title: Complexity of rice-water stool from patients with Vibrio cholerae plays a role in the transmission of infectious diarrhea.
abstract: At the International Centre for Diarrhoeal Disease Research, Bangladesh, one-half of the rice-water stool samples that were culture-positive for Vibrio cholerae did not contain motile V. cholerae by standard darkfield microscopy and were defined as darkfield-negative (DF(-)). We evaluated the host and microbial factors associated with DF status, as well as the impact of DF status on transmission. Viable counts of V. cholerae in DF(-) stools were three logs lower than in DF(+) stools, although DF(-) and DF(+) stools had similar direct counts of V. cholerae by microscopy. In DF(-) samples, non-V. cholerae bacteria outnumbered V. cholerae 10:1. Lytic V. cholerae bacteriophage were present in 90% of DF(-) samples compared with 35% of DF(+) samples, suggesting that bacteriophage may limit culture-positive patients from producing DF(+) stools. V. cholerae in DF(-) and DF(+) samples were found both planktonically and in distinct nonplanktonic populations; the distribution of organisms between these compartments did not differ appreciably between DF(-) and DF(+) stools. This biology may impact transmission because epidemiological data suggested that household contacts of a DF(+) index case were at greater risk of infection with V. cholerae. We propose a model in which V. cholerae multiply in the small intestine to produce a fluid niche that is dominated by V. cholerae. If lytic phage are present, viable counts of V. cholerae drop, stools become DF(-), other microorganisms bloom, and cholera transmission is reduced.
authors.affiliation: Howard Hughes Medical Institute and Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Nelson
authors.forename: Ashrafuzzaman
authors.initials: A
authors.lastname: Chowdhury
authors.forename: Jason B
authors.initials: JB
authors.lastname: Harris
authors.forename: Yasmin A
authors.initials: YA
authors.lastname: Begum
authors.forename: Fahima
authors.initials: F
authors.lastname: Chowdhury
authors.forename: Ashraful I
authors.initials: AI
authors.lastname: Khan
authors.forename: Regina C
authors.initials: RC
authors.lastname: Larocque
authors.forename: Anne L
authors.initials: AL
authors.lastname: Bishop
authors.forename: Edward T
authors.initials: ET
authors.lastname: Ryan
authors.forename: Andrew
authors.initials: A
authors.lastname: Camilli
authors.forename: Firdausi
authors.initials: F
authors.lastname: Qadri
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Calderwood
mesh_terms: D000328:Adult; D001433:Bacteriolysis; D001435:Bacteriophages / Q000302:isolation & purification / Q000502:physiology; D001459:Bangladesh / Q000453:epidemiology; D002771:Cholera / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission*; D015169:Colony Count, Microbial; D004196:Disease Outbreaks; D018562:Disease Transmission, Infectious; D005243:Feces / Q000382:microbiology*; D006801:Humans; D015994:Incidence; D007421:Intestine, Small / Q000821:virology; D008853:Microscopy / Q000379:methods; D009077:Mucins; D012306:Risk; D041241:Vibrio cholerae O1 / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification* / Q000821:virology; D041242:Vibrio cholerae O139 / Q000254:growth & development / Q000302:isolation & purification* / Q000821:virology
chemical_list: D009077:Mucins