食品中沙门菌整合子与耐药性关系研究

目的：研究食品中沙门菌的整合子携带情况及整合子与耐药性之间的关系。方法：PCR检测细菌总DNA中1、2、3类整合酶基因，确定细菌携带整合子的情况。整合子阳性菌档进一步检测整合子的可变区，分析插入基因盒的序列。结果：69株大肠菌中25株携带1类整合子，集中分布在对4种以上抗生素耐药的菌株中。插入基因盒主要是dfr(甲氧苄氨嘧啶)和aadA(氨基糖甙类)基因盒，各种基因盒组合中最常见的是difrl—aadA1。结论：细菌的多重耐药性与整合子携带高度一致，但是单个菌株的耐药谱与整合子的耐药基因盒缺乏对应关系。     

食品中沙门菌整合子与耐药性关系

目的 研究食品中沙门菌的整合子携带情况及整合子与耐药性之间的关系。方法PCR检测细菌总DNA中1，2，3类整合酶基因，确定细菌携带整合子的情况。整合子阳性菌株进一步检测整合子的可变区，分析插入基因盒的序列。结果69株沙门菌中25株携带1类整合子。集中分布在对4种以上抗生索耐药的菌株中。插入基因盒主要是dfr（甲氧氨嘧啶）和aadA（氨基糖甙类）基因盒，各种基因盒组合中最常见的是dfrl-aadA1。结论细菌的多重耐药性与整合子携带高度一致。     

健康人肠道大肠埃希菌整合子和耐药基因盒的研究

目的：研究健康人肠道大肠埃希菌的整合子携带情况与整合子携带的基因盒种类及其与耐药性之间关系.方法：PCR检测Ⅰ类整合子,确定细菌携带整合子的情况.整合子阳性菌株进一步检测整合子的可变区,分析插入基因盒的序列.结果：150株大肠埃希菌中有38株携带Ⅰ类整合子,集中分布在对3种以上抗生素耐药的菌株中.插入基因盒集中在甲氧苄氨嘧啶耐药基因（dfr）和氨基糖甙类抗生素耐药基因（aadA）.结论：细菌的多重耐药性与整合子携带高度一致,但是细菌耐药谱和其整合子无对应关系.     

88株肺炎克雷伯菌中Ⅰ类整合子的分布和耐药性分析

目的:研究Ⅰ类整合子在肺炎克雷伯菌分布、结构及其在介导耐药中的作用。方法:利用多重聚合酶链反应(PCR)方法检测整合酶基因,对其阳性菌株可变区扩增产物进行测序分析;采用微量稀释法测定14种抗生素对试验菌株的敏感性。结果:在其中38株肺炎克雷伯菌DNA上检测到I类整合,阳性率43.2%。所携带的耐药基因盒绝大多数为aadA2和dfr17,整合子阳性组耐药率明显高于阴性组(P<0.05)。结论:目前临床分离的肺炎克雷伯菌耐药性强,并广泛存在I类整合子。菌株携带基因盒和耐药表型之间有较好的对应关系,基因盒介导了细菌耐药性。耐药基因盒是整合子阳性菌株对氨基糖苷类耐药的主要原因。     

健康人群大肠埃希菌Ⅰ类整合子与耐药性关系

目的 研究健康人群大肠埃希菌中Ⅰ类整合子携带情况及分子特征,分析其与细菌耐药性关系.方法 采用Vitek32细菌分析仪和纸片扩散法,检测150株大肠埃希菌抗生素敏感性,PCR检测总DNA中Ⅰ类整合子,扩增产物进行限制性核酸内切酶分析,测序确定携带基因盒种类,脉冲场凝胶电泳对整合子阳性菌株分子分型.结果 150株大肠埃希菌中,83株菌耐受>3种抗生素,耐多药率55.3%;超广谱β-内酰胺酶(ESBLs)阳性5株,阳性率3.3%;携带Ⅰ类整合子42株,扩增子150～3 000 bp,,有8种带型;耐药基因盒主要是dfr和aadA类,最常见基因盒排列dfr17～aadA5;整合子分布在不同基因型菌株中.结论 健康人携带的大肠埃希菌中广泛存在Ⅰ类整合子,与细菌耐多药性密切相关;分子分型结果提示整合子能在细菌种内水平传播,整合子是介导细菌耐药性的重要分子机制.     

致泌尿系统感染中大肠埃希菌Ⅰ类整合子的研究

目的：分析泌尿系统感染中大肠埃希菌Ⅰ类整合子的流行情况和分子特征。方法：应用全自动细菌分析仪Microgcan WalkAway40和纸片扩散法，对40株大肠埃希菌进行抗生索敏感性测定，PCR扩增细菌总DNA上的Ⅰ类整合子。对扩增产物进行测序。并分析其中的基因盒。利用脉冲场电泳（PFGE）对菌株进行分子分型。结果：22株细菌含有Ⅰ类整合子，整合子大小为1000、1200、1700和3000bp，22株细菌各含1-2个整合子。1000bp整合子含基因盒aadA1。1200bp整合子含基因盒dfr1—OFRx，1700bp整合予含基因盒dfr17-aadA5，3000bp整合子两端分别含基因盒aadB、cmlA1，40株细菌被分为不同的基因型，在不同基因型菌株中发现了相同的整合子。结论：整合子在泌尿系统感染大肠埃希中广泛存在，整合子是介导细菌耐药性的重要分子机制，基因分型结果提示整合子在细菌种内水平传播。     

临床耐药性表皮葡萄球菌整合子分子检测分析

目的了解医院临床耐药性表皮葡萄球菌整合子流行现状,以提高治疗效果。方法对2014年1月-2015年1月的18株临床耐药性表皮葡萄球菌进行回顾性分析,采用PCR方法利用特异性引物进行整合子筛查和分类,用PCR法扩增整合子的可变区,联合测序技术分析整合子携带的耐药基因,分析本地区基因盒的种类。结果 18株临床耐药性表皮葡萄球菌均检出整合子基因,检出率为100%;对整合子阳性菌株整合子进行测序分析,发现18株均为Ⅰ类整合子,对基因盒阳性菌株测序分析显示,基因盒排列为dfr A1+orf C。结论医院感染耐药性表皮葡萄球菌中的整合子主要为Ⅰ类整合子,耐药性表皮葡萄球菌整合子主要携带的是二氢叶酸还原酶耐药基因。     

南通地区食源性沙门菌多重耐药性与整合子的相关性研究

目的通过对南通地区食源性沙门菌整合子的检测及耐药性分析,初步探讨整合子、基因盒与耐药性的相关性。方法采用纸片扩散法(kirby-bauer)对67株食源性沙门菌进行耐药性分析,从中选取多重耐药性菌株,提取纯化不同菌株共有的质粒,应用PCR法扩增整合子并进行分类;随机选取1例PCR产物进行DNA测序。结果 67株南通地区食源性沙门菌中31.3%具有多重耐药性;Ⅰ类整合子阳性14株,未发现Ⅱ类、Ⅲ类整合子;10株沙门菌携带质粒,质粒数目为1个~3个,大小为0.5 kb~4 kb;Gen Bank数据库BLAST软件分析1例PCR产物(1.5 kb片段)含有3个开放阅读框,分别与dfr A1、sat2和aad A1耐药基因盒对应。结论南通地区食源性沙门菌对氨苄西林、环丙沙星和哌拉西林等药物出现较高的耐药性;耐药基因可由Ⅰ类整合子携带,并可通过接合试验发生转移,这对细菌多重耐药性的产生和传播转移起到非常重要的作用。     

致病菌耐药因子分布及特征分析

目的 对临床菌株中的整合子分布及其携带耐药基因盒的结构特征进行分析。方法 应用多重PCR方法检测55株临床菌株中的3类整合酶基因intⅠ。并对intⅠ阳性菌株耐药基因盒进行测序及序列分析。结果 55株临床菌株均为第1类整合酶基因阳性（100％）。耐药基因盒特异PCR扩增发现，27株革兰阳性菌株和22株革兰阴性菌株均得到1913bp的扩增产物，携带基因盒为dhfr、orfF和aadA2；6株革兰阴性菌得到1664bp的产物．携带基因盒为aadA5和dfrl7。aadA2和aadA5均为编码对氨基糖苷类抗生素产生耐药的基因盒。dhfr和dfr17均为编码对磺胺类药物甲氧苄氨嘧啶产生耐药的基因盒；orfF为未知功能的开放阅读框。结论 临床致病革兰阳性菌和革兰阴性菌株均广泛存在着整合子结构．应加强对耐药基因在细菌种属间水平转移的监测工作。     

致血液系统感染大肠埃希菌中Ⅰ类整合子参与耐药的研究

目的：探讨致血液系统感染大肠埃希菌中Ⅰ类整合子介导耐药性的分子机制。方法：应用全自动细菌分析仪Microscan WalkAway40和纸片扩散法，对16株大肠埃希菌进行抗生素敏感性测定，PCR扩增细菌总DNA上的Ⅰ类整合子，对扩增产物测序并分析其中的基因盒。结果：8株细菌含有Ⅰ类整合子，整合子大小分别为600bp、1700bp和2500bp，600bp整合子含基因盒dfr2d，1700bp整合子含基因盒dfr17-aadm5。结论：整合子在介导细菌耐药性方面发挥着重要作用。     

Antimicrobial resistance markers of class 1 and class 2 integron-bearing Escherichia coli from irrigation water and sediments

Municipal and agricultural pollution affects the Rio Grande, a river that separates the United States from Mexico. Three hundred and twenty-two Escherichia coli isolates were examined for multiple antibiotic resistance phenotypes and the prevalence of class 1 and class 2 integron sequences. Thirty-two (10%) of the isolates were resistant to multiple antibiotics. Four (13%) of these isolates contained class 1-specific integron sequences; one isolate contained class 2 integron-specific sequences. Sequencing showed that the class 1 integron-bearing strain contained two distinct gene cassettes, sat-1 and aadA. Although three of the four class 1 integron-bearing strains harbored the aadA sequence, none of the strains was phenotypically resistant to streptomycin. These results suggest that integron-bearing E. coli strains can be present in contaminated irrigation canals and that these isolates may not express these resistance markers.     

鸡来源产超广谱β-内酰胺酶大肠埃希菌携带整合子基因的研究

目的 分析鸡肠道内共生的产超广谱β-内酰胺酶(ESBLs)大肠埃希菌整合子携带状况以及其与多重耐药性的关系.方法 从甘肃、湖北、北京、四川地区养殖场鸡粪便标本中分离的大肠埃希菌,肉汤稀释法检测菌株的耐药性,WHONET软件进行耐药性分析;筛选出的ESBLs菌株进行整合子的PCR检测和基因测序. 结果 通过药敏试验从鸡粪中分离的224株大肠埃希菌中共检出产ESBLs的菌株54株,分离率为24.1%.产ESBLs的菌株中I类整合子的携带率为63.0%,I类整合子可变区发现的耐药基因有addA1、aadA2、aadA5、aadA22,dfrA12、dfrA17、dfrI,aar-3,分别介导氨基糖苷类、磺胺类抗生素以及利福平的耐药性.aadA22是在国内菌株中首次报道.Ⅱ类整合子携带率为5.6%,携带的耐药基因包括sat、ereA、aadA1.Ⅲ类整合子酶阳性的有3株菌,但其可变区未检出任何耐药基因. 结论 I类整合子主要介导氨基精苷类抗生素和甲氧嘧啶的耐药性,在大肠埃希菌ESBLs菌株的多重耐药性中具有重要的作用,加强养殖动物大肠埃希菌耐药性以及整合子携带状况的监测,对防止耐药菌株的广泛传播,改善临床抗生素的疗效具有重要意义.     

High Prevalence of Class 1 to 3 Integrons Among Multidrug-Resistant Diarrheagenic Escherichia coli in Southwest of Iran

Objectives

Horizontal transfer of integrons is one of the important factors that can contribute to the occurrence of multidrug-resistant (MDR) bacteria. This study aimed to determine the prevalence of integrons among MDR Escherichia coli strains isolated from stool specimens and investigate the associations between the existence of integrons and MDR properties in the southwest of Iran.

Methods

There were 164 E. coli strains isolated from January 2012 to June 2012. Fecal specimens identified as E. coli by the conventional methods. Subsequently the antibiotic resistance was assessed using Clinical and Laboratory Standard Institute criteria. The presence of class 1–3 integrons and embedded gene cassettes was verified using specific primers by multiplex polymerase chain reaction assay.

Results

Among a total of 164 studied samples, 69 (42.07%) isolates were multidrug resistant. Class 1 and class 2 integrons were present in 78.26% and 76.81% MDR isolates, respectively. For the first time in Iran, class 3 integron was observed in 26.09% MDR isolates. Significant correlations were identified between: class 1 integron and resistance to amikacin, gentamicin, chloramphenicol, ampicillin, tetracycline, nalidixic acid, and co-trimoxazole; class 2 integron and resistance to aminoglycosides, co-trimoxazole, cefalexin, ampicillin, and chloramphenicol; and class 3 integron and resistance to gentamicin, kanamycin, and streptomycin.

Conclusion

Our results indicate that integrons are common among MDR isolates and they can be used as a marker for the identification of MDR isolates. Therefore, due to the possibility of a widespread outbreak of MDR isolates, molecular surveillance and sequencing of the integrons in other parts of the country is recommended.     

水产品中耐药大肠埃希菌整合子与耐药基因盒研究

目的:利用水产品中分离到的耐药大肠埃希菌,研究整合子与耐药性的关系。方法:PCR扩增1类和2类整合酶及整合子,将其进行序列分析。结果:85株耐药大肠埃希菌中88%含有1类整合酶基因;其中68%能扩增此基因;1类整合子可变区PCR扩增产物谱型有17种;1类整合子最常见的基因盒有4种。还发现1株大肠埃希菌同时携带1和2两类不同的整合酶和整合子。结论:大肠埃希菌耐药性与整合子有相关性。     

Antimicrobial resistance and class 1 integrons in pathogenic Escherichia coli from dairy farms

The goal of this study was to assess the prevalence of antimicrobial resistance and class 1 integrons, including integron-associated genes, in 24 Escherichia coli isolates from dairy farms. Escherichia coli isolates (n = 14) from dairy cows with mastitis (ECDM), Shiga toxin-producing (STEC) O157:H7 from cull dairy cow fecal samples (n = 9) and bulk tank milk (n = 1) were evaluated for sensitivity to 19 antimicrobial agents used commonly in human and/or veterinary medicine. Multiplex PCR was used to determine presence of genes associated with class 1 integrons (intI1, qacEDelta1, and sulI1). Class 1 integrons were found only in eight of 10 isolates (one STEC O157:H7 and seven ECDM) that demonstrated antimicrobial resistance, and seven of these were resistant to two or more antimicrobial agents. Eight of 10 STEC O157:H7 and six of 14 ECDM were susceptible to all commonly used antibiotics. Five ECDM demonstrated multiple resistances to four or more antibiotics. Most of the 24 isolates examined exhibited resistance against sulfamethoxazole, followed by streptomycin and tetracycline. STEC O157:H7 strains had less prevalence of antibiotic resistance and integron carriage than ECDM. The multiplex PCR method developed for detection of intI1, qacEDelta1, and sulI1 can be used routinely for monitoring presence of these genes. Class 1 integrons were found in eight of 10 E. coli strains that demonstrated antimicrobial resistance; seven of these were resistant to two or more antibiotics. It appears that integrons played a role in the incidence of antimicrobial resistance of the strains used in this study.