Clinical studies on the selective enrichment of rifampicin-resistant S.aureus mutants in vivo / 解放军医学杂志

ABSTRACT

Objective To study the correlation between mutant selection window (MSW) and selective enrichment of Staphylococcus aureus resistant mutants in vivo. Methods Tuberculosis patients colonized with S. aureus in anterior nares were selected as experimental group. The susceptibility of S. aureus to rifampicin was determined at the beginning of and 2,4 and 5 weeks after the anti-tuberculosis therapy with rifampicin-containing regimens. S. aureus isolates developing acquired resistance were examined by molecular strain typing. Diabetes patients colonized with S. aureus served as an untreated control. Results The S. aureus isolated from 5 patients acquired rifampicin resistance in 58 tuberculosis patients. It was determined by pulsed-field gel electrophoresis and protein A repeat sequence the strains of S. aureus were different, but the isolates obtained from the same patient before and after acquisition of resistance were the same strains. No resistance was acquired in 39 untreated control patients, which differed statistically from treated patients. Conclusion The selective enrichment of rifampicin-resistant S. aureus mutants occurred when rifampicin concentration was in the mutant selection window.