Penicillin-susceptible Staphylococcus aureus bacteremia: Epidemiological and clinical relevance. Possible therapeutic implications.

INTRODUCTION

The increase in penicillin susceptibility among Staphylococcus aureus (SA-PenS) might have therapeutic relevance. We aimed to study the current situation in our environment.

MATERIAL AND

METHODS

Over a 2.5 years period, all SA isolates from bacteraemia in one hospital were analysed. For all isolates, antimicrobial susceptibility profile, beta-lactam resistance genes (blaZ, mecA) and Panton-Valentine leucocidine encoding-genes were studied. For SA-PenS-blaZnegative isolates, spa-type, MLST and the presence of other resistance genes were studied.

RESULTS

Among 84 patients with SA bacteraemia (35.7% MRSA and 64.3% MSSA), 77 were analysed; 22.2% of MSSA isolates were PenS and blaZnegative (Pen-MIC≤0.03μg/ml) corresponding to 14.3% of the total SA. In MSSA-PenS-blaZnegative isolates, eight spa-types and 7 clonal-complexes were detected.

CONCLUSION

A high prevalence of MRSA/SA and MSSA-PenS-blaZnegative/MSSA was detected in blood cultures. Pen-MIC≤0,3μg/ml corresponded to MSSA-PenS-blaZnegative. This situation raises therapeutic options which should be further evaluated in larger studies and clinical trials.