Pathogen name and classification Haemophilus influenzae — a small Gram negative coccobacillus isolated primarily from the human respiratory tract. Six serotypes, based on capsular polysaccharide, have been identified serotypes a through f. Type b strains cause invasive disease, most commonly meningitis, predominantly in infants. Non-encapsulated or so called nontypeable strains frequently colonize the upper respiratory tract of children and adults and cause disease by contiguous spread in the respiratory tract; manifestations include otitis media in children, sinusitis in children and adults, and exacerbations in adults with chronic obstructive pulmonary disease COPD. As a result, ampicillin and amoxicillin should be used only when the susceptibility of the infecting isolate is known.
Haemophilus influenzae is an aerobic pleomorphic gram-negative coccobacillus that requires both X and V factors for growth. It grows poorly, if at all, on ordinary blood agar unless streaked with Staph. It grows well on chocolate agar. Because this medium is often not used in culturing specimens from adults and because the organism may be overgrown by other bacteria, the frequency of H. This is aggravated by the failure of many physicians to obtain blood cultures in suspected bacterial infections and the failure of many laboratories to subculture them routinely onto chocolate agar.
Hib disease used to be more common in the United States — about 20, children got serious Hib infections every year. In infants and young children, Hib disease can be very serious. It can cause infections in different parts of the body — including the brain and lungs.
Disease caused by Haemophilus influenzae can affect many organ systems. The most common types of disease caused by H. Less common infections include endocarditis and osteomyelitis. Non-b H. Nontypeable H.