Evaluation of netilmicin susceptibility discs using bacteria with known aminoglycoside resistance patterns: correlation of in vitro and in vivo test results.
Data obtained with 30 micrograms netilmicin discs on Mueller-Hinton agar have been compared to MIC values obtained in Mueller-Hinton broth. Regression analysis was used to determine susceptibility cutoff points for Pseudomonas and non-Pseudomonas gram-negatives. The utility of these cutoff points for the determination of netilmicin sensitivity was evaluated in tests with 1405 clinical isolates. These tests employed 897 sensitive isolates and 508 strains with known aminoglycoside resistance patterns. Netilmicin was shown to be active against sensitive isolates and those strains with resistance patterns corresponding to the presence of: ANT(2"), ANT(2")+AAC(6'), ANT(4'), APH(2")+AAC(6'), APH(3')-IV and AAC(3)-I modifying enzymes. PD50 values obtained in experimental mouse infection studies with gentamicin, tobramycin and amikacin as well as netilmicin confirmed the excellent activity of netilmicin against strains with the above-mentioned resistance patterns. The good correlation between disc sensitivity test results and MIC and PD50 values suggest that a 30 micrograms netilmicin disc can be used to predict the netilmicin susceptibility of clinical isolates.
D000617:Aminoglycosides / Q000494:pharmacology; D000818:Animals; D004352:Drug Resistance, Microbial; D004755:Enterobacteriaceae / Q000187:drug effects*; D004756:Enterobacteriaceae Infections / Q000188:drug therapy; D005839:Gentamicins / Q000494:pharmacology*; D051379:Mice; D008826:Microbial Sensitivity Tests; D009428:Netilmicin / Q000494:pharmacology*; D011549:Pseudomonas / Q000187:drug effects*; D011552:Pseudomonas Infections / Q000188:drug therapy
D000617:Aminoglycosides; D005839:Gentamicins; D009428:Netilmicin