林-氯霉素-四环素-甲氧苄啶/磺胺甲噁唑)。结论 广西壮族自治区食源性沙门菌耐药状况不容乐观,特别是对青霉素类、氯霉素类、磺胺类、四环素类抗生素严重耐药,提示应对其加强监测,建立科学的防控策略。     

云南省肠炎沙门菌及德尔卑沙门菌脉冲场凝胶电泳分子分型及耐药性研究

目的 了解云南省沙门菌患者中分离最多的肠炎沙门菌及食品中分离最多的德尔卑沙门菌脉冲场凝胶电泳(pulse field gel electrophoresis, PFGE)分子分型及耐药状况。方法 参照中国细菌性传染病分子分型实验室监测网络Pulse Net China的沙门菌PFGE分子分型方法进行分子分型。分析耐药板最低抑菌浓度(minimal inhibitory concentration, MIC)值, 根据美国临床实验室标准化协会(Clinical and Laboratory Standard Institute, CLSI)的相应标准获得S、I、R结果。结果 56株肠炎沙门菌呈11种PFGE带型, 有4种优势带型, 对氨苄舒的耐药率最高, 为57.14%, 对亚胺培南最敏感。27株德尔卑沙门菌呈25种PFGE带型, 对复合磺胺的耐药率最高, 为64.29%, 对亚胺培南最敏感。结论 肠炎沙门菌分子分型有明显的优势带型, 本地区肠炎沙门菌对氨苄舒的耐药率最高。德尔卑沙门菌分子分型呈多样分布, 复方磺胺是本地区德尔脾沙门菌最耐药抗生素。2种沙门菌都对亚胺培南最敏感。     

鼠伤寒沙门菌对抗生素和消毒剂耐药性研究

目的检测302株食品源、动物源和人源鼠伤寒沙门菌(Salmonella enterica Typhimurium)对抗生素和消毒剂的耐药表型,测定消毒剂耐药基因型,并分析鼠伤寒沙门菌对抗生素和消毒剂耐药的相关性。方法纸片扩散法测定鼠伤寒沙门菌对16种抗生素的耐药性,微量肉汤稀释法测定4种消毒剂的最小抑菌浓度(minimal inhibitory concentrations, MICs),聚合酶链式反应(polymerase chain reaction, PCR)检测消毒剂的耐药基因。结果鼠伤寒沙门菌分离株中96.03%(290/302)至少对一种抗生素有耐药性,79.80%(241/302)是多重耐药(multidrug resistant, MDR)菌株。分离株对链霉素的耐药率最高(78.81%,238/302),其次是磺胺复合物(78.15%,236/302)、四环素(75.50%,228/302)、氨苄青霉素(71.85%,217/302),所有分离株均对头孢吡肟和亚胺培南敏感。食品源鼠伤寒沙门菌对磺胺复合物、四环素、氨苄西林、萘啶酸和庆大霉素的耐药率均高于动物源和人源鼠伤寒沙门菌,差异有统计学意义(P0.05);动物源鼠伤寒沙门菌对环丙沙星和氧氟沙星的耐药率高于食品源和人源鼠伤寒沙门菌,差异有统计学意义(P0.05);人源鼠伤寒沙门菌对头孢噻肟和头孢他啶的耐药率高于食品源和动物源分离株。消毒剂苯扎氯铵、三氯生、三氯异氰尿酸和聚维酮碘对鼠伤寒沙门菌分离株的MICs范围分别为2～64、0.031 25～1、32～1 024和256～1 024 mg/L。食品源与动物源鼠伤寒沙门菌对苯扎氯铵、三氯生和聚维酮碘的耐药率高于人源鼠伤寒沙门菌,差异有统计学意义(P0.05)。分离株中消毒剂耐药基因qacEΔ1、sugE(p)和qacE检出率分别为56.95%(172/302)、20.53%(62/302)和2.65%(8/302),qacEΔ1基因与鼠伤寒沙门菌对β-内酰胺类、氨基糖苷类、四环素类、氟喹诺酮类、磺胺类、氯霉素类和喹诺酮类的耐药性显著相关(P0.01)。结论鼠伤寒沙门菌对抗生素耐药普遍,多重耐药率较高,并表现对消毒剂的耐药,鼠伤寒沙门菌对抗生素和消毒剂耐药存在相关性。     

北京市食源性非伤寒沙门菌的分子分型和耐药性研究

目的了解北京市食源性非伤寒沙门菌的分子特征及耐药情况。方法对2004—2010年北京市食源性致病菌监测网收集的100株沙门菌进行脉冲场凝胶电泳(PFGE)分型和抗生素敏感性检测。结果 100株非伤寒沙门菌通过PFGE分型分为62个不同的带型,每个带型包含1~11株菌。抗生素敏感性结果显示,100株菌中有55株菌表现为对至少1种抗生素耐药,其中多重耐药菌株15株。菌株对各抗生素的耐药率为萘啶酸40%、四环素30%、氯霉素15%、庆大霉素10%、甲氧苄啶/磺胺甲恶唑10%、环丙沙星9%、头孢西丁1%、头孢噻肟0%。结论沙门菌PFGE带型和耐药谱均与血清型存在很高的一致性。提示北京市食源性非伤寒沙门菌的耐药情况比较严重,开展对该菌分子分型与耐药特征分析的联合监测意义重大。     

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。     

市售活鸡和腹泻患者中非伤寒沙门菌分子特征和耐药性研究

分析市售活鸡及腹泻患者中非伤寒沙门菌的分子特征的相似性及耐药性,预防沙门菌的感染流行。方法 收集2012年1月—2013年10月从1 054份腹泻患者粪便样品及440份农贸市场的活鸡肛拭子中分离出的非伤寒沙门菌株93株,进行血清分型,对常见的非伤寒沙门菌采用脉冲场凝胶电泳(PFGE)进行分子分型、Bionumerisc v4.0进行聚类分析、纸片扩散法(K-B法)进行药物敏感性试验。结果 1 054份腹泻样品中共检出非伤寒沙门菌88株,分离率为8.35%,分为25种血清型,肠炎沙门菌居多。其中0～2岁的婴幼儿检出率较高,占52.27%(46/88)。PFGE结果:16株肠炎沙门菌分成14个PFGE型、12株斯坦利沙门菌分成11个PFGE型、14株鼠伤寒沙门菌分成14个PFGE型、6株德尔卑沙门菌分成5个PFGE型;对菌株间的相似性进行比较发现两个100%同源的肠炎沙门菌PFGE型,其他菌株的分子特征的相似性不大,鸡源菌株与人源菌株的分子特征相似性不大;对12种抗菌药物的耐药率在50%以下,不同的血清型耐药率各不相同,耐药较严重的为德尔卑沙门菌。440份活体鸡肛拭子分离出的非伤寒沙门菌5株,分离率为1.14%,共分得4种血清型,其中姆班达卡沙门菌病人中未检出。结论 该地区由非伤寒沙门菌引起腹泻的感染率高,尤以婴幼儿多见,患者与鸡未发现有同一克隆株,对常用抗生素有很好的敏感性。     

杨凌及周边地区零售分割鸡肉中沙门菌污染状况及耐药和分型特征研究

目的研究陕西杨凌及周边地区零售分割鸡肉中沙门菌的污染状况及其药敏性、血清型和基于脉冲场凝胶电泳(PFGE)的基因型,为预警食源性沙门菌疾病暴发提供数据基础。方法采用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》对陕西杨凌及周边地区采集的188份零售分割鸡肉中沙门菌进行分离和鉴定,并进行血清学分型。采用PFGE方法确定沙门菌DNA酶切电泳图谱,使用BioNumerics软件聚类分析电泳结果,确定沙门菌基因型。结果 188份零售分割鸡肉中共有34份(18.1%)样品检出沙门菌,农贸市场样品沙门菌检出率(24.6%,29/118)高于超市(7.1%,5/70)。鸡腿、鸡爪、鸡脖和鸡肝样品中沙门菌检出率高于鸡肠和鸡胗。34株沙门菌中共检出10种血清型,其中科瓦利斯沙门菌最为流行,高于德尔卑沙门菌和鼠伤寒沙门菌等,差异有统计学意义(P0.05)。分离株均对磺胺异噁唑、氯霉素、头孢噻呋和环丙沙星耐药,对甲氧苄啶/磺胺甲噁唑、萘啶酮酸、四环素、链霉素、氨苄西林和阿莫西林/克拉维酸的耐药率均在50%以上。34株沙门菌PFGE分型后可被分为11个簇,同一血清型菌株基本聚于同一大簇,同一时间、从相同市场采集的不同样品,其分离株PFGE型相似度均较高,表明分割鸡肉在加工或销售过程可能存在交叉污染。农贸市场分离菌株基因型多样性比较丰富。结论杨凌及周边地区零售分割鸡肉存在沙门菌污染,沙门菌血清型和基因型多样化,耐药菌株比例较高。     

2008—2018年四川省阿贡纳沙门菌分子分型及耐药分析

目的 了解2008—2018年四川省阿贡纳沙门菌(Salmonella agona)脉冲场凝胶电泳(PFGE)型别分布和耐药状况,为阿贡纳沙门菌引起的暴发预警、溯源调查及临床治疗提供依据。方法 对经过生化和血清学鉴定的61株阿贡纳沙门菌进行PFGE分子分型分析,采用微量肉汤稀释法测定14种抗生素对菌株的最小抑菌浓度。结果 61株阿贡纳沙门菌分离株共分为41个PFGE型,从不同年份、不同地区临床病例中分离到的部分菌株具有相同的PFGE型别,1株猪肉分离株与部分临床分离株具有相同的PFGE型别。28株阿贡纳沙门菌对14种抗生素均敏感,其余33株菌存在不同程度的耐药,其中四环素耐药率最高,为47.54%(29/61);多重耐药株共16株,占比为26.23%(16/61)。全部分离株均对亚胺培南敏感。结论 2008—2018年四川省阿贡纳沙门菌分离株PFGE型别呈多样性,在四川省为散发流行状态。耐药情况较严重,耐药性存在上升趋势。     

江西省食源性沙门菌血清分型及脉冲场凝胶电泳指纹图谱研究

研究江西省食源性沙门菌的血清型,用脉冲场凝胶电泳(PFGE)方法对优势血清型进行分子分型,建立江西省食源性沙门菌PFGE指纹图谱资料库,为食源性疾病溯源提供数据。方法 对136株食源性沙门菌进行血清分型,对其中优势血清型德尔卑沙门菌菌株进行PFGE分型,获得分子分型指纹图谱,运用Bionumerics v6.6软件进行聚类分析。结果 136株沙门菌分离株血清群以B群为主,优势血清型主要是德尔卑沙门菌(49.26%),67株德尔卑沙门菌可分为41个型别的PFGE指纹图谱(相似值100%的为同一PFGE型别),主要集中在3个型别中。结论 江西省食源性沙门菌血清型分布呈多样性,优势血清型是德尔卑沙门菌,生肉制品是其主要的来源,同种血清型别的PFGE指纹图谱无相关性。     

Possible horizontal transmission of Salmonella via reusable egg trays in Thailand

Salmonella contamination of eggshells, egg contents, reusable egg trays, and various environmental samples was assessed. Although the overall Salmonella contamination rate from egg farms was low (3.2%), over a quarter (26.7%) of egg trays from farms and more than one third (36.7%) of trays from the market were contaminated. Salmonella strains isolated from reusable egg trays were analyzed by serotyping, antimicrobial susceptibility test and XbaI pulsed-field gel electrophoresis (PFGE) typing. Five serovars (S. Braenderup, S. Emek, S. Weltevreden, S. Stanley, and S. Derby) were isolated, and half of the strains assessed were found to be resistant to one or more of the six antimicrobial agents examined. The overall resistance rates to nalidixic acid, trimethoprim-sulfamethoxazole, tetracycline, and ampicillin were 40.7%, 36.0%, 26.7% and 3.5%, respectively. The PFGE types were matched against sample location and drug resistance. S. Braenderup PFGE type A2 (susceptible to all tested drugs) was isolated from all sample sites; PFGE type A2 (resistant to nalidixic acid) was isolated from Farm C and the market. S. Braenderup PFGE type A1 (resistant to four drugs) was isolated from Farms A and C. S. Weltevreden PFGE type C3 (susceptible to all tested drugs) was isolated from Farms A and B and type C4 (susceptible to all tested drugs) was isolated from Farm A and the market. The distribution of the related genotypes and resistance patterns of Salmonella in egg farms and the market indicate drug-resistant strains of Salmonella may be spread on reusable egg trays.     

Prevalence and antimicrobial resistance of Salmonella in retail foods in northern China

A total of 387 retail meat, seafood and milk powder samples were collected from nine cities in northern China in 2005 and screened for the presence of Salmonella. Salmonella strains isolated were subjected to serotyping and antimicrobial susceptibility testing. Salmonella was isolated from 81 (20.9%, 81/387) samples and classified into 23 serotypes. The isolates were frequently resistant to sulfamethoxazole (86.4%), sulfamethoxazole/trimethoprim (48.1%), nalidixic acid (30.9%), tetracycline (19.8%), carboxybenzylpenicillin (17.3%), amoxicillin (17.3%) and ampicillin (16.0%). The multiple resistance (resistance to ≥ 3 antibiotics) was found in 29.6% (n = 24) isolates. Additionally, 4 isolates from chicken displayed the ACSSuTNx profile, resistant to ampicillin, chloramphenicol, streptomycin, sulfonamide, tetracycline and nalidixic acid, in particular, strain HBS084 showing the resistance to as many as 20 antibiotics. Salmonella from chicken showed the higher frequency of antimicrobial resistance. Our findings indicate that in northern China food products of animal origin can be a source of exposure for consumers to multiresistant Salmonella strains.     

ISOLATION AND CHARACTERIZATION OF NONTYPHOID SALMONELLA FROM HOSPITAL FOOD HANDLERS IN BEIJING, CHINA

Salmonella enterica isolates recovered from stool samples of healthy food handlers in two hospital dining halls in Beijing, China were characterized by serotyping, susceptibility to 15 antimicrobials and pulsed field gel electrophoresis (PFGE). Our data showed that 9.5% (29/305) of food handlers in these two dining halls were Salmonella carriers. Twenty-nine isolates were grouped into five serotypes including Agona, Derby, Enteritidis, Infantis and Senftenberg. All six Enteritidis isolates were resistant to chloramphenicol, nalidixic acid and tetracycline. Identical PFGE patterns were identified from food handlers in the same dining hall that indicated the possible transmission of Salmonella among food handlers and to customers. Our findings underscore the importance of food hygiene education and regular health examination among food handlers in dining halls in China.

PRACTICAL APPLICATIONS

Food handlers in dining halls should be considered as a high-risk group for Salmonella carrier state in China. Food hygiene education and regular health examination among food handlers in dining halls should be carried out.     

Molecular characterization of antibiotic-resistant salmonella isolates from retail meat from markets in northern Vietnam

A total of 118 Salmonella isolates were detected from 283 retail meat samples (135 pork and 148 chicken meat) purchased at retail markets in Northern Vietnam. Thirteen serovars, including Infantis, Anatum, Rissen, Reading, Emek, Typhimurium, Blockley, London, Newport, Derby, Weltevreden, Albany, and Hadar, were determined. Resistance to tetracycline (54.2%), sulfonamides (52.5%), streptomycin (41.5%), trimethoprim (36.4%), chloramphenicol (35.6%), and ampicillin (33.1%) was commonly seen in the Salmonella isolates. Fourteen [bla(TEM), bla(OXA-1), bla(PSE-1), aadA1, sul1, tetA, tetB, tetG, cmlA1, floR, dfrA1, dfrA12, aac(3)-IV, and aphA1-1AB ] of 17 resistance genes were detected from the isolates demonstrating resistance. Genes for plasmid-mediated quinolone resistance, such as qnrA, qnrB, qnrS, qepA, and acc(6')-1b-cr, were not detected in 23 quinoloneresistant isolates. The substitution TCC to TTC at codon 83 of gyrA was found in the 18 quinolone-resistant isolates. The data revealed that resistant Salmonella strains were widely distributed in Northern Vietnam via the food chain and that they might contain multiple genes specifying identical resistance phenotypes. Thus, further studies are necessary to clarify the mechanisms of antibiotic resistance in Salmonella strains and their spread in the livestock market.     

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。     

Antimicrobial-resistant Salmonella serovars isolated from imported foods

A total of 187 Salmonella isolates representing 82 serotypes recovered from 4072 imported foods in the year 2000 by the U.S. Food and Drug Administration field laboratories were tested for their susceptibility to 17 antimicrobials of human and veterinary importance. Fifteen (8%) isolates were resistant to at least one antimicrobial, and five (2.7%) were resistant to three or more antimicrobials. Most of the isolates (n=9) exhibited resistance to tetracycline. Four isolates from catfish or tilapia from Taiwan or Thailand also demonstrated resistance to nalidixic acid. These nalidixic acid-resistant Salmonella isolates possessed a point mutation at the Ser83 or Asp87 position in DNA gryase, resulting in amino acid substitutions to phenylalanine, tyrosine, or asparagine. One Salmonella Derby isolated from frozen anchovies imported from Cambodia was resistant to six antimicrobials including ampicillin, amoxicillin/clavulanic acid, chloramphenicol, sulfamethoxazole, tetracycline, and trimethoprim/sulfamethoxazole. Of seven isolates displaying resistance to sulfonamides, only one S. Derby and one Salmonella Agona contained class 1 integrons that were further shown to possess the aadA and pse-1 genes conferring resistance to streptomycin and ampicillin, respectively. This study indicates that antimicrobial-resistant Salmonella are present in imported foods, primarily of seafood origin, and stresses the need for continued surveillance of foodborne zoonotic bacterial pathogens from imported foods entering the United States.