In vitro antimicrobial susceptibility and virulence genes of the Staphylococcus aureus strains isolated from blood and sterile body fluids / 中国感染与化疗杂志

ABSTRACT

Objective To investigate the antimicrobial susceptibility and associated virulence genes of the Staphylococcus aureus?strains?isolated?from?blood,?cerebrospinal?fluid?and?other?sterile?body?fluids?in?Huashan?Hospital?from?year?1999?to?2014.?Methods MIC values of vancomycin and other antibiotics against S. aureus were measured by agar dilution method. Resistant genes mecA and mecC and virulence genes PVL and sasX were detected by PCR in the S. aureus strains. Results The overall prevalence of MRSA in S. aureus was 54.3 % (140 / 258) and 45.7 % (118 / 258) for MSSA. Resistance rates of MRSA to most antimicrobial agents were higher than MSSA. MSSA strains were still sensitive to all the antibiotics tested, resistance rate not higher than 11% except penicillin. MIC90?values?of?β-lactam?antibiotics?(except?penicillin)?to?MSSA?were?lower?than?1?mg?/?L.?No? staphylococcal strains were found resistant to vancomycin, teicoplanin or linezolid. The mecA gene was present in all the 90 MRSA strains, and sasX gene in 46.7% of the strains. The prevalence?of?MRSA?isolated?from?blood,?cerebrospinal?fluid?and?other?sterile?body?fluids?decreased?year?by?year.?No?mecC gene?or?PVL?gene?was?identified?in?these?MRSA?strains.?Both?sasX-positive MRSA and sasX-negative MRSA were resistant to?β-lactam?antibiotics,?fosfomycin?and?levofloxacin.?The?sasX-positive MRSA strains showed higher resistance rates to amikacin and trimethoprim-sulfamethoxazole than sasX-negative MRSA. Conclusions? The?MRSA?strains?isolated?from?blood,?cerebrospinal?fluid?and?other?sterile?body?fluids?in?Huashan?Hospital?were?resistant to most commonly used anbiotics. MRSA surveillance is critical for rational use of antimicrobial agents.