Disk diffusion susceptibility testing for LY163892 (KT-3777), a new orally administered 1-carbacephem.
LY163892, a new orally administered 1-carbacephem, was found to have a spectrum of antimicrobial activity very similar to that of cefaclor. Diffusion tests with 30-micrograms LY163892 disks produced acceptable interpretive error rates with greater than or equal to 22 mm as the susceptibility zone diameter. This was required to reduce potential false-susceptibility results, particularly among Enterobacter spp. and Providencia stuartii: both species included strains that produce beta-lactamases capable of hydrolyzing Ly163892. Preliminary recommendations for LY163892 disk tests are presented, but the continued use of the 30-micrograms cephalothin "class representative" disk might be the best procedure to minimize LY163892 interpretive errors for clinical trials. A separate LY163892 disk for testing Haemophilus influenzae strains should be seriously considered.
Jones
R N
RN
Clinical Microbiology Institute, Tualatin, Oregon 97062.
Barry
A L
AL
D001419:Bacteria / Q000187:drug effects*; D002433:Cefaclor / Q000494:pharmacology; D002506:Cephalexin / Q000494:pharmacology; D002511:Cephalosporins / Q000494:pharmacology*; D004754:Enterobacter / Q000187:drug effects; D006193:Haemophilus influenzae / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D011237:Predictive Value of Tests; D011532:Providencia / Q000187:drug effects
D002511:Cephalosporins; C054920:loracarbef; D002433:Cefaclor; D002506:Cephalexin