Hello and welcome to a new series of the zero to finals podcast on infectious diseases.

My name is Tom and in this first episode I'm going to be talking to you about bacteria.

And you can find written notes on this topic at zero to finals.com slash bacteria or in the infectious diseases section

of the 0 to finals medicine book. So let's jump straight in. Bacteria are single-celled

organisms that come in many shapes and sizes. Most bacteria are not harmful. Pathogenic bacteria cause infectious diseases,

which is what we're going to be talking about more here. Colonizing bacteria live and multiply

harmlessly without causing disease. The microbiome refers to the trillions of bacteria that colonized the human body,

mostly in the gut. The bacteria in the microbiome play many important roles, such as protecting

against pathogenic bacteria, synthesizing vitamins, and interacting with the nervous system.

Bacteria can be categorized into aerobic and anaerobic, gram positive and gram

negative and atypical bacteria. Learning where bacteria fall within these categories can help

determine which antibiotics will be effective.

Aerobic bacteria require oxygen, whereas anaerobic bacteria do not.

Gram-positive bacteria have a thick peptidoglycan cell wall that stains with crystal violet stain.

Gram-negative bacteria do not have this thick peptidoglycan cell wall or stain with crystal

violet stain, but they will stain with other stains.

A typical bacteria cannot be stained or cultured in the normal way. Bacteria can also

be classified based on their shapes. Rod-shaped bacteria are called bacilli and circle-shaped

bacteria are called cockay. Let's talk about bacteria, physiology and antibiotics.

The cell wall is a structure that surrounds the outer cell membrane in gram-positive bacteria.

Antibiotics that work by inhibiting cell wall synthesis can be divided into those with a beta-lactam ring, for example

penicillins, kephalosporins, and carbapenams, and those that do not have a beta-lactam

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