The Antibacterial Effect of Chitosan against Methicillin-Resistant Staphylococcus aureus (MRSA) Isolated from Beef Meat
The Antibacterial Effect of Chitosan against Methicillin-Resistant Staphylococcus aureus (MRSA) Isolated from Beef Meat
Qais Abdulrahman M. Al-Jaghifi, Zina Saab Khudhir*
ABSTRACT
The effectiveness of chitosan as an antibacterial agent against methicillin-resistant Staphylococcus aureus (MRSA) isolated from frozen and fresh beef was evaluated. Bacterial isolates were confirmed using cultural, biochemical, and the VITEK 2 system. All suspected MRSA isolates tested positive for MRSA. In frozen meat samples (n=50) collected from different markets in Baghdad city, the number and isolation percentage (%) of S. aureus and MRSA were 11/50 (22%) and 4/50 (8%), respectively. In fresh meat samples (n=50), these figures were 16/50 (32%) and 3/50 (6%), respectively. Chitosan solutions at different concentrations (0.5%, 1%, 1.5%, and 2%) were prepared by dissolving food-grade chitosan in 1% acetic acid. Evaluation of bacterial reduction in log units was recorded. The bacterial counts before dipping meat samples in 2% chitosan solution showed initial counts of 5-6 log10 CFU/g. After treatment at both ambient and refrigeration (4ºC) temperatures for 4 hours, counts were reduced to 2-3 log10 CFU/g. The number of MRSA isolated from frozen meat decreased significantly more when treated with 2% chitosan at refrigeration temperature compared to ambient temperature. The antibacterial activity was also evaluated by measuring the zone of inhibition (mm). Results indicated that 2% chitosan was significantly effective (P≤0.05), showing the highest zone of inhibition (38 mm) against MRSA. In conclusion, the application of chitosan as a natural food-grade antibacterial agent against MRSA effectively reduced bacterial counts and maintained the bacteriological quality of beef sold in local markets.
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