Which of the following macrolides is commonly used for respiratory infections?

Clarithromycin is a macrolide antibiotic that is widely used in the treatment of respiratory infections due to its effectiveness against a range of pathogens that are commonly responsible for such conditions. This includes Streptococcus pneumoniae and Haemophilus influenzae, which are frequent causes of pneumonia and bronchitis. Its mechanism of action involves inhibiting bacterial protein synthesis, thereby stopping the growth of bacteria.

In addition to its antibacterial properties, clarithromycin also has good oral bioavailability and a favorable side effect profile compared to some other antibiotics, which contributes to its popularity in treating infections in an outpatient setting. The drug is part of the macrolide class, which is particularly valued in cases where patients may have allergies to beta-lactam antibiotics like penicillins.

The other antibiotics listed serve different purposes: vancomycin is primarily used for serious Gram-positive infections, especially MRSA; ciprofloxacin is a fluoroquinolone that is more effective against Gram-negative bacteria; and linezolid is reserved for specific resistant infections, typically in hospital settings. Thus, clarithromycin stands out as the primary choice for respiratory infections among the options provided.