The growth factors are X-factor(Hematin) and V-factor
(Diphosphopyridine nucleotide). . Requirement for growth factor helps for differentiation of species.
Growth factor required
X and V X factor V factor
influenzae, H. aegyptius, H. hemolyticus
parainfluenzae, H. parahemolyticus
. The main species of medical importance are:
Characteristics: .Gram-negative cocobacilli. . Fastidious bacteria requiring growth factors for isolation. . Found in upper respiratory tract as normal flora in healthy people. Antigenic structure .Capsular polysaccharide . There are six serotypes of H. influenzae, A-F. . Capsular antigen type b is composed of polyribose ribitol phosphate. . H. influenzae type b is the most common cause of disease in humans. . It is the main virulence factor which provides anti-phagocytic property. . Outer membrane protein . Lipo-oligosaccharide