Identify the organism associated with meningitis?

The organism associated with meningitis among the options provided is Haemophilus influenzae. This bacterium is a well-known pathogen responsible for causing bacterial meningitis, particularly in children. H. influenzae type b (Hib) was historically one of the leading causes of bacterial meningitis in young children before the introduction of the Hib vaccine, significantly reducing the incidence of disease.

H. influenzae is a gram-negative coccobacillus that can invade the bloodstream and the central nervous system, leading to severe outcomes such as meningitis and pneumonia. It is characterized by its requirement for factors found in blood for growth, which is why it is often cultured on enriched media.

In contrast, the other organisms listed have specific associations not related to meningitis. H. ducreyi primarily causes chancroid, a sexually transmitted disease; H. aegyptius is associated with conjunctivitis and Brazilian purpuric fever; and H. haemolyticus is not typically recognized as a pathogen causing significant systemic infections like meningitis. This differentiation underscores the specific pathogenic roles that each Haemophilus species plays in clinical disease.