Fosfomycin resistance and f os gene detection in clinical St ap hy lococcus aureus strains / 中国感染与化疗杂志

ABSTRACT

Objective To understand fosfomycin resistance and prevalence of fos gene in clinical Staphylococcus aureus strains . Methods A total of 109 clinical strains of S .aureus were isolated from the patients in Huashan Hospital from January to March in 2014 .Antimicrobial susceptibility testing was performed by agar dilution method .The genes related to fosfomycin resistance including fosA ,fosB and fosC were detected by PCR .The flanking sequences of fos gene were determined by primer walking sequencing .The multilocus sequence typing (MLST) was carried out for fos gene positive strains .Results Forty‐four strains were resistant to fosfomycin (MIC> 32 mg/L) ,including 13 positive for fosB gene .Thirteen of the 109 (11 .9% ) strains carried fosB gene .However ,no fosA or fosC gene was identified .ST1 was a dominant MLST type in the strains carrying fosB gene .The three strains positive for fosB gene and associated with high level fosfomycin resistance (MIC> 512 mg/L) belonged to three different ST types . Walking sequencing showed that the fosB gene located on a transferable element containing a transposase gene .Conclusions High prevalence of f osB gene in fosfomycin‐resistant S . aureus strains indicates that f osB gene may mediate or contribute to fosfomycin resistance .