[产肠毒素基因阳性与阴性脆弱拟杆菌分离株的耐药模式比较]

[Comparison of antimicrobial resistance patterns of enterotoxin gene positive and negative Bacteroides fragilis isolates].

作者信息

Toprak Nurver Ulger, Yağci Ayşegül, Celik Cennet, Cakici Ozlem, Söyletir Güner

机构信息

Marmara Universitesi Tip Fakültesi, Mikrobiyoloji ve Klinik Mikrobiyoloji Anabilim Dali, Istanbul.

出版信息

Mikrobiyol Bul. 2005 Apr;39(2):145-52.

PMID:16128024

Abstract

Some of the Bacteroides fragilis strains produce enterotoxin named fragilysin which is accepted as a virulence factor. In this study, the presence of enterotoxin genes (bft) in clinical B. fragilis strains has been investigated and the antimicrobial resistance patterns of bft positive and negative isolates have been compared. B. fragilis strains isolated from different clinical samples were identified by conventional methods and API 20A system, and the presence of bft genes were searched by using BF3/BF4 primers in polymerase chain reaction. A total of 100 B. fragilis strains of which 50 bft gene positive and 50 bft gene negative were included to the study, and their antimicrobial susceptibilities were determined by agar dilution method as recommended by NCCLS (M11-A4). Of 100 strains, 71 (34 bft negative, 37 bft positive) have been isolated from the stool, and 29 (16 bft negative, 13 bft positive) have been isolated from other specimens (blood, abscess, pleural and peritoneal fluids). beta-lactamase production was detected in 96% of enterotoxigenic B. fragilis (ETBF) and 95% of non-toxigenic strains, and all tested strains were found to be susceptible to amoxicillin/clavulanic acid, imipenem and metronidazole. The resistance rates (with MIC90 values) of bft positive isolates against the other antibiotics were as follows; 96% (256 microg/ml) for ampicillin, 16% (256 microg/ml) for piperacillin, 8% (32 microg/ml) for cefoxitin, 24% (> 256 microg/ml) for clindamycin, 74% (64 microg/ml) for tetracycline and 0% (8 microg/ml) for chloramphenicol. These rates were found as follows for bft negative strains; 95% (256 microg/ml) for ampicillin, 6% (64 microg/ml) for piperacillin, 6% (32 microg/ml) for cefoxitin, 38% (> 256 microg/ml) for clindamycin, 64% (64 microg/ml) for tetracycline and 4% (8 microg/ml) for chloramphenicol. Although the resistance rates and MIC90 values of bft positive strains against the antimicrobials seemed to be higher, there were no statistically significant differences between resistance rates of bft positive and negative strains (P > 0.05; 0.12 and 0.28, respectively).

摘要

一些脆弱拟杆菌菌株可产生名为脆弱类毒素的肠毒素，该毒素被认为是一种毒力因子。在本研究中，对临床脆弱拟杆菌菌株中肠毒素基因（bft）的存在情况进行了调查，并比较了bft阳性和阴性分离株的抗菌耐药模式。通过传统方法和API 20A系统对从不同临床样本中分离出的脆弱拟杆菌菌株进行鉴定，并在聚合酶链反应中使用BF3/BF4引物搜索bft基因的存在情况。共有100株脆弱拟杆菌菌株纳入研究，其中50株bft基因阳性，50株bft基因阴性，按照美国国家临床实验室标准化委员会（NCCLS，M11-A4）推荐的琼脂稀释法测定它们的抗菌敏感性。100株菌株中，71株（34株bft阴性，37株bft阳性）从粪便中分离得到，29株（16株bft阴性，13株bft阳性）从其他标本（血液、脓肿、胸水和腹水）中分离得到。在96%的产肠毒素脆弱拟杆菌（ETBF）和95%的非产毒素菌株中检测到β-内酰胺酶的产生，并且所有测试菌株均对阿莫西林/克拉维酸、亚胺培南和甲硝唑敏感。bft阳性分离株对其他抗生素的耐药率（MIC90值）如下：氨苄西林为96%（256μg/ml），哌拉西林为16%（256μg/ml），头孢西丁为8%（32μg/ml），克林霉素为24%（>256μg/ml），四环素为74%（64μg/ml），氯霉素为0%（8μg/ml）。bft阴性菌株的数据如下：氨苄西林为95%（256μg/ml），哌拉西林为6%（64μg/ml），头孢西丁为6%（32μg/ml），克林霉素为38%（>256μg/ml），四环素为64%（64μg/ml），氯霉素为4%（8μg/ml）。尽管bft阳性菌株对抗菌药物的耐药率和MIC90值似乎更高，但bft阳性和阴性菌株的耐药率之间无统计学显著差异（P>0.05；分别为0.12和0.28）。