青霉素结合蛋白2a胶乳凝集试验检测耐甲氧西林凝固酶阴性葡萄球菌的实验研究

Study on Detection of MRCNS by Latex Agglutination Test for PBP2a

目的探讨青霉素结合蛋白2a(PBP2a)凝集试验检测耐甲氧西林凝固酶阴性葡萄球菌(MRCNS)的诊断价值和临床应用的可行性。方法将临床分离的89株凝固酶阴性葡萄球菌,以聚合酶链反应(PCR)法检测菌株mecA基因的携带情况;并以此为金标准评价在苯唑青霉素诱导和非诱导条件下,PBP2a胶乳凝集试验检测MRCNS的敏感性、特异性、检出率等,并与传统的肉汤稀释法药物敏感试验作比较。结果药物敏感试验检测MRCNS的敏感性为85.9%,特异性为25%,PBP2a凝集试验敏感性为87.1%,特异性为100%,经苯唑青霉素诱导后,敏感性升至95.3%,且检出率与PCR法无统计学意义。苯唑青霉素诱导可使β-内酰胺酶检测的阳性率由76.4%提高到91%。结论PBP2a凝集试验快速、简便且敏感性较高,是一种较好的MRCNS检出方法。

Objective To evaluate the diagnostic value and clinical feasibility of the latex agglutination test for PBP2a on detecting methicillin-resistant coagulase-nagative Staphylococci （MRCNS）. Methods Methicillin resistance in 89 clinical isolates of CNS was detected with PCR for gene mecA, latex agglutination test for PBP2a, and broth dilution for MIC of oxacillin. Based on the PCR results, latex agglutination test was valued by sensitivity, specificity and detection rate with or without the induction of oxacillin and compared with the result of traditional broth dilution antibiotic susceptibility test. Results According to the results of PCR, the sensitivity and specificity of broth dilution antibiotic susceptibility test were 85.9% and 25% respectively. They were 87.1% and 100% in latex agglutination test for PBP2a. The sensitivity rose to 95.3% after the induction of oxaciUin. There was no statistical difference in detection rate between latex agglutination test and PCR. Furthermore, the positive ratio of β-lactamase-producing isolates rose from 76.4% to 91% after induced by oxacillin. Conclusion It is fast and convenient to judge methiciUin resistance of CNS by latex agglutination test. Moreover, its sensitivity is high, so latex agglutination test is a good method to identify MRCNS isolates.