[Use of new methods for detection of beta-lactamases with extended-spectrum substrates (ESBLs)]

The aim of performed examinations was to compare results of two methods applied for the detection of extended-spectrum beta-lactamases (ESBLs). Two hundred and sixty strains of Gram-negative rods were cultured from clinical specimens obtained from hospitalized patients. These strains were identified as ESBL-positive on the basis of the double-disc method (DDST) according to Jarlier et al. (1988) results. Identification of strains was performed in automatic ATB Expression system (bioMerieux, France). All strains were determined using a novel test for detection of ESBL-type enzymes (DD) according to Appleton (1999). Two discs are applied in this test: with cefpodoxime (CPD) and with cefpodoxime/clavulanate (CD 01, diagnostic disc). Consistent results of two methods (DDST and DD) were obtained in the case of 166 from among 260 of examined strains (60.4%). Consistent results concerned 161 out of 222 examined strains of enteric rods (72.5%) and only 5 from among 38 of other strains (mostly belonging to the group of non-fermenting rods). On the basis of performed investigations it can be stated that the novel method of extended-spectrum beta-lactamases (ESBLs) detection (DD) according to Appleton (1999) is more objective and easier for interpretation than the double-disc synergy test (DDST) according to Jarlier et al. (DDST), which is widely applied in the routine microbiological diagnostics.