多黏菌素B、氨曲南和万古霉素药敏纸片在细菌分离及鉴定中的应用

摘要

目的 利用多黏菌素B、氨曲南和万古霉素特殊的抗菌机制,拓展其在细菌分离及鉴定中的应用.方法 将直接涂片或增菌后革兰染色疑似肠杆菌和肠球菌共存的标本,直接接种于哥伦比亚血琼脂平板上,粘贴多黏菌素B 药敏纸片;对变形杆菌与革兰阳性球菌共存的混合培养物则粘贴氨曲南药敏纸片;对于形态不典型、革兰染色性不定的难以鉴定的菌株,采用KB药敏实验方法,同时粘贴多黏菌素B、万古霉素药敏纸片.35℃培养18～24 h观察结果.结果 多黏菌素B抑菌环内肠球菌生长良好而肠杆菌不生长,氨曲南抑菌环内革兰阳性球菌生长良好而变形杆菌不生长.取多黏菌素B、氨曲南抑菌环内细菌转种于哥伦比亚血琼脂平板,从而达到快速分纯菌株的目的.13份肠杆菌和肠球菌共存的胆汁及脓液标本,采取该方法仅需一代就可以将肠杆菌与肠球菌分离;5份变形杆菌与革兰阳性球菌共存的培养物也仅需一代就可将革兰阳性球菌分纯,而采用传统的方法,6份胆汁标本需2～3代才能分纯,剩余7份均未分离出肠球菌;5份变形杆菌与革兰阳性球菌共存的培养物采用传统的分纯方法也均未分离出革兰阳性球菌;对于形态不典型,革兰染色性不定的难以鉴定的菌株,对万古霉素敏感而多黏菌素耐药的多为革兰阳性细菌,对万古霉素耐药、多黏菌素B敏感的多为革兰阴性细菌.结论 利用多黏菌素B、氨曲南药敏纸片可将难以分纯标本中的肠球菌、革兰阳性球菌快速分纯;另外,对于形态不典型、革兰染色染色性不定的难以鉴定菌株,利用其对多黏菌素B、万古霉素的敏感性,可为待鉴定细菌选定正确的鉴定方向.%Objective To expand the application of separation and identification in bacteria with special antibacterial mechanism of polymyxin B, aztreonam and vancomycin. Methods Suspected enterobacter and enterococcus coexisting specimen after Gram's staining from direct smearing or after increased bacteria was directly vaccinated in Columbia blood agar plate and pasted polymyxin B sensitive slip in the plate. Pasted aztreonam sensitive slip for mixed culture with proteus and Gram positive coccus. At the same time,pasted polymyxin B and vancomycin with KB method for not typical, indefinite properties of Gram's staining and hard to identification of strain. Observed the results of training for 18～24 h in 35°C. Results There were good growth of enterococcus not growth of enterobacter inside polymyxin B bacteriostatic ring and good growth of Gram positive coccus and not growth of proteus. Used the bacteria inside polymyxin B,aztreonam bacteriostatic ring to inoculate in Columbia blood agar plate,so as to achieve the purpose of getting pure strains rapidly. With this method,only one generation could separate enterobacter and enterococcus for 13 bile and purulent fluid specimen with enterobacter and enterococcus, and 5 culture of proteus and Gram positive coccus. With traditional method, 2- 3 generations could separated them for 6 bile specimens and the rest of 7 specimens were not separated enterococcus. 5 culture with proteus and Gram positive coccus were not separated gram positive coccus by traditional method. The bacteria that was sensitive to vancomycin and resistance to polymyxin B could be more for Gram positive bacteria and vice versa. Conclusion Use polymyxin B,aztreonam medicine sensitive slip to separate enterococcus and gram positive coccus rapidly, being difficult to points pure specimen. In addition,use sensitivity of polymyxin B and vancomycin to select proper direction for identification of bacteria, wich is not typical,indefinite properties of Gram's staining and hard to identification.