Vancomycin intermediate-Resistant Staphylococcus aureus (VISA) Isolated from a patient who never received Vancomycin treatment

• We isolated a VISA from a patient who had not undergone vancomycin treatment.
• Multiplex PCR revealed that the VISA strain belonged to ST239-t030-agr-1.
• The VISA strain displayed a decreased growth rate and reduced susceptibility to Triton X-100-induced autolysis.
• The thicker cell wall was one feature of this VISA strain.
• All 9 isolates shared the same PFGE banding pattern.

SummaryBackgroundWith the abuse of antibiotics, the methicillin-resistant Staphylococcus aureus (MRSA) strain became prevalent. Furthermore, Staphylococcus aureus with a character of vancomycin intermediate-resistance (VISA) has been found globally since the first report in Japan. The main objectives of this study were to report a case of VISA isolated from a Chinese patient who had never undergone Vancomycin treatment, and to determine its molecular character.MethodsA total of 9 strains were recovered from a patient during the therapeutic process. Antimicrobial susceptibility testing was performed to determine their antibiotic susceptibility patterns. To detect the VISA strain's molecular epidemiological features, growth and morphological characters, we used multilocus sequence typing, autolysis assay and transmission electric microscope tests. Pulsed-field gel electrophoresis (PFGE) was performed to characterize the heterogeneities of all isolates.ResultsOne isolate was found to exhibit vancomycin intermediated-resistant with MIC of 8 μg/ml. It was ST239-T030-agr-1, had thickened cell wall, and displayed a slower growth rate and reduced susceptibility to Triton X-100-induced autolysis than other strains. All 9 strains exhibited the same PFGE pattern.ConclusionThis is the first report of VISA found in central China from a patient who had never received vancomycin treatment.