Studies in vitro of the sensitivity to trimethoprim and sulphonamides of nine strains of N. asteroides, two strains of N. caviae, and one of N. blackwellii are presented. No unequivocal evidence of synergism was found. Despite this, the inclusion of trimethoprim in the drug regime when sulphonamides are used in the treatment of nocardiosis is suggested on empirical grounds.

Colebrook & Kenny (1936), Colebrook, Buttle & O'Meara (1936) and, later, others showed that some time must elapse after bacteria are inoculated into media containing sulphonamide before an inhibitory effect is produced. Multiplication of the organism occurs in the interval. Subsequently, Wolff& Julius (1939) concluded that sulphonamides act on bacteria only when they are multiplying, and O'Mear...