[The in vitro effect of a combination of sulbactam with cephalothin and cefazolin on strains of Escherichia coli and Proteus mirabilis which produce beta lactamase]. / Ucinok kombinácií sulbaktámu s cefalotínom a cefazolínom in vitro na kmene Escherichia coli a Proteus mirabilis produkujúce betalaktamázy.

ABSTRACT

The effect of the combination of sulbactam, cephalothin, and cephazolin was studied in vitro on 88 strains of E. coli and 11 strains of P. mirabilis producing beta-lactamases. Quantitative susceptibility of the tested strains to cephalothin was examined by the disk dilution method and the effect of the combinations with sulbactam by the micromethod. The production of beta-lactamases was determined by the qualitative test with the chromogenic substrate PODAC. Of the total number of 160 E. coli strains beta-lactamases were established in 53.3% of the strains. Of the 47 P. mirabilis strains 23.4% were found to produce beta-lactamases. The effect of the combinations with sulbactam was assessed as synergistic, additive, indifferent or antagonistic. In the combination of sulbactam in the concentration of 16.0 mg/l with cephalothin and cephazolin a higher rate of synergistic and additive effect was recorded on both strains. In none of the combinations did sulbactam exert an antagonistic effect.