CSF Infections

Question 1

CSF (General Anatomy)

Answer 1

• surrounds brain and spinal cord
• produced between 3rd and 4th ventricles
• entire volume exchanged every 3-4 hours

Question 2

CSF (functions)

Answer 2

• cushions brain
• reduces effective weight by factor of 30
• supplies metabolites
• removes wastes

Question 3

Routes of CSF Infections

Answer 3

• Hematogenous spread (most common)
• Direct spread from infected site (close to or contiguous with CNS - sinusitis, etc.)
• Anatomic defects in CNS (surgery, trauma, abnormalities)
• Direct intraneural (along nerves to brain): least common

Question 4

CSF Infections

Answer 4

• Meningitis: infection within subarachnoid space or leptomeninges
• Encephalitis: inflammation of brain parenchyma
• Meningoencephalitis: meningitis and encephalitis

Question 5

Meningitis (pathogenesis)

Answer 5

• bacteria attach via adherence
• invades tissue and disseminates
• protected by humoral immunity (no Ab’s in CSF - STERILE)
• evade destruction (phagocytosis)

Question 6

Meningitis (symptoms)

Answer 6

• stiff neck, fever, headache, nausea

- change in mental status, permanent mental change in kids

Question 7

Meningitis (lab findings)

Answer 7

• CSF of acute bacterial: large number of PMN’s, decreased glucose, increased protein
• CSF of chronic bacterial: same as acute, but continues
• CSF of aseptic: increased lymphocytes, negative bacterial cultures, usually associated with viral
• CSF of encephalitis: like bacterial but cell counts lower, see lymphs later

Question 8

Meningitis (at risk)

Answer 8

• ICP’s
• people with CNS shunts (S. epi)
• those with viral infections
• those with brain abscesses

Question 9

Acute Bacterial Meningitis (agents)

Answer 9

S. pneumo, N. meningitidis, H. flu, S. agalactiae, E. coli, Elizabethkingia meningosepticum, Listeria monocytogenes, GNR’s

Question 10

Newborn meningitis

Answer 10

GNR’s, Group B Strep, Listeria monocytogenes

Question 11

Infant meningitis

Answer 11

Group B Strep, H. flu, S. pneumo, N. meningitidis, E. coli

Question 12

Kids/young adult meningitis

Answer 12

S. pneumo, N. meningitidis, Group B strep, S. aureus, Enterobacter

Question 13

Adult meningitis

Answer 13

S. pneumo, N. meningitidis, Listeria, GNR’s

Question 14

CSF shunt infections

Answer 14

• 2/3 of infections are Staph
• rest are gram-negatives (E. coli, Kleb, Proteus, Propionibacterium)
• Candida

Question 15

Viral meningitis

Answer 15

• aseptic meningitis
• Enteroviruses and herpesviruses (most common)
• mumps virus, LCMV, HIV (less common)

Question 16

Other meningitis causes

Answer 16

• Mycobacteria TB and avium (in AIDS patients)
• spirochetes
• fungal infections (Cryptococcus)
• parasitic infections (protozoa)

Question 17

Meningoencephalitis

Answer 17

• most commonly caused by viruses

- involvement of cerebral cortex

Question 18

Brain abscesses

Answer 18

• commonly bacterial

- Streptococcus

Question 19

CSF fluid collection

Answer 19

• 3-4 tubes collected
• first tube is most contaminated
• tubes 2 and 3 go for cell count and diff
• other tubes go to micro and chemistry
• CSF must be hand-delivered immediately
• NEVER refrigerate CSF (except for viral studies)

Question 20

CSF processing

Answer 20

• centrifuge specimen
• decant supernatant into sterile tube
• vortex