Microbiology Terminology

MyPerioPath® is a laboratory test that screens an oral rinse specimen collection for specific bacteria known to cause periodontal disease. Bacteria are often described using their scientific name, by categorizing as gram-negative or gram-positive, and by identifying their shape. These descriptors provide us with useful information about each bacterium.  For example, it is plausible that motile bacteria are more resistant to localized treatment due to their ability to move away from areas where the environment does not support their survival.  Many health care providers are required to study microbiology through their education. This blog serves as a reminder of some of those terms with possible thoughts for consideration.  As a registered dental hygienist, I studied these terms in addition to others. I may not have used them daily in clinical practice; however I believe the more you know about bacteria, the better you can understand their role in oral and systemic disease processes.

Anaerobic bacteria: bacteria that don’t live or grow when oxygen is present. Anaerobic infections typically cause suppuration and may cause abscesses and tissue necrosis.

Thought for consideration: Do you think anaerobes that replicate in sites with low oxygen would thrive in deep, undisturbed periodontal pockets?

Bacteria: microscopic single-celled organisms lacking a distinct nucleus. They inhabit virtually all environments and come in different shapes.  Most bacteria are not pathogenic.

Bacterial Shape: there are 3-main shapes of bacteria: Cocci (spherical), Spiral (corkscrew), and Bacilli (rod).

Commensal: describes bacteria that are known to be part of the normal micro flora; however, some commensals can become pathogenic at higher concentrations.

Thought for consideration: Might this explain why poor oral hygiene or infrequent dental hygiene appointments can lead to gingivitis?

Facultative: describes bacteria that can grow in the presence or absence of oxygen.  Examples on MyPerioPath® report include Eikenella corrodens (Ec) and Capnocytophaga species (Cs).

Thoughts for consideration: Does this help us to better understand why oxygen-based treatments aren’t effective in all cases? Do you see value in knowing which pathogens are present in a periodontal infection?

Gram-negative: refers to bacteria that do not retain a purple color after the gram stain protocol is applied, rather they appear red/pink.  All four high-risk periodontal pathogens on a MyPerioPath® report are gram-negative. Gram-negative bacteria often cause infections in the bloodstream as well as in wounds or surgical sites.  Gram-negative bacteria have a protective capsule that prevents white blood cells from ingesting the bacteria, as well as protects them from certain antibiotics.

Gram-positive: refers to bacteria with a thick cell wall that retains a purple/blue color after the gram stain protocol is applied.  On a MyPerioPath® report there are two-gram positive bacteria:  Eubacterium nodatum (En) and Peptostreptococcus micros (Pm).

Gram stain: a method of classifying or describing bacteria based on their appearance under a microscope after being exposed to a certain chemical stain.

Thought for consideration: Do you think this is why antibiotics alone (without biofilm disruption) are not effective for treating some periodontal infections?

Motile (motility): refers to the ability of bacteria to move or travel to avoid conditions unfavorable to its survival.

Thoughts for consideration: Do you think these bacteria may migrate away from locally applied medicaments?  Would you consider only site-specific treatment in a patient whose primary pathogen load is comprised of bacteria classified as motile?

Non-motile: refers to bacteria that lack the ability to move under their own power.

Obligate anaerobe: bacteria that are “poisoned” by oxygen.  Eubacterium nodatum is an obligate anaerobe on the MyPerioPath® report.

Thoughts for consideration: Where do you think these bacteria thrive – deep pockets or shallower pockets?  What treatment options available to dentistry might be useful to reduce the numbers of obligate anaerobes in periodontal pockets?  If a patient’s MyPerioPath® report identifies the presence or absence of obligate anaerobes, would it influence your choice of treatment modalities?

Pathogen: an organism that causes disease.  A pathogen can be bacteria, and the words are often used interchangeably.

Taxonomic Name: the scientific name of an organism that identifies its genus and species.

The microbiology definitions in this blog are just a select few; however, from a MyPerioPath® standpoint, they are important when interpreting how to choose treatment options and customize care for our patients based on the results. The Thoughts for Consideration may have resonated with some readers. Please share your cases where these rang true or provide your “Ah-ha” moments where knowledge of microbiology helped you provide better care for your patients.

We hope you enjoyed the throwback blog. This originally posted 07/19/2019.

Kimberly Babauta, RDH, BS, BCPA
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