Methicillin-resistant Staphylococcus aureus biofilm formation on dacryocystorhinostomy silicone tubes depends on the genetic lineage

Abstract

The aim of this study was to investigate biofilm formation on silicone tubes by genetically diverse methicillin-resistant Staphylococcus aureus (MRSA) strains. Capacity of biofilm formation on dacryocystorhinostomy silicone tubes was tested on 30 MRSA strains. Identification and methicillin resistance were confirmed by PCR for nuc and mecA genes. Strains were genotypically characterised (SCCmec, agr and spa typing). Biofilm formation was tested in microtiter plate and on silicone tubes. Tested MRSA strains were classified into SCCmec type I (33.3 %), II (3.3 %), III (20.0 %), IV (26.7 %) and V (16.7 %), agr type I (56.7 %), II (36.7 %) and III (6.6 %), and eight spa clonal complexes (CCs). All tested MRSA strains showed ability to form biofilm on microtiter plate. Capacity of biofilm formation on silicone tubes was as follows: 33.3 % of strains belonged to the category of low biofilm producers, and 66.7 % to moderate biofilm producers. There was statistically significant correlation between spa CC and the category of biofilm production on silicone tubes (p = 0.01): CC5 and CC45 with moderate amount of biofilm, and CC8 with low amount of biofilm. A moderate amount of biofilm formed on silicone tubes correlated with agr type II MRSA strains (p = 0.008). Biofilm formation by MRSA on silicone tubes is highly dependent on genetic characteristics of the strains. Therefore, MRSA genotyping may aid the determination of the possibility of biofilm-related ocular device infections. Genotyping and biofilm quantification may be helpful in determining when decolonisation and cohort isolation are required to prevent device-related infections.