Synergistic antibacterial medicaments - contg. erythromycin and other antibiotic

New medicaments contain enythromycin (I) and at least one antibiotic (II) selected from ampicillin, carbenicillin, mezlocillin, azlocillin, amikacin, gentamicin and sisomicin. The (II):(I) wt. ratio is pref. 0.1-4:1 (esp. 0.1-2:1). Prefd. combinations are (a) (I) and ampicillin (IIa) in a (IIa):(I) ratio of 0.1-1:1 for controlling Staphylococci and other Gram-positive bacteria; (b)(I) and sisomicin (IIb) in a (IIb):(I) ratio of 0.1-0.5:1 for controlling Gram-negative bacteria; and (c) (I) and gentamicin (IIc) in a (IIc):(I) ratio of 0.1-0.5 for controlling E.coli. Combinations of (I) and (II) have synergistically increased activity against Gram-positive and/or -negative bacteria, e.g Staph.aureus and/or E.coli.