ABSTRACT
INTRODUCCIÓN: El aumento de la sensibilidad a penicilina en Staphylococcus aureus (SA-PenS) podría tener relevancia terapéutica. Pretendemos conocer esta situación en nuestro medio. MATERIAL Y MÉTODOS: Se analizaron bacteriemias por SA en un hospital durante 2,5 años (2015-2017). Estudiamos la sensibilidad a antimicrobianos, genes de resistencia a beta-lactámicos (blaZ, mecA) y presencia de leucocidina de Panton-Valentine. En aislados SA-PenS-blaZnegativo se determinó el tipo de spa, MLST y genes de resistencia a antimicrobianos no-beta-lactámicos. RESULTADOS: Hubo 84 pacientes con bacteriemia por SA (35,7% SARM y 64,3% SASM), se analizaron 77. El 22% de los SASM estudiados (n = 11) fueron PenS-blaZnegativo (CMI-Pen ≤ 0,3 μg/ml), correspondiendo al 14,3% del total de SA. En SASM-PenS-blaZnegativo se detectaron 8 tipos-spa y 7 complejos clonales. CONCLUSIÓN: Detectamos alta prevalencia de SARM/SA y de SASM-PenS-blaZnegativo/SASM en hemocultivos. Una CMI-Pen ≤ 0,3 μg/ml se correspondió con SASM-PenS-blaZnegativo. Esta situación plantea opciones terapéuticas que deberán reevaluarse con estudios más amplios y ensayos clínicos
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 ≤ 0.03 μg/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 ≤ 0,3 μg/ml corresponded to MSSA-PenS-blaZnegative. This situation raises therapeutic options which should be further evaluated in larger studies and clinical trials
