Abstract

Our objective was to evaluate the importance and susceptibility pattern of A. baumannii, P. aeruginosa, and K. pneumoniae in Estonian ICUs. From April to December 2003, a total of 128 A. baumannii, 99 P. aeruginosa, and 98 K. pneumoniae strains were collected from North-Estonian Regional Hospital, Tartu University Clinics, East Tallinn Central Hospital, and Narva Hospital. To clear up methodological discrepancies, the data of E-test and disk-diffusion method were compared.

Of the A. baumannii strains 60% were sensitive to to ampicillin/sulbactam and to cefepime, 95% were sensitive to meropenem and imipenem, and 75% to amikacin. Of the P. aeruginosa strains 79% were sensitive to piperacillin/tazobactam, 58% to ceftazidime, 81% to meropenem, 72% to imipenem, 69% to ciprofloxacin and 97% to amikacin. The susceptibility of the K. pneumoniae isolates to meropenem and imipenem was 99%, to ciprofloxacin 91% and to amikacin 98%. In all 4 ICUs, sensitivity among the K. pneumoniae strains was similar, whereas in local discrepancies occurred the susceptibility pattern of A. baumannii and P. aeruginosa. The discordance between E-test and disk-diffusion was pathogen-specific. In the case of K. pneumoniae, less errors were found, while in the case of A. baumannii and P. aeruginosa, E-tests are recommended for susceptibility testing. Most active agents against gram-negative pathogens were carbapenems and amikacin. For empirical treatment, meropenem and imipenem are preferred due to their high activity and the lowest MIC values.