萘啶酸耐药性作为伤寒沙门氏菌氟喹诺酮耐药性标志物的预测效力。

Predictive efficacy of nalidixic acid resistance as a marker of fluoroquinolone resistance in Salmonella enterica var Typhi.

作者信息

Ray Pallab, Sharma Jyoti, Marak Rungmei S K, Garg R K

机构信息

Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.

出版信息

Indian J Med Res. 2006 Jul;124(1):105-8.

PMID:16926465

Abstract

BACKGROUND AND OBJECTIVES

Resistance in Salmonella enterica var Typhi (S. Typhi) to chloramphenicol, amoxicillin and co-trimoxazole has posed a challenge to treatment of typhoid fever. Ciprofloxacin has been the empirical therapy of choice, but the recent increase in minimum inhibitory concentration (MIC) to ciprofloxacin in S. Typhi, not detectable by disc diffusion (DD) tests, may result in delayed response and serious complications. Nalidixic acid (NA) resistance has been used as an indirect evidence of increased ciprofloxacin MIC in S. Typhi. We evaluated the predictive value of NA resistance for fluoroquinolone resistance in clinical isolates of S. Typhi.

METHODS

A total of 70 clinical isolates of S. Typhi were tested for antimicrobial susceptibility according to the National Committee for Clinical Laboratory Standards (NCCLS) method. MIC to fluoroquinolones was carried out by the agar dilution method.

RESULTS

Thirteen (18.6 %) isolates were resistant to amoxicillin, chloramphenicol and cotrimoxazole; all were sensitive to ciprofloxacin and cefotaxime. Fifty (71.4%) were resistant to NA. Nineteen (27.1 %) isolates were resistant to ciprofloxacin by MIC tests. The MIC for ciprofloxacin was 0.03-4 microg/ml for NA(S) and 0.25-4 microg/ml for NA(R) isolates. NA susceptibility showed a predictive value of 95 per cent for ciprofloxacin susceptibility while NA resistance had a predictive value of 36 per cent for ciprofloxacin resistance. Thirty isolates studied were sensitive to gatifloxacin; MIC values were 0.03-0.5 microg/ml for NA(S) and 0.25-0.5 microg/ml for NA(R) isolates.

INTERPRETATION AND CONCLUSION

NA susceptibility was a good marker for fluoroquinolone susceptibility but NA resistance had a poor predictive value for ciprofloxacin resistance. NA resistant isolates should be tested for ciprofloxacin MIC before deciding a change in therapeutic regimen. Higher MIC for gatifloxacin was also noticed in NA resistant isolates.

摘要

背景与目的

伤寒沙门菌（伤寒杆菌）对氯霉素、阿莫西林和复方新诺明产生耐药性，给伤寒热的治疗带来了挑战。环丙沙星一直是经验性治疗的首选药物，但最近伤寒杆菌对环丙沙星的最低抑菌浓度（MIC）升高，纸片扩散法（DD）检测不到，可能导致反应延迟和严重并发症。萘啶酸（NA）耐药性已被用作伤寒杆菌中环丙沙星MIC升高的间接证据。我们评估了临床分离的伤寒杆菌中NA耐药性对氟喹诺酮耐药性的预测价值。

方法

根据美国国家临床实验室标准委员会（NCCLS）方法，对70株临床分离的伤寒杆菌进行了药敏试验。采用琼脂稀释法测定对氟喹诺酮类药物的MIC。

结果

13株（18.6%）分离株对阿莫西林、氯霉素和复方新诺明耐药；所有分离株对环丙沙星和头孢噻肟敏感。50株（71.4%）对NA耐药。通过MIC试验，19株（27.1%）分离株对环丙沙星耐药。NA敏感的分离株中环丙沙星的MIC为0.03 - 4微克/毫升，NA耐药的分离株中环丙沙星的MIC为0.25 - 4微克/毫升。NA敏感性对环丙沙星敏感性的预测价值为95%，而NA耐药性对环丙沙星耐药性的预测价值为36%。研究的30株分离株对加替沙星敏感；NA敏感的分离株加替沙星的MIC值为0.03 - 0.5微克/毫升，NA耐药的分离株加替沙星的MIC值为0.25 - 0.5微克/毫升。