What is the most common type of bacteria that can cause infections in humans?

The most common type of bacteria that can cause infections in humans is Staphylococcus. This genus of bacteria is particularly notable because it includes species such as Staphylococcus aureus, which is known for causing a variety of infections, ranging from minor skin infections to more serious conditions like pneumonia and bloodstream infections. The ability of Staphylococcus to thrive in various environments and form colonies that can resist certain antibiotics makes it a frequent cause of human illness.

In the context of the other types of bacteria mentioned, cocci (which include spherical bacteria) and bacilli (rod-shaped bacteria) encompass a broader category. While bacilli are indeed significant in causing infections, Staphylococcus specifically pertains to a well-documented and prevalent type of cocci. Spirilla, which are spiral-shaped bacteria, are less commonly associated with infections in everyday clinical settings. Therefore, the specificity and prevalence of Staphylococcus in clinical infections clarify its status as the most common cause of bacterial infections in humans.