Phenotypic diversity of enterotoxigenic Escherichia coli (ETEC) isolated from cases of travelers' diarrhea in Kenya.
BACKGROUND
The aim of this study was to characterize phenotypically enterotoxins, colonization factors (CFs) and the antibiotic susceptibility of enterotoxigenic Escherichia coli (ETEC) strains isolated from cases of acute diarrhea that occurred in Europeans traveling to resorts in Mombasa, Kenya; this information is critical for the development of vaccines and empirical treatment.


METHODS
Over a 1-year period from 1996 to 1997, five E. coli-like colonies were obtained from each of 463 cases with acute diarrhea. These strains were characterized for enterotoxins using GM-1 ELISA, for CFs using a dot-blot assay, and for antibiotic susceptibility using antibiotic disks.


RESULTS
Of 164 strains characterized for ETEC phenotype, 30 (18%) expressed heat-labile toxin (LT) only, 83 (51%) heat-stable toxin (ST) only, and 51 (31%) both LT and ST. Analysis for CF expression demonstrated that 107 (65%) of the strains were positive for CFs, including CFA/IV (46%), CFA/II (35%), and CFA/I (5%), while less than 4% expressed less common CFs. All ETEC strains tested were resistant to erythromycin and sensitive to ceftriaxone. Over one-third of the strains were resistant to sulfamethoxazole-trimethoprim or tetracycline. Six strains were resistant to nalidixic acid; none of these were resistant to ciprofloxacin.


CONCLUSIONS
Cumulatively, our findings indicate that ETEC in this region comprises a highly diverse group of bacterial enteropathogens, and that the development of prophylactic agents against ETEC faces major challenges because of this diversity.
Shaheen
Hind I
HI
Naval Medical Research Unit No. 3, Cairo, Egypt.
Kamal
Karim A
KA
Wasfy
Momtaz O
MO
El-Ghorab
Nemat M
NM
Lowe
Brett
B
Steffen
Robert
R
Kodkani
Neville
N
Amsler
Lorenz
L
Waiyaki
Peter
P
David
John C
JC
Khalil
Sami B
SB
Peruski
Leonard F
LF
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003967:Diarrhea / Q000150:complications / Q000453:epidemiology / Q000382:microbiology*; D024881:Drug Resistance, Bacterial; D004768:Enterotoxins / Q000032:analysis*; D004926:Escherichia coli / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000150:complications / Q000453:epidemiology / Q000382:microbiology*; D005260:Female; D006801:Humans; D007630:Kenya / Q000453:epidemiology; D008297:Male; D010641:Phenotype; D014195:Travel
D000900:Anti-Bacterial Agents; D004768:Enterotoxins