Which among the following is NOT TRUE about H. influenzae?
H.influenzae is a small gram negative, non motile, non sporing bacilli. The accessory growth factors named X & Y present in blood are essential for growth. Factor X(hemin) --> It is required for synthesis of cytochrome. Factor V (NAD) - It is essential for oxidation de adenine dinucleotide reduction. There are 3 main antigens:capsular polysaccharide, outer membrane protein, lipooligosaccharide. Influenzae does not secrete any exotoxins, the polysaccharide capsule is considered to be the major factor in virulence. There are "6" types of capsule designated a, b, c, d, e and f of these type "b" is commonly associated with invasive Haemophilus influenzae disease in children. The capsular PRP antigen of Hib induces IgA, IgM, IgA antibodies which are bactericidal, opsonic & protective. Diseases caused by H.influenzae are: meningitis, laryngo epiglottitis, pneumonia, suppurative lesions, bronchitis. Do You Know: HACEK group bacteria - Haemophilus species, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens & Kingella kingae. Ref: Ananthanarayanan & Paniker's textbook of microbiology Ed 8Th pg - 331.
Requires factor X and V for growth
Rarely presents as meningitis in children less than 2 months of age
Capsular polypeptide protein is responsible for virulence
M.C invasive disease of H influenza is meningitis