Relatedness of Vibrio cholerae O1/O139 Isolates from Patients and Their Household Contacts, Determined by Multilocus Variable-Number Tandem-Repeat Analysis

Abstract

The genetic relatedness of Vibrio cholerae O1/O139 isolates obtained from 100 patients and 146 of their household contacts in Dhaka, Bangladesh, between 2002 and 2005 was assessed by multilocus variable-number tandem-repeat analysis. Isolate genotypes were analyzed at five loci containing tandem repeats. Across the population, as well as within households, isolates with identical genotypes were clustered in time. Isolates from individuals within the same household were more likely to have similar or identical genotypes than were isolates from different households, but even within a household, isolates from different individuals often had different genotypes. When household contacts were sampled regularly for 3 weeks after the illness of the household index patient, isolates with genotypes related to the index patient appeared in contacts, on average, ϳ3 days after the index patient, while isolates with unrelated genotypes appeared in contacts ϳ6 days after. Limited data revealed that multiple isolates from the same individual collected within days of each other or even from a single stool sample may have identical, similar, or unrelated genotypes as well. Our results demonstrate that genetically related V. cholerae strains cluster in local outbreaks but also suggest that multiple distinct strains of V. cholerae O1 may circulate simultaneously within a household.Vibrio cholerae is the etiologic agent of cholera, a secretory diarrheal disease with a high mortality rate in humans if untreated (25). Serogroups of V. cholerae, a motile, Gram-negative, curved rod, can be defined serologically by the O side chain of the lipopolysaccharide (LPS) component of the outer membrane (9). V. cholerae is found in a variety of forms in aquatic ecosystems (41, 42), and more than 200 different serogroups have been isolated, mostly from environmental sources (45). However, the vast majority of V. cholerae strains that cause the clinical disease cholera belong to serogroup O1 or O139 (37, 42). V. cholerae O1, the historical agent of epidemic and pandemic cholera and the current leading cause of cholera both globally and in Bangladesh (42), is classified into two major biotypes, classical and El Tor (44), and two major serotypes, Ogawa and Inaba (48). The current global pandemic is caused by V. cholerae O1 El Tor. A second pathogenic serogroup, O139, emerged in the Bengal region in 1992 by horizontal transfer of new LPS biosynthesis-encoding genes into the El Tor biotype (1, 4). This new serogroup continues to cocirculate with El Tor V. cholerae O1 serotypes Ogawa and Inaba as a cause of disease in humans, although it accounts for a smaller proportion of all cholera now than in its first years of circulation (16,20). Recently, comparative genomics has revealed an extensive amount of lateral gene transfer between strains, suggesting that genomic classification may be an alternative to serogrouping for classifying pathogenic V. cholerae strains (11).Toxigenic V. cholerae may be present in environmental sources in regions of endemicity ...

Genomic diversity of 2010 Haitian cholera outbreak strains

“…The identity of presumptive colonies was confirmed by using a battery of specific biochemical, serological, and molecular methods. Five loci for MLVA were analyzed by using methods described in previous studies (10)(11)(12). Genomic DNA of 76 confirmed V. cholerae strains along with eight reference strains were subjected to next generation whole-genome Illumina and hybrid Illumina/454 sequencing.…”

Nontoxigenic Vibrio cholerae Non-O1/O139 Isolate from a Case of Human Gastroenteritis in the U.S. Gulf Coast

“…Multilocus variable-number tandem-repeat (VNTR) analysis (MLVA), a discriminating tool used to trace human V. cholerae infections (43) and resolve distinct populations of clinical isolates from different geographic regions (44), showed that V. cholerae BJG-01 is genotype 12.12.5.10, genetically distinct (see Table S2 in the supplemental material) from V. cholerae non-O1/O139 isolates of clinical and environmental origin, including representative 2010 Haitian V. cholerae isolates (27).…”

Modeling Cholera Outbreaks

“…High secondary attack rates have been observed within households of cases (Mosley et al, 1965; McCormack et al, 1968; Mosley et al, 1968; Harris et al, 2008;Weil et al, 2009; Kendall et al, 2010). Although a common sources of exposure could account for many of these heavily infected households, studies of the time intervals between cases or that genotype infecting strains have found patterns of transmission consistent with ciclo corto transmission (Snow, 1855; Tamayo et al, 1965; Kendall et al, 2010).…”

“…Although a common sources of exposure could account for many of these heavily infected households, studies of the time intervals between cases or that genotype infecting strains have found patterns of transmission consistent with ciclo corto transmission (Snow, 1855; Tamayo et al, 1965; Kendall et al, 2010). A tell-tale sign of ciclo corto transmission would be the rapid appearance of secondary cases consistent with the incubation period of cholera.…”