Identificación de Escherichia coli enteropatógena en niños con síndrome diarreico agudo del Estado Sucre, Venezuela / Identification of enteropathogenic Escherichia coli in children with acute diarrheic syndrome from Sucre State, Venezuela

Introducción. Escherichia coli es uno de los principales agentes causales del síndrome diarreico agudo. Objetivo. Identificar grupos clonales de E. coli enteropatógena en 485 casos de diarrea aguda en niños entre 0 y 10 años de edad atendidos en centros de salud de los municipios de Arismendi, Benítez y Sucre del estado Sucre, Venezuela, entre marzo y diciembre de 2011. Materiales y métodos. Previo consentimiento informado, se recolectaron muestras fecales y se identificó E. coli mediante coprocultivo estándar y serología con antisueros polivalentes y monovalentes. Se aisló el ADN y se amplificaron los genes eae (intimina) y bfpA (bundlina) mediante dos pruebas de reacción en cadena de la polimerasa (PCR) múltiples. Resultados. En 39,6 % de los coprocultivos se determinó la presencia de infección bacteriana. La prevalencia de E. coli fue de 54,7 %; 82,9 % de estas cepas fue positivo por serología para los serogrupos y el serotipo evaluados, principalmente en niños entre los 0 y los 2 años (37,9 %). El 48,6 % de las cepas de E. coli amplificaron para el gen eae y, de estas, 58,8 % se clasificó como cepas de E. coli enteropatógena típica (eae+ y bfp+). El ECEP II fue el serogrupo más frecuente (38,7 %), con predominio de bacterias E. coli enteropatógenas típicas (60 %). El alelo ß de la intimina fue el más identificado (74,5 %) en las cepas positivas para el gen eae. Solo se identificaron cuatro cepas con el serotipo O157:H7 utilizando antisueros, las cuales no amplificaron mediante PCR para los genes eae y bfpA. Conclusiones. Este estudio demostró la importancia de aplicar pruebas moleculares en la identificación de las cepas de E. coli causantes de diarrea de diversa gravedad.

Introduction: Diarrheagenic Escherichia coli is an important causative agent of acute diarrheic syndrome. Objective: To identify clonal groups of enteropathogenic E. coli (EPEC), in 485 children with acute diarrhea aged 0 to 10 years attending health care centers in Arismendi, Benítez and Sucre municipalities, Sucre state, Venezuela, from March to December, 2011. Materials and methods: After obtaining the informed consent, stool samples were collected. Escherichia coli was identified using standard coproculture methods and serology with polyvalent and monovalent antisera. DNA was isolated, and eae (intimin) and bfpA (bundlin) genes were amplified through two multiplex polymerase chain reactions (PCR). Results: The presence of bacterial infection was determined in 39.6% of coprocultures. The prevalence of E. coli was 54.7%; 82.9% of these isolates were positive by serology for the evaluated serogroups and serotypes, which were mostly identified in children between 0 and 2 years (37.9%); 48.6% of E. coli strains amplified the eae gene; of these, 58.8% were classified as typical EPEC (eae+ y bfp+). EPEC II was the most common serogroup (38.7%), with predominance of typical EPEC (60%). In positive strains for eae gene, the ß intimin allele was the most frequently identified (74.5%). Only four strains with O157:H7 serotype were identified, which showed no PCR amplification of the eae and bfpA genes. Conclusion: This study showed the importance of molecular tests to identify diarrheagenic E. coli strains causing clinical conditions of varying severity.

Identification of enteropathogenic Escherichia coli in children with acute diarrheic syndrome from Sucre State, Venezuela.

INTRODUCTION: Diarrheagenic Escherichia coli is an important causative agent of acute diarrheic syndrome.  OBJECTIVE: To identify clonal groups of enteropathogenic E. coli (EPEC), in 485 children with acute diarrhea aged 0 to 10 years attending health care centers in Arismendi, Benítez and Sucre municipalities, Sucre state, Venezuela, from March to December, 2011.  MATERIALS AND METHODS: After obtaining the informed consent, stool samples were collected. Escherichia coli was identified using standard coproculture methods and serology with polyvalent and monovalent antisera. DNA was isolated, and eae (intimin) and bfpA (bundlin) genes were amplified through two multiplex polymerase chain reactions (PCR).  RESULTS: The presence of bacterial infection was determined in 39.6% of coprocultures. The prevalence of E. coli was 54.7%; 82.9% of these isolates were positive by serology for the evaluated serogroups and serotypes, which were mostly identified in children between 0 and 2 years (37.9%); 48.6% of E. coli strains amplified the eae gene; of these, 58.8% were classified as typical EPEC (eae+ y bfp+). EPEC II was the most common serogroup (38.7%), with predominance of typical EPEC (60%). In positive strains for eae gene, the ß intimin allele was the most frequently identified (74.5%). Only four strains with O157:H7 serotype were identified, which showed no PCR amplification of the eae and bfpA genes.  CONCLUSION: This study showed the importance of molecular tests to identify diarrheagenic E. coli strains causing clinical conditions of varying severity.

Molecular characterization of Salmonella strains in individuals with acute diarrhea syndrome in the State of Sucre, Venezuela.

INTRODUCTION: In Venezuela, acute diarrheic syndrome (ADS) is a primary cause of morbi-mortality, often involving the Salmonella genus. Salmonella infections are associated with acute gastroenteritis, one of the most common alimentary intoxications, and caused by the consumption of contaminated water and food, especially meat. METHODS: Conventional and molecular methods were used to detect Salmonella strains from 330 fecal samples from individuals of different ages and both sexes with ADS. Polymerase chain reaction (PCR) was used for the molecular characterization of Salmonella, using invA, sefA, and fliC genes for the identification of this genus and the serotypes Enteritidis and Typhimurium, respectively. RESULTS: The highest frequency of individuals with ADS was found in children 0-2 years old (39.4%), and the overall frequency of positive coprocultures was 76.9%. A total of 14 (4.2%) strains were biochemically and immunologically identified as Salmonella enterica subsp. enterica, of which 7 were classified as belonging to the Enteritidis serotype, 4 to the Typhimurium serotype, and 3 to other serotypes. The S. enterica strains were distributed more frequently in the age groups 3-4 and 9-10 years old. CONCLUSIONS: The molecular characterization method used proved to be highly specific for the typing of S. enterica strains using DNA extracted from both the isolated colonies and selective enrichment broths directly inoculated with fecal samples, thus representing a complementary tool for the detection and identification of ADS-causing bacteria.

Molecular characterization of Salmonella strains in individuals with acute diarrhea syndrome in the State of Sucre, Venezuela / Caracterização molecular de cepas de Salmonella em indivíduos com síndrome da diarreia aguda no Estado de Sucre, Venezuela

INTRODUCTION:In Venezuela, acute diarrheic syndrome (ADS) is a primary cause of morbi-mortality, often involving the Salmonella genus. Salmonella infections are associated with acute gastroenteritis, one of the most common alimentary intoxications, and caused by the consumption of contaminated water and food, especially meat. METHODS: Conventional and molecular methods were used to detect Salmonella strains from 330 fecal samples from individuals of different ages and both sexes with ADS. Polymerase chain reaction (PCR) was used for the molecular characterization of Salmonella, using invA, sefA, and fliC genes for the identification of this genus and the serotypes Enteritidis and Typhimurium, respectively. RESULTS: The highest frequency of individuals with ADS was found in children 0-2 years old (39.4%), and the overall frequency of positive coprocultures was 76.9%. A total of 14 (4.2%) strains were biochemically and immunologically identified as Salmonella enterica subsp. enterica, of which 7 were classified as belonging to the Enteritidis serotype, 4 to the Typhimurium serotype, and 3 to other serotypes. The S. enterica strains were distributed more frequently in the age groups 3-4 and 9-10 years old. CONCLUSIONS: The molecular characterization method used proved to be highly specific for the typing of S. enterica strains using DNA extracted from both the isolated colonies and selective enrichment broths directly inoculated with fecal samples, thus representing a complementary tool for the detection and identification of ADS-causing bacteria.

INTRODUÇÃO: Na Venezuela, síndrome da diarreia aguda (SDA) é a principal causa de mórbi-mortalidade, muitas vezes envolvem o gênero Salmonella. Infecções por Salmonella são associadas com gastroenterite aguda, uma das mais comuns intoxicações alimentares causada pelo consumo de água e alimentos contaminados, principalmente carne. MÉTODOS: Métodos convencionais e moleculares foram usados para detectar cepas de Salmonella em 330 amostras de fezes de indivíduos com SDA de diferentes idades e ambos os sexos. A reação em cadeia da polimerase (PCR) foi utilizada para a caracterização molecular de genes Salmonella invA, sefA e fliC para identificar o gênero e os sorotipos Enteritidis e Typhimurium, respectivamente. RESULTADOS: A maior frequência de indivíduos com SDA foi encontrada em crianças de 0-2 (39,4%) anos, e a frequência total de culturas de fezes positiva foi de 76,9%. Um total de 14 (4,2%) cepas foram bioquímica e imunologicamente identificados como Salmonella enterica subsp. enterica, dos quais 7 foram classificados como pertencentes ao sorotipo Enteritidis, Typhimurium sorotipo 4 e 3 para outros sorotipos. Cepas S. enterica foram distribuídas mais frequentemente em grupos de 3-4 e 9-10 anos de idade. CONCLUSÕES: O método de caracterização molecular usada provou ser altamente específico para tipificar as estirpes dos S. enterica usando tanto DNA extraído de colônias isoladas e direta e caldos de enriquecimento seletivo inoculados com amostras fecais, o que representa uma ferramenta complementar para a detecção e identificação de bactérias que causam a SDA.