Macrolides

•   Erythromycin: This is the treatment of choice for Legionella, Campylobacter, and Mycoplasma pneumoniae infections and for the treatment and prevention of whooping cough. it is used to treat chlamydial and ureaplasma infections in preg­nancy or childhood, when tetracycline is contraindicated. Erythromycin hos only marginal activity against Haemophilus influenzae. it is o useful drug in the treat­ment of infections caused by Streptococcus pyogenes and pneumococci in patients allergic to penicillin.
•   Roxithromycin hos similar antibacterial activity to erythromycin but hos o longer half-life and hos improved activity against Haemophilus influenzae. it is given twice o day.
•   Clarithromycin hos significantly increased activity against organisms traditionally considered susceptible to erythromycin, plus good activity against Mycobacte­rium avium and Helicobacter pylori. The major advantage over erythromycin includes better gastrointestinal absorption and tolerance and activity against Haemophilus influenzae. lt is given once or twice o day.

Azithromycin is less active than erythromycin against staphylococci and strepto­cocci but more active against Haemophilus influenzae. lt hos o long half-life, allowing once daily dosing.