The prevalence of various pathogens isolated from patients treated in an Intensive Care Unit (ICU), was analysed for the period 1990-1995. Changes in the frequency of various pathogens were compared to the resistance of organisms and the use of antibiotics. During this study period, an almost three-fold decrease in the frequency of occurrence of Escherichia coli bacteria, with a simultaneous significant increase in the prevalence of Pseudomonas aeruginosa, was observed together with an increase in the percentage of Gram positive bacteria. Gram positive bacteria constitute approximately 50% of all isolated bacteria. Demographic and clinical data during the period of the study did not differ significantly, nor did they change in a way which would explain such an increase in the prevalence of Gram positive bacteria. Usage of most antibiotics and antimicrobial susceptibility of the most commonly isolated organisms did not differ statistically during the years 1990-93. It is difficult to exclude the possibility that these observed changes among pathogens could be explained by the useage profile of antibiotics used earlier in the ICU, i.e. before the introduction of cephalosporins. The 6-year survey demonstrated the continuous shift in the profile of pathogens found in this ICU toward Gram positive bacteria, with a predominance towards of Staphylococci.

Keywords: Intensive Care, Sepsis, nosocomical infections, six-year survey