Epidemiological analysis of biofilm-forming methicillin-resistant Staphylococcus aureus clinical isolates

Methicillin-resistant Staphylococcus aureus (MRSA) remains a significant global concern in healthcare and community environments, posing serious risks to patients due to its ability to form biofilm. Monitoring and spread control of epidemic MRSA clones require robust epidemiological typing methods.

In this study, 30 MRSA isolates associated with significant morbidity were recovered from King Abdulaziz Specialist Hospital, Taif, Saudi Arabia. The strains were identified using the Vitek 2 automated system. The ability of MRSA to form biofilm on a polystyrene surface was evaluated by the crystal violet method. Genetic diversity of the strains was assessed using three methods: repetitive PCR based on (GTG)₅, BOXA1R sequences, and multiplex PCR of the staphylococcal cassette chromosome mec (SCCmec).

Out of the 30 MRSA isolates, 29 strains were both highly positive (40%) and low-grade positive (56.66%) biofilm producers. Molecular epidemiology based on multiplex PCR of SCCmec showed that 10% of the isolates harbor each of SCCmec IVa and V. While 13.33% of the strains harbor the SCCmec II. In addition, 20% of the isolates were commonly associated with community-acquired, in contrast to 13.33% that were commonly associated with hospital-acquired infections. However, the remaining 66.66% of isolates were not classified into the tested SCCmec types. PCR genomic fingerprinting revealed high genetic variability of MRSA. (GTG)₅ and BOXA1R-PCR generated 26 and 28 clusters with a discriminatory index of 0.99 at 90% similarity.

MRSA isolates exhibited a high ability to produce biofilm, which can pose a serious public health problem. The quantification of biofilm in different clonal lineages is of great importance to develop effective antimicrobial policy and enhance biofilm management during infection. MRSA strains demonstrated significant genetic variability, indicating substantial genetic diversity. (GTG)₅ and BOXA1R-PCR molecular typing methods are reliable for the epidemiological tracking of highly biofilm-forming MRSA strains in hospital environments and can provide essential insights into controlling the spread of MRSA infections.