Incidence of biofilm formation among MRSA and MSSA clinical isolates from hospitalized patients in Israel

Abstract

Aim: To assess the biofilm-producing capacities of Staphylococcus aureus strains isolated from hospitalized patients in Israel.

Methods and results: A total of 16 S. aureus (80 MRSA and 83 MSSA) from screening (nasal swab) and clinical samples (blood and wounds) were characterized. Biofilm-producing capacities were determined using two different biofilm detection assays: Congo Red agar (CRA) and microtiter plate (MtP). In addition, a real-time PCR analysis was performed to detect the presence of biofilm-associated genes (icaA and icaD) and mecA gene. The two assays showed similar biofilm production pattern (28.2% agreement). MRSA strains tended to be greater biofilm-producers than MSSA strains. The presence of mecA was associated with biofilm production (p = 0.030). Additionally, bacteria isolated from blood samples produced less biofilm compared to those from other sources. Finally, no association was found between icaA and icaD presence and biofilm production.

Conclusion: This study supports earlier assumptions that biofilm formation depends strongly on environmental conditions.

Significance and impact of study: This study significantly improved our knowledge on the biofilm production capacity of S. aureus strains in Israel. Moreover, it revealed an association between the mecA gene and biofilm production. Finally, this study underscores the importance of further research to evaluate risk factors for biofilm production.

Keywords: MRSA; S. aureus; Congo red agar; biofilms; icaA; icaD; microtiter plate.