Frequency of isolated Staphylococci species from patients with bacteremia in four hospitals of Ahvaz city

Among bacterial agents involved in bacteremia or septicemia, Staphylococci has a high importance. Surviving on dry surfaces for long times, in addition to colonization on skin and nasopharynx facilitates the spreading of these bacteria particularly from hospital personnel to patients causes increase in nosocomial infections. The main purpose of this study was detection of Staphylococci species and determination of their frequency among bacteremic hospitalized patients in Ahvaz city, Iran. In this cross-sectional study, positive blood cultures collected from patients with Staphylococcal bacteremia were surveyed. These patients were hospitalized in four hospitals dependent to Ahvaz Jundishapur University of Medial Sciences, since Jan.2005 to June.2006. Three blood samples, taken at 2-hour intervals were inoculated into the bottles of culture medium. The samples belonged to the patients with two staphylococcal positive cultures out of 3 samples, were studied. Isolated colonies were stained by Gram`s method and their species were determined by standard biochemical tests. Thirty six (41%) out of 88 Staphylococcal-induced bacteremia cases in Golestan, Talaghani, Razi and Shafa hospitals of ‌Ahvaz caused by Staphylococcus aureus and the other cases of bacteremia caused by coagulase-negative species were as following:: 32 S. epidermidis (36%), 10 S. lugdunensis (11%), 6 S. heamolyticus (7%), 2 S. cohnii (2.5%), and 2 S. xylosus (2.5%). In adition, the most of Staphylococcal isolates belonged to the patients who were hospitalized in burn sections (19.4%), chemotherapy (17%) and infectious section of Razi hospital (17%). The highest number of Staphylococci species (60.2%) was isolated from female patients. The results of our study showed that coagulase-negative Staphylococci was the most common isolate (60%) in the patients with staphylococcal bacteremia. This rate was 85% in Shafa hospital (a centre for thalassemic and patients under chemotherapy). Therefore, special attention is needed to be given to immunocompromised patients, who are the greater risk of bacteremia caused by Staphylococci species. We suggest that attention should be taken during disease surveillance especially for detection of the uncommon coagulase-negative Staphylococci in nosocomial diseases.