Ask Mr Brain...all will be explained

Who invented antibiotics? Like many discoveries and inventions, antibiotics were not the result of just one person's work. At the beginning of the century, what are now considered minor infections could often result in death, since there were no drugs available to kill off the bacteria.

French chemist Louis Pasteur (1822-95) was the first successful fighter in the battle against bacteria. His experiments led to the modern germ theory of infection. He noticed that one species of micro-organism could kill another, which was the basis of antibiotics.

Pasteur's work was taken a step further by the German bacteriologist Paul Ehrlich (1854-1915). His work was in the area of selective toxicity, that is finding drugs which would kill bacteria but not humans.

He was determined to find a cure for syphilis. The only treatments available at that time were so poisonous they killed the patient as well as the bacteria. Although many of his experiments were failures, Ehrlich was an example of perseverance. In his search for a cure for syphilis, Ehrlich had 605 failures. But the 606th - salvarsan - worked.

Salvarsan was extremely difficult to administer to patients and Scottish bacteriologist Alexander Fleming (1881-1955) was one of the few doctors who learned the technique from Ehrlich. The outbreak of World War I saw many soldiers dying from simple infections and Fleming was convinced there must be something which could fight these infections.

After the war he continued his research. Ironically, after all his hard work Fleming discovered a cure by accident.

Fleming carried out so much work that his laboratory was usually a mess. In 1928, one day he was cleaning some Petri dishes in which he had been growing bacteria. One of the dishes had mould growing on it, which apparently was not unusual, given the state of his laboratory. However, he noticed the mould had killed off the bacteria in the dish.

The mould was the antibiotic penicillin, one of the most important medical discoveries of the century. However, little attention was paid to his discovery until the outbreak of World War II renewed the need for something which could cure bacterial infections.

Where did the saying 'by hook or by crook' come from? The saying 'by hook or by crook', meaning to try to get something using all possible means, dates back to medieval England.

At that time, villagers were allowed to collect fallen branches and dead wood from trees on common land. They were allowed to take any wood they could reach with the aid of either a billhook - a tool used for pruning and chopping - or a shepherd's crook. This right to take wood on common land was thus defined as any wood which could be reached 'by billhook or shepherd's crook'. This eventually came to be applied to trying to get anything using all possible means.