Which of the following is a most common cause of pyogenic meningitis in older adults?

NORCET -4 , 2023

Medical Surgical Nursing

Easy

Appeared in: NORCET -4 , 2023

Explanation

Streptococcus pneumoniae is the most frequent cause of community-acquired bacterial meningitis in adults, including the elderly.
It accounts for approximately 50% of all bacterial meningitis cases in adults over the age of 20.
Older adults are particularly susceptible due to age-related declines in immune function (immunosenescence) and a higher prevalence of comorbid conditions like pneumonia, sinusitis, or diabetes, which are risk factors for pneumococcal disease.

Option A: Neisseria meningitidis is a more common cause of meningitis in children, adolescents, and young adults, not older adults.
Option C: Beta-haemolytic streptococcus, specifically Group B Streptococcus (GBS), is the leading cause of meningitis in neonates (newborns).
Option D: The incidence of Haemophilus influenzae type B (Hib) meningitis has been drastically reduced by routine childhood vaccination. It is no longer a common cause in any age group in vaccinated populations.

Visual 1: Bar Chart - A chart comparing the incidence of different meningitis-causing bacteria across various age groups (Neonates, Children, Young Adults, Older Adults) to visually emphasize the prevalence of S. pneumoniae in the elderly.
Visual 2: Micrograph - A Gram stain image of cerebrospinal fluid showing Gram-positive, lancet-shaped diplococci, characteristic of Streptococcus pneumoniae.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Etiology of pyogenic (bacterial) meningitis in older adults as background academic context rather than a clinical decision trigger.
Knowing the most likely causative organism by age group is critical for selecting the correct empirical antibiotic therapy while awaiting culture results. Delay in treatment significantly increases mortality and morbidity.
Nurses play a key role in advocating for and administering vaccinations, such as the pneumococcal vaccine (PCV13, PPSV23) for older adults and the Hib and meningococcal vaccines for children and adolescents, which are primary prevention strategies.
What if the older adult patient was also immunocompromised (e.g., due to cancer or transplant)? The list of potential pathogens would expand, and Listeria monocytogenes would become an even more important consideration, often requiring the addition of ampicillin to the empirical antibiotic regimen.

How to Approach the Question

First, identify the key elements of the question: the condition (pyogenic meningitis), the patient population (older adults), and what is being asked (most common cause).
This is a factual recall question that requires knowledge of infectious disease epidemiology.
Mentally review the common bacterial pathogens that cause meningitis.
Associate each pathogen with the age group it most commonly affects. For example, link Group B strep with neonates, H. influenzae with unvaccinated children, and N. meningitidis with young adults.
Recall that S. pneumoniae is a major cause of meningitis across the adult lifespan and is the single most common cause in older adults.
Evaluate each option based on this knowledge to select the most accurate answer.

Concept Tested & Keywords

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