In-vitro activity of Antimicrobial Agents Combination against carbapenem nonsusceptible Pseudomonas aeruginosa

BACKGROUND AND OBJECTIVESCurrent study was aimed to explore in-vitro antimicrobial combinations effects against planktonic and biofilm forms of carbapenem-resistant Pseudomonas aeruginosa (CRPA).MATERIALS AND METHODSTwenty-four CRPA were isolated from different clinical specimens. The resistance to carbapenem were determined by the disk diffusion assay and PCR. The antimicrobial effect of antimicrobial agents was determined by the broth micro dilution according to the CLSI guideline. To study the inhibitory against the biofilm, the minimum biofilm inhibitory concentration (MBIC) was determined. The synergetic effects of the drugs combinations, the checkerboard assay was used for fractional inhibitory concentration (FIC) determination.RESULTS AND DISCUSSIONThe highest synergic interaction was observed in colistin/fosfomycin and gentamicin/fosfomycin (۱۸ of ۲۴ isolates), and the lowest synergic interaction was observed in gentamicin/imipenem and colistin/gentamicin (۵ of ۲۴ isolates). Colistin/fosfomycin, imipenem/fosfomycin, colistin/imipenem, gentamicin/fosfomycin, and gentamicin/imipenem were shown synergic effect for ۸, ۴, ۴, ۳ and ۳ isolates, respectively.CONCLUSIONThe combination of antimicrobial agents had unlike activity on the biofilm and planktonic forms of CRPA. Thus, a distinct testing of inhibitory activity of the antimicrobial agent’s combination is required. Fosfomycin/colistin and fosfomycin/gentamicin were more effective against planktonic form and fosfomycin/colistin against biofilm forms.

کلیدواژه ها:

Biofilm ، Antimicrobial Combination ، Carbapenem-resistant ، Pseudomonas aeruginosa ، wound