Caracterização de Escherichia coli diarreiogênica isolada de água subterrânea para consumo humano em um assentamento rural / Characterization of diarrheagenic Escherichia coli isolated from underground water for human consumption in a rural settlement

Escherichia coli diarreiogênica (DEC) é um importante agente de infecções gastrointestinais transmitidas pela água. O trabalho teve como objetivo avaliar a qualidade microbiológica e físicoquímica de 58 amostras de água subterrânea in natura para consumo de um assentamento rural e caracterizar os isolados de E. coli, genotipicamente dentro dos patotipos de DEC, pela técnica da PCR, e fenotipicamente. Todas as amostras apresentaram contaminação por coliformes totais e 36 (62,1%) por E. coli. Em células HEp-2, dos 170 isolados de E. coli, 106 (62,36%) apresentaram AA, 15 (8,82%) AD, 17 (10%) adesão não caracterizado e 32 (18,82%) foram não aderentes. Quanto à formação de biofilme, 126 (74,12%) cepas são formadoras, e 44 (25,88%) não formaram biofilme. Foram identificadas DEC em 6,89% das amostras de água: três (5,17%) ETEC e uma (1,72%) EAEC. EAEC apresentou AA e as três cepas de ETEC apresentaram AD, AA e não definida. Todas as DEC foram formadoras de biofilme. Dois isolados de ETEC apresentaram resistência à ampicilina e tetraciclina, uma ETEC à aminoglicosídeos, e EAEC foi sensível a todos os antibióticos testados. As ETEC foram classificadas no filogrupo B1 e a EAEC no E. Os sorotipos encontrados foram: O24:H21, OR:H21, O17:H46 e O6:H12. Todas as amostras estavam dentro dos parâmetros normais de flúor e 13 (22,4%) apresentaram resultados acima do padrão permitido de turbidez. A presença de E. coli e DEC nas amostras de água indica a necessidade de adoção de medidas que evitem a contaminação da água fornecida à população, evitando, assim, a transmissão de doenças.(AU)

Diarrheogenic Escherichia coli (DEC) is an important agent of waterborne gastrointestinal infections. The objective of this work was to evaluate the microbiological and physico-chemical quality of 58 freshwater groundwater samples for the consumption of a rural settlement and to characterize the E. coli isolates, genotyped within the DEC pathophyses, by the PCR technique, and phenotypically. All water samples presented contamination with total coliforms, and 36 (62.1%) with E. coli. In HEp-2 cells, of 170 E. coli isolates, 106 (62.36%) showed AA, 15 (8.82%) AD, 17 (10%) noncharacterized adhesion and 32 (18.82%) were non-adherent. As for biofilm formation, 126 (74.12%) strains are forming, and 44 (25.88%) did not form biofilm. DEC was identified in 6.89% of the water samples with E. coli: three (5.17%) with enterotoxigenic E. coli (ETEC), and one (1.72%) with enteroaggregative E. coli (EAEC). EAEC showed aggregative adherence, whereas various ETEC strains presented diffuse, aggregative, and non-defined adherence. All DEC strains were biofilm forming. Two isolates of ETEC showed resistance to ampicillin and tetracycline, and one isolate showed resistance to aminoglycosides. The EAEC isolate was sensitive to all antibiotics tested. All ETECs were classified into phylogenetic B1 and EAEC in E. The serotypes identified in our study were: O24:H21, ONT:H21, O17:H46, and O6:H12. All water samples were within normal fluorine parameters; however, measured turbidity was above the permitted standard in 13 (22.4%) samples. The presence of E. coli and DEC in water samples indicates the need to take action to prevent contamination of water resources accessed by people to prevent the transmission of diseases.(AU)

Molecular and phenotypic characterization of diarrheagenic Escherichia coli isolated from groundwater in rural areas in southern Brazil.

Water-borne diseases like diarrheagenic Escherichia coli (DEC)-induced gastroenteritis are major public health problems in developing countries. In this study, the microbiological quality of water from mines and shallow wells was analyzed for human consumption. Genotypic and phenotypic characterization of DEC strains was performed. A total of 210 water samples was analyzed, of which 153 (72.9%) contained total coliforms and 96 (45.7%) E. coli. Of the E. coli isolates, 27 (28.1%) contained DEC genes. The DEC isolates included 48.1% Shiga toxin-producing E. coli (STEC), 29.6% enteroaggregative E. coli (EAEC), 14.9% enteropathogenic E. coli (EPEC), 3.7% enterotoxigenic E. coli (ETEC), and 3.7% enteroinvasive E. coli (EIEC). All the STECs had cytotoxic effects on Vero cells and 14.8% of the DEC isolates were resistant to at least one of the antibiotics tested. All DEC formed biofilms and 92.6% adhered to HEp-2 cells with a prevalence of aggregative adhesion (74%). We identified 25 different serotypes. One EPEC isolate was serotype O44037:H7, reported for the first time in Brazil. Phylogenetically, 63% of the strains belonged to group B1. The analyzed waters were potential reservoirs for DEC and could act as a source for infection of humans. Preventive measures are needed to avoid such contamination.