Bacterial Meningitis

Question 1

What is bacterial meningitis?

Answer 1

inflammation of meninges with increased intracranial pressure and pleocytosis (increased WBCs) in cerebrospinal fluid secondary to bacteria in the pia-subarachnoid space and ventricles

Question 2

What is the classic triad of bacterial meningitis?

Answer 2

fever (95%), neck stiffness/nuchal rigidity (88%), and altered mental state (78%) - more common with pneumococcal meningitis - absence of all three essentially excludes bacterial meningitis

Question 3

What are additional common symptoms of bacterial meningitis?

Answer 3

headache (severe and generalized), lethargy, vomiting, nausea, photophobia, seizures, coma, rash (purpura fulminans), myalgia, unilateral cranial nerve abnormality, papilledema, nonreactive pupils, decorticate (damage to corticospinal tracts - arms adducted and flexed)/decerebrate (damage to upper brain stem - arm adducted and extended) posturing

Question 4

What is Kernig’s sign?

Answer 4

positive when the thigh is flexed at the hip and knee at 90 degree angles, and subsequent extension in the knee is painful (leading to resistance)

Question 5

What is Brudzinski’s sign?

Answer 5

severe neck stiffness causes a patient’s hips and knees to flex when the neck is flexed

Question 6

What are the most common causes of bacterial meningitis?

Answer 6

S. pneumoniae (most common in adults), N. meningitidis (most common in children and young adults), L. monocytogenes, for patients with HIV - invasive meningococcal disease

Question 7

How is bacterial meningitis diagnosed?

Answer 7

STAT lumbar puncture as soon as the diagnosis suspected

Question 8

What aspects of CSF examination are consistent with bacterial meningitis?

Answer 8

opening pressure (> 100- 200), WBCs (> 1000/mm3), neutrophilic predominance (> 80%), Gram stain +, protein (> 50 mg/dl), glucose (< 40 mg/dl), culture +, bacterial antigen (50% to 100% sensitivity)

Question 9

What is the workup for bacterial meningitis?

Answer 9

blood cultures, WBC with differential, CSF examination

Question 10

When is empiric IV Abx treatment necessary for bacterial meningitis?

Answer 10

purulent CSF fluid at time of lumbar puncture, PT is asplenic, PT has signs of DIC or sepsis

Question 11

What is the treatment for bacterial meningitis in adults?

Answer 11

vancomycin: 15-20 mg/kg IV q8 to 12 h PLUS 3rd generation cephalosporin (ceftriaxone - 2 g IV q12h or cefotaxime - 2 g IV q4 to 6 h) for 10 to 14 days - for adults over age 50, add ampicillin (2 g IV q4h) to cover Listeria (given for 21 days)

Question 12

What is the treatment for bacterial meningitis in immunocompromised adults?

Answer 12

vancomycin plus ampicillin plus cefepime or meropenem to cover Pseudomonas

Question 13

When should corticosteroids be used in bacterial meningitis?

Answer 13

first 4 days of therapy (dexamethasone 0.15 mg/kg q6h) - main indication is for known or suspected pneumococcal meningitis (only continue if CSF Gram stain or blood cultures reveal S. pneumoniae)

Question 14

What is pleocytosis?

Answer 14

elevated CSF WBC concentration - does not necessarily diagnose an infection

Question 15

What is a normal protein concentration in the CSF?

Answer 15

< 50 mg/dL - proteins are largely excluded from the CSF by the blood-CSF barrier (may be mildly elevated in DM, subarachnoid hemorrhage, or traumatic lumbar puncture)

Question 16

What is a normal glucose concentration in the CSF?

Answer 16

normal ratio of CSF-to-serum concentration is > 0.6 (can take hours for serum glucose to equilibrate with CSF glucose) - concentrations < 18 mg/dL are strongly predictive of bacterial meningitis

Question 17

What are the normal CSF findings in viral meningitis?

Answer 17

WBC < 250/microL (predominance of lymphocytes), protein < 150 mg/dL, glucose > 50% serum concentration

Question 18

What are the normal CSF findings in bacterial meningitis?

Answer 18

WBC > 1000/microL (neutrophilic predominance > 80%), protein > 200 mg/dL, glucose < 40 mg/dL

Question 19

How is severe hypoglycorrhachia defined?

Answer 19

severe reduction of glucose concentration in CSF (< 10 mg/dL)

Question 20

When is rifampin added in the treatment for bacterial meningitis?

Answer 20

in the setting of treatment with dexamethasone because entry of vancomycin into the CSF may be reduced by the decrease in inflammation with treatment by dexamethasone

Question 21

What are the treatment recommendations for N. meningitidis?

Answer 21

3rd generation cephalosporins for 7 days and droplet precautions for first 24 hours

Question 22

When can outpatient antimocrobial treatment be initiated in patients with bacterial meningitis?

Answer 22

after inpatient Tx for > 6 days, afebrile 24-48 hrs, no neurological dysfunction, clinical stability, able to take fluids by mouth, access to home health nurse/physician, reliable IV line, established plan of care, patient/family adherence, safe environment

Question 23

What are clinical features associated with a poor outcome in bacterial meningitis?

Answer 23

hypotension, altered mental status, seizures

Question 24

When is a CT scan of the head recommended prior to lumbar puncture in suspected bacterial meningitis?

Answer 24

age > 60 years, immunocompromised state, Hx of CNS disease (lesion, stroke, or focal infection), new onset (within 1 week) seizure, papilledema, abnormal level of consciousness, focal neurological deficit

Question 25

What are relative contraindications to lumbar puncture in patients with suspected bacterial meningitis?

Answer 25

evidence of increased intracranial pressure, thrombocytopenia, spinal epidural abscess, skin infections at site, abnormal respiratory pattern, bleeding disorders

Question 26

What is the mean opening pressure in a patient with bacterial meningitis?

Answer 26

350 mm H2O

Question 27

What is a normal lactate concentration in the CSF?

Answer 27

< 3.5 mEq/L

Question 28

What is the advantage of Gram stain in evaluation for bacterial meningitis?

Answer 28

can suggest the bacterial etiology 1 day or more before culture results are available: Gram+ diplococci (pneuococcal), Gram- diplococci (meningiococcal), Gram- coccobacilli (Hib), Gram+ rods/coccobacilli (listeria)

Question 29

What is the jolt accentuation of headache test?

Answer 29

patient rotates head horizontally 2-3 times per second - test is positive for bacterial meningitis if patient reports exacerbation of headache with maneuver

Question 30

What are the elements of the Glasgow Coma Scale?

Answer 30

eye opening, verbal response, motor response