Prevalence of Toxin Types and Colonization Factors in Enterotoxigenic Escherichia coli Isolated during a 2-Year Period from Diarrheal Patients in Bangladesh

Author:

Qadri Firdausi1,Das Swadesh Kumar1,Faruque A. S. G.1,Fuchs George J.1,Albert M. John1,Sack R. Bradley2,Svennerholm Ann-Mari3

Affiliation:

1. International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka 1000, Bangladesh1;

2. Department of International Health, The Johns Hopkins University, Baltimore, Maryland2; and

3. Department of Medical Microbiology and Immunology, Göteborg University, S-413 46 Göteborg, Sweden3

Abstract

ABSTRACT The prevalence of toxin types and colonization factors (CFs) of enterotoxigenic Escherichia coli (ETEC) was prospectively studied with fresh samples ( n = 4,662) obtained from a 2% routine surveillance of diarrheal stool samples over 2 years, from September 1996 to August 1998. Stool samples were tested by enzyme-linked immunoassay techniques and with specific monoclonal antibodies for the toxins and CFs. The prevalence of ETEC was 14% ( n = 662), with over 70% of the strains isolated from children 0 to 5 years of age, of whom 93% were in the 0- to 3-year-old age range. Of the total ETEC isolates, 49.4% were positive for the heat-stable toxin (ST), 25.4% were positive for the heat-labile toxin (LT) only, and 25.2% were positive for both LT and ST. The rate of ETEC isolation peaked in the hot summer months of May to September and decreased in winter. About 56% of the samples were positive for 1 or more of the 12 CFs that were screened for. The coli surface antigens CS4, CS5, and/or CS6 of the colonization factor antigen (CFA)/IV complex were most prevalent (incidence, 31%), followed by CFA/I (23.5%) and coli surface antigens CS1, CS2, and CS3 of CFA/II (21%). In addition, other CFs detected in decreasing order were CS7 (8%), CS14 (PCFO166) (7%), CS12 (PCFO159) (4%), CS17 (3%), and CS8 (CFA/III) (2.7%). The ST- or LT- and ST-positive ETEC isolates expressed the CFs known to be the most prevalent (i.e., CFA/I, CFA/II, and CFA/IV), while the strains positive for LT only did not. Among children who were infected with ETEC as the single pathogen, a trend of relatively more severe disease in children infected with ST-positive ( P < 0.001) or LT- and ST-positive ( P < 0.001) ETEC isolates compared to the severity of the disease in children infected with LT only-positive ETEC isolates was seen. This study supports the fact that ETEC is still a major cause of childhood diarrhea in Bangladesh, especially in children up to 3 years of age, and that measures to prevent such infections are needed in developing countries.

Publisher

American Society for Microbiology

Subject

Microbiology (medical)

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