A 2-year-old child was admitted to the hospital with acute meningitis. The Gram stain revealed Gram- positive short rods, and the mother indicated that the child had received "all(tm) of the meningitis vaccinations. What is the most likely cause of the disease?

(C) Listeria # Except during a meningococcal epidemic, H. influenzae is the most common cause of bacterial meningitis in children.> Organism is occasionally found to be associated with respiratory tract infections or otitis media.> H. influenzae, N. meningitidis, S. pneumoniae, and Listeria account for 80 to 00% of all cases of bacterial meningitis.> Purified polysaccharide vaccine conjugated to protein for H. influenzae type B is available.> A tetravalent vaccine is available for N. meningitidis and a 23-serotype vaccine for S. pneumoniae> Listeriosis in human beings may present in many forms. It It may cause meningitis or meningoencephalitis, particularly in neorates and in the elderly.> Infection of pregnant women may lead to abortion or stillbirth.> Asymptomatic infection of the female genital tract may cause infertility.> Listeriosis may also present as abscesses, conjunctivitis, pharyngitis, urethritis, pneumonia, infectious mononucleosis like syndrome, endocarditis or septicemia.