Certain types of bacteria, such as Haemophilus, are able to colonize most people without causing any symptoms. Consequently, people with healthy immune systems often do not develop any symptoms from a Haemophilus infection unless they become exposed to a dangerous or pathogenic strain.
Identification
Haemophilus influenzae, according to Todar's Online Textbook of Bacteriology, is a gram negative bacteria, which means that it lacks an outer cell wall. Haemophilus bacteria get their name because they need a precursor of the heme molecule (a component of blood) to grow. These bacteria are non-motile, which means that they do not have the ability to move on their own.
Location
Haemophilus bacteria are able to live quite easily in the human body, explains Doran's Online Textbook of Bacteriology. In fact, the bacteria can be found in the nose and throat region in 75 percent of healthy humans. Although these bacteria are frequent colonizers of the human respiratory tract, they rarely cause disease unless a person is infected with a pathogenic strain.
Infections
Haemophilus influenzae typically causes infections in the head and respiratory system, according to the University of Virginia Health System. The most common illnesses associated with this bacteria are pneumonia and infections of the eye, middle ear and sinuses. One strain of Haemophilus influenzae (known as type B) is able to cause meningitis and epiglottitis, but vaccines for this strain have mostly eliminated these types of Haemophilus infections.
Diagnosis
In general, physicians can diagnose a bacterial infection based on the patient's symptoms and a physical examination. To accurately diagnose Haemophilus as the cause of an eye, sinus, ear or lung infection, a physician may take a sample of fluid from the infected area and culture it. Because the Haemophilus bacteria require heme to grow, they can be cultured on special growth media called chocolate blood agar.
Treatment
Treatment of a Haemophilus infection is usually done with prescription antibiotics. The choice of antibiotic depends on the severity and type of infection, according to the Merck Manual. Doxycycline, and the cephalosporin and fluoroquinolone classes of antibiotics, can be used to treat most invasive cases. Milder infections caused by Haemophilus can be treated using amoxicillin or macrolide antibiotics.
