Cefaclor is a second generation cephalosporin antibiotic which has stability against b-lactamase inactivation and possesses a broad spectrum of activity. Cefaclor is active against the following organisms in vitro. Alpha and beta haemolytic Streptococci, Staphylococci; including coagulase-positive, coagulase negative and penicillinase-producing strains, Streptococcus pneumoniae, Streptococcus pyogenes (Group A b-haemolytic Streptococci), Branhamella catarrhalis, Escherichia coli, Proteus mirabilis, Klebsiella species Haemophilus influenzae, including ampicillin-resistant strains. Cefaclor is generally effective in the eradication of Streptococci from the nasopharynx.