Escherichia coli Strains Responsible for Cystitis in Female Pediatric Patients with Normal and Abnormal Urinary Tracts Have Different Virulence Profiles.

The role of uropathogenic Escherichia coli (UPEC) in colonization and infection of female patients with anatomical and functional abnormalities of the urinary system is elusive. In this study, the phenotype, genotype and the phylogeny of UPEC strains isolated from the urine of pediatric female patients with cystitis of normal and abnormal urinary tract were determined. Multiplex PCR results demonstrated that 86% of the strains isolated from female patients with normal urinary tract (NUT), belonged to the phylo-groups B2 and D. Their prevalence decreased to 23% in strains isolated from patients with abnormal urinary tract (AUT). More of the isolates from AUT patients produced a biofilm on polystyrene and polyvinyl chloride (PVC), adhered to epithelial cells, and encoded pap and sfa genes than strains isolated from female patients with NUT. In contrast, a higher number of hemolysin-producing strains with serogroups associated with UPEC were isolated from patients with NUT. In summary, the results suggest that cystitis in female patients with NUT is associated with ExPEC, whereas cystitis in female patients with AUT is associated with pathogenic intestinal E. coli strains that have acquired the ability to colonize the bladder.

Distribution of major pilin subunit genes among atypical enteropathogenic Escherichia coli and influence of growth media on expression of the ecp operon

Atypical enteropathogenic Escherichia coil (aEPEC) strains are unable to produce the bundle-forming pilus (BFP), which is responsible for the localized adherence pattern, a characteristic of the pathogenicity of typical EPEC strains. The lack of BFP in aEPEC strains suggests that other fimbrial or non-fimbrial adhesins are involved in their adhesion to the host cells. The aim of this study was to investigate the distribution of major subunit fimbrial genes known to be important adherence factors produced by several E. coil pathotypes in a collection of 72 aEPEC strains. Our results demonstrate that a high percentage (94-100%) of aEPEC strains harbored ecpA, fimA, hcpA, and lpfA fimbrial genes. Other fimbrial genes including pilS, pilV, sfpA, daaC, papA, and sfa were detected at lower frequencies (1-8%). Genes encoding fimbrial subunits, which are characteristic of enteroaggregative E. coli or enterotoxigenic E. coli were not found. No correlation was found between fimbrial gene profiles and adherence phenotypes. Since all aEPEC strains contained ecpA, the major pilin gene of the E. coil common pilus (ECP), a subset of ecpA+ strains was analyzed for transcription of ecpRABCDE and production of ECP upon growth in three different culture conditions at 37 degrees C. Transcription of ecpRABCDE occurred in all conditions; however, ECP production was medium dependent. In all, the data suggest that aEPEC strains are highly heterogeneous in terms of their fimbrial gene profiles. Despite lacking BFP production, other mechanisms of cell adherence exist in aEPEC strains to ensure host colonization, e.g., mediated by other prevalent pili such as ECP. Moreover, the production of ECP by aEPEC strains might be influenced by yet unknown post-transcriptional factors.

Análise do operon perABC em amostras de Escherichia coli enteropatogênica atípicas

Atualmente E. coli enteropatogênica (EPEC) são subdivididas em típicas (tEPEC) e atípicas (aEPEC). A principal diferença entre os dois grupos é a e atípicas (aEPEC). A principal diferença entre os dois grupos é a presença do plasmídio EPEC adherence factor (pEAF) que ocorre somente nas amostras de tEPEC. Além de conter o operon que codifica a fímbria bundle forming pillus (BFP), o plasmídio EAF possui operon plasmid encoded regulator (per ), constituído pelos genes perA, perB e perC. Esse operon codifica proteínas que regulam a expressão do operon BFP e da região LEE, ou locus of enterocyte enterocyte effacement. Embora o plasmídio EAF não esteja presente em amostras de aEPEC, alguns relatos da literatura descrevem amostras que apresentam o gene perAperAperA , mas que não hibridizam com o fragmento sonda EAF (EAFperA +). Com base nesses relatos o objetivo deste estudo foi avaliar a presença do operon perABC em 72 amostras de aEPEC. Os genes perA, perB e perC foram detectados pela técnica de PCR. Apenas 7 (9,7%9,7% 9,7%) amostras foram positivas para os três genes do operon, sendo estas analisadas quanto a outras características do plasmídio EAF. O fragmento sonda EAF não foi encontrado em nenhuma das amostras e em três delas foi detectado o gene bfpAbfpAbfpAbfpA. Para verificar a integridade do operon foi realizado o teste de restriction fragment lengh profile – PCR com a enzima SspI, com o qual foi possível detectar a existência de três padrões restrição diferentes, sendo um deles inédito na literatura...