Antimicrobial resistance pattern of biofilm forming Pseudomonas aeruginosa isolated from patients with nasogastric and endotracheal tubes

Abstract

Biofilms are communities of microorganisms attached to a surface. It has become clear that biofilm-grown cells express properties distinct from planktonic cells, one of which is an increased resistance to antimicrobial agents. A total of 79 non replicate gram negative bioadherent isolates from 113 patients in intensive care units with nasogastric and endotracheal tubes were collected, identified, then tested for their abilities to form biofilm using tube method, tissue culture plate method and genetically. Antimicrobial susceptibility testing and time-kill assay were done to figure out the role of biofilm formation in antimicrobial resistance. Gram negative isolates were Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Enterobacter cloacae and Citrobacter koseri. The microorganisms were classified into three groups (strongly adherent, moderately adherent and non adherent) according to the biofilm formation that was obtained by optical density (O.D.) values. The antibacterial susceptibility testing revealed that more than 70% of the bioadherent isolates were multi-drug resistant (MDR) with resistance to more than 4 antimicrobials. So it has been observed that the resistance of bacteria in biofilms to antibiotics is increased compared with what is normally seen with planktonic cells.