In vitro antibiotic synergy in extensively drug-resistant Acinetobacter baumannii: the effect of testing by time-kill, checkerboard, and Etest methods.
This study examined the in vitro effects of polymyxin B, tigecycline, and rifampin combinations on 16 isolates of extensively drug-resistant Acinetobacter baumannii, including four polymyxin-resistant strains. In vitro synergy was demonstrated in 19 (40%) of a possible 48 isolate-antibiotic combinations by time-kill methods, 8 (17%) by checkerboard methods, and only 1 (2%) by Etest methods. There was only slight agreement between Etest and checkerboard methods and no agreement between results obtained by other methods.
Division of Laboratory Medicine, Changi General Hospital, Singapore, Singapore. thean_yen_tan@cgh.com.sg
Thean Yen
TY
Tan
Tze Peng
TP
Lim
Winnie Hui Ling
WH
Lee
Suranthran
S
Sasikala
Li Yang
LY
Hsu
Andrea Lay-Hoon
AL
Kwa
D040981:Acinetobacter baumannii / Q000187:drug effects*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial; D004357:Drug Synergism; D008826:Microbial Sensitivity Tests; D008911:Minocycline / Q000031:analogs & derivatives / Q000494:pharmacology; D011112:Polymyxin B / Q000494:pharmacology; D012293:Rifampin / Q000494:pharmacology; D000078304:Tigecycline
D000900:Anti-Bacterial Agents; D000078304:Tigecycline; D008911:Minocycline; D011112:Polymyxin B; D012293:Rifampin