Investigación de agentes etiológicos de mediastinitis posquirúrgica cardiovascular en un hospital escuela de adultos

La mediastinitis posquirurgica es una complicacion importante que ocurre en 1 a 2 % de las cirugias cardiovasculares (CCV) y posee una alta morbi-mortalidad. Los objetivos del presente trabajo fueron: investigar la etiologia bacteriana de las mediastinitis posteriores a CCV, analizar las caracteristicas feno y genotipicas del agente etiologico prevalente y establecer la relacion clonal  entre los distintos aislamientos de este ultimo. Durante el periodo 2013-2016 se registraron 36 casos de mediastinitis en pacientes adultos, 2 de los cuales fueron diagnosticados con criterios clinicos y el resto con documentacion microbiologica. De las 34 mediastinitis confirmadas microbiologicamente;  29 resultaron monomicrobianas y 5 polimicrobianas. Se analizaron las monomicrobianas, resultando Staphylococcus aureus  el agente etiologico prevalerte. A 30 pacientes se les realizo ademas extraccion de sangre para cultivo; se obtuvo desarrollo en 13 (43%) hemocultivos y en 10 de estos (77%) el aislamiento coincidio con el de muestras esternales. Los aislamientos de Sau estudiados fueron en su mayoria meticilino sensible (SAMS) y solo uno de ellos fue positivo para leucocidina de Panton-Valentine (LPV). Los tipos spa hallados fueron diferentes para cada una de las cepas. En nuestro hospital, el agente etiologico prevalente de mediastinitis posteriores a CCV fue SAMS,  hubo baja portacion del gen pvl y gran diversidad genomica de los aislamientos estudiados durante el periodo de cuatro anos. Palabras claves: Staphylococcus aureus ; mediastinitis posquirurgica; cirugia cardiovascular; leucocidina de Panton-Valentine; gen spa Titulo corto: Mediastinitis postcirugia cardiovascular EN INGLES: Investigation of etiologic agents in postoperative mediastinitis in an adult school hospital ABSTRACT Postoperative mediastinitis is a serious complication in 1 to 2% cardiac surgeries (CS) associated with high morbidity and mortality The aims of this study were to investigate the bacterial ethiology of postoperative mediastinitis after CS, to analyze pheno and genotypical characteristics of the prevalent etiologic agent and to determine clonal relationship between differents isolates of this agent. Thirty-six cases of mediastinitis were registered in adult patients with CS during the 2013-2016 period. Two of them were diagnosed by clinical criteria and the rest had also microbiological documentation; 29 were monomicrobial and 5 polimicrobial. The prevalence was analyzed in the first ones, with Staphylococcus aureus (Sau) as the prevalent etiologic agent. Blood samples were taken for culture in 30 patients, 13 of them were positive with 10 isolates identical to their corresponding strains in sternal samples. In regard to Sau characteristics, most of the strains were supceptible to methicilin and only one of them was positive for Panton-Valentine leucocidin (PVL). Spa-typing was performed and no matching was found. We concluded that in our hospital the prevalent etiologic agent was methicillin-sensitive Sau, the carriage rate of PVL was low and there was high genomic diversity between the isolates causing mediastinitis during the analyzed period Palabras claves: Staphylococcus aureus, post-operative mediastinitis, cardiac surgery, Panton-Valentine leucocidin, spa gen Titulo corto: Post-operative mediastinitis