Microbiology Practice Exam

Which bacterium is known to cause Pneumococcal meningitis?

1. Staphylococcus aureus

2. Mycobacterium tuberculosis

3. Streptococcus pneumoniae

4. Treponema pallidum

The correct answer is: Streptococcus pneumoniae

Streptococcus pneumoniae is known to cause pneumococcal meningitis, which is a serious infection of the membranes covering the brain and spinal cord. This particular bacterium is a leading cause of bacterial meningitis in both children and adults. It is a gram-positive cocci that often appears in pairs (diplococci) and has a polysaccharide capsule, which enhances its virulence by helping it evade the immune system. Pneumococcal meningitis typically develops following pneumonia, sinusitis, or otitis media because S. pneumoniae can spread from these areas to the central nervous system. The bacterium's ability to cause disease is also influenced by factors such as the host's immune response and the presence of additional risk factors. Other bacteria listed have different associations; for instance, Staphylococcus aureus is better known for skin infections or conditions like endocarditis but not typically for meningitis. Mycobacterium tuberculosis primarily causes tuberculosis and can lead to tuberculosis meningitis, but it is not the primary organism for pneumococcal meningitis. Treponema pallidum is the causative agent of syphilis and is not linked to meningitis in the same way. Understanding the pathogenic mechanisms and