Detection of Heteroresistant Vancomycin-Intermediate Staphylococcus aureus among Methicillin-Resistant Staphylococcus aureus

Background: The testing of heteroresistance vancomycin-intermediate Staphylococcus aureus (hVISA) by the population analysis profile-area under the curve (PAP-AUC) is tedious and laborious. The goal of this study was to determine the prevalence of hVISA among methicillin-resistant S. aureus (MRSA) and compare two screening tests: brain heart infusion agar with vancomycin 4 mg/L (BHIV4) and macromethod E-test (MET) with PAP-AUC as the gold standard. Materials and Methods: Antibiotic sensitivity test and detection of MRSA were performed according to the CLSI guidelines. PAP-AUC, BHIV4, and MET were used to detect hVISA. Results: A total of 288 MRSA isolates were tested for hVISA, with 48 (16.66%) being detected by PAP-AUC. With PAP-AUC, BHIV4's sensitivity, specificity, positive predictive value, and negative predictive value were 70.83%, 96.66%, 80.95%, and 94.3%, respectively. The majority of hVISA isolates were found in the vancomycin minimum inhibitory concentration range 1-2 mg/L. Conclusions: hVISA was found to be 16.6% in this investigation. When compared to MET, BHIV4 had a higher sensitivity, and teicoplanin and linezolid were found to be the most effective drug against hVISA.