Comparative in vitro antimicrobial susceptibilities of nosocomial isolates of Acinetobacter baumannii and synergistic activities of nine antimicrobial combinations
- 1 May 1997
- journal article
- research article
- Published by American Society for Microbiology in Antimicrobial Agents and Chemotherapy
- Vol. 41 (5) , 881-885
- https://doi.org/10.1128/aac.41.5.881
Abstract
The in vitro susceptibilities of 69 nosocomial Acinetobacter isolates were determined by the broth microdilution method. Fourteen (20%) isolates were resistant to at least two aminoglycosides and two extended-spectrum penicillins. Nine antimicrobial combinations were then tested for synergy against these 14 isolates by checkerboard titration: imipenem with ciprofloxacin, amikacin, and tobramycin and ampicillin-sulbactam, piperacillin-tazobactam, and ticarcillin-clavulanate with amikacin and tobramycin. Synergy was detected with one or more antimicrobial combinations against 9 of 14 (64%) isolates, partial synergy was detected with one or more combinations against all 14 isolates, and an additive effect alone was observed with two different combinations against two isolates. No antagonism was detected with any combination. Imipenem plus either amikacin or tobramycin resulted in a synergistic or partial synergistic response against all 14 isolates. Specific combinations showing synergy against A. baumannii isolates were imipenem with tobramycin (four isolates), imipenem with amikacin (three isolates), ampicillin-sulbactam with tobramycin (six isolates), ampicillin-sulbactam with amikacin (three isolates), and ticarcillin-clavulanate with tobramycin (one isolate). Genotyping by randomly amplified polymorphic DNA analysis showed that 9 of the 14 isolates were of one strain, 4 isolates were of a second strain, and the remaining isolate was of a different strain. Eight of 14 (57%) patients infected with resistant A. baumannii isolates died. Only 3 of 14 patients had received a therapeutic regimen which was tested for synergy. Clinical studies are needed to determine the significance of these findings.Keywords
This publication has 23 references indexed in Scilit:
- In vitro activites of antimicrobial agents, alone and in combination, against Acinetobacter baumannii isolated from bloodDiagnostic Microbiology and Infectious Disease, 1995
- Bacteremia with Acinetobacter Species: Risk Factors and Prognosis in Different Clinical SettingsClinical Infectious Diseases, 1994
- Effect of Sulbactam on Infections Caused by Imipenem-ResistantAcinetobacter calcoaceticusBiotypeanitratusThe Journal of Infectious Diseases, 1993
- Use of Cefotaxime for Treatment of Acinetobacter InfectionsClinical Infectious Diseases, 1992
- A study of the relationships between antibiotic resistance phenotypes, phage-typing and biotyping of 117 clinical isolates of Acinetobacter spp.Journal of Hospital Infection, 1990
- Enzymatic resistance to β-lactams and aminoglycosides in Acinetobacter calcoaceticusJournal of Antimicrobial Chemotherapy, 1987
- Epidemiology of nosocomial infections due to Acinetobacter calcoaceticusJournal of Hospital Infection, 1987
- Plasmid Transfer and Behaviour in Acinetobacter calcoaceticus EBF65/65Microbiology, 1985
- Pharmacokinetics of Imipenem and Cilastatin in VolunteersClinical Infectious Diseases, 1985
- Significance of antimicrobial synergism for the outcome of gram negative sepsisThe Lancet Healthy Longevity, 1977