Final answer:
The question relates to normal flora, nonpathogenic bacteria like Staphylococcus epidermidis found on the skin and mucous membranes, which become opportunistic pathogens in certain conditions, particularly in immunocompromised individuals or when medical devices are involved.
Step-by-step explanation:
The subject of the question pertains to the concept of normal flora, which are nonpathogenic bacteria that live on various parts of the body such as the skin, mucous membranes, oropharynx, and the gastrointestinal tract. These organisms include species such as Staphylococcus epidermidis, which are ubiquitous in the environment and are considered part of the normal skin flora. While they are usually nonpathogenic, acting as a defensive barrier against harmful microbes, in immunocompromised individuals or in the presence of medical devices like catheters, they can become opportunistic pathogens.
It's important to recognize that while the normal flora is highly beneficial to their host by outcompeting disease-causing organisms, pathogens can still cause disease if they enter the body through skin abrasions or collect on mucosal surfaces in large numbers. Staphylococcus aureus, including methicillin-resistant strains (MRSA), can sometimes cause opportunistic infections if they enter other parts of the body or through surgical sites. Respiratory pathogens, on the other hand, can cause infections by producing virulence factors and overcoming immune defenses.