The investigation presents data on the prevalence of bacterial pathogenic microorganisms in patients of the Paediatric Clinic of the Faculty Hospital in Olomouc and on the development of resistance to antimicrobial drugs during the three-year period from 1995 - 1997, incl. provisions within the framework of the antibiotic policy. The most frequently isolated bacteria were Escherichia coli (19.1 - 20.9%), Staphylococcus epidermidis (12.1 - 16.7 %), Streptococcus viridans (10.3 - 11.4 %), Klebsiella pneumoniae (4.3 - 8.9 %), Staphylococcus aureus (5.4 - 8.5 %), Haemophilus influenzae (5.0 - 7.9 %), Pseudomonas aeruginosa (4.4 - 5.8 %) and Enterococcus sp. (3.3 - 5.7 %). At the Paediatric Clinic a significant rise (p = 0.05) was recorded in the resistance of Pseudomonas aeruginosa to ceftazidime (from 1.9% in 1995 to 34.5% in 1997). This very negative trend could be associated among others with an increase of the selective pressure of this preparation by 122% (when using parameter RDDDATB). There was also a significant rise (p = 0.05) of the resistance of strains of Pseudomonas aeruginosa to ofloxacine (from 1.9% to 18.2%) and to ciprofloxacine (from 1.1% to 13.8%), whereby the increase of the selective pressure of fluoroquinolones can be characterized by the increase of RDDDATB from 0.08 in 1996 to 0.21 in 1997, which is an increase of 162.5%. An adverse trend is also the increased frequency of gentamicin resistant strains of Pseudomo- nas aeruginosa (from 8.8% to 24.1%). The increased resistance of Klebsiella pneumoniae to cefotaxime (from 2.0% to 57.1%) and ceftazidime (from 1.5% to 52.2%) in 1996 was due to ESBL positive bacterial strains at the neonatal department.

        Key words: pathogenic bacteria, resistance, antibiotherapy, antibiotic policy