RESUMEN
Hospital surveillance was established in the Nile River Delta to increase the understanding of the epidemiology of diarrheal disease among Egyptian children. Between September 2000 and August 2003, samples obtained from children less than 5 years of age who had diarrhea and who were seeking hospital care were cultured for enteric bacteria. Colonies from each culture with a morphology typical of that of Escherichia coli were tested for the heat-labile (LT) and heat-stable (ST) toxins by a GM-1-specific enzyme-linked immunosorbent assay and colonization factor (CF) antigens by an immunodot blot assay. Enterotoxigenic E. coli (ETEC) isolates were recovered from 320/1,540 (20.7%) children, and ETEC isolates expressing a known CF were identified in 151/320 (47%) samples. ST CFA/I, ST CS6, ST CS14, and LT and ST CS5 plus CS6 represented 75% of the CFs expressed by ETEC isolates expressing a detectable CF. Year-to-year variability in the proportion of ETEC isolates that expressed a detectable CF was observed (e.g., the proportion that expressed CFA/I ranged from 10% in year 1 to 21% in year 3); however, the relative proportions of ETEC isolates expressing a CF were similar over the reporting period. The proportion of CF-positive ETEC isolates was higher among isolates that expressed ST. ETEC isolates expressing CS6 were isolated significantly less often (P < 0.001) than isolates expressing CFA/I in children less than 1 year of age. Macrorestriction profiling of CFA/I-expressing ETEC isolates by using the restriction enzyme XbaI and pulsed-field gel electrophoresis demonstrated a wide genetic diversity among the isolates that did not directly correlate with the virulence of the pathogen. The genome plasticity demonstrated in the ETEC isolates collected in this work suggests an additional challenge to the development of a globally effective vaccine for ETEC.
Asunto(s)
Diarrea/microbiología , Escherichia coli Enterotoxigénica/genética , Escherichia coli Enterotoxigénica/metabolismo , Infecciones por Escherichia coli/microbiología , Toxinas Bacterianas/biosíntesis , Preescolar , Análisis por Conglomerados , Dermatoglifia del ADN , ADN Bacteriano/metabolismo , Desoxirribonucleasas de Localización Especificada Tipo II/metabolismo , Diarrea/epidemiología , Egipto/epidemiología , Electroforesis en Gel de Campo Pulsado , Escherichia coli Enterotoxigénica/clasificación , Escherichia coli Enterotoxigénica/aislamiento & purificación , Enterotoxinas/biosíntesis , Infecciones por Escherichia coli/epidemiología , Proteínas de Escherichia coli/biosíntesis , Proteínas Fimbrias/biosíntesis , Variación Genética , Hospitales , Humanos , Lactante , Recién Nacido , Epidemiología Molecular , Polimorfismo de Longitud del Fragmento de RestricciónRESUMEN
Military personnel with traveler's diarrhea (n=202) while deployed to Incirlik Air Base, Turkey, from June to September 2002 were evaluated for pathogen-specific immune responses. Serologic and fecal immunoglobulin A (IgA) titers to enterotoxigenic Escherichia coli antigens (CS6, CS3, and LT) were quite low. In contrast, subjects with Campylobacter infections had high serologic and fecal IgA responses.
Asunto(s)
Anticuerpos Antibacterianos/sangre , Infecciones por Campylobacter/inmunología , Campylobacter jejuni/inmunología , Disentería/inmunología , Escherichia coli Enterotoxigénica/inmunología , Infecciones por Escherichia coli/inmunología , Personal Militar , Antígenos Bacterianos/inmunología , Infecciones por Campylobacter/microbiología , Disentería/microbiología , Infecciones por Escherichia coli/microbiología , Heces/microbiología , Femenino , Humanos , Inmunoglobulina A/sangre , Inmunoglobulina G/sangre , Masculino , Viaje , TurquíaRESUMEN
Infection caused by enterotoxigenic Escherichia coli (ETEC) poses a significant health problem in children and adults residing in endemic developing countries. Acute and convalescent paired stool and serum samples were obtained from 27 U.S. military personnel with ETEC-induced diarrhea during a military exercise in Egypt. In general, the concentration of total fecal and circulatory anti-LT IgA was significantly increased in convalescent specimens than in the paired acute ones in almost 65 % of the cases. The pattern of specific antibody responses in fecal and serum samples from cases with ETEC expressing the antigens coil surface 1 (CS1), CS2, CS3 and CS6 were, on the other hand, not conclusive due to the small numbers of the study cases. Further research is still required to understand the immunologic responses during the natural course of disease. The data obtained, nevertheless, may help current research efforts on the development of vaccines for humans against ETEC infection.