Inhibition of Methicillin Resistant Staphylococcus aureus (MRSA) Biofilm Proliferation by Chitosan Isolated from Portunus Pelagicus (Linnaeus 1758)

The dramatic increase of microorganisms capable of producing structures which render them drug resistant calls for novel antimicrobial agents. MRSA, a nosocomial drug-resistant pathogen, is capable of adhering to surfaces of medical devices and produce biofilm which render it antibiotic resistant. This study investigated the potential antibiofilm activity of chitosan extracted from Portunus pelagicus (Linnaeus, 1758) against MRSA biofilms. Chitosan was extracted using a 3-step process: demineralization with an acid solution, deproteination with a low concentration of alkaline and deacetylation with concentrated alkaline solution. Preformed biofilms of MRSA were then treated with the extracted chitosan (treatment group) and 0.1M acetic acid (control group). The chitosan extracted had antibiofilm activity against MRSA. Films treated with chitosan showed optical density values of 0.5392±0.0454, 0.4897±0.0638, and 0.4284±0.0500 (control group with 0.6951±0.0659, 0.7373±0.0618, and 0.8064±0.0418) at 24, 48, and 72 hours respectively. On the average, optical density of group treated with 0.1M acetic acid (M=0.746,SE=0.012,95% CI[0.720,0.772]) was significantly higher than group treated with chitosan (M=0.486,SE=0.009,95% CI[0.466,0.506]). The ability of chitosan to inhibit biofilm proliferation was demonstrated as an increase in the calculated percent biofilm inhibition values as incubation time was lengthened with mean percent (%) inhibition of biofilms of 22.06±6.71, 33.27±9.63, and 46.92±5.03 at 24, 48, and 72 hours correspondingly. Viewed on scanning electron microscope, significant morphologic membrane changes were noted at Chitosan treatment group after 72 hours seen as misshapen shrunken deformities in the cell membrane, however, no gross membrane disruption or pore formation were noted.