Clinics and Departments

Laboratory Services

Lab Dept:


Test Name:


General Information

Lab Order Codes:

MRSP (Routine testing), SMRSP (IC surveillance testing)


MRSA PCR screen, Methicillin-resistant Staphylococcus aureus PCR screen

CPT Codes:

87641 - Staphylococcus aureus, methicillin resistant, amplified probe technique

Test Includes:

Direct detection of nasal colonization by methicillin-resistant Staphylococcus aureus by PCR (polymerase chain reaction).


Lab Testing Sections:

Molecular Diagnostics, Mpls campus

Phone Number:


Test Availability:

Specimens accepted daily, 24 hours

Turnaround Time:

24-48 hours

Special Instructions:

Requisition must state site of specimen and date/time of collection.


Specimen Type:

Anterior nares


Swab transport medium with liquid Stuart medium (white)


One swab


Anterior Nares

1. Insert swab, premoistened with sterile saline, approximately 1-2 cm into the nostril. (1/2 inch from edge of nares)
Rotate the swab against the nasal mucosa approximately 5 times.
Insert the same swab into the second nostril and repeat sampling as in steps 1 and 2.
Place in swab transport medium.
Label container and transport to the laboratory.


Transport to the Microbiology Laboratory at room temperature within 48 hrs of collection. Upon arrival in laboratory, store specimens at 2 - 8 C. Specimens can be stored up to 5 days at 2-8 C before testing. Protect from freezing or exposure to excessive heat.

Sample Rejection:

NP wire swab (green); unrefrigerated specimen(s) with a transit time exceeding 48 hours after collection; improper source; improperly labeled specimen; external contamination. If an unacceptable specimen is received, the patient’s caregiver will be notified and another specimen will be requested before the specimen is discarded.


Reference Range:

Negative: No MRSA DNA detected, MRSA nasal colonization unlikely

Unresolved results due to PCR inhibition are inconclusive. Consider repeat collection if clinically indicated.

Significant Finding:

Positive: MRSA DNA detected, MRSA nasal colonization


● Blood, excessive nasal secretions/mucus, decongestants and substances used to relieve nasal dryness or irritation may inhibit PCR and give unresolved results.
● Negative results may occur from improper specimen collection, handling and storage or because the number of organisms in the specimen is below the analytical sensitivity of the test.
● Results should be used as an adjunct to nosocomial infection control efforts to identify MRSA nasal carriers. This test is not intended to identify patients with staphylococcal infection.
● A positive test result does not necessarily indicate the presence of viable organisms.
● Mutations or polymorphisms in primer or probe binding sites may affect new or unknown MRSA variants resulting in a false negative result.


Polymerase Chain Reaction (PCR)


Henry D. Isenberg (2004), section editor, Section 2, Specimen Collection, transport, and Acceptability, In H.D. Isenberg (ed) Clinical Microbiology Procedures Handbook, American Society for Microbiology, Washington, D.C.

Miller, J. Michael (1999), A Guide To Specimen Management in Clinical Microbiology, American Society for Microbiology, Washington, D.C.

BD GeneOhm™ MRSA ACP Assay (2010/01), Circular DOPS09-V1E1, Becton Dickinson and Co., 7 Loveton Circle, Sparks, MD 21152.


9/1/2010: Transport time extended from 2 hours to 1 day.
11/30/2011: Updated availability from M-S to Daily. Changed sample storage, previously listed as 2-5 degrees C. BD reference for ACP updated. Transport extended from 1 day to 2 days @ room temp.
2/20/12: Changed from Critical value to Significant finding.

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