Bacteria, Viruses, Moulds — Why Antibiotics Don't Touch a Cold

Three families in one name

The swimming things of piece 1; the lactic bacteria, mould and yeast of piece 2. We called them all microbes. But that word only means 'small living thing'. Apart from being small they share nothing.

Inside the name live three families: bacteria, fungi and viruses. They differ from each other as much as a person differs from a tree. Let's look inside each house.

Bacteria — a one-room house

A bacterium is a living thing made of one cell. A house with a single room. Eating, breathing and the blueprint all sit in that one room. Given food, it eats by itself, grows, and splits in two.

The splitting is frightening. Under good conditions it doubles every twenty minutes. One in the evening can be billions by morning. That is why spoiled food goes bad overnight. Of course, when the food runs out, it stops.

Three shapes: balls, rods and spirals. Kimchi's lactic bacteria are rods, the stomach's Helicobacter is a spiral, the acne bacterium is a rod.

Fungi — a house woven from threads

A fungus has a separate room inside its cell for the blueprint: the nucleus. In this it is closer to a person than to a bacterium, since our cells have nuclei too.

Most grow as long threads. The fuzz on old bread is those threads. Bundle the threads and you get a mushroom — mushrooms are fungi. Makgeolli's nuruk, athlete's foot, and the blue mould that gave us penicillin all live here. Yeast is a one-room fungus that does not make threads.

Viruses — not a house, a letter

A virus is not a cell. Not a house. It is one sheet of blueprint wrapped in a coat. More like a letter. It does not eat. It does not grow. It cannot multiply on its own.

So how does it spread? It enters someone else's house. Push the letter into a cell and the cell reads the blueprint and builds the virus for it. The cell is a factory; the virus is an order form. The factory prints thousands of copies, the cell bursts, and the letters move on to the next house.

It is about a hundredth the size of a bacterium. If a bacterium is a football, a virus is a pea. The merchant's lens of piece 1 could not see it. Its face was first seen in the 1930s, with the electron microscope.

People knew it existed before they saw it, thanks to a tobacco disease. Juice from sick leaves was passed through a filter too fine for bacteria — and the filtered juice still spread the disease. Something smaller than a bacterium was there. It happened in Delft, the merchant's own town.

So antibiotics do nothing for a cold

An antibiotic breaks a bacterium's wall or stops its factory. Bacteria have walls and factories, so it works. A virus has neither. There is nothing to break.

Colds, flu and COVID are all viruses. Take antibiotics and the virus is untouched; the only casualties are the neighbours sharing your meals in the gut. Piece 5 tells that story. Drugs and vaccines against viruses are a different matter — piece 7.

A little further in

Then is a virus alive?

It does not eat, does not grow, cannot multiply alone. In the 1930s a scientist turned a virus into crystals, like salt, and kept them in a jar. Years later he dissolved them in water and they spread disease again.

So scientists still argue. Does the virus belong on the list of living things or not? The question is really the door to a larger one: what does it mean to be alive? There is no answer yet. It is a question that can stay open.

Now you can tell the three families apart. Piece 1 said it took two hundred years after seeing them to learn that they cause disease. At the end of those two hundred years a doctor asked his colleagues to wash their hands. Nobody believed him. Next piece.

The question that remainsSomething that neither eats nor grows, yet multiplies — should we call it alive?