PCR-based Detection of Low Levels of Staphylococcus aureus Contamination in Pharmaceutical Preparations

Polymerase Chain Reaction (PCR) was perfonned to verify the utility of this technique in detecting low levels of microbial contamination in quality control of pharmaceutical products. Universal and specific primers were applied to identify Staphylococcus aureus at both genus and species levels, as one of the objectionable microorganisms in Pharmaceuticals especially topical products. Samples were deliberately inoculated with a defined number of bacterial cells and subsequently exposed to mild lysis. The crude lysate was subjected to PCR amplification. Agarose gel electrophoresis revealed amplified fragments as predicted, with no interference from other bacterial strains included in the study. The sensitivity of the assay was about 10 super(2) cfu mL super(-1) which improved to 1 cfu mL super(-1) after an overnight preenrichment. Combination of this simple lysis and rapid PCR protocol provided a highly sensitive and practical approach in detecting trace amounts of Staphylococcus aureus contamination in pharmaceutical preparations. In contrast to conventional culturing methods that require a mean of 5-6 days for identification of microorganisms, the entire mentioned PCR assay lasted about 1-2 h.