Epidemiology of Shigella species isolated from diarrheal children and drawing their antibiotic resistance pattern

Shigellosis accounts for majority of cases of bacterial diarrhea in infants in developing countries. The present study was conducted to determine the distribution and pattern of antimicrobial resistance of Shigella species among children 0-14 years of age with acute diarrhea in Hamadan. The study included all acute diarrhea patients who admitted in the pediatric department from January 2001 to December 2004. Antibiogram test was performed by gel-diffusion method and ten commonly used antibiotics were applied. Of 1686 stool samples, 166 (9.8%) were positive for Shigella species. Shigella flexneri was the predominant serogroup (40.3%) followed by S. dysentriae (33.7%), S. boydii (15.1%) and S. sonnei (10.8%). Of Shigella isolates, 91% were resistant to one or more antimicrobial agent(s), and 88% were multi-drug resistant. Most strains were resistant to chloramphenicol (90%), ampicillin (89%), co-trimoxazole (84%), tetracycline (83%) and nalidixic acid (51%). Resistance to amoxicillin-clavulanic acid (co-amoxiclav), ceftriaxone, amikacin, nitrofurantoin and ciprofloxacin was observed in 34.9%, 23.4%, 6.6%, 3.6% and 1.8% of the isolates, respectively. Emerging resistance against nalidixic acid (42.3%) was observed. Our experiences suggest that Shigella species could be an important etiological agent of diarrhea in this area, while the drugs of choice for the treatment of Shigella infection should be ciprofloxacin and nitrofurantoin. Amikacin was the third drug of choice