Temporal shifts in traits of Vibrio cholerae strains isolated from hospitalized patients in Calcutta: a 3-year (1993 to 1995) analysis

Abstract

This study presents results of a surveillance on cholera conducted with hospitalized patients admitted to the Infectious Diseases Hospital, Calcutta, India, from January 1993 to December 1995. The O139 serogroup of Vibrio cholerae dominated in 1993 but was replaced by O1 as the dominant serogroup in 1994 and 1995. The isolation rate of V. cholerae non-O1 non-O139 did not exceed 4.9% throughout the study period, while the isolation rate of the O139 serogroup in 1994 and 1995 was below 9%. No temporal clustering of any non-O1 non-O139 serogroup was observed. With the exception of 1 strain, none of the 64 strains belonging to the non-O1 non-O139 serogroup hybridized with ctx, zot, and ace gene probes, while 97.3 and 97.7% of the O139 and O1 strains, respectively, hybridized with all the three probes. Multiplex PCR studies revealed that all the O1 strains belonged to the ElTor biotype. There was a progressive increase in the cytotoxic response on CHO and HeLa cells evoked by culture supernatants of strains of V. cholerae non-O1 non-O139 isolated during 1994 and 1995 compared with the response evoked by those isolated in 1993. Dramatic shifts in patterns of resistance to antibiotics between strains of V. cholerae belonging to different serogroups and within strains of a serogroup isolated during different time periods were observed. There was a discernible increase in the incidence of multidrug-resistant strains of V. cholerae O1 isolated in 1994 and 1995 compared with that in 1993. On the basis of the results of this study, we predict the possibility of newer variants of V. cholerae emerging in the future.

Wild waterfowl as potential vectors of Vibrio cholerae and Aeromonas species

“…Isolates belonging to non-O1/O139 serogroups can cause cholera-like diarrhoeal disease [19,30,31]. Mukhopadhyay et al [31], who studied 2511 patients with cholera in Kolkata, identified 93 cases of choleralike diarrhoea caused by non-O1/O139 serogroups, including the following serogroups that were also identified in our study: O6, O8, O9, O13, O36, O39, O65 and O128. Dutta et al [30], who studied 281 cases of cholera-like diarrhoea in Kolkata, found serogroups O6, O11, O34, O37, O59 and O97.…”

Phenotypic and genotypic changes in Vibrio cholerae O139 Bengal

“…Therefore, it was speculated that V. cholerae O139 might be the causative agent of the eighth pandemic of cholera (37). However, continued surveillance of cholera infection in the Indian subcontinent has suggested that V. cholerae O139 infection is on the decline and that the El Tor biotype of V. cholerae O1 has again become the dominant strain (11,30,34). We speculated that the changing epidemiology of V. cholerae infections might be due to changes in the properties of V. cholerae which determine their survival in the human intestine and in the aquatic environment.…”

“…Many developed countries also reported imported cases of cholera due to V. cholerae O139 (7,8). When cholera due to V. cholerae O139 was at its peak in the Indian subcontinent, the existing strains of the El Tor biotype of V. cholerae O1 virtually disappeared (11,30,34). Therefore, it was speculated that V. cholerae O139 might be the causative agent of the eighth pandemic of cholera (37).…”

Functional genotypes are associated with commensal Escherichia coli strain abundance within‐host individuals and populations

“…Symbiotic species such as those found in the vertebrate gut often consist of multiple strains or genotypes that co-occur both within-host individuals and across the host population (for example, Helicobacter pylori; Cover & Blaser 2009; Escherichia coli; Moreno et al 2009;and Salmonella enterica;Bull et al 2012). At both ecological levels, strains vary greatly in abundance (Mukhopadhyay et al 1996;Delport et al 2006;Le Gall et al 2007;Bull et al 2012) with the factors influencing abundance differing between the two levels. Within the host, abundance typically depends on the strain's competitive ability, the initial densities and identity of other strains present, as well as the strain's compatibility with the host's physiology (Freter et al 1983;Fons & Tuomo Karjalainen 2000;Baltzis & Fredrickson 2004;Diard et al 2010;O'Brien & Gordon 2011).…”