What classification of bacteria typically causes diseases?

The classification of bacteria that typically causes diseases is pathogenic bacteria. These are microorganisms capable of causing illness or disease in a host organism, which can include humans, animals, and plants. Pathogenic bacteria invade host tissues, evading or overcoming the host's immune defenses, and can produce toxins that contribute to the symptoms of illness.

Understanding pathogenic bacteria is crucial in the context of infection control, particularly in environments like barbershops where skin breaches or compromised hygiene can lead to infection. For example, commonly known pathogenic bacteria include strains of Staphylococcus and Streptococcus, which can lead to skin infections or systemic illnesses.

In contrast, non-pathogenic bacteria do not cause disease and often play important roles in processes such as digestion or nutrient cycling. Commensal bacteria live on or in a host without causing harm and may even provide benefits, such as contributing to the host’s immune defense. Mutualistic bacteria engage in a symbiotic relationship, benefiting both the bacteria and the host. Thus, while all these categories describe different interactions between bacteria and hosts, only pathogenic bacteria are specifically associated with disease causation.