CNS Infections (meningitis & encephalitis)

2 lecture hours - includes classification of bugs that cause meningitis as FYI

What are the big three s/s of meningitis in adults?

1. Fever

2. Nuchal rigidity

3. Altered mental status

What are 3 major s/s of meningitis in pediatrics?

1. feeding intolerance

2. apnea

3. bulging fontanelle

What pathogen is most common for community acquired meningitis in the following age groups?

1. <1 month

2. 1 month to <18 years

3. 18-50 years

4. >50 years

1. <1 month - Group B Streptococcus

2. 1 month to <18 years - S. pneumoniae

3. 18-50 years - N. meningitidis

4. >50 years - N. meningitidis

What is the recommended empiric IV therapy for community-acquired meningitis in neonates?

ampicillin + cefotaxime

or

ampicillin + aminoglycoside

FYI - (ampicillin would cover the gram positives… GBS & listeria)

(cefoxatime or aminoglycoside would cover the gram (-)s = e.coli, klebsiella, and enterobacter)

What is the recommended empiric IV therapy for community-acquired meningitis in >1 month and older? (also for the one patient group that is different)

vanco + 3rd gen cephalosporin (ceftraixone)

vanco + 3rd gen cephalosporin + ampicillin as well in > 50 y/o

What is the recommended empiric IV therapy used for healthcare-associated meningitis in the patient group of a basilar skull fracture?

vanco + 3rd gen cephalosporin (ceftriaxone)

Bug that accounts for 58% of community-acquired meningitis

streptococcus pneumoniae

CSF findings change depending on the cause of meningitis (e.g., fungal, viral, bacterial).

Give the parameters for the following that are indicative of bacterial meningitis:

1. Opening pressure (mm H2O) (pressure where LP needle enters spinal canal)

2. WBC

3. Protein

4. Glucose

1. Opening pressure - increased (>250)

2. WBC - 1-5 x 10³

3. Protein - increased (100-500)

4. Glucose - decreased (<45)

-might be sufficient for exam to just know increased or decreased?

most important diagnostic test for meningitis and other CNS infections.

lumbar puncture

When a patient is admitted with a suspicion for bacterial meningitis:

1. First step when bacterial meningitis is suspected?

Determine if patient has risk factors requiring CT before lumbar puncture.

When a patient is admitted with a suspicion for bacterial meningitis:

2. Which patients require CT scan before lumbar puncture in suspected meningitis? List at least 2.

• Immunocompromised

• History of CNS disease

• New onset seizure

• Papilledema

• Altered consciousness

• Focal neurologic deficit

• Delay in performing LP

When a patient is admitted with a suspicion for bacterial meningitis:

If NO CT risk factors are present in suspected meningitis, what should be done?

Blood cultures + lumbar puncture STAT

Then start dexamethasone & empiric antibiotics

When a patient is admitted with a suspicion for bacterial meningitis:

If CT risk factors ARE present in suspected meningitis, what is the next step?

Blood cultures THEN start dexamethasone + empiric antibiotics THEN Obtain CT scan

When do you perform CT before lumbar puncture in suspected meningitis?

if any of the risk factors… if not then blood cultures + LP ASAP

What are some of the pros and cons of adjunctive dexamethasone in the management of meningitits?

CONS - immunosuppression, decreased abx penetration into BBB, may mask WBC signs of abx response + normal steroid complications

PROS - image

The IDSA recommends dexamethasone 0.15mg/kg (up to 10mg) IV Q6H for up to 96 hours. When should it be administered?

Should be administered 10-20 minutes prior to, or concomitant with first dose of antimicrobial therapy

(FYI - from E2) What is the coverage of the natural penicillins? (Pen V and Pen G)

1. streptococci

2. meningococci (n. meningiditis)

3. syphilis

4. clostridium

(narrow)

(FYI - from E2) What is the coverage of the 3rd gen cephalosporins?

1. resistant streptococci (like s. pneumoniae and viridans)

2. staph

3. gram positive anaerobes

4. resistant strains of HNPEK (HNPEK = h. influenzae, neisseria spp., proteus, e. coli, klebsiella)

(FYI - from E2) - List some of the (more common) 3rd generation cephalosporins:

two groups -

gp 1 - ceftriaxone (IV/IM), cefoxatime (IV/IM), cefdinir (PO), cefixime (PO)

gp 2 - ceftazidime, which lacks gram (+) activity but covers pseudomonas

Bacterial classification of Neisseria (n. meningitidis & gonorrhoeae)

(gram + or - ? Oxygen? Catalase/Oxidase?)

gram-negative diplococcus; aerobic; catalase and oxidase postitive

So if you’re treating - FYI but know logic of attachment

bacterial classification of listeria

gram positive non-spore forming rod

*remember that cephalosporins don’t cover listeria

-meningitis in neonates and >50 y/o’s (underlined in slides)

Classify pseudomonas aeruginosa

(gram + or - ? Oxygen? Catalase/Oxidase?)

gram (-) rod that is aerobic, oxidase positive & non-fermenting

List at least 2 drugs that BOTH cross the BBB and cover pseudomonas

• ceftazidime (crosses BBB even when meninges inflamed)

• cefipime

• meropenem

Less preferred and alternative in bacterial meningitis:

• aztreonam

• FQ

• meropenem

^^ doubt she will get this granular

(FYI - E2) Classify H. influenzae

(oxygen?)

gram negative coccobacillus that is a facultative anaerobe

(FYI - E2) What is the coverage of the aminopenicillins? (amp & amox)

Gram +

• Strep & enterococcus

• Enterococcus

• Listeria

Gram −

• H. influenzae

• E. coli

• Proteus mirabilis

• Salmonella

• Shigella

HEPSS + SEL

*most s.aureus is resistant if no B-lactamase inhibitor added

What is encephalitis?

inflammation of the brain

What is the most common cause of encephalitis?

HSV-1&2

When encephalitis is suspected we usually do a lumbar puncture, viral testing, and radiologic imaging. What are some of the hallmark findings on an MRI that point towards a diagosis?

significant edema and hemorrhage within the temporal lobes

CSF findings change depending on the cause of meningitis (e.g., fungal, viral, bacterial).

Give the parameters for the following that are indicative of encephalitis:

1. Opening pressure (mm H2O) (pressure where LP needle enters spinal canal)

2. WBC

3. Protein

4. Glucose

1. Opening pressure - variable but rarely increased

2. WBC - 5-500

3. Protein - normal or slight increase

4. Glucose - normal

Which drug should be initiated in all patients with suspected encephalitis?

acyclovir

What are some of the ADRs on acyclovir? List at least three:

1. N/V

2. inc. LFTs

3. inc. BUN/SCr

4. neurotoxicity

5. injection site rxns

What are the warnings on acyclovir?

neurotoxicity and renal failure