Nov 3, 2017




Clinical Hub,Tools & Resources,UWHC Lab Test Directory,Microbiology


MRSA/MSSA by PCR (HCMSSA) Microbiology Lab Test


Test Name: MRSA/MSSA by PCR

Health Link Test Code: HCMSSA

LIS Test Code: MSSA

CPT Code(s): 87641; if MRSA is negative add cpt 87640

Methodology: PCR

Clinical Information:

Staphylococcus aureus(SA) is a significant cause of community acquired and nosocomial infections and has been associated with prolonged hospitalizations and increased costs. Further, an increase in mortality among patients infected with methicillin-resistant Staphylococcus aureus (MRSA) has been found.

In-Lab Turnaround Time: 1 - 3 days.

Stat In-Lab Turnaround Time: Not available stat.

Specimen: Nasal swab, throat swab

Collection Container: See collection instructions.

Collection Instructions:

Use one DOUBLE culture swab (CS#4005445) to collect both left and right nares.  

Use one DOUBLE culture swab (CS#4005445) to collect left and right axilla and groin. 

Use one DOUBLE culture swab (CS#4005445) for throat.

Stability Ambient:

24 hours

Stability Refridgerated:

Up to 6 days

Stability Frozen:

Not acceptable

Specimen Transport:

Transport specimen to the laboratory as soon as possible.

Unacceptable Criteria:

Two separate swabs where one swab is collected from groin and the other swab is collected from axilla are not acceptable for testing.  One DOUBLE swab MUST be used to collect a pooled right and left axilla/groin specimen.



Interpretation Type: Expected Results

Test Limitations:

A false negative MRSA PCR may result when testing borderline resistance and when mechanisms of resistance are due to factors other than the presence of the MecA gene.

Additional Information:

At UWHC, a Pre-Surgical screen consists of collecting both left and right nares using one DOUBLE culture swab (CS#4005445).


This test detects both MRSA and MSSA.  For MRSA only testing, see MRSA by PCR.


This assay can not detect MSSA if MRSA is present.


This test was performed using a modification of an FDA approved method. The performance characteristics of this test were determined by the UWHC Clinical Laboratories and meet the standards for clinical testing.


Negative results may occur from improper specimen collection, handling or storage, presence of inhibitor or because of the number of organisms in the specimen is below the analytical sensitivity of the test.


A positive test does not necessarily indicate the presence of viable organisms.