异质性万古霉素中介金黄色葡萄球菌的筛选和生物被膜形成能力的研究

Screening of Heterogeneous Vancomycin-Intermediate Resistant Staphylococcus Aureus and its Biofilm Formation Ability Study

目的调查笔者医院异质性万古霉素中介金黄色葡萄球菌(hVISA)的分离率,并探索hVISA菌株的生物被膜形成能力.方法收集临床139例MRSA菌株,采用浓度为5mg/L的替考拉宁脑心浸液琼脂平皿(BHIA5T)进行hVISA筛选,应用改良菌群分析-曲线下面积(PAP-AUC)法进行确证,报告笔者医院hVISA的发生率.用刚果红琼脂和结晶紫染色法检测hVISA的生物被膜形成能力,微量肉汤稀释法和K-B纸片法检测生物被膜中细菌对抗生素的敏感度.结果经过PAP-AUC方法检测,从139株MRSA中确定1例为hVISA阳性,hVISA的分离率为0.72%.分离出来的hVISA菌株可以形成生物被膜,hVISA菌株的最低抑制生物被膜浓度(MBIC)明显升高,K-B法检测显示它对利奈唑胺和替加环素敏感.同时,研究发现低浓度的万古霉素可能对生物被膜的形成有促进作用.结论笔者医院hVISA的发生率虽然不高,但此菌株可以形成生物被膜,形成生物被膜后细菌对万古霉素敏感度降低,需要引起临床的高度重视,此时可尝试换用利奈唑胺或替加环素.

Objective To investigate the isolation rate of heterogeneous vancomycin-intermediate resistant staphylococcus aureus(hVISA)in our hospital and explore the biofilm formation ability of hVISA strain.Methods A total of 139 MRSA clinical isolates were collected and screened for hVISA with 5mg/L teicoplanin brain-heart infusion agar plate(BHIA5T).We chosed the modified population analyzed profile-area under the curve(PAP-AUC)method as the gold standard to validate hVISA strains and reported the incidence rate of hVISA in our hospital.Congo red agar and crystal violet staining were used to detect the biofilm formation ability of hVISA strain,and we tested the sensitivity of bacteria in the biofilm to vancomycin using the standard broth microdilution and Kirby-Bauer methods.Results After detecting by PAP-AUC method,one of the 139 MRS A strains was confirmed to be hVISA positive,and the isolation rate of hVISA was 0.72%.The isolated hVISA strain could form a biofilm,and the minimum biofilm inhibitory concentration(MBIC)of the hVISA strain was significantly increased.It was found to be sensitive to linezolid and tigecycline by Kirby-Bauer method.At the same time,we found that low concentrations of vancomycin may promote the formation of biofilm.Conclusion Although the incidence rate of hVISA in our hospital is not high,it also needs to be given great attention in clinic because of its biofilm formation ability.Once the biofilm is formed,the sensitivity of bacteria to vancomycin will be reduced.At this time,it is better to use other antibiotics such as linezolid or tigecycline.