Indications for Macrolides Macrolides are active against Aerobic and anaerobic gram-positive cocci, except for most enterococci, many Staphylococcus aureus strains (especially methicillin-resistant strains), and some Streptococcus pneumoniae and S pyogenes strains Mycoplasma pneumoniae Chlamydia trachomatis Chlamydophila pneumoniae Legionella species Corynebacterium diphtheriae Campylobacter species Treponema pallidum Cutibacterium acnes (formerly Propionibacterium acnes) Borrelia burgdorferi Bacteroides fragilis is resistant.