Shahid Rafi, Ayaz Hussain, Waseem Saeed, Arif Ali, Saeed Afzal Khawaja.
Changing epidemiology and sensitivity pattern of Vibrio cholerae at Rawalpindi.
Pak J Med Sci Jan ;20(4):357-60.

Objective: To establish the serotypes of Vibrio cholerae (VC) endemic in our set up and to determine the sensitivity pattern of the organism. Methods: The study was carried out on 123 isolates of Vibrio cholerae isolated from stool samples of patients of diarrhea. Samples were collected in plain containers/alkaline peptone water. Inoculation was done on TCBS agar, McConkey`s agar and Salmonella Shigella agar. Identification of the organisms was based on, sucrose fermentation on TCBS agar a positive oxidase test and biochemical profile by API 20 E galleries. Serological confirmation was done by standard antisera. Biotypes were confirmed by Voges-Proskauer (vp) reaction, Polymixin B (50 i.u) sensitivity and sheep red cell haemolysis. Antibiotic sensitivity was carried out against Ampicillin,Tetracycline, Trimethoprim/Sulphamethoxazole, Erythromicin, Nalidixic acid, Ofloxacin and Ciprofloxacin by Kirby Bauer disc diffusion technique. Results: A total of 123 isolates recovered during the period 1997-2002 were studied. All strains belonged to sero type O1. Till 1998 all strains were of biotype EL Tor. Classical biotype appeared in 1999 and remained the dominant variety during 2000-2001. Year wise comparison of the antimicrobial sensitivity pattern shows that resistance to Nalidixic acid emerged in 1999 and is uniformly continuing whereas resistance to Ampicillin and Tetracycline has fallen to very low levels. No isolate was resistant to the fluoroquinolones. Conclusion: 1. Vibrio cholerae O1 is endemic in Rawalpindi. 2. EL Tor was the biotype causing epidemics predominantly in our set up till 1998. Now the Classical variety has emerged and both types are probably co-existing. 3. All the isolates in our study were completely resistant to Nalidixic acid but sensitive to the fluoroquinolones and Erythromycin. Ampicillin and Tetracycline which were earlier resistant have reverted to sensitive.

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