Lincomycin in selective medium for the isolation of Neisseria gonorrhoeae

For the isolation of gonococci, the selective culture medium containing colistin, vancomycin, nystatin and trimethoprim which is usually employed has been changed by substituting lincomycin for vancomycin. The best result was obtained if a concentration of 1/2 mug lincomycin/ml medium was used. This is a concentration of lincomycin considerably lower than that which by other investigators is considered most suitable for the purpose. However, the culture medium used by the latter did not contain trimethoprim. The use of 1/2 mug lincomycin/ml instead of vancomycin 3 mug/ml in the medium caused a slightly more pronounced growth of unwanted organisms. In spite of this, the results obtained by the medium containing lincomycin showed that the number of samples positive for gonococci was 7 per cent higher, and that the number of patients with gonococcal infections to be discovered was 4 per cent higher than the numbers obtained by the medium containing vancomycin. The results were considered highly favourable and, accordingly, by now our laboratory uses 1/2 mug lincomycin/ml medium in the routine isolation of gonococci.