Staphylococcus Aureus Methicillin Resistant/Susceptible (MRSA/MSSA) Nucleic Acid Amplification Test (NAAT) 
Mnemonic SA NAAT
CPT 87640, 87641
Test Code 6650026
Synonyms S. aureus PCR, MSSA, MRSA
Test Includes Testing for the presence of colonizing Staphylococcus aureus. If present, testing for the detection of methicillin resistance markers is also performed.
Specimen Bronchial Alveolar Lavage (BAL); Mini-BAL; Nose; Nasopharyngeal; Sputum; Transtracheal Aspirate
Volume BAL: 5.0 mL; Mini-BAL: 5.0 mL Sputum: 5.0 mL; Transtracheal Aspirate: 5.0 mL
Container Red-Capped Bacterial Transport Dual Swab with Liquid Stuart's medium; Sterile container
Special Instructions If source is anything other than nasal (BAL, Mini-BAL, Sputum, or ETA) please do NOT submit a swab. Testing will be performed on the primary specimen. Concurrent culture is required on non-nasal sources.
Specimen Prep NASAL: (Insert Swab (if using dual swab system, insert both swabs at once) into the left nares. Apply slight pressure to nose with finger and turn swab(s). Remove and insert into the right nares and repeat. Swab both nares with the same swab(s). Replace swab(s) in tube, label, and transport. BAL, or MINI-BAL: Collect specimen using aseptic technique and accepted methods. Avoid contamination with mouth flora (saliva). Submit 5.0 mL (0.5 mL minimum). SPUTUM: Early morning specimen is optimal. Have patient cough deeply and collect entire specimen (0.5 mL minimum) of expectorated sputum in a sterile container. TRANSTRACHEAL ASPIRATE: Collect transtracheal aspirate into sterile container.
Storage Refrigerate
Transport Temp Refrigerated
Stability Rm Temp 24 hours
Stability Refrig Nasal: 5 days; All other sources: 2 days
Stability Frozen  
Methodology Polymerase Chain Reaction (PCR)
Rejection Criteria Inappropriate specimen, inadequate volume, inappropriate transport device, delay in transport, bronchial washing or brush specimens. For non-nasal specimens, repeat testing sooner than 5 days will be rejected. Patients positive for MRSA from a non-nasal 
Reference Value Negative 
Performed/TAT Monday - Sunday   24 Hours    
Comments This test can be used to determine nasal colonization with either methicillin susceptible or methicillin resistant Staphylococcus aureus (MSSA or MRSA). Other specimen types may be used to ascertain the presence of MSSA or MRSA in patients with suspected ventilator-associated pneumonia. Concurrent culture is required on non-nasal sources.