Vibrio choleraeNon-O1, Non-O139 Serogroups and Cholera-like Diarrhea, Kolkata, India

We identified 281 Vibrio cholerae non-O1, non-O139 strains from patients with diarrhea in Kolkata, India.Choleralike diarrhea was the major symptom (66.0%); some patients (20.3%) had severe dehydration.These strains lacked the ctxA gene but many had hlyA, rtxA, and rtxC genes.Pulsed-field gel electrophoresis showed no genetic link among strains. The StudyDuring 2002-2010, a total of 12,719 fecal specimens were collected, which represented every fifth hospitalized diarrhea patient at the Infectious Diseases Hospital in Kolkata and all children at the outpatient unit at B.C. Roy Memorial Hospital for Children in Kolkata.Fecal specimens were screened for V. cholerae and other enteric pathogens as described (8).NAGs were serotyped by using 206 polyclonal O antisera according to the protocol developed at the National Institute of Infectious Diseases (Tokyo, Japan) (2).Antimicrobial drug susceptibility assays were performed by using the disk diffusion method and commercially available disks (Becton Dickinson, Sparks Glencoe, MD, USA), according to standards of the Clinical and Laboratory Standards Institute (9).Because these standards do not include interpretive criteria for V. cholerae, breakpoints for Enterobacteriaceae were adopted.Escherichia coli ATCC 25922 was used as a quality-control strain.Simplex and multiplex PCRs were performed by using published methods specific for ctxA, tcpA, rtxA, rtxC, stn, and hlyA genes (classical/El Tor) and the TTSS-coding genes (7).Pulsed-field gel electrophoresis was performed according to the PulseNet standardized protocol for V. cholerae (www.pulsenetinternational. org/SiteCollectionDocuments/pfge/5.71_2009_PNetStandProtVcholerae.pdf.Gel Compare II software (Applied Maths NV, Sint-Martens-Latem, Belgium) was used for comparison of electrophoresis patterns.This software uses a Dice similarity index and contains an unweighted pair group with arithmetic mean method.Of the 12,719 diarrhea feces specimens screened, 2,206 (17.3%) contained V. cholerae, which included V. cholerae O1 in 1,841 (83.4%), and O139 in 84 (3.8%).In the remaining 281 (12.7%) specimens, V. cholerae strains did not agglutinate with serogroups O1 or O139.This result was confirmed by species-specific ompW PCR, which included strains collected during 2003 (7).Among 281 strains, 175 (62.3%)NAGs were the only enteric pathogen found, and 106 (37.7%) of those NAGs were found with other enteric pathogens.The isolation frequency of NAGs ranged from 1.2% to 3.2% (Table 1).