Characterization and epidemiologic subtyping of Shiga toxin-producing Escherichia coli strains isolated from hemolytic uremic syndrome and diarrhea cases in Argentina.

Argentina has a high incidence of hemolytic uremic syndrome (HUS); 12.2 cases per 100,000 children younger than 5 years old were reported in 2002. Shiga toxin (Stx)-producing Escherichia coli (STEC) is the primary etiologic agent of HUS, and STEC O157 is the predominant serogroup isolated. The main objective of the present work was to establish the phenotypic and genotypic characteristics of the STEC strains in general isolated from Argentine children during a prospective study and the clonal relatedness of STEC O157:H7 strains using subtyping techniques. One hundred and three STEC strains isolated from 99 children were included. The phenotypic and genotypic features were established, and a polymerase chain reaction-restriction fragment length polymorphism (PCRRFLP) was performed to determine stx2 variants. The clonal relatedness of E. coli O157 isolates was established by phage typing and pulsed-field gel electrophoresis (PFGE). The 103 STEC strains belonged to 18 different serotypes, and 59% were of serotype O157:H7. Stx2 was identified in 90.3%, and stx1 in 9.7%. Among the 61 STEC O157 strains, 93.4% harbored the stx2/stx2vh-a genes; PT4 (39.3%) and PT2 (29.5%) were the predominant phage types. Using PFGE with the enzyme XbaI, a total of 41 patterns with at least 80% similarity were identified, and seven clusters with identical profiles were established. Some of the clusters were further split by PFGE using BlnI as the second enzyme. Isolates with indistinguishable PFGE patterns were with one exception also indistinguishable by phage typing and stx genotyping. These findings confirmed that some isolates were genetically related. However, no epidemiological linkages were identified. STEC strains with different genotypes and belonging to diverse serotypes were isolated in Argentina. Some STEC O157 strains could not be distinguished by applying subtyping techniques such as PFGE and phage typing.

[Is dental plaque a normal Helicobacter pylori reservoir?]. / Es la placa dentaria reservorio habitual de Helicobacter pylori?

The mechanisms of transmission and reservoir of Helicobacter pylori is still unclear; even it has been suggested that dental plaque could be the bacterial reservoir and one important factor in the reinfection. The aim of the study was to evaluate the prevalence of Helicobacter pylori in dental plaque in 20 patients with non ulcer dyspepsia (12 females, 7 males; mean age 40.5 years) and antral infection; and to establish the presence of bacteria in dental plaque and gastric mucosa after eradication. Gastric colonization in all of them was confirmed by five samples (three of antrum and two of body) with Giemsa conventional technique, clotest and culture. When clotest was positive in gastric mucosa, we performed the scrape of dental plaque and sending the material for culture. All patients were treated with a scheme of seven days with one protom pump inhibitor and two antibiotics. After four weeks all the patients were controlled with endoscopy and culture of dental plaque to confirm eradication. Dental plaque culture was positive in 1/20 patients (5%), and this results was similar to developed countries, using as detection method culture or polymerase chain reaction (PCR).

Es la placa dentaria reservorio habitual de Helicobacter pylory? / Is dental plaque reservoir of Helicobacter pylori?

Si bien la forma de transmisión y el reservorio del Helicobacter pylori no son claros, se ha sugerido que la placa dentaria puede ser reservorio del germen y poseer inplicancias en la reinfección, una vez erradicada la bacteria. El objetivo de este trabajo fue evaluar la prevalencia del Helicobacter pylori en placa dentaria en 20 pacientes portadores de dispepsia no ulcerosa (12 mujeres y 7 varones con media etaria de 40.5 años)e infección antral por Helicobacter pylori y establecer la presencia en placa dentaria y mucosa gástrica luego de la erradicación. En todas ellas se confirmó la colonización gástrica mediante 5 biopsias (3 de antro y 2 de cuerpo) realizándose histología convencional com Giemsa clotest y cultivo en medio de anaerobiosis com generador de microaerofilia, usando como medio de transporte Stuard-carbón activado. Confirmada la positividad del clotest en mucosa gástrica, se procedió al raspado de placa dentaria en el servicio de odontología, enviándose el material en las mismas condiciones descriptas para el cultivo de la bacteria. Todos los pacientes fueron tratados com un esquema de erradicación a 7 días que incluía un IBP en dos tomas diarias; amoxicilina 1 gr. X 2 y claritromicina 500 mg. X 2. Cuatro semanas después de finalizado el esquema se realizó nueva endoscopía y cultivo de placa dentaria para confirmar erradicación. El cultivo de placa dentaria fue positivo en 1 de 20 es decir el 5 por ciento, confirmándose su erradicación com la terapeútica en el control a las 4 semanas. Nuestros resultados en cuanto a prevalencia de Hp en placa dentaria son similares a los obtenidos en países desarrollados, utilizando como método de detección de la bacteria el cultivo de PCR.