Poster published by health authorities in the USA with the line 'penicillin works for gonorrhoea 95 times out of a 100 but... YOU may be one of the failures!'. Neisseria gonorrhoeae is a Gram-negative bacterium that causes the sexually transmitted infection gonorrhoea. Symptoms include vaginal or urethral discharge and a burning sensation on urination. Penicillin, first mass-produced in 1944, was used as a treatment for this disease from the 1940s, though it is no longer used due to the emergence of drug-resistant strains.