Antibiotic resistance among clinical isolates of Acinetobacter in the UK, and in vitro evaluation of tigecycline (GAR-936).
A survey was conducted of the antimicrobial susceptibilities of 595 Acinetobacter spp. isolated from routine clinical specimens in 54 sentinel laboratories throughout the UK during 2000. Isolates of the Acinetobacter baumannii complex (genomic groups 2, 3 and 13TU; n = 443) were distinguished from other genomic groups (n = 152) by PCR fingerprinting of tDNA spacer regions. MICs of amikacin, cefotaxime, ceftazidime, ciprofloxacin, colistin, gentamicin, imipenem, meropenem, minocycline, piperacillin, piperacillin/tazobactam, rifampicin, sulbactam and tetracycline were determined on IsoSensitest agar and interpreted, wherever possible, using BSAC breakpoints. Tigecycline (GAR-936), a new glycylcycline, was also tested. Resistance to cephalosporins, aminoglycosides and ciprofloxacin was widespread, but carbapenems, colistin, sulbactam, minocycline and tigecycline were each active against >80% of the isolates. Isolates of A. baumannii were more often resistant to cefotaxime, ceftazidime, piperacillin, piperacillin/tazobactam, ciprofloxacin, gentamicin and tetracyclines than those belonging to other genomic groups, but were less often resistant to colistin; no significant differences between genomic groups were noted in the susceptibilities to amikacin, carbapenems, rifampicin or sulbactam. The relative activities of the tetracyclines were minocycline > tigecycline > tetracycline. Thirteen carbapenem-resistant isolates (MICs > or =8 mg/L; 2.2%) were received from six centres; four centres sent single isolates; one sent three and one sent six. An allele of bla(IMP) was detected in one of these isolates, but the other 12 isolates either had carbapenemase-independent resistance, or undetectable carbapenemase activity combined with other resistance mechanisms. In conclusion, carbapenems, colistin and minocycline retained greatest activity against the Acinetobacter isolates collected. Tigecycline was less active than minocycline, but both agents overcame most tetracycline resistance.
Henwood
Caroline J
CJ
Antibiotic Resistance Monitoring and Reference Laboratory, Central Public Health Laboratory, 61 Colindale Avenue, London NW9 5HT, UK.
Gatward
Tess
T
Warner
Marina
M
James
Dorothy
D
Stockdale
Mark W
MW
Spence
Richard P
RP
Towner
Kevin J
KJ
Livermore
David M
DM
Woodford
Neil
N
D000150:Acinetobacter / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D000151:Acinetobacter Infections / Q000382:microbiology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015780:Carbapenems / Q000494:pharmacology; D024881:Drug Resistance, Bacterial / Q000235:genetics; D016680:Genome, Bacterial; D006801:Humans; D008826:Microbial Sensitivity Tests; D008911:Minocycline / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000078304:Tigecycline; D006113:United Kingdom
D000900:Anti-Bacterial Agents; D015780:Carbapenems; D000078304:Tigecycline; D008911:Minocycline