Diagnosis of Cholera
A patient history of watery stools especially during an epidemic should raise the suspicion of cholera.
► Macroscopic / Gross Examination-
Stools resembles ‘rice water’ and contain mucus
► Microscopic Examination-
Dark field microscopic examination of stool sample shows rapidly motile V.cholerae bacteria. Epithelial cells are also present in the stool sample.
A stool culture may be done to confirm the presence of V. cholerae. Enrichment is done in alkaline peptone water at pH 8.7 for 6-8 hours incubation.
Typical yellow color colonies appear in thiosulfate-citrate-bile salts-sucrose (TCBS) agar after 18 hours of incubation. Organisms can be confirmed from culture by staining and examining under microscope.
Vibrio cholerae are further identified by slide agglutination tests using anti-O group 1 antiserum and by biochemical reactions.