A survey on drug resistance in Shigella organisms in 3 hospitals in Tehran over a six month period

Abstract number: 1134_03_84

Chamani L., Noyan Ashraf M.A., Asadi S.

Objectives:  

Shigellosis is a common disease in Asian countries esp in warm months. Knowledge of the pattern of resistance in a given population which changes by time is useful. We designed this study to evaluate drug resistance in Shigella spp in 3 hospitals of Tehran in order to find the suitable empirical antibiotic therapy in shigellosis.

Methods:  

It was a cross sectional prospective study in three different hospitals of Tehran from March to April 2003. Fresh stool samples of patients with dysentery were cultured on MacConkey agar and Hectoen enteric agar and incubated overnight at 37 degrees. Lactone negative colonies were transferred to triple sugar iron agar and lysine-iron agar slants and reincubated. Those with characteristic reaction (alkaline salt, acid butt, and no gass) were tested biochemically and then serologically identified with shigella grouping and typing antisera. Drug Resistance was evaluated in cultured Shigella organisms by disk diffusion susceptibility testing.

Results:  

Shigella spp. Were cultured in 96 of 1476 stool cultures (6.5%).

The antibiotic susceptibility testing results were as bellow:

- Shigella spp. Were completely(100%) sensitive to Ciprofloxacin, Ofloxacin & Norfloxacin and 96% sensitive to Nalidixic Acid.

1. They were 100% sensitive to Ceftriaxone and Cefotaxime but 85% to Ceftizoxime and 80% to Cefazolin.

2. There was 100% resistance to Ampicilline and 85% resistance to Cotrimoxazole.

- They were 54% sensitive,12% resistant and 34% intermediatly resistant to Gentamicin.

Conclusion:  

It seems that new Fluoroquinolones for adults and Nalidixic Acid for chidren are suitable empirical antibiotic therapy of shigellosis in Tehran. Ceftriaxone and Cefotaxime are suitable for severe cases and hospitalized patients and ceftizoxime & cefazoline may be useful alternatively. Ampicilline and Cotrimoxazole should not be used for treatment any more. Supported by the BIB, Avesina Research Institute, Tehran, Iran.