Association between Biofilm Formation and Antimicrobial Resistance in Carbapenem-Resistant Pseudomonas Aeruginosa.

Recently, carbapenem resistance in P. aeruginosa is an increasingly important problem globally. Biofilm formation is a well-known pathogenic mechanism of P. aeruginosa, and the gene, pslA, plays an important role in its primary stages. We studied the association between biofilm formation and pslA in carbapenem-resistant P. aeruginosa isolates, along with antimicrobial resistance and the prevalence of metallo-β-lactamase (MBL) genes, based on the presence of pslA 82 carbapenem-resistant P. aeruginosa isolates were collected from a tertiary hospital in Daejeon, Korea, between March 2008 and June 2014. Minimum inhibitory concentrations (MICs) of nine antimicrobial agents were determined using the agar dilution method. Biofilm formation was measured by microtiter plate assay. PCR and sequencing were used to identify pslA and the MBL gene. 76 (92.7%) carbapenem-resistant isolates were biofilm producers. These biofilm producers showed higher levels of amikacin, ceftazidime, and cefepime resistance than non-producers. pslA was detected in 71 (93.4%) biofilm-producing isolates and these results were statically significant (p<0.01). 11 isolates carrying pslA and blaIMP-6 were extremely resistant to all antimicrobials tested. In this study, biofilm formation was significantly associated with pslA Furthermore, the coexistence of pslA and the MBL gene in carbapenem-resistant isolates likely contributed to the increase in antimicrobial resistance.