13: CNS infections

Question 0

Meningitis- cc

Answer 0

Bacteria- S. pneumonia, N. meningitidis, H. influenzae
Virus- Echo, Enterovirus, HSV, HIV, CMV, EBV
Protozoa- Naegleria fowleri, Acanthamoeba
Spirochetes- Neurosyphilis

Question 1

Chronic meningitis

Answer 1

At least 4 weeks of sx*

Question 2

0-4 weeks

Answer 2

S. agalactiae (group B strep)*

Listeria

Question 3

4-12 weeks

Answer 3

S agalactiae* (group B strep)
E coli
H influenzae

Question 4

3month- 18yrs

Answer 4

N meningitidis*

S pneumoniae

Question 5

18-50yrs

Answer 5

S pneumoniae*

N meningitidis

Question 6

> 50yrs and Immunocompromised

Answer 6

S pneumoniae*
N meningitidis
Listeria
Aerobic Gram (-) bacilli

Question 7

Intracranial manipulation

Answer 7

S aureus*
Goagulase (-) staph
Aerobic Gram (-) bacilli

Question 8

Basilar skull fracture

Answer 8

S pneumoniae*

H influenzae

Question 9

CSF shunts

Answer 9

S aureus*
Aerobic Gram (-) bacilli

Question 10

Acute meningitis

Answer 10

Hrs to a few days of onset

Question 11

Signs of meningeal irritation

Answer 11

Kernigs sign (elevate the leg and extend the knee-> pain at the back of the thigh)
Brudzinski sign (Flex the neck and the hips and knee will also bend)
Nuchal rigidity (less severe in viral)

the 2 signs are absent in viral infection

Question 12

Signs of ICP

Answer 12

Deteriorating level of consciousness
Papillaedema (blurring of optic disc margins)
Dilated, poorly reactive upil
Cushing’s reflex (Bradycardia, Hypertension, Irregular respiration)

Question 13

Systemic keys to the etiology

Answer 13

Direct extension- Sinusitis or Otitis
Basilar skull fracture- Rhinorrhea or Otorrhea
Infective endocarditis- Murmur
Erythematous maculopapular rash- Meningococcemia

Question 14

Lumbar puncture

Answer 14

Key- Posterior superior iliac spine-> gap is L3-L4

Puncture on either L3-4 or L4-5 with more space

Question 15

Bacterial- dx

Answer 15

WBC: 100-5000; >80% PMNs
Glucose: 100

Question 16

Viral- dx

Answer 16

WBC: 10-300; lymphocytes
Glucose: Normal
Protein: Normal

Question 17

Tuberculous- dx

Answer 17

WBC: 100-500; lymphocytes
Glucose: same as bacteria
Protein: same as bacteria

Question 18

S pneumoniae- tx

Answer 18

DOC: 3rd generation cephalosporins (ceftriaxone or cefotaxime) + vancomycin for 2 weeks
or PenG

Question 19

N meningitidis- tx

Answer 19

DOC: PenicillinG or Ampicillin x 7days

for Resistant strains-> Ceftriaxone or Cefotaxime

Question 20

H influenzae- tx

Answer 20

DOC: Ceftriaxone or Cefotaxime

Question 21

Aerobic Gram(-) bacilli- tx

Answer 21

DOC: Ceftriaxone or Cefotaxime x3wks

Question 22

P aeruginosa- tx

Answer 22

DOC: Ceftazidime (still 3rd gen but others are not effective**)

Question 23

Staphylococcus species- tx

Answer 23

Nafcillin or Oxacilliin

Vancomycin-> MRSA, Coagulase(-) Staph

Question 24

Use of Steroids

Answer 24

To attenuate the detrimental effects of inflammatory response due to IL-1 and TNF
MUST be given BEFORE the antibiotic therapy (killing of bacteria will worsen the immune response-> suppress immune before killing bugs)**
20mins before first dose of antimicrobial agent**

Question 25

Most important dx tool for CNS viral infection

Answer 25

PCR amplification

Investigation of choice for Enteroviruses, HSV, CMV, EBV

Question 26

Viral meningitis- tx

Answer 26

Acyclovir for HSV

Vaccination: MMR, VZV

Question 27

Viral encephalitis- cc

Answer 27

They show tropism to specific tissue
Arbo virus
Enterovirus (Polio: LMN)
HSV-1 (Limbic system in Temporal lobe)

Question 28

Arbo virus

Answer 28

US: Eastern Equine Encephalitis virus (EEE)
World: Japanese Encephalitis virus

Question 29

HSV-1 encephalitis- sx

Answer 29

Olfactory hallucinations
Personality changes

due to its effect on Limbic system/ Temporal lobe
Perivascular inflammatory infiltrates and Inclusion bodies usually present

Question 30

Encephalitis- dx

Answer 30

CSF PCR**
EEG: Periodic lateralized epileptiform discharges (PLEDs)**- sudden repeated spikes
MRI: most sensitive

Question 31

Cerebral abscess- sites

Answer 31

Temporal lobe: Otits media, Mastoiditis
Posterial frontal/parietal lobe: Hematogenous spread
Interface of gray-white matter: Metastatic abscess

Question 32

Cerebral abscess- cc

Answer 32

S aureus- MC**

Mycobacteria, Toxoplasma gondii, Cryptococcus- Immunocompromised*

Question 33

Cerebral abscess- stages

Answer 33

1: Early cerebritis stage (day 1-3)
2: Late cerebritis stage (day 4-9)
3: Early capsule formation stage (day 10-13)- ring enhancing capsule on MRI
4: Late capsule formation stage (>14 days)

Question 34

Cerebral abscess- tx

Answer 34

3rd gen cephalosporins
Surgical aspiration and drainage for lesion >2.5cm*
Anti-convulsant
Steroids (Dexamethasone)