Escherichia coli ehl1 Gene-Positive Serotype O18ac:H31 Associated with an Outbreak of Diarrhea in a Neonatal Nursery in Neuquén City, Argentina

Abstract

, an outbreak of bloody diarrhea occurred in the neonatal nursery ward of the Policlínico Neuquén, in Neuquén, a city in the southwestern region of Argentina. Seven patients of the intermediate care unit were affected. Isolates of Escherichia coli O18ac:H31 that were non-lactose and -sorbitol fermenting were recovered from outbreak cases. Although the strains were negative for a number of virulence factors typically found in diarrheagenic groups of E. coli, all isolates from the present neonatal outbreak possessed the enterohemolysin gene, ehl1. All isolates showed resistance to the antibiotics ampicillin and chloramphenicol. These isolates showed a low adherence property in HeLa cells without any recognizable pattern. In order to evaluate the outbreak dissemination in the neonatology ward, a prevalence study was conducted on 13 November. Stool specimens were obtained from 16 neonates hospitalized in the sector and from 33 medical staff members. E. coli isolates with identical biochemical characteristics of the outbreak strain were recovered from 11 of 16 inpatients and from 4 of 33 staff members during the prevalence study. A total of 15 E. coli strains recovered both from the outbreak and the prevalence study were processed by random amplified polymorphic DNA (RAPD)-PCR and pulsed-field gel electrophoresis (PFGE). By RAPD-PCR 14 of 15 strains showed patterns with 85 to 100% similarity, and by PFGE these strains were identical, each showing a unique pattern with 15 bands between 40 and 400 kb. One strain isolated from a nurse during the prevalence study presented a pattern not related to the others, and this was characterized as E. coli O81:HNM resistant to ampicillin only and negative for all the virulence factors studied. This outbreak occurred despite strict regulations in place to prevent cross-infection in the hospital. Postoutbreak prevalence studies were performed weekly thereafter without detecting new cases.

Detection in Escherichia coli of the Genes Encoding the Major Virulence Factors, the Genes Defining the O157:H7 Serotype, and Components of the Type 2 Shiga Toxin Family by Multiplex PCR

“…Other major virulence factors ascribed to the pathogen include a plasmid-encoded enterohemolysin from STEC (enterohemorrhagic E. coli [EHEC] hlyA) that is often associated with severe clinical disease in humans (33,34) as well as intimin, the product of the eaeA gene involved in the bacterial attaching and effacing adherence phenomenon and clustered in a pathogenicity island termed the locus for enterocyte effacement (22,23). In addition, the presence of the ehl1 gene, which encodes an enterohemolysin that is unrelated to the EHEC hlyA genotype, has been associated with a severe outbreak of E. coli disease among neonates (2).…”

Subcutaneous clostridial infection in Adelie penguins in Hope Bay, Antarctica

“…These samples were simultaneously cultured on 5% sheep's blood agar (Difco) which were then incubated under anaerobic conditions at 37°C for 24 h. Identification of aerobes was carried out by means of standardized methodology (Koneman et al 1999a). E. coli isolates were characterized at Servicio Fisiopatogenia (Instituto Nacional de Enfermedades Infecciosas, Argentina) by PCR using specific primers, with regard to the following virulence markers: attaching and effacement factor (eae) of enteropathogenic E. coli (EPEC); heat labile toxin (LT) and heat stable toxin (ST) of enterotoxigenic E. coli (ETEC); Shiga toxin (Stx1 and Stx2); enteroaggregative plasmid of enteroagreggative E. coli (EaggEC), as previously described (Chinen et al 2002). Staphylococcus isolates were identified by biochemical tests according to Koneman et al (1999b).…”

Caracterización fenotípica y subtipificación molecular de aislamientos de <i>Salmonella Gallinarum</i> de diferentes regiones de la República Argentina y de 5 cepas de vacunas 9R comercializadas en el país

“…Se considera que PFGE es la "técnica de oro" para la subtipificación bacteriana. Varios autores obtuvieron excelentes resultados al utilizar PFGE en la investigación epidemiológica de una variedad de microorganismos, incluyendo E. coli (85), S.…”