ID-CNS Infections Flashcards
What is “aseptic” meningitis and what is the most common cause?
Aseptic meningitis is when CSF bacterial cultures are negative and is most commonly caused by viral meningitis.
What is the most common cause of viral meningitis?
Enteroviruses: Mostly circulate in summer and fall. Include coxsackievirus, echovirus, or other nonpolio enteroviruses.
What are three ways that herpes simplex virus can cause meningitis?
- primary infection of the CNS
- secondary infection (primary infection at another site), such as HSV-2 and someone with genital ulcers
- reactivation of a latent infection presenting as aseptic meningitis
What are the difference in typical presentations from HSV-1 and HSV-2?
HSV-1: Presents as an encephalitis
HSV-2: Presents as a meningitis
What is Mollaret meningitis? What virus is it associated with?
It is a benign recurring form of lymphocytic meningitis and HSV-2
Aside from enteroviruses and herpesviruses, what are other viral causes of meningitis?
- Primary HIV infection, usually self limited, rash and pharyngitis
- Mumps virus, less common now because of the MMR, but can occur in unvaccinated kids
- Arboviruses: West Nile or St. Louis encephalitis virus
- EBV, adenovirus, CMV, VZV
What are clinical clues of a mumps meningitis?
Unvaccinated
Parotitis (inflammation of parotid glands)
Orchitis (testicular inflammation)
Clinical Description: It typically starts with a few days of fever, headache, muscle aches, tiredness, and loss of appetite. Then most people will have swelling of their salivary glands. This is what causes the puffy cheeks and a tender, swollen jaw
Difference in CSF profile between patients with viral versus bacterial meningitis.
Parameters: opening pressure leukocyte count leukocyte predominance glucose protein gram stain culture
CSF PARAMETER VIRAL BACTERIAL
opening press <250 200-500
leukocyte count <1000 >1000
leukocyte predom lymphocytes neutrophils
glucose >45 <40
protein <200 100-500
gram stain negative positive 60-90%
culture negative positive 70-85%
Describe the presentation of meningitis in primary HIV infection
Primary HIV infection, usually self limited, rash and pharyngitis
Diagnosis of viral meningitis
- PCR-enterovirus and HSV
- Ab detection-West Nile
- Serological testing-for mumps, could provide adjunctive testing and additional testing to assist with clinical suspicion
Nonviral causes of aseptic meningitis?
spirochetes fungi mycobacteria syphilis Borrelia burgdorferi (Lyme disease) Fungal organisms medicaitons autoimmune malignancy
Treatment of viral meningitis
Supportively with empiric antibiotics given until CSF fluid cultures exclude bacterial meningitis
What are risk factors for bacterial meningitis?
- Colonization of the nasopharynx with potential meningeal pathogens
- Complement deficiency
- Anatomic or functional asplenia
- Glucocorticoid use
- Diabetes
- Hypogammaglobulinemia
- Altered cell-mediated immunity
- Exposure to someone infected with Neisseria meningitides or traveling to areas of the world where certain organisms are more prevalent and endemic (such as sub-saharan Africa)
Most common causes of bacterial meningitis?
S. pneumoniae and N. meningitidis, both now have vaccines but may show up in the unvaccinated or people with appropriate risk factors
Aside from pneumococcal and meningococcal, what are the most common causes of bacterial meningitis?
- Group B Strep: diabetes, alcoholism, malignancy, liver disease
- Staph: neurosurgery, CNS prosthetic device, secondary from bacteremia
- H. influenzae: pediatric vaccines now… but at risk if not vaccinated. Especially if functionally or anatomically splenic.
- Listeria monocytogenes: Elderly, immunosuppressed, decreased cell-mediated immunity because of meds or medical conditions
- Gram negative bacterial: nosocomial setting, complication of neurosurgery
When is CT of the head required before lumbar puncture?
If signs or symptoms of increased intracranial pressure or a CNS mass lesion, such as papilledema, focal neurological deficits, or altered mental status are present, immunocompromised, or history of CNS disease (mass lesion, stroke, focal infection)
Diagnosis of bacterial meningitis
- Elevated CSF lactate
- CSF culture, gram stain
- Elevated opening pressure
What is the management of adults suspected of having bacterial meningitis?
If CT is performed, lumbar puncture performed…
+Gram stain: Dexamethasone+TARGETED antimicrobial therapy
- Gram stain: Dexamethasone+EMPIRIC antimicrobial therapy
- dexamethasone is used to help avoid neurological complications, including: seizures, hearing loss, cranial nerve deficits, paresis
DURATION:
7 days-meningococcal, haemophilus influenza
10-14 days- pneumococcal meningitis
21 days-staphylococcal, gram negative, Listeria
Empiric antibiotic regimen for bacterial meningitis:
-immunocompetent host age <50 with community acquired bacterial meningitis
IV Ceftriaxone OR Cefotaxime
PLUS
IV Vancomycin
Empiric antibiotic regimen for bacterial meningitis:
-Patient age >50 or those with altered cell-mediated immunity (T or B cell issues)
IV ampicillin (Listeria)
IV ceftriaxone OR cefotaxime
IV vancomycin
Empiric antibiotic regimen for bacterial meningitis:
-Allergies to beta lactams
IV moxifloxacin instead of cephalosporin
IV Bactrim instead of ampicillin
Empiric antibiotic regimen for bacterial meningitis:
Hospital-acquired bacterial meningitis
IV vancomycin plus either IV ceftazidime, cefepime, or meropenem
Neurosurgical proccedures
IV vancomycin plus either IV ceftazidime, cefepime, or meropenem
Diagnostic workup for a brain abscess
Clinical: severe headache, occasional fever, don’t really get neck stiffness, if severe get nausea and vomiting
Imaging: contrast enhanced CT
Treatment for brain abscess
Empiric antibiotics
> 2.5cm: Surgical drainage or stereotactic drainage
Empiric antibiotic for brain abscess with:
Otitis media or mastoiditis
- streptococci, bacteroides (anaerobic), Prevotella (GNs), Enterobactereceae (GNs)
- Metronidazole + third generation cephalosporin (ceftriaxone or cefotaxime)
Sinusitis
- Streptococci, Bacteroides, Enterobacteriaceae, Staphylococcus aureus, Haemophilus species
- Metronidazole + third generation cephalosporin (ceftriaxone or cefotaxime)
Dental Sepsis
- Mixed Fusobacterium, Prevotella, and Bacteroides species, Streptococci
- Penicillin plus metronidazole
Penetrating trauma after Neurosurgery
- S. aureus, streptococci, Enterobacteriaceae, Clostridium species
- Vancomycin plus a third generation cephalosporin (ceftriaxone or cefotaxime)
Lung abscess, Empyema, Bronchiectasis
- Fusobacterium, Actinomycetes, Bacteroides, and Prevotella species, Streptococci, Nocardia species
- Penicillin plus metronidazole plus a sulfa drug (TMP-SMX)
Endocarditis
- S. aureus, streptococci
* Vancomycin plus gentamicin
Hematogenous spread from pelvic, intra-abdominal, or gynecological infections
- Enteric gram-negative bacteria, anaerobic bacteria
* Metronidazole plus a third generation cephalosporin
Immunocompromised patients, HIV-infected patients
- Listeria species, fungal organisms (cryptococcus neoformans), or parasitic, or protozoal organism (Toxoplasma gondii); Aspergillus, Coccidioides, Nocardia
- Metronidazole plus a third generation cephalosporin, anti-fungal or parasitic agent
Spinal epidural abscess–how do they form?
Hematogenous or through an infected vertebrae
Risk factors for epidural abscess
IVDU, epidural catheter, paraspinal glucocorticoids, analgesic injections, diabetes mellitus, HIV infection, trauma, tattooing, alcoholism, and acupuncture
Most common organism causing an epidural abscess
Staph aureus
Less common: gram negative bacilli, strep, anaerobic organisms, fungi or unusual pathogens
Signs and symptoms of an epidural abscess
Back pain with accompanying neurological symptoms such as bowel or bladder dysfunction, lower extremity weakness, paresthesias, and in last stages paralysis
Diagnosis of epidural abscess
MRI preferred
Microbiologic sampling with CT guided needle aspiration and blood cultures
Treatment of epidural abscess
surgical drainage and empiric antibiotic therapy
followed by serial imaging to watch for resolution (4-6 weeks after therapy)
Cranial subdural empyema–anatomy
occurs between the dura mater and the arachnoid mater
Treatment of a subdural empyema
Immediate neurosurgical intervention
Risk factors for subdural empyema
sinusitis, otitis media, mastoiditis
Clinical presentation of subdural empyema
Fevers, altered mental status or deteriorating mental status, nausea, vomiting
Empiric antibiotic therapy for cranial subdural empyema
vancomycin, ceftriaxone (good CNS penetration), flagyl
What is an encephalomyelitis
inflammation of the spinal cord
Definition of encephalitis
alteration in mental status for 24h or more, in addition to: fever, focal neurologic deficit, seizure, CSF pleocytosis, abnormal findings on EEG or neuroimaging
Diagnosis and treatment of encephalitis
- Neuroimaging to exclude a mass lesion or cerebral edema as a contraindication to a lumbar puncture
- If no cerebral edema then do LP
- EEG in its with depressed consciousness, even without seizure activity (non convulsive status epilepticus)
- No treatment for most, just supportive care
HSV-1 encephalitis:
- Epi and transmission
- Clinical features
- Laboratory diagnosis
- Treatment
-Epi and transmission: Reactivation of latent virus
-Clinical features: fever, AMS, temporal lobe seizures
-Lab: HSV Type I PCR on CSF
Treatment: IV Acyclovir
VZV encephalitis:
- Epi and transmission
- Clinical features
- Laboratory diagnosis
- Treatment
- Epi and transmission: can occur at time of acute infection or reactivation, increased risk in HIV
- Clinical features: cutaneous lesions variably present
- Lab: VZV PCR on CSF, CSF antibodies (if vasculitis suspected)
- Treatment: Acyclovir
Enterovirus encephalitis:
- Epi and transmission
- Clinical features
- Laboratory diagnosis
- Treatment
Epi and transmission: Typically late summer-fall
Clinical features: fever, altered mental status, variable rash or oral lesions
Lab: Enterovirus PCR on CSF
Treatment: Supportive care
West Nile Virus encephalitis:
- Epi and transmission
- Clinical features
- Laboratory diagnosis
- Treatment
Epi and transmission: Mosquito-borne (summer-fall)
Clinical features: fevers, altered mentation with or without muscle weakness (asymmetric flaccid paralysis); seizures rare
Lab: West Nile Virus IgM antibody on CSF (obtain CSF serology)
Treatment: Supportive
Rabies Virus encephalitis:
- Epi and transmission
- Clinical features
- Laboratory diagnosis
- Treatment
- Epi and transmission: bite from an infected animal
- Clinical features: Paresthesia at site of inoculation, hydrophobia, progressive obtundation
- Lab diagnosis: Nape of neck skin biopsy for immunohistochemistry; rabies PCR of saliva or CSF (testing coordinated with local health department)
What is normally seen on an LP of an HSV encephalitis patient? MRI? EEG?
LP:
Lymphocyte Pleocytosis
Erythrocytes (usually if necrosis occurs)
MRI: unilateral or bilateral temporal lobe changes
EEG: periodic lateralizing epileptiform discharges
What are the ways VZV infects the CNS?
- You can see a skin rash, but not always
- Herpes sine zoster, is CNS infection without a rash
- Infects cerebral arteries causing ischemic strokes
CNS presentations of WNV
encephalitis, meningitis, myelitis
What is WNV testing cross-reactive with?
Other flaviviruses!
So be careful if previous exposure to or vaccination from: Japanese encephalitis virus, St. Louis encephalitis virus, yellow fever virus, dengue virus,
Autoimmune encephalitis
anti-NMDAR encephalitis is confirmed by finding the antibody in serum
Clinical features include: choreoathetosis, psychiatric symptoms, seizures, autonomic instability
Most common causes of prion disease and how does it occur
CJD is most common and occurs sporadically
Describe CJD
Occurs sporadically
Most commonly in seventh decade of life
Most common clinical sign is cognition issues
Other neurological signs: spasticity, ataxia, myoclonus, changes in sensory perception
Progressive neurological decline that usually occurs over 6-12 months until death
Describe variant CJD
Infectious!
Occurs after consumption of infected beef, but can get transmission through blood products or through blood
Signs: ataxia, spasticity, and myoclonus
Place on differential for rapidly progressive dementia
Diagnosis: 14-3-3 protein
