In fact, whether you think of bacteria, virus or protozoa, they can all be part of the large germ family. For your information, a germ is characterized as a very small organism that can cause disease and can be shared between hosts.
Bacteria
To begin with, bacteria are the organisms with the simplest known cell structure. They are usually made up of a single loop of DNA, which sits in their "control center". It can happen that some bacteria have additional genetic material. This additional material, called a plasmid, can serve as a DNA loop that allows the bacteria to develop resistance to a certain antibiotic.
- Fact: Plasmid, in microbiology, refers to a DNA molecule that is distinct from the chromosomal DNA of an organism and has the ability to reproduce independently.
In addition to being found everywhere, bacteria have the ability to exist as single cells, in pairs, chains or clusters. Moreover, they are divided into 5 major families: cocci (spherical), bacilli (rod), spirilla (spiral), vibrios (comma) and spirochaetes (corkscrew). Finally, to return to the fact that bacteria can be found everywhere, some of them exist within our bodies and can be good for us. In other words, although some bacteria can be dangerous to our health, others can be necessary for the proper functioning of our body.
Viruses
Recognized as the smallest of the microbes, viruses have the characteristic of only being able to live or multiply when they are inside a living cell; call it the host cell.
- Microbes are microscopic organisms that are too small to be seen with the naked eye. It is a very generalized term to describe several types of life forms including bacteria, viruses and protozoa.
Viruses consist of a core of genetic material, either RNA or DNA, which is then enveloped by a protective layer known as the capsid and is primarily made up of protein. Some viruses may also have an additional layer called the envelope which is shaped like a spike.
A key fact about viruses is that they live only to reproduce and have this ability through the invasion of living cells. When a virus invades a cell, it multiplies through the cell. Since viruses live inside a host's cells, it is very difficult to treat them with drugs. This is why the immune system must be trained to deal with viruses. This is why vaccines were created.
Protozoa
Protozoa are single-celled animals that are found in most habitats around the globe. Whether asymptomatic or fatal, virtually every species of higher animals is infected with one or more species of protozoa.
Protozoa are single-celled organisms of the eukaryotic family with a relatively complex internal structure that sometimes allows them to propel themselves. Unlike viruses, protozoa have the ability to exist without a host. On the other hand, they usually feed on or at the expense of their host.
- Eukaryotes are any cell or organism with a clearly defined nucleus.
There are 4 types of protozoa that can be infectious to humans: Sarcodina, Mastigophore, Ciliophora and Sporozoa.
In summary, bacteria are organisms with a simple cellular structure. Viruses are microbes that require a host to survive and protozoa are single-celled animals.