Detection of Diarrheogenic Escherichia coli in Children Less than Ten Years Old with and without Diarrhea in New Caledonia Using Seven Acetylaminofluorene-Labeled DNA Probes

E. BegaudLaboratorie des Bacteries Enteropathogenes et Department de Microbiologie, Institut Pasteur de Nouvelle-Caledonie, Noumea, New Caledonia

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P. JourandLaboratorie des Bacteries Enteropathogenes et Department de Microbiologie, Institut Pasteur de Nouvelle-Caledonie, Noumea, New Caledonia

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M. MorillonLaboratorie des Bacteries Enteropathogenes et Department de Microbiologie, Institut Pasteur de Nouvelle-Caledonie, Noumea, New Caledonia

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D. MondetLaboratorie des Bacteries Enteropathogenes et Department de Microbiologie, Institut Pasteur de Nouvelle-Caledonie, Noumea, New Caledonia

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Y. GermaniLaboratorie des Bacteries Enteropathogenes et Department de Microbiologie, Institut Pasteur de Nouvelle-Caledonie, Noumea, New Caledonia

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We report the use of seven acetylaminofluorene (AAF)-labeled DNA probes in evaluating the incidence of various Escherichia coli pathotypes in New Caledonia among 448 children with acute diarrhea (1,278 E. coli pathotypes studied) and 88 controls (264 E. coli pathotypes studied) in 1990. Diarrheogenic E. coli were detected using cloned gene probes for heat-labile and heat-stable enterotoxins, Shiga-like cytotoxins (SLTI and SLTII), the cell invasion phenotype (INV), and enteropathogenic-adherence factor (EAF). Isolates were also studied using bioassays and radioactive DNA probes as reference methods. Enterotoxigenic E. coli (ETEC) were isolated from only 5.36% of the patients; E. coli with localized adherence (LA) to HEp-2 cells was much more common in patients (14.4%) than in controls (3.4%; x2 = 7.54, P < 0.01), but most of the E. coli with an LA pattern were members of traditional enteropathogenic E. coli (EPEC) serogroups (x2 = 92.95, P < 0.001). Non-enteropathogenic E. coli with an LA pattern were weakly associated with diarrheal disease (8.9%). Escherichia coli with a diffuse or an aggregative pattern did not show a significant association with infantile diarrhea. Eight EPEC serogroups were identified and the frequency of positivity for the LA pattern was 70.5%; the EAF was significantly associated with the 0119:K9 serogroup. No enteroinvasive or SLT-producing E. coli were identified. An evaluation of the AAF probes in comparison with 32P-labeled probes and conventional bioassays was made during this epidemiologic survey. The positive and negative predictive values of the ETEC probes were 0.91 and 1, respectively (overall agreement = 99.8%). The positive and negative predictive values of the EAF probe were both 1. No false positive results were observed using AAF INV, SLTI, and SLTII probes. Furthermore, all AAF probes were controlled on 95 nondiarrheogenic E. coli and well-characterized enteropathogenic strains, and all E. coli strains were correctly identified.

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