Meningitis Flashcards
(45 cards)
What is meningitis?
Meningitis is the inflammation of the leptomeninges (pia and arachnoid mater) of the brain and spinal cord due to infectious and non-infectious causes.
What are the common causes of bacterial meningitis?
The most common bacteria include Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, and Listeria monocytogenes.
What are the two major classifications of bacterial meningitis?
Community-acquired bacterial meningitis and health care-associated meningitis.
Which bacteria is the most common cause of bacterial meningitis worldwide?
Streptococcus pneumoniae (responsible for 25-41% of cases).
Which bacteria is the leading cause of epidemic meningitis in sub-Saharan Africa?
Neisseria meningitidis (previously serogroup A, now reduced due to vaccines).
What are risk factors for bacterial meningitis?
Recent infection, head trauma, CSF leak, immunodeficiency, recent travel, and post-neurosurgical procedures.
What is the pathogenesis of bacterial meningitis?
Pathogens colonize mucosal surfaces, invade the bloodstream, evade immune defenses, and enter the subarachnoid space, triggering inflammation.
How do bacteria evade host defenses in meningitis?
By using polysaccharide capsules to inhibit complement deposition and secreting IgA protease to neutralize mucosal immunity.
What are the three classic symptoms of bacterial meningitis?
Fever, neck stiffness, and altered sensorium (mental status changes).
What clinical features are seen in meningococcal meningitis?
Petechial rash, palpable purpura, arthritis, and possible septicemia.
What is Kernig’s sign?
Resistance or inability to fully extend the knee when the hip is flexed at 90 degrees.
What is Brudzinski’s sign?
Involuntary flexion of the hips and knees when the neck is passively flexed.
What is jolt accentuation of headache?
A test where horizontal head rotation at 2-3 times per second worsens headache, suggesting meningitis.
What are the indications for a CT scan before lumbar puncture?
Immunocompromised state, new-onset seizure, papilledema, focal neurologic deficit, or abnormal consciousness.
What are the typical cerebrospinal fluid (CSF) findings in bacterial meningitis?
Elevated WBCs (>1000/µL, predominantly neutrophils), high protein (>200 mg/dL), low glucose (<40 mg/dL), and positive Gram stain.
What CSF findings suggest pneumococcal meningitis?
Gram-positive diplococci on Gram stain.
What CSF findings suggest meningococcal meningitis?
Gram-negative diplococci on Gram stain.
What CSF findings suggest Haemophilus influenzae meningitis?
Small pleomorphic gram-negative coccobacilli.
What CSF findings suggest listerial meningitis?
Gram-positive rods and coccobacilli.
What is the empiric antibiotic regimen for bacterial meningitis in immunocompetent adults?
Ceftriaxone or cefotaxime plus vancomycin; add ampicillin if age >50 years to cover Listeria monocytogenes.
What is the first-line empiric antibiotic regimen for bacterial meningitis in immunocompromised patients?
Vancomycin + ampicillin + cefepime or meropenem.
What antibiotic is used for bacterial meningitis in patients with beta-lactam allergy?
Vancomycin + fluoroquinolone (moxifloxacin or levofloxacin) + trimethoprim-sulfamethoxazole for Listeria coverage.
What is the empiric treatment for bacterial meningitis during an epidemic?
Ceftriaxone or long-acting chloramphenicol (oily suspension).
What role do corticosteroids play in bacterial meningitis treatment?
Dexamethasone reduces mortality and neurological complications, especially in pneumococcal meningitis.
