In-vitro Effect of Meropenem, Colistin, and Amikacin Combination against Carbapenem-resistant and Biofilm-forming Klebsiella pneumoniae

BACKGROUND AND OBJECTIVESThe present study was aimed to investigate in-vitro inhibitory effects of meropenem, colistin, and amikacin alone and the various combinations against carbapenem-resistant and biofilm-forming Klebsiella pneumoniae.MATERIALS AND METHODSTen carbapenem-resistant and biofilm-forming K. pneumoniae isolates were isolated from clinical specimens. The resistance to carbapenem were determined by determination of meropenem minimum inhibitory concentration (MIC) by the agar dilution methods according to the Clinical & Laboratory Standards Institute (CLSI) guideline. To study any inhibitory effect of antimicrobial agents on biofilm, the minimum biofilm inhibitory concentration (MBIC) was determined. The synergetic effect of the antibiotics combinations was studied using the checkerboard assay and the fractional inhibitory concentration (FIC).RESULTS AND DISCUSSIONThe highest synergic effect against planktonic form was observed in meropenem/amikacin (۸ of ۱۰ isolates), and the lowest synergic effect was found in amikacin/colistin (۲ of ۱۰ isolates). Colistin/meropenem were shown synergic effect for ۵ isolates. The highest synergic effect against biofilm was observed in colistin/meropenem (۷ of ۱۰ isolates) followed by meropenem/amikacin (۳ of ۱۰ isolates) and colistin/amikacin (۲ of ۱۰ isolates).CONCLUSIONThe combination of antimicrobial agents had shown the different effects on biofilm and planktonic forms of K. pneumoniae. Therefore, a separate determination of inhibitory effects of the antibiotic in the combination is necessary for biofilm forms. amikacin/meropenem was more effective against planktonic and colistin/meropenem against biofilm forms of K. pneumoniae.

کلیدواژه ها:

Carbapenem ، Biofilm ، K. pneumoniae ، Synergic effect