Epidemiología molecular de un brote de infecciones por streptococucus pyogenes en una unidad de quemados / Molecular epidemiology of a streptococcus pyogenes related nosocomial outbreak in a burn unit

Group A Streptococcal (GAS) infections have increased in frequency and severity worldwide. During April 1996, a nosocomial outbreak associated to GAS infections affected seven patients admitted to a pediatric burn unit. The causative organism was likely disseminated from the source patient to another child in the emergency room before he was transferred to the burn unit. Patients developed burn infections or invasive disease. One of them died due to a toxic shock syndrome and 3 other lost their skin grafts. Perineal and nasal microbiological surveillance of 42 related health care workers identified only one of them as carrier of S pyogenes. Aim: To report a molecular analysis of an apparently clonal outbreak. Material and methods: The available isolates were analyzed by molecular methods including random amplified polymorphic DNA analysis (RAPD) with 4 different primers, Sma-I pulsed field gel electrophoresis (PFGE) analysis, and speA, speB and speC detection by polymerase chain reaction (PCR). Results: Two phylogenetically distant and sequentially isolated bacterial groups were identified either by RAPD analysis with selected primers or by Smal-PFGE analysis. The first group involved isolates identified in two patients that included the lethal case. The second bacterial group comprised 5 clinical isolates and the perineal and nasal isolates obtained from a health care worker. Only strains belonging to the first group harbored the speA gene and were associated with invasive disease. The second group could be split further in two subgroups according to their speB profile. Conclusions: RAPD analysis with selected primers can reproduce the PFGE-discriminating ability on the epidemiological analysis of GAS infections

Diversidad clínica de las infecciones invasivas por streptococcus pyogenes y asociación con el superantíngeno SpeA / Clinical diversity of invasive infections by streptococcus pyogenes and SpeA superantigen association

Se presenta una serie de 5 casos con infecciones invasivas por S. pyogenes observados durante 1999, con el objetivo de ilustrar la diversidad clínica de estas infecciones. Todos los pacientes presentaron bacteremia y tenían condiciones mórbidas asociadas. Tres pacientes presentaron shock, dos de ellos de tipo tóxico y el mismo número de pacientes presentó manifestaciones cutáneas. Dos pacientes tuvieron alteraciones de coagulación. Todos los casos tenían leucocitosis (valor promedio 16800 por mm3) y aumento de la proteína C reactiva (300 mg/L en promedio). Los valores de desviación a izquierda y eritrosedimentación presentaron una amplia variación en sus resultados, observando pacientes con cifras normales. Cuatro pacientes recibieron tratamiento quirúrgico y 3 pacientes gamaglobulina endovenosa. Tres pacientes fallecieron (dos de ellos a las 72 horas). Los pacientes que sobrevivieron tuvieron una hospitalización prolongada que superó el mes de duración. Todos los aislamientos bacterianos portaban el gen que codifica por el superantígeno SpeA