Diseminación de cepas Staphylococcus aureus sensible a meticilina (SASM) relacionadas genéticamente, pertenecientes al CC45, entre portadores nasales sanos de hogares infantiles de Medellín, Colombia / Spread of genetically related methicillin-susceptible Staphylococcus aureus belonging to CC45, in healthy nasal carriers in Child Day Care Centers of Medellin, Colombia

INTRODUCCIÓN: La colonización por Staphylococcus aureus desempeña un papel importante en la epidemiología y patogénesis de las infecciones que causa. La población infantil es una de las más susceptibles a colonizarse; sin embargo, en Colombia los estudios en comunidad y en población infantil son escasos. OBJETIVO: Determinar la relación clonal de aislamientos colonizantes de S. aureus en menores de 8 hogares infantiles de Medellín y describir las características epidemiológicas presentes en esta población. MÉTODOS: Se realizó un estudio observacional transversal donde se seleccionó una muestra de 200 menores entre los 6 meses y los 5 años de edad, provenientes de 8 hogares infantiles de Medellín, Colombia, durante 2011. Las muestras fueron tomadas de fosas nasales. Los aislamientos de S. aureus y la resistencia a meticilina se confirmaron molecularmente, empleando los genes nuc y mec. La genotipificación incluyó tipificación del SCCmec, tipificación de spa, PFGE y MLST. La información epidemiológica fue obtenida de los padres y analizada en SPSS® 21.0. RESULTADOS: La frecuencia de colonización en los hogares varió entre el 16,7% (n = 3) y el 53,6% (n = 15). En el interior de 4 hogares infantiles se identificaron aislamientos de S. aureus relacionados entre sí. Adicionalmente, el 50% de todos los aislamientos de S. aureus sensible a meticilina se agruparon en 3 clúster, que pertenecían a los complejos clonales CC45, CC30 y CC121. CONCLUSIÓN: La tipificación molecular de los aislamientos de los menores colonizados y el análisis realizado en el interior de los hogares permitió describir la diseminación de las cepas colonizantes en el interior de los hogares infantiles de la ciudad de Medellín, principalmente del CC45, un clon exitoso en colonización

INTRODUCTION: Colonization plays a major role in the epidemiology and pathogenesis of Staphylococcus aureusinfections. The child population is one of the most susceptible to colonization; however, community and children studies are limited in Colombia. OBJECTIVE: To assess the clonal relationship of S. aureus strains isolated from colonized children in eight day care centers (DCCs) from Medellin and to determine the presence of epidemiological characteristics in these populations. METHODS: An observational cross-sectional study was conducted on a sample of 200 children aged from 6 months to 5 years attending eight DCCs in Medellin, Colombia, during 2011. Nasal samples were collected from each nostril. The isolates species and methicillin resistance were molecularly confirmed using nuc and mec genes. Genotypic analysis included SCCmec typing, spa typing, PFGE and MLST. Epidemiological information was obtained from the parents and analyzed using the statistics program SPSS 21.0 RESULTS: The colonization frequency in DCCs ranged from 16.7% (n = 3) to 53.6% (n = 15). Genetically related isolates were identified inside four DCCs. Half (50%) of the isolates were grouped in 3 clusters, which belonged to the clonal complexes CC45, CC30, and CC121. CONCLUSION: Molecular typing of isolates from colonized children and comparison among DCCs showed the spread of colonizing strains inside DCCs in Medellin; predominantly the CC45 clone, a successful child colonizer

[Spread of genetically related methicillin-susceptible Staphylococcus aureus belonging to CC45, in healthy nasal carriers in Child Day Care Centers of Medellin, Colombia]. / Diseminación de cepas Staphylococcus aureus sensible a meticilina (SASM) relacionadas genéticamente, pertenecientes al CC45, entre portadores nasales sanos de hogares infantiles de Medellín, Colombia.

INTRODUCTION: Colonization plays a major role in the epidemiology and pathogenesis of Staphylococcus aureus infections. The child population is one of the most susceptible to colonization; however, community and children studies are limited in Colombia. OBJECTIVE: To assess the clonal relationship of S.aureus strains isolated from colonized children in eight day care centers (DCCs) from Medellin and to determine the presence of epidemiological characteristics in these populations. METHODS: An observational cross-sectional study was conducted on a sample of 200 children aged from 6 months to 5 years attending eight DCCs in Medellin, Colombia, during 2011. Nasal samples were collected from each nostril. The isolates species and methicillin resistance were molecularly confirmed using nuc and mec genes. Genotypic analysis included SCCmec typing, spa typing, PFGE and MLST. Epidemiological information was obtained from the parents and analyzed using the statistics program SPSS 21.0 RESULTS: The colonization frequency in DCCs ranged from 16.7% (n=3) to 53.6% (n=15). Genetically related isolates were identified inside four DCCs. Half (50%) of the isolates were grouped in 3 clusters, which belonged to the clonal complexes CC45, CC30, and CC121. CONCLUSION: Molecular typing of isolates from colonized children and comparison among DCCs showed the spread of colonizing strains inside DCCs in Medellin; predominantly the CC45 clone, a successful child colonizer.