Application of PCR for detection of Vibrio cholerae using primers targeted against the gene of outer membrane protein ompW and comparison with conventional methods

ABSTRACT

Vibrio cholerae, the etiologic agent for the diarrheal disease of cholera, continues to be an important cause of mortality and morbidity in many parts of the world. V. cholera serotypes Ol and O139 are associated with classic cholera, however, other V. cholera strains, including non-agglutinable vibrios [NAG] are occasionally isolated from the cases of diarrhea. Identification of V. cholera is usually achieved through a series of culture and biochemical tests, but close relatedness among V. cholera and other member of Vibrio spp. or Aeromonas spp. has often made identification of the organism quite difficult. The objective of this study was evaluation of PCR targeting outer membrane proteins [ompW] for detection of V. cholera in comparison with conventional method of culture and biochemical tests. A total of 156 V. cholera isolates from both clinical and environmental sources identified on the basis of conventional culture, biochemical tests and serotyping. Polymerase chain reaction [PCR] assay was carried out using primers targeting the gene of outer membrane proteins. Second PCR assay was also performed using primers based on O139-rfb region within the V. cholerae chromosome. Based on the results from biochemical tests and serotyping, 6 isolates were identified as V. cholera 01, serotypes Ogawa [five cases] and Hikojima [one case] and 150 non-agglutinable vibrios [NAG]. PCR showed 136 isolates [87.9%] were positive for V. cholera and 20 others [12.1%] were negative. PCR results on NAG isolates revealed none of the isolates were belong to 0139 serotype. In the present study, PCR assay showed no priority over the conventional methods. The prevalent V. cholerae isolates in the region of study were NAG and the least dominant isolates were Ol Ogawa-serotype. No 0139 serotype was detected among the isolates