Open AccessIn vitro efficacy of various antibiotic combinations against Pseudomonas aeruginosa isolates
Author(s) -
Ebru Nazli,
Yasemin Zer,
Fahriye Ekşi
Publication year - 2014
Publication title -
journal of international medical research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.421
H-Index - 57
eISSN - 1473-2300
pISSN - 0300-0605
DOI - 10.1177/0300060514553490
Subject(s) - amikacin , colistin , ceftazidime , pseudomonas aeruginosa , microbiology and biotechnology , imipenem , levofloxacin , antibiotics , minimum inhibitory concentration , medicine , ciprofloxacin , biology , bacteria , antibiotic resistance , genetics
Objective Pseudomonas aeruginosa is one of the leading causes of nosocomial infection. The present study tested the in vitro efficacy of ceftazidime or imipenem combined with amikacin, levofloxacin and colistin in P.aeruginosa isolates.Methods P.aeruginosa strains, isolated from clinical samples, were assessed for antibiotic susceptibility using the disc diffusion method. Antibiotic combination tests were performed using minimum inhibitory concentration (MIC) test strips and the sum of the Fractional Inhibitory Concentration (ΣFIC) index was used to assess synergy.Results Out of 60 isolated P.aeruginosa strains, 100% were susceptible to colistin and 26.7% (16 strains) were multidrug resistant. MIC50 and MIC90 values were 2 and 32 µg/ml for imipenem; 1.5 and 24 µg/ml for ceftazidime; 3 and 8 µg/ml for amikacin; 0.38 and 32 µg/ml for levofloxacin; 1 and 1.5 µg/ml for colistin, respectively. Antagonism was not found in any of the antibiotic combinations tested. The amikacin–ceftazidime combination was found to have a synergistic effect in 15% of the strains, but no synergistic effect was detected for other combinations.Conclusions In Pseudomonas infection, alternative treatment options using different antibiotic combinations should be tested in vitro and findings should be confirmed by clinical studies.