CNS/Opthalmic Infections Flashcards
3 causes of bacterial meningitis in the neonate
- E. coli
- GBS
- Listeria monocytogenes
Causes of bacterial meningitis in adults
- S. pneumoniae
- N. meningitidis
- H. influenzae
Patho of bacterial meningitis
- Nasopharyngeal colonization
- Local invasion
- Bacteremia
- Endothelial cell injury
- Increased BBB permeability + meningeal invasion
- Subarachnoid space inflammation -> cerebral vasculitis
- Problems
Complications of bacterial meningitis
- Edema (vasogenic, interstitial, cytotoxic) results in increased ICP
- Increased ICP leads to decreased cerebral blood flow –> death
- Cerebral vasculitis can cause cerebral infarction, which may also decrease cerebral blood flow, causing death
Classic triad of meningitis
- Fever
- Neck stiffness
- Headache
Clinical Sx associate with meningitis
- Photophobia
- N/V
- Petechial rash = meningococcal meningitis
- Neurological symptoms (seizures etc.)
Findings suggestive of meningitis on physical exam
- Fever
- Petechial rash
- Neck stiffness
- Kernig sign
- Brudzinski sign
- Increased headache with jolt
- Cranial nerve palsies
What is Kernig’s sign?
Resistance or pain in lower back or posterior thigh when the knee is extended (when hip flexed to 90 degrees)
What is Brudzinski’s sign?
When passive neck flexion in the supine pt results in flexion of the knees and hips
What is papilledema?
Blurring of the edges of the optic disk, which indicates increased ICP
What investigations might you perform for suspected meningitis?
- LP to obtain CSF for: WBC diff, protein, glucose, Gram stain, culture
- CT or MRI head
When is a head CT indicated prior to doing a LP?
Concerned about increased ICP, where LP leads to cerebral herniation and death
- Immunocompromised state
- Focal neuro deficits
- Hx of CNS disease
- New onset seizures
- Papilledema
- Altered LOC
Tx of meningitis
- Start antibiotics ASAP
- If LP delayed, do blood cultures and start antibiotics
- Empiric Tx = Ceftriaxone + Vancomycin
- Can also add Ampicillin and/or dexamethasone
What is the prognosis for meningitis?
- Overall 15% mortality
2. 28% have neuro complications
What differentiates meningitis from encephalitis?
Encephalitis presents with brain function abnormalities, such as:
- Altered LOC
- Motor or sensory deficits
- Change in behaviour/personality
- Speech or mvmt disorder
Infectious causes of encephalitis
- Viral: HSV-1 (life threatening), VZV, other herpes viruses, Arboviruses, Enteroviruses, Measles
- Non-viral: tick-borne, bacteria, protozoa
Clinical presentation of encephalitis
- Fever
- Headache
- Altered mental status
- Seizures
- +/- rash
Dx approach to encephalitis
- LP and CSF analysis (culture, WBC, protein, glucose)
- PCR the CSF sample
- Serology for Arboviruses
- Brain biopsy as last resort
- CT head or MRI
- EEG
Tx for encephalitis
- Acyclovir IV
Risk factors for a brain abscess
- Immunosuppression
- Chronic cardiopulmonary conditions
- Penetrating head trauma
Cause of brain abscess
- Immunocompetent = polymicrobial
2. Immunocompromised = Toxoplasmosis, Cryptococcus, TB
Clinical presentation of brain abscess
- Headache
- Fever
- Focal neuro deficits - dependent on location in brain affected
- Change in mental status
- Seizures
- N/V
- Neck stiffness
How to Dx a brain abscess
- CBC - normal WBC
2. CT scan with contrast or MRI
Tx for brain abscess
- Aspiration
- Ceftriaxone + Metronidazole +/- Vancomycin, OR
- Meropenem +/- Vancomycin
- Dexamethasone when significant swelling
Risk of epidural abscess?
Can expand and compress the spinal cord, leaving neuro complications
Risk factors for epidural abscess
- Manipulation of epidural space
- Spread from other infection
- IVDU
- DM, alcoholism, HIV
- Trauma
Top 4 causes of epidural abscess
- S. aureus
- Gram -ve bacilli
- Streptococci
- CNS
Patho of epidural abscess
Damage to spinal cord from:
- Direct compression
- Cutting of blood supply
- Bacterial toxins and inflammatory mediators
Clinical presentation of epidural abscess
Initially non-specific (fever and malaise)
Classic triad = Fever, back pain, neuro deficits
Progression of untreated epidural abscess
Back pain -> nerve root pain -> motor weakness, sensory changes, bladder or bowel dysfunction -> paralysis
Preferred Dx imaging for epidural abscess
MRI (can use CT, but X-ray not very good)
Specimen collection for Dx of epidural abscess
- Abscess content
- Blood
- CSF
Management of epidural abscess
- Surgery and drainage
2. Antibiotics, empiric Tx = Ceftriaxone + Metronidazole + Vancomycin
Prognosis of epidural abscess
- 5% mortality
2. 4-22% irreversible paraplegia
What are the viral causes of conjunctivitis?
- Adenoviruses
2. Enteroviruses (and coxsackieviruses)
Clinical presentation of viral conjunctivitis (AKA pink eye)
- Watery discharge (morning crust of eyebrows)
- Irritation
- Burning/itching of eyes
- Conjunctival hyperemia
- Conjunctival edema (chemosis)
Key negatives for viral conjunctivitis
- No eye pain
2. Vision not affected
Adenoviral conjunctivitis is associated with what 2 clinical manifestations
- Pharyngoconjunctival fever
2. Epidemic keratoconjunctivitis
What is the clinical presentation of pharyngoconjunctival fever?
- Pharyngitis
- Fever
- Conjunctivitis
- Pre-auricular adenopathy
Clinical presentation of keratoconjunctivitis
- Subconjunctival bleeding
2. Conjunctival membranes
Epidemic keratoconjunctivitis
- Inflammation of conjunctivitis and cornea
- May be vision threatening
- Lasts 1-3 weeks
Dx of viral conjunctivitis
- Clinical
2. Viral swab for PCR
Tx of viral conjunctivitis
- Cold compress, eye lubricant drops, decongestant eye drops
- May be excluded from school/work, should resolve within 2 wks
- Epidemic keratoconjunctivitis needs opthalmology referral
Prevention of viral conjunctivitis
HIGHLY contagious
- Frequent hand washing
- Avoid sharing towels, eye drops, eye make up, contact lens solution
- Proper sterilization of clinic instruments
Top 4 pathogens that cause acute bacterial conjunctivitis
- S. aureus
- S. pneumoniae
- H. influenzae
- GAS
Clinical presentation of acute bacterial conjunctivitis
- Redness in eye
- Greenish-yellow discharge (matted eyelids)
- Conjunctival hyperemia
- Eyelid swelling
Clinical presentation of hyperacute bacterial conjunctivitis caused by N. gonorrhea
- PROFUSE purulent discharge
- Chemosis, hyperemia, and eyelid edema
- Severe - vision threatening
- Transmitted from genitals to hands to eyes
- Send to Opthalmologist
What is the most common cause of preventable blindness in the world?
C. trachomatis (chlamydial conjunctivitis)
Dx bacterial conjunctivitis
- Clinical
2. Culture eye discharge
Prophylaxis for gonococcal conjunctivitis in the newborn
Erythromycin ointment
Tx for opthalmia neonatorum
- N. gonorrhea = Ceftriaxone IV
2. C. trachomatis = Erythromycin
Tx of gonococcal and chlamydial conjunctivitis in adults
- Gonococcal = Ceftriaxone IV/IM
2. Chlamydial = Doxycycline PO
What are red flags for an opthalmogy referral?
- Reduced vision
- Photophobia
- Severe foreign body sensation
- Corneal opacity
- Severe headache and nausea
What is keratitis?
Inflammation of the cornea
Patho of keratitis
- Disrupted corneal epithelium
- Entrance of microbes to corneal stroma
- Microbe proliferation –> ulcerations
- Infected epithelium and stroma swell and become necrotic
- May lead to inflammation in anterior chamber (hypopyon)
Risk factors for keratitis
- Prolonged wear of contact lenses
- Eye trauma
- Eye surgery
- Chronic ocular surface disease
- DM
- Topical corticosteroids
Bacterial causes of keratitis
- S. aureus
- S. pneumoniae
- GAS
- Gram -ve organisms
Viral, fungi, and parasitic causes of keratitis
Viral = HSV-1, adenovirus, VZV Fungi = Fusarium spp. Parasites = Acanthamoeba spp.
Clinical presentation of keratitis
- Eye pain
- Decreased vision
- Foreign body sensation
- Photophobia
- Tearing and discharge
- Corneal infiltrate or ulcer (change in transparency)
- SEND to Opthalmologist
Dx of keratitis
- Slit lamp exam
2. Corneal scrapings (bacterial/viral/fungal culture, PCR, staining/microscopy)
Tx for bacterial keratitis
- Non-contact user = fluoroquinolone drops
2. Contact user = aminoglycoside + pipercillin drops
Tx for viral keratitis
- Trifluridine drops or Acyclovir ointment
Difference btw conjunctivitis and keratitis
- Moderate to severe eye pain with keratitis
- Reduced vision with keratitis
- Hazy cornea with keratitis
What is endopthlamitis?
Infection of the vitreous and/or aqueous humors
Clinical presentation of endopthalmitis
- Decreasing vision
- Eye ache
- Conjunctiva may be edematous
- Hypopyon
Dx for endopthalmitis
- Aspiration of aqueous and vitreous humor
- Vitrectomy
- Send sample for culture
Causes of endopthalmitis
- CNS
- S. aureus
- Streptococci
- Gram -ve organisms
- Candida spp.
Tx for endopthalmitis
This is an emergency
- Intravitreal antibiotics (Vancomycin + Ceftazidime)
- Vitrectomy (severe)
- Systemic antibiotics (severe)
What is periorbital cellulitis?
Infection of the anterior portion of the eyelid
What might lead to periorbital cellulitis?
- Local trauma (bites, surgery, foreign body)
- URTI
- Dacrocystitis
- Sinusitis
What are infectious causes of periorbital cellulitis?
- S. aureus
- S. pneumoniae (and other strep)
- Anaerobes
- H. influenzae
Clinical presentation of periorbital cellulitis
- Ocular pain
- Eyelid swelling
- Erythema
How to Dx periorbital cellulitis
- Hx
- Physical (full eye ROM, no double vision, no increase in pain with eye mvmt, no eye bulging)
- CT of orbits and sinuses
Tx for periorbital cellulitis
- Clindamycin OR
2. TMP-SMX + Amoxicillin (or amox-clav)
Clinical presentation of orbital cellulitis
- Ocular pain
- Eyelid swelling with redness
- Pain with eye mvmt
- Proptosis (eye bulging)
- Limitation of eye mvmt (opthalmoplegia)
- Double vision
- Fever
- Chemosis
What are 2 complications of orbital cellulitis?
- Vision loss
2. Brain abscess
How to Dx orbital cellulitis
- Blood or surgical cultures
- Imaging (CT or MRI of orbits/sinuses): inflammation of extraocular muscles, fat stranding, and anterior displacement of the eye
Tx for orbital cellulitis
- Vancomycin IV + Pip-taz IV
- Vancomycin IV + Ceftriazone IV/Cefotaxime IV
- Surgery for poor response to antibiotics, worsening vision, or abscess
Common causes of viral meningitis
- Enteroviruses (coxsackieviruses, echoviruses)
2. Herpesviruses