In Vitro Susceptibility of Neisseria gonorrhoeae to Nine Antimicrobial Agents

Abstract

The in vitro action of nine antibiotics was tested by the agar streak method against 45 gonococcal strains isolated from penicillin-therapy failures. The penicillin susceptibility range of these strains was 0.003 to 1.32 μg/ml, and the tetracycline susceptibility range was 0.125 to 2.0 μg/ml. Minimal inhibitory concentrations of minocycline and doxycycline paralleled the activity of tetracycline and ranged from 0.125 to 1.0 μg/ml and 0.125 to 2.0 μg/ml, respectively. Rifampicin, with a narrow range of 0.5 to 1.0 μg/ml, inhibited 75% of the strains at 0.5 μg/ml. The range for cephaloridine and cephaloglycine was 0.5 to 20.0 μg/ml, but another cephalosporium derivative, cephalexin, exhibited greater activity in its range of 0.25 to 20.0 μg/ml. A semisynthetic penicillin, carbenicillin, with a range of 0.025 to 0.75 μg/ml, displayed more activity against the lower susceptible penicillin G gonococcal strains.

Recent Advances in Venereology: II Gonorrhoea and other Sexually‐transmitted Diseases

“…Increasing proportions of circulating strains of gonococci less sensitive to penicillin have been noted in most parts of the world. In many areas, for example, the USA (Martin et al , 1969) and the United Kingdom (Wilkinson, 1971) the rise has been gradually progressive although the upper limit of resistance in London remains about the same as in 1957 (Wilkinson, 1971). The degree of resistance varies geographically and as regards time, being more marked in the Far East — particularly in relation to the war zones — and in Africa, while it is least marked in Northern Europe (Table II).…”