Detection of Biofilm Formation in Pseudomonas aeruginosa Isolates from Clinical Specimens

The ability of a microorganism to develop biofilm is considered as a marker of clinically relevant infection. Infections caused by P. aeruginosa are difficult to treat as the majority of isolates exhibit high level of innate resistance to many antibiotics and tendency to form biofilms. The study was undertaken to investigate biofilm-forming capabilities of P. aeruginosa isolated from clinical specimens by two main different methods tissue culture plate (TCP) method, and congo red agar (CRA) method. Further, to investigate the antimicrobial resistance profile among biofilm producing isolates. A total of 300 specimens were collected from patients. Ninety six isolates of P. aeruginosa were obtained from various clinical samples. We applied Vitek-2 automated system as a panel of antimicrobial agents. TCP method and CRA method assay was chosen to detect the biofilm formation. Out of the 96 isolates, the results by TCP method and CRA method were 84(87.5%) and 76(79.1%) isolates respectively. TCP method was the most sensitive method for detection of biofilm production. TCP method detected 78 as strong, 6 as moderate and 12 as weak or non- biofilm producers. By CRA method, 65,11and 20 of isolates were strong, moderate and weak or non-biofilm producers, respectively. The antibiotic resistance pattern of P. aeruginosa was found higher in biofilm producers than in biofilm non-producers.TCP method was considered as the gold standard and reliable method for detection of biofilm formation. We conclude that there has been a positive association between drug resistance and biofilm formation of P. aeruginosa.