Concomitant detection of biofilm and metallo-beta-lactamases production in gram-negative bacilli

Abstract

Carbapenems are mainstay of treating serious multidrug resistant gram-negative biofilm-based infections. However, recent emergence of metallo-beta-lactamases (MbL) producing gram-negative bacilli in different parts of world may be related to gain of virulence factors associated with biofilm production. To explore the association of MbL and biofilm production in various gram-negative bacilli. In this study, 110 non-repetitive ceftazidime resistant gram-negative bacilli were evaluated for biofilm and MβL production. Biofilm forming ability of isolates obtained from various specimens was tested by the tube method. Disks of ceftazidime (30 μg) and ceftazidime with ethylenediaminetetraacetic acid (30 μg + 750 μg, prepared in house) for MβL detection were used. Chi-square test was used to study the association between biofilm and MβL production. P value <0.05 was considered significant. 88 (80%) bacilli had shown biofilm producing ability. The association of biofilm and MβL was significant in cases of non-fermenters as compared to enterobacteriaceae members. The particular combination of virulence factors (biofilm and MβL) in bacteria may be a species specific effect which needs to be investigated at molecular level in detail. This may help in designing newer therapies based on interference with biofilm formation and thus countering clinical episodes of antibiotic resistance.