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Journal of Clinical Microbiology, Oct 1997, 2588-2592, Vol 35, No. 10
MJ Albert, NA Bhuiyan, KA Talukder, AS Faruque, S Nahar, SM Faruque, M Ansaruzzaman and M Rahman
To find reasons for the recent decline of Vibrio cholerae O139 Bengal
cholera in Bangladesh, phenotypic and genotypic changes in O139 isolates
obtained from patients with cholera from 1993 to 1996 were studied. The
isolates were tested for the presence of ctx and tcpA genes,
hemagglutinin/protease (HA/P), capsule, D-mannose-sensitive hemagglutinin
(MSHA), L-fucose-sensitive hemagglutinin (FSHA), tube test (tube) and CAMP
test (CAMP) hemolytic activities, resistance to 2,4-diamino-6,7-diisopropyl
pteridine (O/129) and trimethoprim- sulfamethoxazole (TMP-SMX), and
genotype by pulsed-field gel electrophoresis (PFGE). All isolates possessed
ctx and tcpA genes, HA/P, and a capsule. Most isolates were negative for
FSHA, but although the majority of the isolates were positive for MSHA, no
discernible trend in the activity was found during the study period. All
early isolates were CAMP hemolysin positive and resistant to the
vibriostatic compound O/129 and TMP-SMX, the two properties that could be
used for the presumptive diagnosis of O139 cholera. However, subsequently,
isolates that were CAMP hemolysin negative and susceptible to TMP-SMX and
O/129 were increasingly encountered, with all the 1996 isolates being so,
which suggested that these properties can no longer be used for the
presumptive diagnosis of O139 cholera. V. cholerae O139 isolates that were
CAMP hemolysin positive and resistant to O/129 and TMP-SMX produced a
disease of greater severity than that caused by the CAMP hemolysin-negative
and susceptible isolates on the basis of the lengths of stay of the
hospitalized patients. The study period witnessed the evolution of four
different genotypes by PFGE. All of these data suggested that the V.
cholerae O139 isolates have undergone changes in some properties. However,
how these changes influenced their prevalence relative to that of V.
cholerae O1 in human infection is not clear. Studies of the environmental
factors will provide the key for an understanding of the relative abundance
of these vibrios.
Copyright © 1997 by the American Society for Microbiology. All rights reserved.
Phenotypic and genotypic changes in Vibrio cholerae O139 Bengal
International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka. albert@cholera.bangla.net
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