95个猪场大肠杆菌耐药表型及氨基糖苷类药物耐药基因型调查

Phenotypic and Aminoglycosides Genotypic Antimicrobial Resistance Characterization of Escherichia coli Isolated from 95 Pig Farms

为调查我国规模化猪场大肠杆菌细菌耐药性及其氨基糖苷类药物耐药基因的流行状况,采用K-B(Kir-by-Bauer)法检测2006-2007年从四川、重庆、湖北等19个省95个规模化猪场分离的480株大肠杆菌对19种抗生素的耐药性。结果表明:仅有多黏菌素B(85.6%)、头孢噻肟(85.3%)、阿米卡星(84.8%)和大观霉素(65.0%)相对敏感。480株大肠杆菌以多重耐药菌株为主,其中13、14、15、16和17重耐药较多,并且有26株18重耐药,14株19重耐药。采用WHONET5.4软件分析大肠杆菌耐药性,对阿米卡星、头孢噻肟和多黏菌素B耐药的猪场相对较少,分别是29、26和24个。采用PCR方法检测氨基糖苷类相关耐药基因,耐药基因检出率分别是aadA1(65.89%)、aaC2(52.35%)、aaC4(12.91%)和aphA3(10.95%)。耐药基因型检出率较高的是aadA1/aaC2(29.61%)、aadA1(18.04%)。Excel软件统计相关耐药基因的猪场分布,表明耐药基因型aadA1/aaC2(43)、aa-dA1/aaC2/aaC4(20)和aadA1/aaC2/aaC4/aphA3(20)在猪场分布较普遍。耐药基因和耐药性比较表明大肠杆菌对氨基糖苷类药物耐药表型与耐药基因型符合率较高的是阿米卡星(68.39%)。本研究表明猪肠道内常在大肠杆菌菌群不仅产生较高的多重耐药性,也成为耐药基因的储存库,对猪场环境中耐药基因在致病菌和非致病菌间传播发挥重要作用,能够作为检测细菌耐药性的指示菌。

The objective of this study was to investigate the prevalence of antimicrobial resistance and aminoglycosides resistance genes （aadA1, aaC2, aaC4 and aphA3） among 480 commensal Escherichia coli isolates, which were collected from weaning piglets of 95 large scale pig farms among 19 provinces in China from 2006 to 2007. The resistance of those E. coli strains toward 19 broad-spectrum antibiotics were tested by K-B（Kirby-Bauer） method, and 4 aminoglyeosides resistance genes were detected by multiplex PCR. The results showed that E. coli isolates were relatively sensitive to polymycin B （ 85.6 % ） , cefotaxime sodium （ 85.3 % ） , amikacin （ 84.8 % ） and spectinomycine （65.0%）. Most of 480 isolates were multidrug resistant strains. The number of E. coli isolates, which were resistant to 13,14,15,16 or 17 antibiotics, was relatively more than others. Moreover, there were 26 isolates resistant to 18 antibiotics and 14 isolates resistant to 19 antibiotics. By WHONET5.4 analysis, the number of swine farms resistant to amikacin, cefotaxime sodium and polymycin B was relatively less than others, and they were 29,26 and 24, respectively. The mainly detected aminoglycosides resistance genes were aadAl（65.89%）, aaC2 （52.35%）,aaC4（12.91%） and aphA3（10. 95%）. The antimicrobial resistance genetype of aadA1/aaC2（29.61%） and aadA1 （18.04%） were detected frequently among commensal E. coli isolates. The antimicrobial resistance genotype of aadA1/aaC2（43）, aadA1/aaC2/aaC4（20） and aadA1/aaC2/aaC4/aphA3（20） were relatively prevalent among 95 pig farms by excel analysis. By comparing the coincidence rate of antimicrobial resistant phenotype and genes, the coincidence rate of amikacin（68. 39%） was relatively higher than other antibiotics. The results indicated that the commensal E. coli could produce multidrug resistant to antibiotics, be potential reservoir to preserve and disseminate antimicrobial resistance genes between pathogenic and nonpathogenic bacteria, and could be used as indicator to survey antimicrobial resistance in swine farm environment.