CARACTERIZAÇÃO DE FATORES DE VIRULÊNCIA EM AMOSTRAS DE Escherichia coli ISOLADAS DE LAGOAS DO PARQUE ESTADUAL DO RIO DOCE, MINAS GERAIS OURO PRETO 2006

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The fecal coliforms whose main representative is the Escherichia coli belong to the intestinal flora of humans and other warm-blooded animals, these microorganisms have been extensively used at water quality control and when found at water are an indicator of recent contamination by feces, and as consequence, enteric pathogenic microorganisms are made present. Beyond the commensal strains, there are various distinct types of diarrhoeagenic E. coli are acknowledged: enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enterohaemorragic E. coli or shiga toxine producer (EHEC/STEC), enteroinvasive E. coli (EIEC), enteroaggregative E. coli (EAggEC), diffusely adherent E. coli (DAEC). The pathogenic strains of E. coli that are intestine infectious host numerous factors of virulence located at chromossome, plasmidis or DNA phages. Thus, the objective of the research was to determine the frequency of ocurrence and the virulence of E. coli samples isolated at lakes inside the "Parque Estadual do Rio Doce-M.G." (PERD - MG). The sample collection happened in a monthly basis between May, 2004 and February, 2005 at Carioca, Jacaré, Gambazinho and Dom Helvécio lakes. By using the Multiple Tube Technique, it was verified that the researched lakes with samples inside had low rate of fecal coliform at the broad majority of the analysed samples. The fecal coliform density varied meaningfully (E. coli F=2,11 ; p = 0,35) but only in relation to the sample gathering months. The final results were of 458 (91%) of the environment strains of Escherichia coli isolated at the sampled lakes showed positive results regarding the specific biochemical tests for recognition of the E. coli species. The PCR technique was used for detection of the virulence genes stx1 and stx2 of EHEC, eae of EPEC and eltI of ETEC. The stx2 gene was detected within five E. coli strains, when isolated at the Carioca and Jacare lakes. None of the 80 isolated E. coli examinated showed the DNA segment corresponding to the stx1 gene, for the eae and elt I gene, only the isolated E. coli 373 (C LT) and E. coli 58 (C LT), respectively amplified the segment of the relevant gene. By using the agglutination technique at a sample 61,3% of the isolated E. coli agglutinated within the presence of a classic EPEC specific serum, 18.2% of the strains agglutinated to the serum type O157:H7 of EHEC and 20,5% were agglutinated at the presence of xii the EIEC specific serum. The characterization of the serym type O157: H7, five environments E. coli isolated did not ferment the sorbitol and only two did not ferment the rhamnose. High frequencies of E. coli strains which were resistant to ampiciline (20%), cefalotine (50%) and cefuroxime (14%) were verified, to the other antibiotics tested, the resistance when verified occurred in less than 10% of the isolated. All the sampled lakes showed fecal coliform levels much below than the allowed values by the CONAMA, as it refers to the batheability. In another side, the presence of virulence genes at the E. coli strains analysed sugests that there is a possibility to that the bather acquires gastrointestinal disease transmitted by the waters of the researched lakes. The Agglutination Technique, specificly meant for some determined types of serum is not always relationed to the pathogenicity of the strains and discrimination of sub-groups of EPEC, ETEC, EHEC and EIEC, requires the use of molecular techniques based in virulence genes. High frequency of antibiotic multi-resistant isolated E. coli will indicate possible spread of resistant strains by the bather and animals, there is also a risk for their health. The obtained data at this research can contribute to the keep of the ballance at the researched ecosystems and to amplify the research of the ecology of the E. coli Species considerating the isolation of the subtypes at the environment.

ASSUNTO(S)

ecologia 1. escherichia coli - teses. 2. Água - qualidade - minas gerais - teses. 3. virulência (microbiologia) - teses.

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