What is the first-line antibiotic for atypical pneumonia caused by M. pneumoniae?

The first-line antibiotic for atypical pneumonia caused by Mycoplasma pneumoniae is doxycycline. This choice is particularly effective because tetracyclines, including doxycycline, are known to be effective against atypical pathogens such as Mycoplasma, which lacks a cell wall and does not respond to beta-lactam antibiotics like amoxicillin.

Doxycycline works by inhibiting protein synthesis in bacteria, which is crucial for managing infections caused by atypical organisms. It is also favored for its oral bioavailability, good tissue penetration, and a favorable side effect profile.

While azithromycin is also effective against M. pneumoniae and is a common alternative, doxycycline is often preferred due to considerations of antibiotic resistance patterns and patient population factors, such as age and comorbidities. Levofloxacin is another option but is usually reserved for more severe cases or when patients have contraindications to other first-line therapies.

Thus, doxycycline stands out as the preferred first-line treatment for atypical pneumonia caused by Mycoplasma pneumoniae.