Final answer:
Disinfection refers to the second level of infection control which effectively kills vegetative cells and certain viruses but does not destroy resistant bacterial spores. Secondary infections may follow primary infections if the immune system is compromised or the normal microbiota is impacted by antibiotics. The process can be local, focal, or systemic based on pathogen spread.
Step-by-step explanation:
The second level of infection that does not eliminate bacterial spores is commonly referred to as disinfection. Disinfection is effective against vegetative cells and certain enveloped viruses, but not against the more resistant bacterial endospores. During the process of infection, a pathogen such as bacteria or virus enters the body through various portals of entry and if the immune system or the normal microbiota are compromised, a secondary infection can develop.
This secondary infection is usually a result of the primary disease compromising immune defenses or due to broad-spectrum antibiotics eliminating protective microbiota, which in turn allows for opportunistic pathogens to cause infection. In the context of treatments, a level of germicide that kills vegetative cells but not endospores is often used, since endospores are highly resistant to most germicidal treatments.