Activity of gentamicin against Pseudomonas and hospital Staphylococci.

Gentamicin is a new basic antibiotic complex isolated from an actinomycete, Micromonospora purpurea, in the Research Laboratories of the Schering Corporation, New Jersey. It consists of two components, referred to as gentamicin C1 and gentamicin C2, which are closely related in structure and have a similar antibacterial spectrum. Both substances contain a 2-deoxystreptamine component and are chemically related to the streptomycin group of antibiotics (Rosselet et al., 1963). Gentamicin is supplied as the sulphate, which is a white powder readily soluble in water. Gentamicin has been shown to be bactericidal in vitro against a wide range of Gram-positive and Gram-negative bacteria, including hospital drug-resistant strains of Staphylococcus aureus and coliform bacilli, and has outstanding activity against Pseudomonas pyocyanea (see White, 1963 ; Weinstein et al., 1963 ; Rubenis et al., 1963; Rabinovich et al., 1963). Early clinical trials showed that the antibiotic is effective in the treatment of infections of the urinary tract due to many Gram-negative bacilli, including Ps. pyocyanea (Bulger et al., 1963; Jao and Jackson, 1963; Brayton and Louria, 1964; Klein et al., 1964), but if the blood level rises to about 15 ,ug./ml. or more there is a danger of severe vestibular damage (Jao and Jackson, 1964). Stone et al. (1964, 1965) reported the successful treatment of severe burns with Ps. pyocyanea septicaemia, both systemic treatment and local gentamicin ointment being used. The present investigation w~as undertaken in order to compare the activity of gentamicin with that of other streptomycin-like antibiotics against strains of Staph. aureus and coliform bacilli isolated in a British hospital.