Activities of various beta-lactams and beta-lactam/beta-lactamase inhibitor combinations against Acinetobacter baumannii and Acinetobacter DNA group 3 strains.
Acinetobacter baumannii and Acinetobacter DNA group 3 are members of the so-called A. calcoaceticus-A. baumannii complex and are important nosocomial pathogens. Multiresistance in these organisms is increasingly frequent, and alternative treatment options are needed. The beta-lactamase inhibitors clavulanate, sulbactam and tazobactam have intrinsic activity against Acinetobacter strains. In the present study, broth microdilution was used to assess the in-vitro activities of currently available beta-lactam/beta-lactamase inhibitor combinations and sulbactam alone against 469 Acinetobacter isolates (A. baumannii, n=395; Acinetobacter DNA group 3, n=74) collected from various laboratories in Germany. Fixed concentrations and fixed ratios of beta-lactamase inhibitors were used. Sulbactam-containing combinations (susceptibility rates of 90.4-92.7% for A. baumannii and 97.3-100% for Acinetobacter DNA group 3) and sulbactam alone were superior to clavulanate- and tazobactam-containing combinations. The activity of sulbactam-containing combinations against members of the A. calcoaceticus-A. baumannii complex was conferred exclusively by the intrinsic activity of the beta-lactamase inhibitor and did not result from enhanced beta-lactam activity. Testing with the inhibitor added at a fixed ratio of inhibitor to beta-lactam appeared to give more reliable results than testing at a fixed concentration of the inhibitor. Resistance to carbapenems (0.3%) remains low in Germany.
Brauers
J
J
Antiinfectives Intelligence GmbH, Bonn, Germany.
Frank
U
U
Kresken
M
M
Rodloff
A C
AC
Seifert
H
H
D000150:Acinetobacter / Q000145:classification / Q000187:drug effects*; D040981:Acinetobacter baumannii / Q000187:drug effects*; D016954:Acinetobacter calcoaceticus / Q000187:drug effects; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D004359:Drug Therapy, Combination; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D013407:Sulbactam / Q000494:pharmacology; D065093:beta-Lactamase Inhibitors; D047090:beta-Lactams / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D004791:Enzyme Inhibitors; D065093:beta-Lactamase Inhibitors; D047090:beta-Lactams; D013407:Sulbactam