Background: With respect to the importance of microbial organisms as the cause of gastroenteritis, prompt diagnosis, proper treatment and follow up is of utmost importance. The present study was conducted on patients referring to Kashan Central Lab with the diagnosis of gastroenteritis to determine the frequency of protozoal and bacterial microorganisms.

Materials and methods : For this descriptive study, 500 consecutive cases of gastroenteritis were enrolled. Initial data were gathered and 3 separate stool samples (with 3-day interval) were obtained and examined by direct observation and ether-formalin method to detect possible microorganisms. Meanwhile, specific media and cultures were used.

Results : Of 500 cases, 50 were excluded due to weak cooperation. Of the remaining, the infection rate of protozoal, bacterial and other microorganisms were 50.9%, 13.5%, and 35.6%, respectively. Among protozoa, giardia was the most common (21.8%), however among bacteria, shigella was more frequently cultured (6.4%). Most of the infection did occur in summer among 7-11 year-old subjects.

Conclusion : Infection with shigella, giardia and salmonella is quite common. Necessary health care activities are strongly recommended.