Synergy between sulphadiazine and trimethoprim against Escherichia coli has been demonstrated in culture media not containing lysed horse blood despite the presence of pus or a pus extract which inhibited the action of each drug separately. Synergy may therefore be important where pus is present in vivo.

The efficacy of 5 drugs was tested against experimental Babesia felis infection in domestic cats. Two of the drugs, rifampicin and a sulphadiazine-trimethoprim combination, appeared to have an anti-parasitic effect, but were inferior to primaquine. The other 3 drugs, buparvaquone, enrofloxacin and danofloxacin, had no significant anti-babesial effect.

Focal encephalitis occurred in a girl with activation of chorioretinitis which on clinical and serological grounds was taken to be caused by toxoplasma. The encephalitis and acute ocular inflammation resolved with treatment with pyrimethamine and sulphadiazine. This is presumably an example of reactivation of congenital cerebral toxoplasmosis.

A 24-year-old man who was initially thought to have nocardiosis of his mediastinal lymph node which progressed to involve his right lung, had to undergo a right pneumonectomy when he failed to respond to treatment with sulphadiazine. Histology of the right lung specimen and a subsequent axillary lymph node biopsy revealed that he actually had lymphocyte-depleted Hodgkin's disease.