Concomitant Detection of Biofilm Formation and MBL Production in Meropenem Resistant Isolates of Pseudomonas Aeruginosa

The purpose of this study was to detect biofilm formation and to examine the correlation between
biofilm and Metallo-β-lactamases (MBL) production in Pseudomonas aeruginosa. A total of 64
P. aeruginosa isolates were identified using standard microbiological methods and antimicrobial
susceptibility testing (AST) was performed on them according to Clinical and Laboratory Standards
Institute (CLSI) guidelines. The isolates were screened for biofilm production using both qualitative
and quantitative methods. The presence of MBL genes were checked by multiplex PCR assay. Out of
all 30 meropenem resistant P. aeruginosa, 2 isolates were found producing all the three genes (i.e.
blaIMP, blaVIM, blaSIM) for MBL production and they were found to produce biofilm. Resistant to four
antibiotics such as aztreonam (85.7% vs 11.1%, P< 0.000), Cefepime (82.1% vs 2.8%, P<0.000)
gentamycin (82.1% vs 27.8%, P< 0.000) and Pipercillin/Tazobactum was also high (28.6% vs 2.8%
P< 0.003) was comparatively higher among biofilm producers than non biofilm producers. In biofilm
production, both qualitative method and quantitative plate method showed 16 isolates (53.3%) as
biofilm producers for MBL genes. Out of these 16, only 9 isolates showed MBL production along with
biofilm production having significant association (P<0.004).
The prevalence of MBLs has been increasing worldwide, particularly among P. aeruginosa, leading to
severe limitations in the therapeutic options for the management. Presence of MBL genes has a role
in inducing biofilm production and significant association in P. aeruginosa isolates. Overall, drug
resistance was found to be more in biofilm producing isolates than non biofilm isolates.