Induction potency of various beta-lactam derivatives in gram-negative rods.
The induction potency of various beta-lactams as well as that of 'nonspecific' inducers such as the media employed or body fluids were studied in gram-negative clinical isolates and in their resistant corresponding counterparts. In all wild-type isolates quite a few beta-lactams (mainly cefoxitin and imipenem) shared the ability to induce the chromosomal beta-lactamase, whereas all beta-lactams - including 6-APS and 7-CPS clavulanic acid, and sulbactam (both beta-lactamase inhibitors), exhibited strong induction potency in their corresponding resistant counterparts. Moreover, all resistant counterparts exhibited the phenomenon of 'nonspecific' induction, whereas the wild-type strains did not. Interestingly, in both Proteus vulgaris 4917 W and Providencia rettgeri 862 W wild-type strains most beta-lactam compounds were potent inducers, thus providing an explanation for resistance against beta-lactamase-unstable compounds. The addition of subinhibitory concentrations of the quinolone compound enoxacin or chloramphenicol did not influence the phenotypic beta-lactamase expression, neither in wild-type strains nor in their resistant counterparts, whereas the addition of clindamycin or gentamicin resulted in a marked decrease of enzyme production in cephalosporinase overproducers, the P. vulgaris and the P. rettgeri isolates.
Cullmann
W
W
Department of Medical Microbiology and Immunology, Ruhr University, Bochum, FRG.
Dick
W
W
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004790:Enzyme Induction; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000201:enzymology; D007202:Indicators and Reagents; D008826:Microbial Sensitivity Tests; D001618:beta-Lactamases / Q000096:biosynthesis / Q000378:metabolism; D047090:beta-Lactams
D000900:Anti-Bacterial Agents; D007202:Indicators and Reagents; D047090:beta-Lactams; D001618:beta-Lactamases