| ObjectiveTo developed a method by real-time PCR for rapid identification methicillin-resistant Staphylococcus aureus and provide a new laboratorial foundation for clinical diagnosis.MethodsApplying real-time PCR to detecte the nuc gene for Staphylococcus aureus and mecA gene for methicillin-resistant Staphylococcus aureus directily from whole blood.The result contrast the positive in blood culture.Results1. The real-time PCR analysis show, Staphylococcus aureus group , the nuc gene all positive, the mecA gene all negative; methicillin-resistant Staphylococcus aureus group, the nuc gene all positive, the mecA gene all positive; Staphylococcus epidermidis group, the nuc gene all negative, the mecA gene all negative.2. The Bacterial genome DNA extract kit failed to extract Bacterial DNA from blood culture when the colony formine unit is lower than 10-2.The plate count results are 3.83×109 CFU/ml, 4.10×109 CFU/ml, 8.37×109 CFU /ml, 3.65×109 CFU /ml and 5.36×109 CFU /ml respectively. The rusults demonstrates Bacterial DNA can be extracted when MRSA colony formine unit in blood is higher than 107 CFU/ml.3. Clinical verification results show, by real-time PCR detection of 135 samples consisting of 13 samples of methicillin-resistant Staphylococcus aureus, 9 samples of methicillin-susceptible Staphylococcus aureus, 10 samples of Staphylococcus epidemidis. Analysis of the 13 samples of methicillin-resistant Staphylococcus aureus with mecA results found the mecA test had a sensitivity of 46.15% (6/13), specificity of 100% (9/9), positive predictive value of 100% (6/6) and negative predictive value of 56.25%(9/16).For the 22 samples of Staphylococcus aureus with nuc test had a sensitivity of 45.45%(10/22), specificity of 100%(10/10), positive predictive value of 100% (10/10) and negative predictive value of 45.45%(10/22). ConclusionReal-time PCR can rapidly detect methicillin-resistant Staphylococcus aureus directly from whole blood. But the sensitivity isn't high; it's needs improve.
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