title: In vitro effects of sulbactam combinations with different antibiotic groups against clinical Acinetobacter baumannii isolates.
abstract: Treatment of multidrug resistant (MDR) Acinetobacter baumannii infections causes some problems as a result of possessing various antibacterial resistance mechanisms against available antibiotics. Combination of antibiotics, acting by different mechanisms, is used for the treatment of MDR bacterial infections. It is an important factor to determine synergy or antagonism between agents in the combination for the constitution of effective therapy. The study aimed to determine In vitro interactions interpreted according to calculated fractional inhibitory concentration (FIC) index between sulbactam and ceftazidime, ceftriaxone, cefepime, ciprofloxacin, gentamicin, meropenem, tigecycline, and colistin. Ten clinical isolates of A. baumannii were tested for determination of synergistic effects of sulbactam with different antimicrobial combinations. Minimal inhibitory concentration (MIC) values of both sulbactam and combined antibiotics decreased 2- to 128-fold. Synergy and partial synergy were determined in combination of sulbactam with ceftazidime and gentamicin (FIC index: ≤ 0.5 or >0.5 to <1) and MIC values of both ceftazidime and gentamicin for five isolates fell down below the susceptibility break point. Similarly, MIC value of ciprofloxacin for six ciprofloxacin resistant isolates was determined as below the susceptibility break point in combination. However, all isolates were susceptible to colistin and tigecycline, MIC values of both were decreased in combination with sulbactam. Although synergistic and partial synergistic effects were observed in the combination of sulbactam and ceftriaxone, all isolates remained resistant to ceftriaxone. The effect of cefepime-sulbactam combination was synergy in five, partial synergy in one and indifferent in four isolates. Meropenem and sulbactam showed a partial synergistic effect (FIC index: >0.5 to <1) in three, an additive effect (FIC index: 1) in one and an indifferent effect (FIC index: >1-2) in six isolates. Antagonism was not determined in any combination for clinical A. baumannii isolates in the study. In conclusion, sulbactam is a good candidate for combination treatment regimes for MDR A. baumannii infections.
authors.affiliation: Department of Infectious Diseases and Clinical Microbiology, Faculty of Medicine, Ondokuz Mayis University, Samsun, Turkey. adeveci2001@yahoo.com
authors.forename: Aydin
authors.initials: A
authors.lastname: Deveci
authors.forename: Ahmet Yilmaz
authors.initials: AY
authors.lastname: Coban
authors.forename: Ozlem
authors.initials: O
authors.lastname: Acicbe
authors.forename: Esra
authors.initials: E
authors.lastname: Tanyel
authors.forename: Gorkem
authors.initials: G
authors.lastname: Yaman
authors.forename: Belma
authors.initials: B
authors.lastname: Durupinar
mesh_terms: D040981:Acinetobacter baumannii / Q000187:drug effects*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002511:Cephalosporins / Q000494:pharmacology; D003091:Colistin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004336:Drug Antagonism; D004338:Drug Combinations; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects*; D004357:Drug Synergism; D005839:Gentamicins / Q000494:pharmacology; D000077731:Meropenem; D008826:Microbial Sensitivity Tests; D008911:Minocycline / Q000031:analogs & derivatives / Q000494:pharmacology; D013407:Sulbactam / Q000494:pharmacology*; D013845:Thienamycins / Q000494:pharmacology; D000078304:Tigecycline
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D004338:Drug Combinations; D005839:Gentamicins; D013845:Thienamycins; D000078304:Tigecycline; D000077731:Meropenem; D008911:Minocycline; D013407:Sulbactam; D003091:Colistin