<prompt> A 2 years old child is brought to the emergency with history of fever and vomiting. On examination he has neck rigidity. The CSF examination shows polymorphs more that 2000m1 protein 100 mgdl and glucose 10mgd1. The Gram stain shows the presence of Gram negative coccobacilli. The culture shows growth of bacteria only on chocolate agar and not on blood agar. The caustive agent is ?Neisseria meningitidesHaemophilus influenzaeBranhamella catarrhalisLegionella pneumophila  <response>: Ans. is b i.e., Haemophilus influenzae . The impoant clues in this question are ? The organism is gram negative coccobacilli. It grows only on chocolate agar and not on blood agar. Causing meningitis in children. . Haemophilus influenzae : - Gram negative Coccobacilli - Can not grow in blood agar because utilization of V factor NAD or NADP is limited by the presence of serum NADase. - Grows well on chocolate agar blood agar which is heated up to 70-80degC because, on heating extra X and V factors are liberated from the lysed red cells. - Is a common cause of meningitis in children. About other options - N. Meningitis . It occur as diplococci not coccobacilli . It can grow on blood agar. - Legionella pneumophilia . Does not cause meningitis. - Bramanhella catarrhalis . It occur as diplococci not coccobacilli . It can grow on blood agar. 