CHANGE IN BIOTYPE TREND OF Vibrio cholerae IN NEPAL

CHANGE IN BIOTYPE TREND OF Vibrio cholerae IN NEPAL

Rojina Maharjan¹, Dina Shrestha¹, Jyoti Acharya², Nabaraj Adhikari¹ and Upendra Thapa Shrestha^1*

¹Department of Microbiology, Kantipur College of Medical Science, Sitapaila, Kathmandu

²Sukraraj Tropical and Infectious Disease Hospital, Teku, Kathmandu

*Corresponding email: upendrats@gmail.com

ABSTRACT

Background: Cholera is an acute diarrheal illness caused by the toxigenic bacteria Vibrio cholerae serogroup O1 and O139 and is associated with rapid loss of body fluids leading to dehydration, electrolyte disturbances and hypovolemic shock; without treatment, death can occur within hours. V. cholerae is classified into more than 200 serogroups based on the O antigen of the lipopolysaccharide; of these, only O1 and O139 serogroups cause epidemic cholera. Again, V. cholerae O1 is further classified into two biotypes: classical and El Tor and contain two major serotypes: Ogawa, Inaba and additional serotype Hikojima contains both specific antigens, is rare.

Method: The study was carried out in Sukraraj Tropical and Infectious Disease Hospital, Teku, Kathmandu, Nepal from June to November 2012. This research was ethically approved by Nepal Health Research Council, Kathmandu, Nepal. A total of 450 stool samples from diarrheal patients were collected and transported to the laboratory as soon as possible. Firstly, inoculating alkaline (pH 8.5) peptone broth with the specimen and then streaking for isolation after an approximate 6-hours incubation period; this process both enables the rapidly growing vibrios to multiply and suppresses much of the commensal microflora. For cultural diagnosis, culture was done on both nonselective media MacConkey agar (MA) and selective media thiosulfate-citrate-bile salts-sucrose (TCBS)agar on which the sucrose-fermenting cholera vibrios produce a distinctive yellow colony. The colony characteristics were observed and sub­cultured on Nutrient Agar (NA), futher identification done by gram staining and appropriate biochemical tests. Isolated V. cholerae were subjected for serotyping using kit Mast Group as per kit's instruction. All the isolated strains of V. cholerae were subjected to biotyping by Polymyxin B (50U) sensitivity test, Voges Proskauer reaction and chicken RBC agglutination tests.

Result: Out of 450 samples, 22 (4.9%) were positive for V. cholerae. All isolated strains of V. cholerae strains belonged to serogroup O1, serotype Ogawa and biotype classical. Children and the elderly people are mostly affected by cholera. Cholera outbreaks occurred more in moonsoon season (July and August) . Patients consuming untreated water for drinking purpose were having more cholera cases 10 (10.9%); whereas patients drinking boiled water did not have any cholera case. Vomiting, dehydration, abdominal pain, anorexia and nausea and stool passage frequency ≥ 10 were the clinical features and Patients suffering from diarrhea for 2 or more days yet unrecovered were having more cholera cases. However, all V. cholerae isolates were sensitive to tetracycline and found to be multi-drug resistant.

Conclusion: It is suggested that V. cholerae infection remain a serious problem like in our developing countries due to the poor hygienic condition. It can be concluded that proper identification of V. cholerae can be done by phenotyping method which helps in manangement for diarrhoeal population.

Key words: Diarrhoea, V. cholerae, serotyping, Nepal

Note: The full version of this manuscript is coming soon.