【摘要】 目的评价自主研发的艰难梭菌显色培养基(CDCA)性能。方法选用艰难梭菌及其他细菌的标准株进行CDCA显色的特异性评价;将艰难梭菌标准菌株梯度稀释后测定BD公司CDSA、生物梅里埃公司CDIF和CDCA的灵敏度。收集临床120份粪便样本分别采用3种培养基进行艰难梭菌分离培养,并对生长菌落进行质谱鉴定和tpi基因检测,以3种平板中任1种能培养出艰难梭菌的样本定义为真阳性。结果在CDCA平板上除了梭形梭菌、双酶梭菌、第三梭菌、脆弱拟杆菌等菌种能够少量生长并显色外,对其他实验菌种均有抑制作用。CDSA、CDIF和CDCA检测艰难梭菌的灵敏度分别为2.0×10~5 CFU/mL、8.0×10~1 CFU/mL和4.0×10~2 CFU/mL。120份标本中检出艰难梭菌31份(25.8%),CDSA、CDIF和CDCA培养阳性标本分别为25份(20.8%)、28份(23.3%)和26份(21.7%),3种显色培养基对临床腹泻标本检测阳性率差异无统计学意义(χ~2=0.418,P=0.811)。3种显色培养基的敏感性、特异性、阳性预测值、阴性预测值分别为:CDCA 83.8%、100%、100%、94.7%;CDIF 90.3%、98.9%、96.6%、96.7%;CDSA 80.6%、100%、100%、93.7%。结论本实验室研发的CDCA的特异性和灵敏度较高,可用于临床艰难梭菌的初步分离。更多还原

【Abstract】 Objective To evaluate the performance of a chromogenic agar developed by our laboratory for the isolation and culture of Clostridium difficile(CDCA). Methods The chromogenic specificity of CDCA was evaluated by inoculation of C. difficile and other standard strains, and the sensitivities of CDSA(BD), CDIF(BioMérieux) and CDCA were determined by the C. difficile standard strains respectively. A total of 120 clinical stool specimens were cultured for C. difficile by three chromogenic media respectively. The colonies were further identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and tpi gene was also detected. The sample which could be identified as C. difficile in any of the three chromogenic medium was defined as true positive. Results Most of standard strains were inhibited by CDCA, however some Clostridium species including C. clostridiiforme, C. bifermentans, C. tertium and Bacteroides fragilis grew lightly with chromogenic reaction. The sensitivities of CDSA, CDIF and CDCA were 2.0×10~5 CFU/mL, 8.0×10~1 CFU/mL and 4.0×10~2 CFU/mL, respectively. Among the 120 samples, 31(25.8%) were defined as true C. difficile positive samples, while the positive rate of CDSA, CDIF and CDCA were 25(20.8%), 28(23.3%) and 26(21.7%), respectively. There was no significant difference for clinical diarrhea specimens among the three chromogenic media(χ~2=0.418, P=0.811). In comparison to the standard, the sensitivity, specificity, positive predictive value and negative predictive value were 83.8%, 100%, 100% and 94.7% for CDCA; 90.3%, 98.9%, 96.6% and 96.7% for CDIF; and 80.6%, 100%, 100% and 93.7% for CDSA. Conclusion The CDCA developed by our laboratory could be used to preliminarily isolate C. difficile with good specificity and sensitivity.更多还原