Influenza prevalence fluctuates seasonally with the onset of “flu season” typically beginning its upswing in the month of December. It is important for providers to have an awareness of influenza prevalence (in addition to other respiratory viruses) to help guide when influenza testing should be pursued.
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Infectious Disease
Effective Date: September 3, 2025
The MRSA Screen PCR [LAB1231076] detects the presence or absence of colonization with methicillin-resistant Staphylococcus aureus (MRSA) and may be used to guide antimicrobial prophylaxis decisions. To improve and standardize test utilization across all Corewell Health regions, the following restrictions will be added to this test order:
- Ordering will be restricted to one test every 7 days.
- An indication for ordering must be provided for each order. Acceptable indications are:
- Pneumonia
- Skin and soft tissue (use for non-purulent infections)
- Surgical prophylaxis
Studies have shown that there is minimal utility in re-testing within 2 weeks as MRSA conversion rates are low and the PCR negative predictive values remain high for at least 14 days after initial testing.
Absence of nasal colonization with MRSA cannot be used to reliably rule out MRSA infection in scenarios other than those listed above.
Test Information
This winter, West Michigan influenza infections peaked in February 2024 and significantly declined throughout March and April 2024. Now with a low prevalence of circulating influenza, using the most sensitive diagnostic test is recommended in order to obtain accurate and actionable results. Influenza antigen testing (e.g. Sofia instrument) is no longer appropriate at this time and Influenza PCR testing should be ordered when clinically indicated.
| Low Influenza Prevalence |
High Influenza Prevalence |
|
| Recommended Order | Influenza PCR (LAB3255) | Influenza antigen testing (e.g. Sofia instrument) or Influenza PCR (LAB3255) |
More detailed information can be found as published by the CDC:
With several suspected cases of measles within Michigan, we thought it would be an excellent time to highlight Corewell Health West’s guidance on testing suspected patients. Specimens are sent to a reference lab for testing, which must be coordinated with local public health departments. Typically an upper-respiratory swab (throat or nasopharyngeal) is collected for PCR testing in addition to a serum for measles IgM if collection is possible.
- Patients should not be directed to a Corewell Health Laboratory or other healthcare facility for serum collection if patient is within 4 days after the onset of rash (with onset of rash considered to be Day 0). If Day 5 of rash or later, immunocompetent patients are no longer considered contagious and may be sent to a laboratory for a serum draw.
- Corewell Health Providers:
- Please reach out to Corewell Health Infection Prevention (IP) via Perfect Serve to make them aware of the situation.
- Corewell Health Infection Prevention will contact the appropriate county.
- Non-Corewell Health Facilities:
- The provider’s office must coordinate with the county health department that the patient lives in to obtain permission to send measles testing.
- Visit the following link for county health department contact information: Slide 1 (michigan.gov)
- The county will coordinate with MDHHS for testing permission.
The preferred testing specimen is a throat or nasopharyngeal swab collected in office. Corewell Health Laboratories do not collect swabs.
For further collection and ordering instructions, please visit: Measles PCR – Laboratory Test Catalog | West
Any additional questions or concerns, please use the contact us link above or reach out to your local health department.
Influenza cases numbers are currently increasing throughout West Michigan. Influenza prevalence guides the most appropriate testing approach and sufficient prevalence has now been reached for influenza rapid antigen or point of care testing (e.g. Sofia instrument) to have improved performance. The use of point of care testing as a screening method during high prevalence reduces both the cost to the patient and turn-around-time as compared to lab-based molecular methods. Point of care tests generally have high analytical specificity, but lack the sensitivity of nucleic acid amplification methods (e.g. PCR). For this reason, PCR testing is still recommended for hospitalized patients and for outpatients with a negative result if influenza is still suspected and if the result will impact clinical decision making.
| Low influenza prevalence | High influenza prevalence | |
| Recommended order | Influenza PCR | Influenza Point of Care Testing or Influenza PCR |
Effective September 13, 2023, Corewell Health Laboratory will discontinue the Chlamydia Culture orderable. For patients 14 years of age and older, please order Chlamydia PCR.
• This specimen can be either a swab (genital, rectal, or throat) or a urine sample.
• The collection container is the STD-Multi-Collection Kit.
• For more information please visit: Chlamydia PCR
For patients that are under 14 years of age, a “Reference Miscellaneous Test” [LAB 848], must be ordered.
• This specimen can be either a swab (genital, rectal, or throat) or a urine sample.
• The collection container is the Aptima
• For more information please visit: APTIMA Chlamydia, NAAT, ThinPrep, Swab, Urine
As a reminder, PCR testing is also preferred for gonorrhea, when the specimen types are compatible.
Effective August 30, 2023, the COVID-19 Total Antibody test, which includes the qualitative detection of spike and nucleocapsid antibodies against COVID-19, will be discontinued as an orderable test at Corewell Health West Laboratories. Symptomatic patients suspected to have acute COVID-19 infection should be tested using a molecular assay.
To aid in the clinical diagnosis of multisystem inflammatory syndrome in children or adults (MIS-C or MIS-A), the COVID-19 IgG, Qualitative by CIA will be available as a send out test. This test is a qualitative detection of IgG antibodies against the nucleocapsid protein of COVID-19 that develop in response to natural infection with COVID-19. This test is performed on Monday, Wednesday, and Fridays, and reported within 1-5 days.
The management of sinusitis is often aided by bacterial and fungal cultures from which Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus, and occasionally aerobic Gram-negative bacilli are the most commonly recovered pathogenic organisms. The Corewell Health West Microbiology Lab has several orders available for culturing sinus specimens collected as fluid aspirates, tissue, or swabs. Though more challenging to collect, aspirates are preferred over swab cultures that often grow mixed normal upper respiratory flora for which it is difficult to interpret the clinical significance.
| Available Sinus Culture Orders | Default Specimen Type | Comments |
| Body Fluid Culture [LAB2111016]
Respiratory Culture [LAB3095] Tissue Culture [LAB2111173] |
Aspirated fluid
Swabbed collection Tissue |
For aerobic bacteria |
| Fungal Culture [LAB240] | Aspirated fluid or tissue, preferred
Swabbed collection |
For fungal organisms |
| Anaerobic Culture [LAB233] | Aspirated fluid or tissue* | For anaerobic bacteria |
This winter, West Michigan influenza infections peaked in December 2022 and significantly declined throughout February and March 2023. Now with a low prevalence of circulating influenza, using the most sensitive diagnostic test is recommended in order to obtain accurate and actionable results. Influenza antigen testing (e.g. Sofia instrument) is no longer appropriate at this time and Influenza PCR testing should be ordered when clinically indicated.