Rapid detection of methicillin-resistant Staphylococcus aureus by mecA gene targeted colloid gold nanoparticies probes

Objective To establish hybridization method by using the DNA-modified colloid gold nanopartieles probes for rapid and specified detection of methicillin resistant Staphylococcus aureus (MRSA). Methods DNA-modified nanoparticles probes were prepared by using two mereapto-modified mecA gene-specific oligonucleotide probes bounding with 6Ohm-diameter colloid gold nanoparticles through covalent binding. Genomic DNA of Staphylococcus aureus strains were extracted and then fragmented by ultrasonic waves. The fragmentized DNA was hybridized with the DNA-modified colloid gold nanoparticles probes. The reaction products were centrifuged and then detected by reversed-phase thinlayer chromatography plate to observe any colloid gold nanoparticles precipitation. The results of mecA gene detected by the colloid gold nanoparticles probes hybridization were compared with the results of PCR and the accuracy of the hybridization method was evaluated. Results Of total 95 tested strains, 71 strains were confirmed as MRSA and 24 swains were confirmed as methicillin susceptible Staphylococcus aureus (MSSA) by PCR. Of 71 MRSA strains, 69 strains were positive by colloid gold nanoparticles probes hybridization, the sensitivity of this method was 97.2%. All of the 24 MSSA strains were negative by using this technique. The specificity of this method was 100%. Of total 95 test strains ,93 strains were detected correctly. The accuracy was 97.9%. Conclusions Colloid gold nanoparticles probes hybridization test is well consistent with the gold standard method of PCR in detection of MRSA. Detection of MRSA by using the technique of the DNA-modified colloid gold nanopartichs probes hybridization is rapid, simple and accurate. It is potent to be a new method for rapid diagnosis of MRSA infection. Key words: MethiciIlin resistance; Staphylococcus aureus; DNA probes; Nanoparticles; Gold colloid