Difference Between MRSA and MSSA

The key difference between MRSA and MSSA is that MRSA stands for methicillin-resistant Staphylococcus aureus referring to the strains of Staphylococcus aureus that are resistant to β-lactam antibiotics, while MSSA stands for methicillin-sensitive Staphylococcus aureus referring to the strains of Staphylococcus aureus that are susceptible to β-lactam antibiotics.

Methicillin is a narrow-spectrum β-lactam antibiotic that helps to combat bacterial diseases. Staphylococcus is a genus of bacteria that cause skin infections, blood poisoning, pneumonia and other infections. Some strains of Staphylococcus aureus are resistant to a range of β-lactam antibiotics. The term that refers to these resistant strains is “Methicillin-Resistant Staphylococcus aureus” or MRSA. On the other hand, some strains of Staphylococcus aureus are sensitive or susceptible to these β-lactam antibiotics. The term used to refer to this group of bacteria is “Methicillin-Sensitive Staphylococcus aureus” or MSSA.

1. Overview and Key Difference
2. What is MRSA
3. What is MSSA
4. Similarities Between MRSA and MSSA
5. Side by Side Comparison – MRSA vs MSSA in Tabular Form
6. Summary

What is MRSA?

Methicillin-resistant Staphylococcus aureus (MRSA) refers to a group of Staphylococcus aureus strains that are resistant to β-lactam antibiotics. They are gram-positive bacteria. They have gained resistant over time due to horizontal gene transfer and natural selection. Since MRSA are resistant to multiple drugs, it is really difficult to treat the diseases caused by these bacteria. They are very common in hospitals, prisons, and nursing homes. They easily infect people with weak immune systems.

Figure 01: MRSA

The most common diseases caused by MRSA are skin infections, pneumonia (lung infection) and other infections. However, MRSA infections can be prevented by maintaining good hygiene, keeping cuts, wounds, scrapes covered, avoiding sharing of personal items such as towels and razors, and getting care infections early.

What is MSSA?

MSSA refers to the Staphylococcus aureus bacterial strains that are susceptible to methicillin and a range of β-lactam antibiotics. Generally, many Staphylococcus aureus strains are methicillin sensitive. These bacteria normally cause skin infections such as pimples, boils, abscesses or infected cuts. But, they also can cause pneumonia. Since they are susceptible to antibiotics, the MSSA diseases can be treated easily by the correct doses of antibiotics.

Figure 02: Staphylococcus aureus

Spreading of MSSA can be prevented easily by frequent hand-washing with medicated soap or using alcohol-based hand sanitizers. Furthermore, we can easily prevent MSSA by keeping cuts and wounds clean, dry and covered.

What are the Similarities Between MRSA and MSSA?

MRSA and MSSA are Staphylococcus aureus
Both cause skin infections and pneumonia.
Maintaining good hygiene and keeping wounds and cuts covered and clean are some easy methods that can prevent the spread of MRSA and MSSA.

What is the Difference Between MRSA and MSSA?

MRSAs are Staphylococcus aureus strains that are resistant to numerous antibiotics. In contrast, MSSAs are Staphylococcus aureus strains that are susceptible to antibiotics. Thus, this is the key difference between MRSA and MSSA. Moreover, MRSA is more virulent than MSSA. Thus, MRSA causes a high mortality rate than MSSA.

Below is a comprehensive summary of the difference between MRSA and MSSA.

Summary – MRSA vs MSSA

MRSA and MSSA are two groups of Staphylococcus aureus bacterial strains. MRSA is methicillin-resistant, while MSSA is methicillin susceptible. So, this is the key difference between MRSA and MSSA. Furthermore, MRSA is more virulent and cause a higher mortality rate, while MSSA is less virulent and cause a low mortality rate. MRSA disease cannot be treated by antibiotics, while MSSA diseases can be easily cured by antibiotics.

Reference:

1. Nichols, Hannah. “MRSA: Treatment, Causes, and Symptoms.” Medical News Today, MediLexicon International, 13 Nov. 2017, Available here.
2. “What Is MSSA?” Healio, Available here.

Image Courtesy:

1. “Human neutrophil ingesting MRSA” By National Institutes of Health (NIH) – National Institutes of Health (NIH), (Public Domain) via Commons Wikimedia
2. “staphylococcus aureus, bacteria” (CC0) via Pixino