shigella spp frequency, serotyping and antibiotic resistance pattern in acute diarrheic patients in zanjan shahid beheshti hospital, during 2003-2007

background and objective: gastroenteritis is one of the most important diseases in the world. this disease is more critical among children, people with immune deficiency and the sufferers from mal-nutrition. shigella spp. as the most important cause of dysentery, causes much mortality around the world. increasing antibiotic resistance is one of the major health problems. this research aimed to study the pattern of antibiotic resistance of shigella spp. in zanjan shahid beheshti hospital. materials and methods: shigella spp. was isolated from stool samples of diarrheic patients during 2003-2007 using common microbioloyic methods. they were examined for serotyping and antibiogram using disc diffusion method. results: shigella spp were found in 134 out of 682 (19.6%) diarrheic stool samples. they comprised of 53% males and 47% females. the highest number of positive samples was found in august and the lowest number was seen in march. the shigella species isolated from 134 positive cultures, identified as sh.flexeneri (62.7%), sh.boydii (20.1%) and sh.dysenteriae (17.2%). in the antibiogram, ciprofloxacin was the most sensitive antibiotic (88.8%) and ampicillin showed the highest resistance (100%). conclusion: due to irregular use of antibiotics and increasing antibiotic resistance to shigella species it can be suggested that some of antibiotics can be omitted from the list of drug choice.