(D) Motility at 25degC # Common causes of Meningits according to age are;> First 2 months of life: Group B and D streptococci (Streptococcus agalactiae) Gram negative enteric bacilli (Escherichia coli) Listeria monocytogenes H. influenzae (type b & non-encapsulated strain) - Rare> 2 months to 12 years of age: S. pneumoniae N. meningitidis H. influenzae type b> Subsequent to the implementation of universal immunization against the H. influenzae (beginning at 2 months of age), the incidence of H. influenzae dropped precipitously.> Meningitis (2 months -12 years) now is most commonly caused by S. pneumoniae & N. meningitidis.> T-lymphocyte defect (congenital or acquired by chemotherapy, AIDS or malignancy): t risk of L. monocytogenes infection.> Peak incidence of H. influenzae type B: 6-9 months of age.> Possible diagnosis in this 3 week old child.> Streptococci (Ruled out cause CSF shows gram positive bacilli).> E. coli - (Ruled out gram Negative)