Drug Resistance in Biofilm and Planktonic Cells of spp., spp., and Clinical Isolates.

Biofilm production in nonfermenting Gram-negative bacteria influences drug resistance. The aim of this work was to evaluate the effect of different antibiotics on biofilm eradication of clinical isolates of , , and . Clinical isolates were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry in a third-level hospital in Monterrey, Mexico. Crystal violet staining was used to determine biofilm production. Drug susceptibility testing was determined by broth microdilution in planktonic cells and biofilm cells. Resistance in planktonic cells was moderate to trimethoprim-sulfamethoxazole, and low to chloramphenicol, minocycline, levofloxacin ( and ), ceftazidime, and meropenem ( and ). Biofilm eradication required higher drug concentrations of ceftazidime, chloramphenicol, levofloxacin, and trimethoprim-sulfamethoxazole than planktonic cells ( < 0.05). Levofloxacin showed biofilm eradication activity in minocycline and meropenem in , and meropenem in . Drug resistance increased due to biofilm production for some antibiotics, particularly ceftazidime and trimethoprim-sulfamethoxazole for all three pathogens, chloramphenicol for and and levofloxacin for Some antibiotics could be used for the treatment of biofilm-associated infections in our population, such as levofloxacin for minocycline and meropenem for , and meropenem for .