927. Biofilm Formation by Clinical Strains Isolated from Patients in a Military Treatment Facility
Session: Poster Abstract Session: Bacterial Pathogenesis
Saturday, October 22, 2011
Room: Poster Hall B1
Background: Infections caused by multidrug-resistant organisms, including methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii, are a common complication of combat-related injuries sustained by U.S. personnel during armed conflicts which makes medical management of these wounds difficult. Considerable evidence suggests that the development of microbial biofilms is a critical event facilitating disease and antimicrobial resistance. Importantly, the potential relationship between biofilm formation and pathogenicity of clinical isolates commonly associated with combat-related injuries are unknown. Herein, we sought to determine the prevalence of biofilm-forming cultures obtained from patients with acute and chronic wounds.

Methods: 150 clinical isolates, including 30 isolates of MRSA, P. aeruginosa, K. pneumoniae, A. baumannii, and E. coli, recovered from patients admitted for treatment at a military treatment facility between 2006 and 2010 were screened for their ability to form biofilms in vitro using a high-throughput polystyrene microtiter plate assay. Clinical isolates were characterized by pulsed-field gel electrophoresis and antimicrobial susceptibility testing.

Results: Of the 150 clinical isolates tested, 97 strains (64.6%) developed biofilms greater than or equal to the positive control, a strain of Staphylococcus epidermidis. Significant variability in biofilm formation among the clinical isolates was observed. Biofilm development for strains of MRSA (90%, 27 strains) and P. aeruginosa (80%, 24 strains) were observed to be the highest, whereas those for E. coli were the lowest (5%, 5 strains). Strains of A. baumannii (67%) and K. pneumoniae (70%) were also observed to develop biofilms. No relationship between biofilm formation and antimicrobial resistance or pulse field type was observed; however there was a strong correlation between biofilm formation and the site of isolate collection.

Conclusion: These studies demonstrate that isolates from combat-related injuries have the ability to develop biofilms and suggests a possible role for biofilms in the development of infections in wounds sustained by military personnel.

Subject Category: B. Bacterial pathogenesis, studies in animal models, molecular pathogenicity

Carlos Sanchez Jr., MS1, Katrin Mende, PhD2, Miriam Beckius, MPH3, Joseph Wenke, PhD1 and Clinton K. Murray, MD3, (1)US Army Institute of Surgical Research, Fort Sam Houston, TX, (2)Infectious Disease Clinical Research Program, Uniformed Services University of the Health Sciences, Bethesda, MD, (3)San Antonio Military Medical Center, Fort Sam Houston, TX


C. Sanchez Jr., None

K. Mende, None

M. Beckius, None

J. Wenke, None

C. K. Murray, None

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.