Toxigenic Potential of Vibrio cholerae O1and O139 Serotypes Isolated from Cases of Diarrhea in Baghdad hospitals

Abstract

Cholera is most important water borne pathogen. The public health significance of a V. cholerae isolate is routinely assessed by two critical properties: the production of cholera toxin CT and the possession of either the O1 or O139 antigen, which acts as a marker of epidemic potential. The objective of this study is to detect V. cholerae serotypes directly from stools and determines their toxiginicity potential. Sixty four stool samples were collected from four hospitals in Baghdad from November 2010 to February 2011. The age of patients was ranging from two months to 12 years, 26 females and 38 males. Immunochromatographic test used for qualitative detection of O1and /or O139 serotypes was used in addition to routine culture for isolation of V. cholerae. Using specific primer cholera toxin gene, ctxA2-B, was amplified and the PCR product was detected by agarose gel electrophoresis. Out of 64 stool samples only 16 (25%) was positive. Fifeen 93.7% of these samples were positive for O1serogroup and just one 6.3% was positive for O139 serogroup. Stool sample culture on alkaline peptone water and then on TCBS agar enhance the growth of 11(17.2%) V. cholerae isolates, 10 (90.9%) were belong to O1 serotype and one 9.1% belong to O139. The results of ctxA2-B gene amplification show that, 9 (90%) out of 10 O1serotypes was positive. While the only one 100% O139 serotype was positive. As conclusion, the incidence of cholera caused by V. cholerae O1 is more than that caused by V. cholerae O139 in Baghdad hospitals. Immunochromatographic test is a rapid and sensitive test in recover V. cholerae O1 and O139 serotypes. PCR is a simple molecular tool to determine the toxigenicity of V. cholerae isolates.