Detection of Staphylococcus aureusin in Frozen Chicken Rinse through Bacteriological and AfocGene Specific PCR Methods and their Drug Resistance Patterns in Southern Chittagong, Bangladesh

摘要

Staphylococcus aureus are gram positive cocci that can cause sporadic cases and outbreaks of food borne illness. The aim of the present study was to detect and identify this organism in samples of refrigerated chicken rinse obtained from different super stores in Chittagong city. The prevalence of infection and antimicrobial susceptibility of Staphylococcus aureus were also studied. The PCR was performed to detect these microorganisms in a chicken rinse microbial consortium and the traditional cultural techniques were performed based on bacteriological analytical manual. To compare PCR and bacterial culture methods for detection of S. aureus, 150 chicken rinse samples from different supermarkets in the Chittagong city were collected and tested. Samples were cultured on selective mannitol salt agar media and contamination by Staphylococcus was confirmed by gram staining, catalase test and coagulase test. Overall 95.83% of the samples were found to be infected with S. aureus. About 68.53% samples were coagulase positive Staphylococcus and 31.46% were negative. Bacterial counts of 100000 or more CFU cm"2 were found on 16.67% of the frozen chicken samples (p<0.01). Simultaneously, total DNA obtained by thermal extraction from samples was subjected to PCR using a set of primers designed for specific regions of Staphylococcus nuc gene and PCR products were analyzed by agarose gel electrophoresis. Culture sensitivity test and antibiogram study was done to determine the antibiotic sensitivity pattern of Staphylococcus isolates against eight commercially available antibiotic discs (Ampicillin, Amoxycillin, Cephalexin, Ciprofloxacin, Erythromycin, Gentamycin, Doxycycline hydrochloride and Oxytetracycline). All of the samples were resistant to two or more than two antibiotics. The samples showed 100% resistant to Ampicillin, more than 80% were resistant to Oxytetracyclin, Doxycycline hydrochloride and Amoxicillin. Ciprofloxacin showed 77.5%, Cephalexin 38.33% and Gentamycin showed the least resistance 13.33%. The results of this study indicate that the PCR can permit a rapid and reliable means of assessing the bacteriological safety of food and should provide an alternative methodology than conventional viable culture method. The PCR may permit sufficient sensitivity and specificity for the direct detection of Staphylococcus in food samples.