Ciprofloxacin, imipenem and rifampicin: in-vitro synergy of two and three drug combinations against Pseudomonas cepacia.

The in-vitro activity of ciprofloxacin, imipenem and rifampicin, singly, and in two and three drug combinations was evaluated against 16 isolates of Pseudomonas cepacia. All 16 isolates were resistant to rifampicin; nine isolates were susceptible to ciprofloxacin; six were susceptible and seven had intermediate susceptibility to imipenem. The imipenem and rifampicin combination was synergistic for one of 16, imipenem and ciprofloxacin synergistic for seven of 16 and the three antibiotic combination was synergistic for 12 of 16 isolates. The three antibiotic combination demonstrated synergism with two isolates which were resistant to all three drugs. Combinations of two and three antibiotics resulted in enhanced killing of P. cepacia in this in-vitro study.