Academic journal article Journal of Health Population and Nutrition

Increasing Antimicrobial Resistance of Vibrio Cholerae O1 Biotype El Tor Strains Isolated in a Tertiary-Care Centre in India

Academic journal article Journal of Health Population and Nutrition

Increasing Antimicrobial Resistance of Vibrio Cholerae O1 Biotype El Tor Strains Isolated in a Tertiary-Care Centre in India

Article excerpt

INTRODUCTION

Vibrio cholerae O1, the causative organism of epidemic cholera, continues to be a major health problem in most parts of developing nations in the world. The outbreaks of cholera follow a seasonal pattern in regions of endemicity, reflecting the shifts in climatic conditions that lead to preferential selection of hosts by the causal organisms (1-3). The replacement of fluid and electrolytes plays a major role in treating cases of cholera. Antibiotics as well play a major role in reducing the shedding of the bacillus, thereby preventing the spread of the disease, in treating severe illness by reducing the volume of diarrhoea, and also reducing the duration of illness and hospitalization (4).

The antibiotics commonly used in the treatment of cholera include tetracycline and fluoroquinolones, such as ciprofloxacin, among others. The antimicrobial susceptibility patterns of V. cholerae O1 strains from newly-infected patients are on constant change following the recent emergence and spread of multidrug-resistant strains (1-6). Results of recent studies in India showed that most isolates of V. cholerae O1 were resistant to the commonlyused antibiotics, such as ampicillin, furazolidone, ciprofloxacin, and tetracycline (4,6). Resistance of V. cholerae to ceftriaxone has been reported from Argentina (7) and recently from Delhi, India (8).

There is no report regarding resistance to the thirdgeneration cephalosporins from our region, this being the first. Also, no consolidated data are available on the antimicrobial susceptibility patterns of the organism concerned. The present study was conducted to determine the antibiotic susceptibility patterns of V. cholerae O1 isolated during 2008-2010 at the hospital of the Jawaharlal Nehru Institute of Post Graduate Medical Education and Research (JIPMER), Puducherry, India.

MATERIALS AND METHODS

The study was conducted at the Department of Microbiology, JIPMER, Puducherry, India. The study samples included strains of V. cholerae O1 obtained from 2,658 consecutive stool samples of patients with cholera-like disease during January 2008-December 2010.

The stool samples were inoculated onto MacConkey agar and thiosulphate-citrate-bile salts-sucrose agar (HIMEDIA, Mumbai). Enrichment was done with alkaline peptone water, from which subculture was performed after six hours of incubation at 37°C onto MacConkey agar and thiosulphate-citrate-bile salts-sucrose agar. Suspected colonies were identified as V. cholerae by the standard biochemical tests (9-11), and the serogroup was confirmed by agglutination with specific antiserum (BD DifcoTM, Becton Dickinson, Sparks, Maryland, USA). Antimicrobial susceptibility testing was done using the Kirby-Bauer method (12-14). The antibiotic disks tested were tetracycline (30 Êg), furazolidone (100 Êg), ampicillin (10 Êg), ceftriaxone (30 Êg), and ciprofloxacin (5 Êg). Escherichia coli ATCC 25922 was used as the control organism. The minimum inhibitory concentrations (MICs) of ciprofloxacin, ceftriaxone, and tetracycline were determined by the agar dilution method (14,15) and the E-test (BioMe Lrieux) method. The MICs of ceftriaxone, ciprofloxacin, and tetracycline were determined by the agar dilution method for all the strains. The E-test method was used for the strains which had either intermediate resistance or were resistant to the antibiotics by the agar dilution method.

The double-disk synergy test was performed as described earlier (16) on the three strains which had intermediate resistance to ceftriaxone.

RESULTS

Of the 2,658 stool samples obtained from patients, 154 isolates of V. cholerae were reported during January 2008-December 2010, of which 34 were reported in 2008 and 2 in 2009. These cases were usually documented in May to August of every year. Subsequently, 118 cases were reported in 2010 as there was an outbreak of cholera in Puducherry.

The majority of the reported isolates were from children aged 0-5 year(s)-70. …

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