For an 18-year-old patient with a Mycoplasma pneumoniae infection, which alternative treatment is appropriate if erythromycin cannot be used?

Azithromycin is appropriate as an alternative treatment for Mycoplasma pneumoniae infection, particularly when erythromycin cannot be used due to allergy or other contraindications. Both erythromycin and azithromycin belong to the macrolide class of antibiotics, which are effective against atypical pathogens like Mycoplasma pneumoniae.

Azithromycin not only has a similar mechanism of action to erythromycin, inhibiting bacterial protein synthesis, but it also has a longer half-life, allowing for once-daily dosing and a shorter treatment course in many cases. This can enhance patient compliance and ease of administration.

Other options, while antibiotics, are not typically used as first-line treatments for Mycoplasma infections. Cephalexin is a first-generation cephalosporin that is effective against certain types of bacteria but does not cover atypical pneumonia pathogens like Mycoplasma. Amoxicillin, though effective against various infections, is associated with a different spectrum of activity that does not target Mycoplasma pneumoniae well. Clindamycin is effective against anaerobes and some gram-positive bacteria but is not recommended for treating Mycoplasma pneumoniae due to its limited efficacy against atypical pathogens.

Thus, azithromycin stands