Lack of cross-resistance between efrotomycin and antibacterial agents used in the therapy of human and animal infections.
Efrotomycin is an N-methylhydroxypyridone glycoside antibiotic with activity primarily against Gram-positive bacteria. It is intended for use as a feed additive for swine. Although efrotomycin is unrelated to any antibacterial drug used in human or veterinary medicine, the possibility of cross-resistance with other antibacterials is of concern. The minimum inhibitory concentrations (MICs) of efrotomycin were determined for a broad panel of bacterial isolates. In addition, the susceptibility of each isolate to 12-15 antibacterials was determined using a standardized disk susceptibility test. No evidence of cross-resistance between efrotomycin and any of the 12-15 antibacterial compounds was observed. When the MIC of efrotomycin for nine selected isolates was increased from 16- to greater than 100-fold by serial passage in subinhibitory concentrations of efrotomycin, no increased resistance to the 15 antibacterials was noted. Subinhibitory concentrations of efrotomycin had no effect on the conjugative transfer of antibacterial-resistance plasmids between K-12 strains of Escherichia coli. The data from this study suggest that if resistance to efrotomycin should occur, it is unlikely to result in the appearance of multiply-resistant bacterial populations.
Jacks
T M
TM
Animal Drug Evaluation, Merck Institute for Therapeutic Research, Rahway, NJ 07065-0900.
Frazier
E G
EG
Abruzzo
G K
GK
Graham
A C
AC
Fromtling
R A
RA
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001424:Bacterial Infections / Q000188:drug therapy* / Q000382:microbiology; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics; D006801:Humans; D008826:Microbial Sensitivity Tests; D010957:Plasmids; D011728:Pyridones / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D011728:Pyridones; C012954:efrotomycin