Colonização intestinal de recém-natos por enterobactérias multirresistentes a antimicrobianos em unidade neonatal

Abstract

Objective

To evaluate the occurrence of intestinal colonization by multidrug-resistant enterobacteria strains (MDRES) in newborns during hospital stay after birth. We used selective culture media to determine the relationship between isolation of these strains and some of the colonization risk factors. Method: We studied 30 consecutive newborns in the neonatal unit of the HUPE, State University Hospital, a general 600-bed tertiary hospital. We obtained clinical and epidemiological information from medical records and collected a fecal sample from each newborn. The samplse were plated in gentamicin (8mg/ml) medium and potassium tellurite (25mg/ml) medium. The isolated strains were biochemically identified and also tested for antimicrobial susceptibility. An assay to identify transfer of plasmid via conjugation was used to analyze 9 MDRES. Results: We isolated 56 distinct MDRES from 14 (46.7%) of the 30 newborns. Klebsiella pneumoniae was the most common species (38/56 [68%]). We found a significant statistical association between individual MDRES isolation and the presence of 3 or 4 of the following colonization risk factors: antimicrobial use, low weight (<2500g), more than 6 days of hospitalization, and artificial milk feeding (P< 0.02). We detected transfer of resistance plasmid via conjugation for 8 of the 9 MDRES analyzed. Conclusion: The seletive culture media were useful to detect the high frequency of newborns colonized by MDRES in association with well established infection risk factors. We emphasize the importance of reinforcing control rules to prevent intestinal colonization, which is viewed as a risk factor for nosocomial infection.

Method

We studied 30 consecutive newborns in the neonatal unit of the HUPE, State University Hospital, a general 600-bed tertiary hospital. We obtained clinical and epidemiological information from medical records and collected a fecal sample from each newborn. The samplse were plated in gentamicin (8mg/ml) medium and potassium tellurite (25mg/ml) medium. The isolated strains were biochemically identified and also tested for antimicrobial susceptibility. An assay to identify transfer of plasmid via conjugation was used to analyze 9 MDRES. Results: We isolated 56 distinct MDRES from 14 (46.7%) of the 30 newborns. Klebsiella pneumoniae was the most common species (38/56 [68%]). We found a significant statistical association between individual MDRES isolation and the presence of 3 or 4 of the following colonization risk factors: antimicrobial use, low weight (<2500g), more than 6 days of hospitalization, and artificial milk feeding (P< 0.02). We detected transfer of resistance plasmid via conjugation for 8 of the 9 MDRES analyzed. Conclusion: The seletive culture media were useful to detect the high frequency of newborns colonized by MDRES in association with well established infection risk factors. We emphasize the importance of reinforcing control rules to prevent intestinal colonization, which is viewed as a risk factor for nosocomial infection.

Results

We isolated 56 distinct MDRES from 14 (46.7%) of the 30 newborns. Klebsiella pneumoniae was the most common species (38/56 [68%]). We found a significant statistical association between individual MDRES isolation and the presence of 3 or 4 of the following colonization risk factors: antimicrobial use, low weight (<2500g), more than 6 days of hospitalization, and artificial milk feeding (P< 0.02). We detected transfer of resistance plasmid via conjugation for 8 of the 9 MDRES analyzed. Conclusion: The seletive culture media were useful to detect the high frequency of newborns colonized by MDRES in association with well established infection risk factors. We emphasize the importance of reinforcing control rules to prevent intestinal colonization, which is viewed as a risk factor for nosocomial infection.

Conclusion

The seletive culture media were useful to detect the high frequency of newborns colonized by MDRES in association with well established infection risk factors. We emphasize the importance of reinforcing control rules to prevent intestinal colonization, which is viewed as a risk factor for nosocomial infection.

Resumen

Objetivo

Buscamos avaliar a ocorrência de colonização intestinal de recém-natos por cepas de enterobactérias multirresistentes a antimicrobianos (CEMA) no curso da hospitalização. Utilizamos meios de cultura seletivos, tentando correlacionar o isolamento de tais cepas bacterianas a alguns presumíveis fatores de risco para a colonização.

Métodos

Realizamos um estudo de inclusão seqüencial de 30 recém-nascidos internados no Berçário do HUPE-UERJ, hospital universitário público, terciário, de 600 leitos. Obtínhamos informações clínico-epidemiológicas e coletávamos uma amostra fecal de cada recém-nascido, que eram semeadas em meios de cultura contendo gentamicina (8mg/ml) ou telurito de potássio (25mg/ml). As cepas isoladas foram submetidas à identificação bioquímica e a testes de sensibilidade a antimicrobianos. Nove CEMA foram submetidas a ensaios de transferência da resistência plasmidial por conjugação bacteriana.

Resultados

Detectamos 56 cepas de enterobactérias multirresistentes a antimicrobianos em 14 dos 30 recém-nascidos estudados (46,7%). Klebsiella pneumoniae foi a espécie bacteriana mais freqüentemente isolada (68%). Constatamos a associação entre o isolamento de CEMA e a presença de 3 ou 4 dos seguintes fatores de risco para a colonização: uso de antimicrobianos, baixo peso (<2500g), hospitalização por mais do que 6 dias e alimentação com leite artificial (p<0,02). Para 8 de 9 CEMA, obtivemos transferência da resistência plasmidial por conjugação bacteriana.

Conclusões

Os meios de cultura seletivos contribuíram na constatação de uma alta freqüência de colonização intestinal de recém-nascidos hospitalizados por espécies de enterobactérias multirresistentes a antimicrobianos associáveis a um conjunto de fatores já bem reconhecidos como de risco para infecções. Isso confirma a necessidade de reforço das medidas de controle de transmissão de microrganismos visando a prevenção de condições predisponentes para infecções, endêmicas ou epidêmicas por cepas hospitalares.