Evaluation of the susceptibility and antimicrobial resistance of strains of Shigella spp. isolated from patients with nosocomial diarrhea

Abstract

Cases of acute diarrhea that require antibiotics, the correct choice of antibiotics depends on prior knowledge of local strains. This study aims to assess the susceptibility and resistance of strains of Shigella spp. isolated from culture of patients with nosocomial diarrhea. Stool cultures for Shigella spp. were analyzed and collected from July/1988 to February/1993 and from November/1991 to July/1993. After purified and identified by biochemical testing it was held the serotyping in the strains of Shigella spp. isolated using as reference the antigen O. To determine the pattern of susceptibility and antimicrobial resistance it was used the method of diffusion with discs of paper in the agar environment. The strains of Shigella spp., isolated, were identified as Shigella flexneri. The antimicrobial activity in vitro against the strains of Shigella flexneri, presented a 100% resistance rate to ampicillin and streptomycin, 85.71% for trimetroprimsulfamethoxazole, tetracycline and chloramphenicol, respectively. 66.66% of strains were resistant to ampicillin plus clavulonic acid. Resistance to kanamycin and gentamicin were seen on 42.86%, respectively, and only 14.29% of these strains were resistant to nalidixic acid. No resistance was observed to ciprofloxacin and ceftriaxone. In conclusion, Shigella flexneri is the main species isolated from patients with nosocomial diarrhea and presented a pattern of multiple resistances to ampicillin, trimethoprim-sulfamethoxazole, streptomycin, tetracycline and chloramphenicol. These antibiotics are ineffective for the treatment of shigelose at the Hospital Universitário Walter Cantídio. Continuous monitoring of resistance patterns in Shigella spp. is essential for the establishing and updating guidelines for antibiotic treatment in shigellosis.