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Flashcards in CNS Infections Deck (51)
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1

Acute Bacterial Meningitis - Delayed Treatment

-Meningococcal meningitis: kill in 6-12 hrs, patient may deteriorate in ER while undergoing diagnostic testing
-treat empirically & as soon as you suspect diagnosis

2

Acute Bacterial Meningitis - Pathogenesis

-blood born (bacteremia, sepsis)
-nearby infection (sinusitis, ear infection)
-CSF communication with outside (cranial trauma, neurosurgical procedure, myelomeningocele, spinal dermal sinus)

3

Acute Bacterial Meningitis - Pathophysiology

-bacterial surface (capsule, pili) penetrate endothelial cells & cross BBB
-meningeal inflammation
-vasculitis
-thrombophlebitis
-brain ischemia, infarction, & edema
-raised intracranial pressure
-brain herniation
-cardiovascular collapse

4

Exudative (Pus) Meningitis

-it's not the pathogen that causes the CNS damage
-meningeal inflammation is responsible
-abx - lyse bacteria - wall fragments - cytokines interleukins, & inflammatory cascade - vasculitis & thrombophiebitis

-Dexamethasone inhibits inflammatory cascade & reduces CNS damage

5

Causes of Meningitis: Community Acquired

-streptococcus pneumoniae (pneumococcus)
-neisseria meningitidis (meningococcus)

6

Causes of Meningitis: Neonates

-Group B Strep
-E. coli
-Listeria

7

Causes of Meningitis: Immune Suppressed, Pregnancy, Elderly

-Listeria monocytogenes

8

Causes of Meningitis: Trauma, post-neurosurgical

-Straphylococcus aures
-Gram neg (E. coli)
-Pneumococcus

9

Meningococcal Meningitis

-colonizes nasopharynx in 5% "normal" pop.
-spread by respiratory droplets, close contact
-epidemics in military, boarding schools, (3 ft rule)
-Fluminant course: shock, Waterhouse-Friderichsen syndrome - hemorrhagic necrotic adrenals

10

Pneumococcal Meningitis

-alcoholics
-chronic otitis
-sinusitis, mastoiditis
-CSF leaks (head trauma)
-Pneumococcal pneumonia
-Sickle cell disease
-Asplenia

11

Listeria Meningitis

-up to 10% of all meningitis
-older patients above 50
-immune-suppressed: autoimmune, organ transplant, pregnant women, neonates & elderly
-Chronic illness: renal failure, liver disease
-Unpasteurized diary
-Meat counters, hot dogs

12

Clinical Presentation of Bacterial Meningitis in Infants?

-fever
-irritability
-vomiting
-high pitched cry
-lethargy
-convulsions
-bulging fontanel

13

Clinical Presentation of Bacterial Meningitis in Older Kids, Adults?

-URI prodrome, sore throat
-fever
-headache
-stiff neck
-vomiting
-lethargy & confusion
-cranial neuropathy
-seizures, coma

14

Physical Exam for Bacterial Meningitis?

-VItal Signs: high fever, shock (low BP, high pulse)
-Skin: petechiae, purpura, dermal sinus
-Cranial: trauma, CSF leak, otitis, sinusitis, mastoiditis, ventricular shunt
-Neck: stiff, Kerning's & Brudzinski signs

-ausculate for pneumonia, endocarditis
-urinary tract infection

15

Meningismus

-neck stiffness, rigid & hard to move
-Kerning's sign: + if knee can't be fully extended when patient lies supine with hip flexed at 90 deg.
-Brudzinski sign: + when passive neck flexion causes reflex flexing of both legs & thighs

16

Aseptic Meningitis

-Viral
-Drug induced: Ibuprofen/NSAIDS, sulfa-containing abx (bactrim), isoniazid, immune modulation (OKT3, IVIG, Cyclocsporine)
-Craniopharyngioma (leakage of contents)
-Lead poisoning
-Parameningeal inflammation
-Viral encephalitis
-Fulminant TB or fungal meningitis
-Lyme disease, neurosyphilis, Rocky Mountain Spotted Fever

17

Labs for Bacterial Meningitis

-CBC & Diff.
-Electrolytes (Syndrome of Inappropriate Antidiuretic Hormone or SIADH, metabolic acidosis)
-PT, PTT, INR (DIC)
-Cultures: nasal nares, throat, sputum, skin lesions, urine, blood, CSF
-Gram stain of blood
-Blood bacterial PCR
-Much higher in bacterial meningitis than viral
Serum Procalcitonin (>2 ng/mL)
C-reactive protein (>40 mg/L)
-Cranial CT
-Lumbar Puncture

18

Lumbar Puncture Tests

-opening pressure, CBC/differential, Glucose, Protein, Latex agglutination, Gram Stain, Cultures for bacteria, TB, fungi & viruses, cryptococcal antigen, VDRL (veneral disease research lab), Special (PCR, IgM, IgG)

19

CSF Abnormalities

Purulent Bacterial: inc. WBC, neutrophils, 0-25 glucose, inc. protein

Non-purulent Bacterial: lymphs, 25-50 glucose, inc. protein

20

Treatment for Bacterial Meningitis

-don't wait for diagnostic studies
-Steroids 1st: dexamethasone 10mg within 15 min of abx) and next 4 days (every 6 hrs), suppresses cytokines & inflammatory cascade induced by lysed cell components (IL-1, TNF)
-ABX: empirical: Vancomycin, 3rd or 4th gen cephalosporin or meropenem, Ampicillin (Listeria), Acyclovir (Herpes virus), Doxycycline (tics)
-Gram stain directed

21

Treat Bacterial meningitis

-fluids, electrolytes
-ventriculostomy for high intracrainal pressure & coma
-isolation
-prophylaxis for close contacts (rifampin)

22

Subacute Bacterial Endocarditis

-veggies, infection on heart valves, usually with gram + cocci, widespread septic embolism
-splinter hemorrhage
-Presentation: fever, delirium to coma. Possible meningeal signs, septic emboli to brain causes:
1. stroke
2. cerebritis to abscess (single/multiple)
3. Mycotic aneurysm

-streptococcus viridans 50%

23

Septic Emboli Cause:

1. Splinter Hemorrhages
2. Osler's Nodes
3. Janeway Lesions
4. Roth's spots (retinal hemorrhage with central clearing)

24

How to treat Subacute Bacterial Endocarditis

-antibiotics
-heart failure occurs, valve replacement may be necessary
-large cerebral abscesses must be drained

25

Clinical Diagnosis of Cerebral Abscess

1. Headache (worse lying down, present upon awakening) "tumor headache"
2. Papilledema & transient visual obscurations
3. Seizures
4. Focal neurological deficits
5. Contract CT or MRI: ring enhancing mass with surrounding edema
6. Risk factors: pulmonary AV shunt (hereditary hemorrhagic telangiectasia), sinusitis, sepsis

26

Spinal Epidural Abscess: Clinical Diagnosis

1. Severe back pain, worse lying down, point tenderness
2. Fever & Malaise
3. Bowel & bladder dysfunction (incontinence or constipation) & male impotence
4. Paraparesis or quadriparesis depending on level
5. Sensory Level (absent pin prick sensation below level of involvement)
6. High sed rate
7. Elevated WBC with left shift
8. Spinal MRI or CT myelogram
9. Blood cultures

27

Spinal Epidural Abscess: Risk Factors

-staphylococcus is most common pathogen
1. Skin infection (IV drugs) - staphylococcus
2. Trauma (surgery) - staphylococcus
3. Osteomyelitis - staphyloccus
4. GU instrumentation - Gram - (elderly)
5. Sepsis
6. Often accompanied by local discitis & osteomyelitis

28

Spinal Epidural Abscess: Treatment

1. High dose steroids
2. Abx to cover staph, strep, & anaerobes
3. Surgical drainage

29

Rocky Mountain Spotted Fever

-Rickettsia
-gram - obligate intracellular coccalbacillary rods
-attack vascular endothelia cells
-cause systemic vasculitis
-transmitted by ticks

30

Rocky Mountain Spotted Fever: Symptoms

-Fever, headache, flu-like symptoms 3-14 days after bite
-early petechial rash in distal extremities
-delirium - coma - death
-nromal CSF or mild inc. lymphocytes
-IgG and IgM (indirect immunofluorescence)
-Treatment: IV doxycycline