Original Article
The prevalence and detection methods of hetero-resistant vancomycin intermediate Staphylococcus aureus
Liu Cailin, Chen Zhongju, Sun Ziyong, Qiu Hong, Ke Jun, Shi Li, Zhang Fuhong, Chen Tong, Zou Jiuming, Gong Ping, Zou Xiaoyan, Peng Jiaowu, Zhang Caishi, Wang Yue, Ou Guoping
Published 2014-01-11
Cite as Chin J Lab Med, 2014,37(01): 41-45. DOI: 10.3760/cma.j.issn.1009-9158.2014.01.011
Abstract
ObjectiveTo investigate the prevalence of hetero-resistant vancomycin intermediate Staphylococcus aureus(hVISA) from clinical methicillin-resistant Staphylococcus aureus (MRSA) in Hubei province and explore a simple method for detecting hVISA isolates.
Methods The minimum inhibitory concentrations (MIC) of 214 MRSA strains to oxacillin, cefoxitin,vancomycin and teicoplanin were determined using agar dilution method.The hVISA isolates were detected by MHA5T(M-H agar containing 5mg/L teicoplanin), MET(Etest macromethod) and PAP/AUC (population analysis profiles/area under the curve).When PAP/AUC method as the gold standard, the sensitivity and specificity of MHA5T and MET methods were compared.The autolysis of hVISA and methicillin-sensitive Staphylococcus aureus (VSSA) was detected by Triton X-100 induced autolysis, SPSS18.0 software was used to analyze the differences.
ResultsThe positive rate of hVISA were 17.8% (38/214), 20.6% (44/214), 45.8% (98/214) by PAP/AUC, MET, MHA5T, respectively.PAP/AUC method as the gold standard, the sensitivity and specificity of MET and MHA5T were 81.6%(31/38), 92.6%(163/176) and 89.5%(34/38), 63.6%(112/176), respectively.Four hours later, the autolysis of hVISA dropped to 52%, and VSSA isolates dropped to 28%, compared with VSSA, the autolysis of hVISA had significant decline (χ2=18.3486,P=0.024).
ConclusionsThe prevalence of hVISA was 17.8% in Hubei Province and should be paid attention. In order to reduce the tedious workload of doing PAP/AUC and the using of E-test, MHA5T could be used as the primary screening method of hVISA.(Chin J Lab Med,2014,37:41-45)
Key words:
Methicillin resistance; Staphylococcus aureus; Vancomycin; Laboratory techniques and procedures
Contributor Information
Liu Cailin
Department of Clinical Laboratory,Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
Chen Zhongju
Sun Ziyong
Qiu Hong
Ke Jun
Shi Li
Zhang Fuhong
Chen Tong
Zou Jiuming
Gong Ping
Zou Xiaoyan
Peng Jiaowu
Zhang Caishi
Wang Yue
Ou Guoping