Single-celled microorganisms that lack a membrane-bound nucleus and can live in diverse environments, including on and inside the human body.
Bacteria are a large and diverse group of microorganisms. Many are harmless or beneficial, including bacteria that form part of the normal human microbiome. Others can cause infectious diseases.
Bacteria reproduce independently under suitable conditions and can sometimes exchange genetic material, including genes that contribute to antimicrobial resistance.
QUICK FACT
Not all bacteria cause disease. The human body normally contains large communities of bacteria that can contribute to health.
COMMONLY CONFUSED WITH
Virus: Bacteria are cellular organisms that can reproduce independently under suitable conditions; viruses are not cells and require host cells to reproduce.
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