Final answer:
Mycoplasma pneumoniae is the most common cause of 'walking pneumonia,' particularly among adolescents and young adults due to their close contact environments like colleges and military bases. Infants are more often affected by RSV, and the elderly by Streptococcus pneumoniae.
Step-by-step explanation:
Mycoplasma pneumoniae is the causative agent of walking pneumonia, also known as primary atypical pneumonia. This type of pneumonia is often mild and self-limiting, with symptoms including low fever and a persistent cough. It is especially common amongst adolescents and young adults, frequently occurring in places where people are in close contact, such as college campuses and military bases.
Mycoplasma pneumoniae infections are not typically associated with the very young or the elderly in terms of being the most common agent of lower respiratory tract infections. Rather, respiratory syncytial virus (RSV) is more common among infants, while older adults may be more susceptible to bacterial pneumonia caused by pathogens like Streptococcus pneumoniae.