难辨梭菌鉴定培养基临床应用评估

Evaluation of performance of chrom ID Clostridiu difficile agar

目的评估难辨梭菌鉴定培养基(CDIF)的应用价值。方法用方法学评估研究。对临床收集的255份粪便标本同步进行CDIF培养基和环丝氨酸-头孢西丁-果糖琼脂培养基(CCFA)培养,并对CDIF培养基上的所有菌株及CCFA培养基上的典型菌株进行基质辅助激光解吸/电离飞行时间质谱鉴定。结果 255份粪便标本中,经CDIF培养24 h后出现典型菌株64株,经质谱鉴定为难辨梭菌58株;另有3株无色透明菌落的菌株被质谱鉴定为难辨梭菌。以质谱鉴定结果为参考,CDIF培养基对难辨梭菌鉴定的敏感性、特异性、阳性预测值、阴性预测值分别为95.1%(58/61)、96.9%(188/194)、90.6%(58/64)和98.4%(188/191)。CCFA培养48 h后生长的典型菌株经质谱鉴定为难辨梭菌61株。CDIF培养基和CCFA培养基上经质谱鉴定为难辨梭菌的菌落中,分离单一菌种比例分别为80.3%(49/61)和77.0%(47/61);CDIF培养基上菌落生长密度高于CCFA培养基。结论 CDIF培养基具有快速准确、操作简便、成本较低的特点,为难辨梭菌感染的实验室诊断提供了新的选择。

Objective To evaluate the performance of chromlD C. difficile agar （CDIF） for the identification of Clostridium difficile. Methods The study on methodological evaluation of identifications for Clostridiu diffieile was conducted. A total of 255 stool speci- mens were inoculated on CDIF and cyeloserine-cefoxitin-fruetose-agar （CCFA） respectively. All the isolates on CDIF and the typical colonies on CCFA were identified by matrix-assisted laser desorption/ionization time of flight mass spectrometry （ MALDI-TOF MS）. Results Among the 255 stool specimens, 64 showed typical colony characteristics on CDIF after incubation for 24 hours, and 58 iso- lates were identified to be C. difficile by MALDI-TOF MS, and 3 isolates with transparent colony were also identified to be C. difficile. Compared with the results of MALDI-TOF MS, the sensitivity, specificity, positive predictive value and negative predictive value of CDIF were 95.1% （58/61）, 96.9% （ 188/194）, 90.6% （58/64） and 98.4% （ 188/191 ） respectively. Sexty-one C. difficile strains were isolated on CCFA. The mono-bacteria percentage of the isolates on CDIF and CCFA was 80.3% （49/61） and 77.0% （47/61） respectively. The richness of the bacteria on CDIF was over those on CCFA. Conclusion CDIF should be rapid, accurate, easy and economic for the identification of Clostridium difficile, which provides a new diagnostic strategy for the infection of Clostridium difficile.