For adults over 65 years, which pathogens are commonly involved in meningitis?

For adults over 65 years, which pathogens are commonly involved in meningitis?

• A. Streptococcus pneumoniae, Listeria monocytogenes, and Gram-negative bacilli
• B. Neisseria meningitidis and Haemophilus influenzae
• C. Streptococcus pyogenes and Staphylococcus aureus
• D. Escherichia coli alone

Answer: (A)

Older adults with meningitis are most likely to have a mix of organisms that reflect age-related risk factors, including Streptococcus pneumoniae, Listeria monocytogenes, and Gram-negative bacilli. Streptococcus pneumoniae is the leading cause of bacterial meningitis in adults, and this holds true for those over 65. Listeria monocytogenes is particularly important in the elderly and in people with weakened immune systems, often requiring ampicillin to cover it in empiric therapy. Gram-negative bacilli, such as enteric organisms like Escherichia coli and Klebsiella, are also seen more commonly in older adults, especially in healthcare-associated cases or with comorbidities. Other options don’t fit the typical elderly pattern as closely. Neisseria meningitidis and Haemophilus influenzae are more common in younger individuals. Streptococcus pyogenes and Staphylococcus aureus can cause meningitis but are not the most representative pathogens for community-acquired meningitis in the elderly. Escherichia coli alone would miss the important coverage for Listeria and the broader group of Gram-negative bacilli.

Older adults with meningitis are most likely to have a mix of organisms that reflect age-related risk factors, including Streptococcus pneumoniae, Listeria monocytogenes, and Gram-negative bacilli. Streptococcus pneumoniae is the leading cause of bacterial meningitis in adults, and this holds true for those over 65. Listeria monocytogenes is particularly important in the elderly and in people with weakened immune systems, often requiring ampicillin to cover it in empiric therapy. Gram-negative bacilli, such as enteric organisms like Escherichia coli and Klebsiella, are also seen more commonly in older adults, especially in healthcare-associated cases or with comorbidities.

Other options don’t fit the typical elderly pattern as closely. Neisseria meningitidis and Haemophilus influenzae are more common in younger individuals. Streptococcus pyogenes and Staphylococcus aureus can cause meningitis but are not the most representative pathogens for community-acquired meningitis in the elderly. Escherichia coli alone would miss the important coverage for Listeria and the broader group of Gram-negative bacilli.