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Flashcards in CNS Infections Deck (51)
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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


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)


Acute Bacterial Meningitis - Pathophysiology

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


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


Causes of Meningitis: Community Acquired

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


Causes of Meningitis: Neonates

-Group B Strep
-E. coli


Causes of Meningitis: Immune Suppressed, Pregnancy, Elderly

-Listeria monocytogenes


Causes of Meningitis: Trauma, post-neurosurgical

-Straphylococcus aures
-Gram neg (E. coli)


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


Pneumococcal Meningitis

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


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


Clinical Presentation of Bacterial Meningitis in Infants?

-high pitched cry
-bulging fontanel


Clinical Presentation of Bacterial Meningitis in Older Kids, Adults?

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


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



-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


Aseptic Meningitis

-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


Labs for Bacterial Meningitis

-CBC & Diff.
-Electrolytes (Syndrome of Inappropriate Antidiuretic Hormone or SIADH, metabolic acidosis)
-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


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)


CSF Abnormalities

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

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


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


Treat Bacterial meningitis

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


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%


Septic Emboli Cause:

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


How to treat Subacute Bacterial Endocarditis

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


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


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


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


Spinal Epidural Abscess: Treatment

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


Rocky Mountain Spotted Fever

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


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