Assessment and Comparative Study of Biofilm Formation with Frequency of Multi Drug Resistance in Strains of Staphylococcus aureus

Abstract

Background: The study was conducted to identify the role of biofilms in the antibiotic susceptibility in the strains of Staphylococcus aureus. A total of 19 non-repeated pus/wound swab samples from different anatomic locations and 17 samples that were previously identified as Staphylococcus aureus and preserved in the labs were included in the study. The Staphylococcus aureus was identified based on colony morphology, Gram’s stain, biochemical tests (catalase and coagulase tests) and molecular identification through PCR amplification. Methodology: A total of 26 samples were recovered out of the 31 samples. Kirby-Bauer disk diffusion susceptibility test was used to determine the sensitivity or resistance of Staphylococcus aureus to methicillin. Out of the 26 strains, 4 were highly resistant, 10 were moderately resistant and 12 strains were sensitive. Three different protocols (Tube Method, Congo Red Agar Method and Tissue Culture plate method) were used for the detection of biofilm formation for both resistant and sensitive strains. Result: Comparative analysis of the antibiotic susceptibility and biofilm formation by different protocols showed that 70% strains that are resistant to antibiotic methicillin produced moderate-strong biofilms. 50% have produced the moderate-strong biofilms in all 3 protocols. In case of sensitive, 50% strains had produced none-weak biofilms in all 3 protocols. Decisions: The strains that had zone of inhibition of close to resistance produced weak-strong biofilms but they all produced weak biofilms in CRA method. It can be concluded that the strains of Staphylococcus aureus that have the ability to produce biofilms become methicillin resistant.