The aim of the present work was to investigate the occurrence of Serratia species in diagnostic material as well as to evaluate the sensitivity of these bacteria to antibiotics. 166 study strains of Serratia spp. were isolated from diagnostic material during the period of 2 years. The identification of species was based upon the results obtained in API 20E tests (bio-Merieux). Sensitivity of isolated strains to antibiotics was assessed with the help of disc-diffusion method, in accordance to NCCLS guidelines. In 1995, isolated strains constituted 3.5% and in 1996 - 7.9% of all isolated Enterobacteriaceae rods. Most of the strains (96.4%) were isolated from hospitalised patients. Over 70% of strains were isolated from urine. S. marcescens prevailed (75.3%). Only S. liquefaciens strains were isolated from blood. Patients treated in the departments of neurosurgery, neurology as well as in intensive medical care units are at the greatest risk of infections with these micro-organisms. All the strains were sensitive to imipenem only. Due to the increasingly frequent isolation of Serratia spp. from diagnostic material as well as multiresistance of these bacteria to antibiotics, it becomes necessary to take them into account during microbiological diagnostics and clinical interpretation of the results of these investigations.

Keywords: urinary tract infection, hospital infections, antibiotic resistance