Biofilm Formation by Bacteria Isolated from Intravenous Catheters

Background: Reports on the association of nosocomial bacterial infections with indwelling medical devices such as intravenous catheters (IVC) has increased in recent years. The potential to form biofilm on these devices seems to be the main reason for establishment of such infections. The aim of this study was to measure the potential of biofilm formation by bacterial isolates from IVCs. Methods: Seventy-one IVCs were collected from hospitalized patients in ICU, NICU, hematology and oncology wards at Taleghani Hospital from Jan 2010 to Jan 2011. The bacterial isolates were identified using the standard biochemical tests and the potential to form biofilms was determined by the microtiter plate assay method (MTP) and colony morphology using Congo red agar plates (CRA). Results: Overall, 54 (71%) IVCs were colonized and 76 bacteria were isolated among which, 64 (84.2%) were coagulase negative staphylococci (CoNS), 3 (3.9%) S. aureus, 3 (3.9%) Enterococcus spp., 2 (2.6%) E. coli and 4 (5.3%) were miscellaneous isolates not further identified. Among the CoNS, biofilm formation was observed in 68.7% and 82.8% of bacteria using MTP and CRA methods, respectively. S. aureus and E. coli isolates also were biofilm producers but Enterococcus and other unknown isolates were biofilm negative. Conclusions: Our results confirm that the prevalent biofilm forming bacteria on IVCs were CoNS and that was the reason for high rates of nosocomial infections.