title: Diagnostic limitations to accurate diagnosis of cholera.
abstract: The treatment regimen for diarrhea depends greatly on correct diagnosis of its etiology. Recent diarrhea outbreaks in Bangladesh showed Vibrio cholerae to be the predominant cause, although more than 40% of the suspected cases failed to show cholera etiology by conventional culture methods (CMs). In the present study, suspected cholera stools collected from every 50th patient during an acute diarrheal outbreak were analyzed extensively using different microbiological and molecular tools to determine their etiology. Of 135 stools tested, 86 (64%) produced V. cholerae O1 by CMs, while 119 (88%) tested positive for V. cholerae O1 by rapid cholera dipstick (DS) assay; all but three samples positive for V. cholerae O1 by CMs were also positive for V. cholerae O1 by DS assay. Of 49 stools that lacked CM-based cholera etiology despite most being positive for V. cholerae O1 by DS assay, 25 (51%) had coccoid V. cholerae O1 cells as confirmed by direct fluorescent antibody (DFA) assay, 36 (73%) amplified primers for the genes wbe O1 and ctxA by multiplex-PCR (M-PCR), and 31 (63%) showed El Tor-specific lytic phage on plaque assay (PA). Each of these methods allowed the cholera etiology to be confirmed for 97% of the stool samples. The results suggest that suspected cholera stools that fail to show etiology by CMs during acute diarrhea outbreaks may be due to the inactivation of V. cholerae by in vivo vibriolytic action of the phage and/or nonculturability induced as a host response.
authors.affiliation: Enteric and Food Microbiology Laboratory, Laboratory Sciences Division, International Center for Diarrheal Disease Research, Bangladesh, Dhaka, Bangladesh. munirul@icddrb.org
authors.forename: Munirul
authors.initials: M
authors.lastname: Alam
authors.forename: Nur A
authors.initials: NA
authors.lastname: Hasan
authors.forename: Marzia
authors.initials: M
authors.lastname: Sultana
authors.forename: G Balakrish
authors.initials: GB
authors.lastname: Nair
authors.forename: A
authors.initials: A
authors.lastname: Sadique
authors.forename: A S G
authors.initials: AS
authors.lastname: Faruque
authors.forename: Hubert P
authors.initials: HP
authors.lastname: Endtz
authors.forename: R B
authors.initials: RB
authors.lastname: Sack
authors.forename: A
authors.initials: A
authors.lastname: Huq
authors.forename: R R
authors.initials: RR
authors.lastname: Colwell
authors.forename: Hidemasa
authors.initials: H
authors.lastname: Izumiya
authors.forename: Masatomo
authors.initials: M
authors.lastname: Morita
authors.forename: Haruo
authors.initials: H
authors.lastname: Watanabe
authors.forename: Alejandro
authors.initials: A
authors.lastname: Cravioto
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods*; D001459:Bangladesh / Q000453:epidemiology; D002771:Cholera / Q000175:diagnosis* / Q000453:epidemiology* / Q000382:microbiology; D004196:Disease Outbreaks; D005243:Feces / Q000382:microbiology*; D006801:Humans; D025202:Molecular Diagnostic Techniques / Q000379:methods; D012680:Sensitivity and Specificity; D041241:Vibrio cholerae O1 / Q000235:genetics / Q000254:growth & development / Q000276:immunology / Q000302:isolation & purification*