The first pediatric case of Staphylococcus aureus with heterogenous resistant to vancomycin endocarditis in Thailand

Staphylococcus aureus with reduced susceptibility to vancomycin has been reports worldwide. Here we report the first pediatric case of heterogeneous vancomycin intermediate resistance Staphylacoccus aureus (hVISA) causing endocarditis in Thailand. A 4 months old girl with truncus arteriosus type IV and ventricular septal defect developed methicillin-resistant S. aureus (MRSA) bacteremia and endocarditis after total repair operation. The patient did not respond to combination antimicrobial treatment including vancomycin. The strain was susceptible to trimethoprim-sulfamethoxazole and vancomycin by conventional antimicrobial susceptibily test. The vancomycin minimal inhibitory concentration by E-test was 2 microg/ml. The strain was judged to be possible heteroresistant when screening was done by one-point population analysis. The subsequent population analysis and testing for the emergence of mutants with reduced susceptible to vancomycin confirmed that this strain was hVISA. Despite the treatment with vancomycin, amikacin, rifampicin and cotrimoxazole, the patient died. hVISA should be suspected in MRSA infections that were refractory to vancomycin therapy could be due to. The emergence hVISA underscored the importance of the prudent use of antibiotics, the laboratory capacity to identify MRSA and hVISA and proper communication with treating clinicians, and the meticulous infection-control measures to prevent transmission.