Biofilm Formation in Clinical Isolates of S. aureus is Associated with Presence of Device and Dissemination of Infection

Abstract

Introduction: Biofilms are complex microbial communities attached to abiotic or biotic surfaces. These communities produce their own extracellular matrix, where they interact with one another and with the environment. Aim: To observe the biofilm formation isolates of Staphylococcus aureus from South Brazil. Materials and Methods: A total of 126 consecutive S. aureus isolates were collected, causing a variety of infections at a tertiary hospital from 2011 to 2014. We investigated biofilmforming ability by using a microtiter plate assay (crystal violet method) and compared the clinical characteristics and outcomes of infected patients with biofilm-forming ability. The following clinical characteristics were evaluated: presence of polymicrobial infection; presence of another micro-organism (in another clinical material at the same time); recurrence of infection; presence of device and site of infection. Results: Biofilm forming bacteria were categorized as high producers (n=46, 36.5%), moderate producers (n=59, 46.8%) and weak producers or non-producers (n=21, 16.7%). The presence of another microorganism isolated in the same day in another clinical specimen was significantly associated with biofilm-formation (p<0.006) as well the presence of invasive devices (p<0.02). Conclusion: This study allows planning medical conducts, e.g., the choice of appropriate antimicrobials, in patients with devices such as catheters and patients with infections at different sites to adequately adjust treatment of infections by biofilm-forming bacteria.

Keywords

• bacterial dissemination
• biofilm production
• hospital infection
• medical device