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| ORIGINAL ARTICLE |
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| Year : 1990 | Volume
: 36
| Issue : 3 | Page : 128-30 |
A study of V. cholerae strains isolated in Bombay.
Saraswathi KK, Deodhar LP
Department of Microbiology, Lokmanya Tilak Municipal Medical College, Bombay, Maharashtra.
Correspondence Address:
Department of Microbiology, Lokmanya Tilak Municipal Medical College, Bombay, Maharashtra.
Of 935 faecal samples studied over a period of one year, V. cholerae 01 was isolated from 102 samples (10.9%). All the strains were found to be E1 Tor Ogawa. The strains belonging to the phage types 2 and 4 were encountered in our study, type 2 being the highest (76.5%). The sensitivity pattern of all strains to the commonly used antibiotics was determined. Strains sensitive to gentamicin (92.2%), nalidixic acid (85.3%), kanamycin (83.3%), cotrimoxazole (80.4%) and chloramphenicol (75.5%) were observed. Out of the total, 36.3%, 29.4% and 28.4% of V. cholerae strains were found to be resistant to ampicillin, streptomycin and tetracycline respectively. V. cholerae was isolated throughout the year indicating the endemicity of cholera in Bombay.
How to cite this article:
Saraswathi K, Deodhar L P. A study of V. cholerae strains isolated in Bombay. J Postgrad Med 1990;36:128 |
Cholera has been considered as an endemic infection in Mumbai. Dharavi, the biggest slum, accounts for the endemicity of cholera in Mumbai. This slum is located 1 km, from Sion Hospital. In Dharavi, the problem is of overcrowding, lack of safe drinking water, contamination of water by sewage and that of open drainage system. During the period of study (Jan. 1985 to Dec. 1985), the specimens were received from suspected cases of cholera from Dharavi and other peripheral hospitals. The present report describes the prevalence of V. cholerae in Mumbai and their antibiotic sensitivity pattern to routinely used antibiotics.
A total of 935 faecal samples / rectal swabs, received at Sion Hospital during a period of Jan. 1985 to Dec. 1985 from patients of all age groups with acute diarrhoea, were screened for the presence of V cholerae by standard laboratory methods[3].
Specimens were cultured directly on MacConkey's agar and thiosulfate-citrate-bile salts-sucrose (TCBS) agar. In addition to direct plating, specimens were subcultured on MacConkey's agar and TCBS agar after selective enrichment in alkaline peptone water. Plates were examined after overnight incubation at 37?C. Colonies suggestive of V cholerae were iddentified by biochemical tests and confirmed by serotyping with antisera obtained from National Institute of Cholera and Enteric Diseases, Calcutta.
Susceptibility of all isolates to eight cornmony used antimicrobial agents was determined by Kirby-Bauer disc diffusion method[2].
From a total number of 935 samples, V. cholerae was isolated from 102 samples, with an isolation rate of 10.9 percent. All the strains were El Tor Ogawa. Phage types 2 and 4 were the prevalent phage types in our study [Table - 1]; phage type 2 being the highest (76.5%) followed by type 4 (19.4%), As far as age distribution is concerned, majority of the cases were from young adults (16-30 years). V cholerae was isolated throughout the period of study, though isolations were more in monsoon.
In the present study, a high degree of in vitro efficacy was shown by gentamicin and nalidixic acid inhibiting 95.2% and 85.3% of V. cholerae strains respectively. The antibiotic sensitivity test results of all the V cholerae strains are shown in [Table - 2]. Approximately 36.3%, 29.4% and 28.4% of V. cholerae strains were found to be resistant to ampicillin, streptomycin and tetracycline respectively. Serum strains were found to be multi-drug resistant. These strains were resistant to five drugs kanamycin, tetracycline, chloramphenicol, streptomycin and ampicillin.
Since the early 1960s, V. cholerae biotype E1 Tor has been spreading throughout the world. At present, E1 Tor vibrios, have completely replaced the V cholerae biotype Classical. The results of the present study confirm these reports. All the strains were EI Tor Ogawa and phage types 2 and 4 were the prevalent phage types in our study. Similar pattern of phage types and serotypes have been reported[4],[7],[8],[10],[11],[12]. Majority of cases were from young adults which is in concurrence with the reports from Calcutta[5]. However, reports from Karnataka12 showed increased incidence of cholera in the paediatric age group.
In addition to fluid replacement, chemotherapy has also proved a useful adjunct to the treatment of cholera[8]. However, an indiscriminate use of antibiotics calls for regular sensitivity testing of V. cholerae strains, so that effective chemotherapy can be instituted.
As shown in [Table - 2], majority of the strains were sensitive to gentamicin, nalidixic acid, kanamycin and cotrimoxazole, though relatively resistant to ampicillin, streptomycin, tetracycline and chloramphenicol. Our results are in broad agreement with those of previous reports [11]. However, Agarwal et al[1] have reported 100% resistance of V. cholerae strains to kanamycin and streptomycin and 100% sensitivity to tetracycline, which is in contrast to our study.
Strains of multiple antibiotic resistant V. cholerae were first recognised in December 1979. Outbreaks due to multiple drug resistant strains of V. cholerae have been reported by Glass et al[6]. In our study, 7 strains were multidrug resistant, thus clearly indicating the emergence of multi-drug resistant strains. V. cholerae was isolated throughout the year, indicating the endemicity of cholera in Mumbai.
The authors are grateful to the Director, National Institute of Cholera and Enteric Diseases, Calcutta for carrying out the phage typing of the stains.
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