If you're interested in understanding more about staph colonization, mannitol salt agar (MSA) plates offer an easy, at-home option for basic testing. Here’s a simple guide to help you self-test and interpret your results.
This guide is for informational purposes only and is not intended to diagnose or treat any disease.
What is a Mannitol Salt Agar (MSA) Plate?
MSA is a specialized growth medium that supports the growth of Staphylococcus bacteria. Its high salt concentration discourages the growth of other bacteria, and it includes mannitol, which turns the plate from red to yellow if Staphylococcus aureus is present due to acid production.
Understanding the Difference Between MARCoNS and Staphylococcus aureus
Staphylococcus aureus (S. aureus): This is a common bacterium that can colonize the skin and nasal passages. While many people carry it without any issues, certain strains of S. aureus can produce toxins and cause infections ranging from mild skin irritations to severe illnesses like pneumonia or bloodstream infections. On MSA plates, S. aureus ferments mannitol, turning the agar yellow.
Multiple Antibiotic-Resistant Coagulase-Negative Staphylococci (MARCoNS): These are coagulase-negative staph species, meaning they do not produce the enzyme coagulase, which helps clot blood. MARCoNS are often found in patients with chronic inflammatory conditions, such as Chronic Inflammatory Response Syndrome (CIRS), particularly after mold exposure. MARCoNS are biofilm-forming bacteria that are often resistant to multiple antibiotics, making them more difficult to treat. Unlike S. aureus, MARCoNS usually do not ferment mannitol, so the agar remains red.
Both S. aureus and MARCoNS can coexist in the nasal passages, often forming resilient biofilms that complicate treatment. Identifying which bacteria are present is critical for tailoring an effective treatment strategy.
How Staph-Produced Neurotoxins Can Affect You
Certain strains of Staphylococcus produce toxins, such as alpha-toxin or superantigens, that can act as neurotoxins. These toxins can:
Disrupt nerve signaling by damaging cell membranes and causing inflammation.
Interfere with normal immune function, leading to chronic inflammation.
Contribute to symptoms like brain fog, fatigue, and headaches, especially in individuals already dealing with systemic inflammation or immune dysfunction.
Form biofilms that can harbor other pathogens and toxins, perpetuating inflammation and immune system activation
Materials You’ll Need
Mannitol Salt Agar (MSA) plate (available on Amazon: https://a.co/d/1wVFZ5G )
Cotton swab (preferably sterile to avoid contamination, but not essential)
Disposable gloves (optional but recommended)
Clean space for testing
Step-by-Step Instructions
Step 1: Prepare Your Space
Find a clean, well-lit area to conduct the test.
Wash your hands thoroughly and consider wearing disposable gloves to prevent contamination.
Step 2: Collect the Sample
Take a cotton swab and gently insert it into one nostril, swabbing the inner surface. Repeat in the other nostril with the same swab. Swab inside the tip of the nose, as this area can harbor Staph.
Carefully avoid touching the swab to any surface other than the inside of the MSA plate.
Step 3: Inoculate the MSA Plate
Open the MSA plate lid carefully to avoid contamination.
Gently roll the swab across the surface of the agar, taking care not to press too hard as this can damage the agar medium.
Close the lid and label the plate with the date and sample location.
Step 4: Incubate the Plate
Store the plate in a warm, dry area (ideally at room temperature, around 70°F to 77°F) away from direct sunlight.
Allow it to sit undisturbed for 24 to 48 hours.
Step 5: Observe and Interpret Results
After incubation, check the plate for the following signs:
Growth: If bacteria grow on the plate, it may indicate the presence of Staphylococcus.
Yellow Color: If you see a yellow color change in the agar around the colonies, this suggests the presence of Staphylococcus aureus.
No Color Change: Growth without a yellow color change may indicate the presence of Staph species other than S. aureus, although is rare as the mannitol salt in not conducive to species other that S. aureus.
Important Notes
This is a preliminary test: An MSA plate can indicate staph presence but cannot diagnose infection or differentiate specific strains conclusively. For a more definitive analysis, consider sending a sample to a lab or consulting a healthcare professional. MicrobiologyDX has developed a MARCoNS test that is widely used by functional practitioners, it is available from Nutrition With Judy (https://www.nutritionwithjudy.com/shopping/functional-tests/marcons-testing)
Biofilms: An MSA plate cannot detect biofilms. The MicrobiologyDX test mentioned above does include an assessment of biofilm levels for those interested in finding out more information about their nasal microbiome.
Follow Safety Precautions: After observing your results, dispose of the MSA plate properly by sealing it in a plastic bag and discarding it in the trash.
Next Steps
If your test indicates staph colonization, a healthcare provider can guide you on treatment options. This may include prescription antibiotics, biofilm disruptors, or other interventions. Biofilm Clear products may help reduce biofilm presence and support nasal health. It is important to note that Staph colonization of the nasal cavity is common and is not the same as an active Staph infection.
By understanding the nuances of staph colonization, you can take proactive steps toward improving your health and well-being.
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