When did scientists find out what caused infections?

People have long suspected that dirt in wounds caused infections, but why was a complete mystery. Doctors and nurses knew that wounds had to be kept clean and that it was important to remove hair and other debris from a wound before sewing it shut, but what they understood as 'clean' is very different from our understanding. The standard explanation was that God was punishing the victim, or that demons were doing it, and the cure was prayer.

The invention of the microscope about 1600 revealed strange things in pond water, but it was a long time before these were identified as living organisms, and another century or two before it finally dawned upon people that bacteria caused infections. I think the first such dangerous bacilli known was cholera, which happened in 1854 in England. By 1870 doctors began to believe that dirty hands and surgical equipment caused infections; the campaign to get doctors to wash their hands ran into stiff opposition. But all this vanished when Koch and Pasteur proved that bacteria caused infections (viruses weren't discovered until about 1920).

It was a doctor in Vienna, Austria in 1847, Dr. Ignaz Semmelweiss.

https://waterandhealth.org/newsletter/new/feb-1998...

In the mid 19th century Louis Pasteur discovered germs and bacteria.

At 3:27 pm, exactly. They thought they'd got it around 2-ish, but it was a false alarm.

in the 1900s scientists started looking at bacteria through microscopes and began to understand this unknown world was very much a part we didn't know about

Penisfingers