Detection of Staphylococcus aureus in Chicken Macaroni Salad
Cardinez, M.C.C.a, Delos Reyes, A.J.J.a, Jacosalem, G.M.a, Quiatchon, P.A.N.a, Tumambing, V.K.Ma
a Department of Food Science and Nutrition, College of Home Economics, University of the Philippines, Diliman, Quezon City 1101, Philippines
The macaroni salad is a pasta salad served cold usually made from elbow macaroni and mayonnaise as its dressing. Like potato salad and coleslaw, macaroni salad is commonly presented as a side dish of barbecued chicken and meat meals. However, in the Philippines, the macaroni salad is served as a dessert because of its sweeter taste compared to other macaroni salads ...view middle of the document...
Staphylococcus, which is a Gram-positive, catalase positive bacteria have been well known to cause several infections to human. Some of these include pimples, boils, pneumonia, food-borne gastroenteritis, wound infections and nosocomial or hospital-associated infections (J.M.Jay, 2005, Tortora, et.al. 2007). Some more extraintestinal infections of Staphylococcus to human are burn infections, impetigo, pseudomembraneous colitis, scalded skin syndrome, bacteraemia, meningitis and toxic shock syndrome (Varnam, 1996).
The antimicrobial properties of penicillin against Staphylococcus had been a success until the 1950's when hospitals were bothered by the emergence of penicillin- resistant strains of Staphylococcus and lead to use of methicillin. In 1980, methicillin- resistant S. aureus emerged and required the use of yet another antimicrobial known as vancomycin and in 2002, a case of vancomycin- resistant S. aureus was recorded (Tortora, et.al. 2007).
Ranking 1 as the microorganism which caused most number of nosocomial infections was coagulase-negative I which caused 25 % of sepsis reported, 89% of this is resistant to antibiotics. It caused 16% of pneumonia cases, where 60% are antibiotics- resistant (Tortora, 2007).
This study was conducted to determine the presence of Staphylococcus aureus in ready-to-eat foods like the home-made macaroni salad and to discern the factors that led to the contamination of this food with this microorganism.
2. MATERIALS AND METHODS
2.1 Acquisition of food sample
The food sample used was chicken macaroni salad which was prepared at home. During the preparation of the food sample, the ingredients had a lot of contact with bare hands. The stripping of the chicken meat, slicing of cheese and ham and washing of the macaroni were all done with bare hands. After preparation of the macaroni salad, it was stored in the refrigerator at -5°C for 5 days. The sample was placed in a plastic bag and brought to the laboratory for analysis.
2.2 Determination of Staphylococcus aureus
Approximately 25 g of chicken macaroni salad was randomly obtained as food sample using a triple beam balance (Ohaus, 700/800 Series, USA). The food sample was then homognized with 225 mL of sterile Peptone Water (PW) (HiMedia, HiMedia Laboratories, India) using a sterile blender (Moullinex Type Q48, Mexico) for 60 sec at medium speed to make the 10-1 dilution. Ten-fold serial dilutions upto 10-3 were prepared by aseptically obtaining 1 mL from the homogenate and mixing with 9 mL of PW.
The dilutions were then inoculated by spread plating 0.4 mL of the each dilution onto the pre-solidified Baird-Parker Agar with Egg Yolk Tellurite using a sterile glass hockey stick. The Baird-Parker agar with egg yolk Tellurite was prepared by mixing 8.84 mL egg yolk Tellurite solution into 150 mL Baird-Parker agar(HiMedia, HiMedia Laboratories, India). Inoculation was done in duplicates. A control plate with Baird-Parker...