title: The role of femA regulating gene on methicillin-resistant Staphylococcus aureus clinical isolates.
abstract: OBJECTIVE
  The authors investigated the role of femA regulating gene on methicillin-resistant Staphylococcus aureus (MRSA).
  
  
  METHODS
  High-level MRSA, low-level MRSA, and methicillin-susceptible Staphylococcus aureus (MSSA) were determined by agar diffusion methods. β-lactamase was then detected by nitrocefin and the presence of mecA was determined by PCR. Only β-lactamase-negative but mecA-positive isolates were included in further studies. The femA gene and its 250 bp upstream sequence were amplified by PCR. Expression levels of femA were determined by real-time fluorescent quantitative PCR. The 250 bp upstream sequence of femA was labeled by BrightStar Psoralen-Biotin and was detected by electrophoretic mobility shift assay (EMSA).
  
  
  RESULTS
  The expression levels of femA in the three different groups (MSSA, low-level MRSA, and high-level MRSA) ranged from 3.53×10-3% to 29.91%, 5.54×10-3% to 3.1×102%, and 13.88% to 5.50×104%, respectively. EMSA could detect the signal shift in 55 high-level MRSA isolates but not in four low-level MRSA and four MSSA strains.
  
  
  CONCLUSIONS
  The expression levels of femA in high-level MRSA (non-β-lactamase-producing) were higher than in low-level MRSA and MSSA. The femA regulating gene probably lies in the 250 bp upstream sequence in MRSA. High-level expression of femA seems to be essential for high-level MRSA.
authors.affiliation: Digestive System Department, the First People's Hospital of Chengdu, Sichuan, China. lixiaofang0902@126.com
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.forename: Y
authors.initials: Y
authors.lastname: Xiong
authors.forename: X
authors.initials: X
authors.lastname: Fan
authors.forename: P
authors.initials: P
authors.lastname: Feng
authors.forename: H
authors.initials: H
authors.lastname: Tang
authors.forename: T
authors.initials: T
authors.lastname: Zhou
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D001483:Base Sequence; D002473:Cell Wall / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D024202:Electrophoretic Mobility Shift Assay; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005809:Genes, Regulator; D006801:Humans; D016106:Methicillin Resistance / Q000235:genetics; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D046915:Penicillin-Binding Proteins; D012329:RNA, Bacterial / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D060888:Real-Time Polymerase Chain Reaction; D012045:Regulatory Sequences, Nucleic Acid; D013203:Staphylococcal Infections / Q000382:microbiology*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; C096686:FemA protein, Bacteria; D046915:Penicillin-Binding Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; C487789:mecA protein, Staphylococcus aureus