In vitro activity of ceftaroline in combination with other antimicrobials active against Staphylococcus spp.

Abstract

Introduction

We evaluated the in vitro activity of the combination of ceftaroline with daptomycin, linezolid and vancomycin against methicillin-resistant Staphylococcus aureus and coagulase-negative Staphylococcus (CNS).

Material and methods

We analysed 70 staphylococcal strains (31 S. aureus and 39 CNS) with the Etest using the MIC:MIC ratio method and calculation of fractional inhibitory concentration indexes.

Results

The combination of ceftaroline with daptomycin showed an additive effect (53.2%) and synergy (6.6%) against methicillin-susceptible S. aureus, and an additive effect (81.2%) against methicillin-resistant S. aureus (MRSA). This combination also showed an additive effect against 33% of linezolid-susceptible CNS and was not synergistic against linezolid-resistant CNS. The combination of ceftaroline with vancomycin was synergistic (87%) and ceftaroline with linezolid was additive (37%) against MRSA.

Conclusions

The combinations of ceftaroline with daptomycin, vancomycin or linezolid showed additive and/or synergistic effects against methicillin-resistant Staphylococcus.

Resumen

Introducción

Evaluamos la actividad in vitro de la combinación de ceftarolina con daptomicina, linezolid y vancomicina frente a aislados de Staphylococcus aureus (S. aureus) y Staphylococcus coagulasa negativa (SCN) resistentes a meticilina.

Material y métodos

Se analizaron 70 cepas de estafilococos (31 S. aureus y 39 SCN) utilizando el método de CMI:CMI ratio con Etest y cálculo de los índices de concentración inhibitoria fraccionaria.

Resultados

La combinación de ceftarolina con daptomicina resultó aditiva (53,2%) y sinérgica (6,6%) frente a S. aureus sensibles a meticilina y aditiva (81,2%) frente a S. aureus resistentes a meticilina (SARM). También resultó aditiva frente al 33% de SCN sensibles a linezolid y no hubo sinergia frente a SCN resistentes a linezolid. Ceftarolina con vancomicina mostró sinergia (87%) y ceftarolina con linezolid adición (37%) frente a SAMR.

Conclusiones

Las combinaciones de ceftarolina con daptomicina, vancomicina o linezolid presentan efectos aditivos o sinérgicos frente a Staphylococcus resistentes a meticilina.