**2.2** *Staphylococcus aureus*

*Staphylococcus aureus* (*S. aureus*) is also a common bacterium in the human body. This Gram-positive bacterium possesses a cell wall bearing only a thick peptidoglycan layer followed by a plasma membrane, as shown in **Figure 2**. It is present in the mucous membranes (nose) and in the skin [14]; 30% of healthy adults have these bacteria in the nose, and about 30% has it in the skin [15]. These percentages are increased in people who work in hospitals. *S. aureus* is spread by contact with infected people or by contact with contaminated objects.

Some common infections caused by *S. aureus* are:

• Pneumonia that causes fever, shortness of breath, and cough, causing abscesses in the lungs and accumulation of pus

**Figure 2.** *Optical image of S. aureus stained using Gram's method.*


UV radiation can inhibit the bacteria growth. This is commonly used in medicine to sterilize surgical instruments. UV radiation kills the bacterium by disrupting its reproduction mechanism [16].
