Skip to Main Content
Home > Books > Internal Medicine: A Guide to Clinical Therapeutics >

Chapter 30. Meningitis

Allana J. Sucher

++

  • Bacterial etiology of meningitis varies by patient age, immune status, & history of neurosurgical procedure or head trauma
  • Aseptic meningitis: all nonbacterial causes (viruses, fungi, parasites, medications, cochlear implants, malignancies)
  • Nasopharyngeal (bacteria) or mucosal surface (viral) colonization → bacteremia or viremia → invasion into CNS → replication → meningeal inflammation → neurological sequelae

++
Table Graphic Jump Location
Table 30-1 Etiology of Bacterial Meningitis by Age & Predisposing Factors (Clin Infect Dis 2004;39:1267)
View Table|Favorite Table|Download (.pdf)
Table 30-1 Etiology of Bacterial Meningitis by Age & Predisposing Factors (Clin Infect Dis 2004;39:1267)

Predisposing Condition

Organism

Age*

   2–50y

   >50y

Streptococcus pneumoniae, Neisseria meningitidis

S. pneumoniae, N. meningitidis, Listeria monocytogenes, enteric gram-negatives (Escherichia coli)

Head trauma

   Basilar skull fracture

   Penetrating trauma

S. pneumoniae, Streptococcus pyogenes, Haemophilus influenzae

Staphylococcus aureus, Staphylococcus epidermidis, aerobic gram-negatives (including Pseudomonas aeruginosa)

Postneurosurgery

S. aureus, S. epidermidis, aerobic gram-negatives (including P. aeruginosa)

*Any age that is immunocompromised is at risk for infection by L. monocytogenes.

++

Pertinent Positive Labs

++

  • Lumbar puncture for cerebrospinal fluid (CSF) analysis
  • CSF laboratory values & Gram stain help determine cause of meningitis
  • Further work-up of aseptic meningitis: PCR for HSV/enteroviruses; CSF cryptococcal antigen for cryptococcal meningitis in immunosuppressed patients (in HIV, CD4+ <50cells/mm3)

++
Table Graphic Jump Location
Table 30-2 CSF Laboratory Interpretation (Lee M. Basic Skills in Interpreting Laboratory Data, 4th ed., 2009)
View Table|Favorite Table|Download (.pdf)
Table 30-2 CSF Laboratory Interpretation (Lee M. Basic Skills in Interpreting Laboratory Data, 4th ed., 2009)

Normal

Bacterial Meningitis

Aseptic Meningitis

WBC (mm3)

<5

>1000

5–500

Differential

No predominance

>80% PMNs

>50% lymphocytes

Protein (mg/dL)

<50

>100

30–150

Glucose (mg/dL)

2/3 serum

<1/2 serum

<30–70

Gram stain (Table 30-3)

Negative

60–90% sensitive

Negative

CSF: cerebrospinal fluid; PMNs: polymorphonuclear neutrophils (segmented neutrophils).

++
Table Graphic Jump Location
Table 30-3 Gram Staining Characteristics of Bacteria (Levinson W. Review of Medical Microbiology & Immunology, 2010)
View Table|Favorite Table|Download (.pdf)
Table 30-3 Gram Staining Characteristics of Bacteria (Levinson W. Review of Medical Microbiology & Immunology, 2010)

S. pneumoniae

Gram-positive diplococci (α-hemolytic)

N. meningitidis

Gram-negative cocci

L. monocytogenes

Gram-positive rods

E. coli

Gram-negative rods (lactose positive)

S. pyogenes

Gram-positive cocci (β-hemolytic)

H. influenzae

Gram-negative rods

S. aureus

Gram-positive cocci in clusters (coagulase positive)

S. epidermidis

Gram-positive cocci in clusters (coagulase negative)

P. aeruginosa

Gram-negative rods (lactose negative, oxidase positive)

*All microorganisms in this table are aerobic.

++

Treatment goals: ameliorate signs & symptoms, eradicate infection, prevent development of neurological sequelae

++
Table Graphic Jump Location
Favorite Table | Download (.pdf) | Print
Clinical Pearl 30-1

Start empiric ABX as soon as possible in all patients with suspected meningitis

++

Principles of treatment: high-dose parenteral therapy; agent must penetrate blood-brain barrier, be bactericidal in the CSF, & have antimicrobial activity against infecting pathogen

++

Pharmacological Treatment ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.

This site uses cookies to provide, maintain and improve your experience. MHE Privacy Center Close