A study of the regulating gene of femA from methicillin-resistant Staphylococcus aureus clinical isolates

作者：Li X; Xiong Y; Fan X^*; Zhong Z; Feng P; Tang H; Zhou T

来源：Journal of International Medical Research, 2008, 36(3): 420-433.

• methicillin-resistant Staphylococcus aureus (MRSA)
• femA
• methicillin-sensitive Staphylococcus aureus (MSSA)
• regulating gene
• real time fluorescent quantitative polymerase chain reaction (RT-QPCR)
• electrophoretic mobility shift assay (EMSA)

The regulating gene of femA was studied in methicillin-resistant Staphylococcus aureus (MRSA). High-level MRSA, low-level MRSA and methicillin-sensitive S. aureus (MSSA) were identified by agar diffusion. beta-Lactamases were detected by nitrocephin and the presence of the mecA gene was determined by polymerase chain reaction (PCR). Only isolates that were both p-lactamase-negative and mecA-positive were used. The femA gene and its 250 base pair (bp) upstream sequence were amplified by PCR and expression was determined by real-time fluorescent quantitative PCR. The 250 bp upstream sequence was labelled by BrightStar (R) Psoralen-Biotin and detected by electrophoretic mobility shift assay (EMSA). Expression levels of femA in MSSA, low-level MRSA and high-level MRSA were 3.53 x 10(-3)% - 29.91%, 5.54 x 10(-3)% - 3.1 x 10(2)% and 13.88 - 5.50 x 10(4)%, respectively. EMSA detected a signal shift in 57 high-level MRSA isolates but not in four low-level MRSA and four MSSA strains. Expression of femA in high-level MRSA (non-P-lactamase-producing) was higher than in low-level MRSA and MSSA. The femA regulating gene probably lies in the 250 bp upstream sequence in MRSA and high-level expression is essential for high-level methicillin resistance.

• 出版日期2008-6
• 单位四川大学