Infections can be caused by bacteria, viruses, fungus or mycobacteria. Bacterial infections such as Strep cause Strep Throat. Staph infections have become more common.They have many forms.One form, called Staph epidermis lives normally on our skin. They can acquire new genes which make them more resistant to several antibiotics.These are commonly called MRSA. Viruses are smaller than bacteria and require living hosts to multiply.When a virus enters the body, it invades the cells and takes over the cell machinery, redirecting it to produce the virus. The most important distinction between bacteria and viruses is that antibiotics kill bacteria but they are not effective against viruses. Several diseases, such as pneumonia, meningitis , or diarrhea are caused by either bacteria or viruses.

Fungus can be found in the soil, on plants, and on our skin and mucus membranes. Most fungus are not dangerous.For example, penicillin and bread use ingredients made by fungus.The symptoms of fungal diseases depend on the type of infection and the location in the body. Patients who have a weakened immune system, such as HIV, chemotherapy or transplant have a higher likelihood of developing fungal infections. Mycobacteria are slow growing bacteria.They have properties of fungus and bacteria.They are also found in nature among plants and soil. The most dangerous one causes tuberculosis.This can be spread easily in the air, thereby infecting many people.Tuberculosis and other mycobacteria need several antibiotics to be treated effectively. In addition, therapy can last for one year or longer.