Most human pathogens are classified as mesophiles.
Mesophiles thrive at moderate temperatures, typically between 20°C and 45°C (68°F and 113°F). Since the average human body temperature is around 37°C (98.6°F), it provides the ideal environment for these organisms to grow and multiply.
In contrast, psychrophiles prefer colder temperatures, typically below 20°C (68°F), while thermophiles are suited for higher temperatures, above 45°C (113°F). Additionally, acidophiles thrive in acidic environments, and saccharophiles prefer sugary conditions. These conditions do not align with the human body, making mesophiles the most adaptive group for survival and infection in humans.