Abstract:

Objective  To investigate the prevalence of heteroresistant vancomycin-intermediate staphylococcus aureus and compare three screening methods. Methods  216 strains of methicillin-resistant staphylococcus aureus(MRSA) were preliminarily screened by brain heart infusion agar with 2mg/liter vancomycin (BHIV2), 4mg/liter vancomycin (BHIV4) or 5mg/liter teicoplanin (BHIT5). Positive strains were confirmed by macroEtest(MET) and population analysis profile-area under the curve（PAP-AUC）. Results  In 216 strains of clinical MRSA, isolating rate of hVISA was at least 13.4%. In BHIV2, BHIV4 and BHIT5 screening methods, the preliminarily screened positive strains were 143, 19 and 110, respectively, with finally confirmed rates of 16.1%, 73.7% and 19.1%, respectively. Conclusion  Some certain strains of hVISA exist in MRSA isolated from clinics of Jinan region . Among the three methods, sensitivities in BHIV2 and BHIT5 methods are higher than that in BHIV4 method. However, specificities in BHIV2 and BHIT5 methods are lower than that in BHIV4 method. There are no significant differences in sensitivity and specificity between BHIV2 and BHIT5 methods.

Key words: Staphylococcus aureus； Vancomycin； Heteroresistance