A bacterial infection occurs when bacteria enter or establish themselves in a host and multiply or otherwise cause harm to the host.
Bacteria are microscopic organisms, and many normally live harmlessly on or in the human body. A bacterial infection occurs when disease-causing bacteria invade tissues, multiply in an inappropriate location, or produce substances that damage the host.
Bacterial infections can affect almost any part of the body and range from mild, localized infections to life-threatening illnesses. Some can be treated with antibiotics, but antibiotic treatment is not appropriate for every bacterial infection.
QUICK FACT
Not every bacterium is harmful, and not every bacterial infection requires an antibiotic. Some infections resolve without antibiotic treatment, depending on the organism, site, severity, and the person’s health.
COMMONLY CONFUSED WITH
Viral infection — Bacterial infections are caused by bacteria, while viral infections are caused by viruses. The two can produce similar symptoms, so symptoms alone do not always reliably distinguish them.
SEE ALSO
- Bacteria
- Antibiotic
- Antimicrobial
- Antimicrobial resistance
- Infectious agent
- Viral infection
