<prompt> Which among the following is NOT TRUE about H. influenzae?Requires factor X and V for growthRarely presents as meningitis in children less than 2 months of ageCapsular polypeptide protein is responsible for virulenceM.C invasive disease of H influenza is meningitis  <response>: 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 Xhemin -- 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 Panikers textbook of microbiology Ed 8Th pg - 331. 