Prevalence of toxin types and colonization factors in enterotoxigenic Escherichia coli isolated during a 2-year period from diarrheal patients in Bangladesh.
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.
Qadri
F
F
International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka 1000, Bangladesh. fqadri@icddrb.org
Das
S K
SK
Faruque
A S
AS
Fuchs
G J
GJ
Albert
M J
MJ
Sack
R B
RB
Svennerholm
A M
AM
D000942:Antigens, Bacterial / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000302:isolation & purification; D001427:Bacterial Toxins / Q000145:classification* / Q000302:isolation & purification; D001459:Bangladesh / Q000453:epidemiology; D002675:Child, Preschool; D003906:Developing Countries; D003967:Diarrhea / Q000453:epidemiology / Q000382:microbiology*; D004768:Enterotoxins / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology*; D029968:Escherichia coli Proteins; D005243:Feces / Q000382:microbiology; D036781:Fimbriae Proteins; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D011446:Prospective Studies; D012621:Seasons
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; C022924:colonization factor antigens; C034151:heat stable toxin (E coli); D036781:Fimbriae Proteins; C027538:heat-labile enterotoxin, E coli