All Sample Questions

Meningitis 1

Question

Vignette: A 35-year-old male presents to the emergency department with high fever, severe headache, and neck stiffness. He mentioned he has recently returned from a hiking trip in New Mexico. Physical examination reveals nuchal rigidity, and a lumbar puncture is performed. The CSF analysis shows increased lymphocytes, decreased glucose, and increased protein. Gram stain of the CSF shows small, pleomorphic gram-negative coccobacilli. Which of the following is the most likely causative agent?

Choices

A. Haemophilus influenzae

B. Neisseria meningitidis

C. Streptococcus pneumoniae

D. Listeria monocytogenes

E. Coccidioides immitis

Answer

A. Haemophilus influenzae

Explanation

The patient's clinical presentation of headache, fever, and neck stiffness along with the CSF findings indicates bacterial meningitis. The gram-negative coccobacilli found in the CSF are indicative of Haemophilus influenzae. It is a common cause of meningitis, especially in unvaccinated individuals. The patient's recent hiking trip is a distractor in this question. Coccidioides immitis, which is often associated with soil and dust in the southwestern United States (including New Mexico), causes pneumonia and disseminated disease, not meningitis. Neisseria meningitidis, Streptococcus pneumoniae, and listeria monocytogenes also cause meningitis but appear differently on gram stain. neisseria meningitidis is a gram-negative diplococcus, streptococcus pneumoniae is a gram-positive diplococcus, and Listeria monocytogenes is a gram-positive rod.