A common misconception about microorganisms like bacteria is that most of them are pathogenic. This raises another question – what are pathogens? A pathogen is an organism which causes a disease by infecting the body of the host. It acts as a parasite and is dependent on a host for nutrition.
There are only about 5% of bacteria that are pathogenic and human bacterial pathogens make up less than 1% of it. Most of the pathogenic bacteria are dependent on the host for their daily nutrition and most come under the Staphylococcus genus of bacteria. Examples are S. aureus, S epidermidis, S. enteritis, etc. They are responsible for many types of infections in humans such as skin infections, skin lesions and food poisoning.
Most of the bacteria are free-living in nature and can perform various metabolic functions themselves. On the contrary, pathogenic bacteria are dependent on the host for various factors that help them for growth. A human host provides nutrients and a warm and moist environment to the pathogens. Since the human body has a constantly maintained temperature most of the time, this makes humans one of the best hosts.
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