AAM Project - Methicillin-resistant Staphylococcus aureus

AAM Project

Methicillin-resistant STAPHYLOCOCCUS aureus (MRSA)

ABOUT MRSA

MRSA is a strain of Staphylococcus aureus that is resistant to methicillin
Most common in hospitals where patients have open wounds that are prone to infections
Prime example of antibiotic resistance in the medical field

Taxonomy

Domain: Bacteria
Kingdom: Eubacteria
Phylum: Firmicutes
Class: Bacilli
Order: Bacillales
Family: Staphylococcaceae
Genus: Staphylococcus
Species: Staphylococcus aureus

Visualizing the Microbe

The color shows us that the image is a grain strain and it is gram-positive because the bacteria show up purple colored.
The peptidoglycan layer in MRSA is thick and absorbed the violet dye heavily.

The morphology indicates that it is coccus (or cocci in clusters) as they are clumped together as small purple spheres.
- More specifically, they are staphylococci due to the specific clumping pattern seen in the image.
SEM (Scanning Electron Microscope) used for the both images.

Diagnostics Tests

The image shows that MRSA has a little of clear areas around the colonies, indicating that little or no beta-hemolysis is present within MRSA. There is a change in color to appear yellowish but very faintly indicating that it is beta-hemolysis and not gamma. Beta-hemolysis indicates that there is a total lysis of the red blood cells in the area via an exotoxin around the colonies of MRSA.

Mannitol is selective for S. aureus which is very similar to MRSA. From the image, it is clear that MRSA also ferments mannitol as shown by the yellow color in the image. This indicates that the pH has been lowered when mannitol is fermented and changes the color of the phenol red dye to yellow.

The image shows that a clear zone around MRSA has been formed on the DNase plate indicating that it is a positive test. This is due to the polymerization of DNA around the colony leading to the breaking down of the methyl-green DNA complex on the plate.

Gram-staining reveals that MRSA is gram-positive. This indicates that MRSA has a thick peptidoglycan wall which has absorbed the purple dye, showing a relatively purple image under the microscope.

Image of E. coli is not for MRSA or S. aureus but shows the same test result as would MRSA shows. MRSA would show both a change in color (red to yellow) and gas production, which is seen in the example with E. coli. This indicates that carbohydrates are present when fermentation occurs.

Although this isn’t MRSA, S. aureus shares many similarities to MRSA. This test result of bubbles indicates that the test is positive for catalase as oxygen bubbles are present, showing a response.

Disease and Treatment

DISEASE:

MRSA is a pathogen and can primarily cause skin infections and sometimes pneumonia.
- Extreme cases are found when left without treatment and MRSA can lead to sepsis.
S. aureus is normally found within our nasal cavity and is the non-methicillin resistant form of MRSA.
- MRSA is typically non-harmful if there are no open wounds for MRSA to infect but can still spread from person to person and potentially cause harm to someone with an open wound.
MRSA can be found anywhere but most commonly is found within hospitals where patients are at risk to infection by contact with other patients or unclean medical equipment.

TREATMENT:

MRSA can be prevented by maintaining cleanly behaviors as well as cleaning shared items that are used to create a wound or around open wounds (razors, needles, etc.)
- These behaviors include: washing hands, sanitizing equipment, keeping cuts and open wounds clean and covered until they are healed or closed, and not sharing items such as razors or needles with others.
Some common oral antibiotics are effective in treatment: clindamycin, trimethoprim/sulfamethoxazole (Bactrim), tetracycline (doxycycline or minocycline [Minocin]), or a linezolid (Zyvox)
Besides taking antibiotics, the infection may be drained or the use of ointments and medicinal soap may be implemented.

WHY SHOULD WE CARE?

MRSA is important to prevent spread within settings like a hospital where spread of infections can be detrimental to patients that are recovering from an open wound (surgical or not). When left untreated, MRSA can become life-threatening, so practicing good hygiene and keeping medical equipment sanitized will play a large role in preventing the spread of MRSA in hospitals.
MRSA also is evidence for the antimicrobial-resistance movement in lots of different pathogens and demonstrates the effects of overuse of antibiotics with common pathogens like S. aureus in the medical field. MRSA can be more difficult to treat than strains like S. aureus because of its resistance to methicillin and other antibiotics more commonly used to treat S. aureus.

AGRICULTURAL APPLICATION OF MRSA:

MRSA does have a strain associated with livestock (LA-MRSA) where MRSA strains have emerged. This is due to overuse of antibiotics outside of humans but also with livestock in agricultural settings leading to the development of MRSA strains that are resistant to those antibiotics used in livestock (pigs or companion animals in specific). There is potential for animal to human transference with LA-MRSA and vice versa which could be cause for concern

References

Olmsted R, Calfee DP, Chopra V, Popovich K. 2020. MRSA101. CDCLivonia.

Seubert H. 2008. Classification. MRSA.

Mehndiratta PL, Bhalla P. 2014. Use of antibiotics in animal agriculture & emergence of methicillin-resistant Staphylococcus aureus (MRSA) clones: need to assess the impact on public health. The Indian journal of medical research. Medknow Publications & Media Pvt Ltd.

CDC. 2019. General Information. Centers for Disease Control and Prevention. Centers for Disease Control and Prevention.

Lambert M. 2011. IDSA Guidelines on the Treatment of MRSA Infections in Adults and Children. American Family Physician.

Harris A. 2015. Patient education: Methicillin-resistant Staphylococcus aureus (MRSA) (Beyond the Basics). UpToDate.

Public Health Image Library (PHIL). 2019. MRSA Bacteria Photo 1. Centers for Disease Control and Prevention. Centers for Disease Control and Prevention.

Public Health Image Library (PHIL). 1998. Bacteria under Microscope MRSA (methicillin-resistant Staphylococcus aureus). bacteriainphotos.

Hans N. 2019. Staphylococcus aureus Bacteria. Microbiology in Pictures.

Gathany J. 2014. Details - Public Health Image Library(PHIL).

Arunachalam K, Ramanathan S, Nivetha A, Annapoorani A. 2019. Anti-virulence potential of 2-hydroxy-4-methoxybenzaldehyde against methicillin-resistant Staphylococcus aureus and its clinical isolates. Research Gate.

Natalie. 2019. Fast facts on methicillin-resistant Staphylococcus aureus (MRSA). BCIT News.

Hans N. Bacteria photos: The catalase test. The catalase test; positive catalase test The catalase test result with Staphylococcus aureus Principle of the catalase test.

Hans R. 2020. Phenol Red Fermentation Test – Principle, Procedure, Uses and Interpretation. Laboratory Insider- Medical research advances and health news. Blogger.

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