Naslov
Comparison of five different methods for detection of SHV extended-spectrum beta-lactamases

Autori
Bedenić, Branka ; Randegger, Corine ; Boras, Arijana ; Haechler, Herbert

Izvornik
Journal of Chemotherapy (1120-009X) 13 (2001), 1; 24-33

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
extended-spectrum beta-lactamases; double-disk-synergy test; SHV ESBLs; inhibitor-potentiated disk diffusion test; three dimensional test;
(extended-spectrum beta-lactamases; double-disk syergy test; inhibitor-potentiated disk-diffusion test; three-dimensional test)

Sažetak
Five different methods for detection of different types of SHV extended-spectrum b-lactamases (ESBL) were compared: MIC determination of b-lactam with and without clavulanic acid, double-disk synergy test (DDST), inhibitor potentiated disk diffusion test (IPDDT), three-dimensional test (TDT) and PCR/Nhe I test. MIC determination of b-lactam with and without clavulanic acid was the most sensitive method regardless of the type of b-lactamase. However the specificity of this method was a little above 90%. Inhibitor potentiated disk diffusion test turned out to be a very sensitive method too but it lacks specificity because 26.9% of ceftazidime sensitive strains (putative ESBL negative), gave a positive result. It is important to put all four disks on the plate because ceftazidime and aztreonam were more sensitive indicators for SHV-5 and SHV-12 b-lactamase producers while cefotaxime and ceftriaxone were more reliable in detecting SHV-2 b-lactamase producers. Double disk synergy test detected all SHV-5 and SHV-12 b-lactamase producers and 95.2 % of SHV-2, so it was less sensitive than MIC determination but it was highly specific, since there were no false negative results observed. The sensitivity of DDST can be improved by using all four disks and placing them at the smaller distance from the central disc (2.5 cm). Three-dimensional test was the least sensitive method particularly for SHV-5 and SHV-12 b-lactamase producers. PCR/Nhe I test for detection of ESBL blaSHV genes is highly sensitive and specific method but it is rather laborious and thus not very practical for use in routine clinical laboratories. Nevertheless it has a potential to serve as a gold standard in epidemiological investigations on ESBLs. According to the results of this investigation MIC determination of b-lactam with and without clavulanic acid, even if only one antibiotic is used and PCR/Nhe I tests are the most reliable methods for detection of SHV ESBLs.

Izvorni jezik
Engleski

Znanstvena područja
Temeljne medicinske znanosti

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