ID-CNS Infections #2 Flashcards
Two ways that brain abscesses occur
1-Hematogenous: typically multifocal brain abscesses in this scenario
2-Contiguous: infection from anatomic structures in close proximity
3-No source: 20-40%
Do you perform a lumbar puncture for a known or suspected brain abscess?
NO! This could cause brain herniation due to an increase in intracranial pressure.
Ways to diagnose a brain abscess
MRI is more sensitive, but CT is usually sufficient. CT-guided aspiration can be performed but is invasive and gets a microbiological diagnosis, but oftentimes you just treat without doing this
Treatment/Management of a brain abscess
- If it is suspected, empiric treatment are based on predisposing conditions and causative agents.
- If >2.5 cm then it should be surgically excised or drained stereotactically
- If not drained, follow-up CNS imaging should occur within several days to assess for worsening cerebral edema. Repeat CNS imaging urgently if there are any mental status or neurological changes.
- Add glucocorticoids if there is evidence of cerebral edema
- Duration: 4-8 weeks
Empiric antibiotic choice for bacterial brain abscess? What are the expected/most common organisms?
Source: Otitis Media or Mastoiditis
Streptococci (aerobic or anaerobic)
Bacteroides
Prevotella
Enterobacteriaceae
*Metronidazole plus a third-generation cephalosporin (ceftriaxone or cefotaxime)
Empiric antibiotic choice for bacterial brain abscess? What are the expected/most common organisms?
Source: Sinusitis
Streptococci Bacteroides Enterobacteriaceae Staphylococcus aureus Haemophilus species
*Metronidazole plus a third-generation cephalosporin (ceftriaxone or cefotaxime)
Empiric antibiotic choice for bacterial brain abscess? What are the expected/most common organisms?
Source: Dental sepsis
Streptococci
Bacteroides
Prevotella
Fusobacterium
*Penicillin plus metronidazole
Empiric antibiotic choice for bacterial brain abscess? What are the expected/most common organisms?
Source: Penetrating trauma after neurosurgery
Staphylococcus aureus
Streptococci
Enterobacteriaceae
Clostridium species
*Vancomycin plus third generation cephalosporin (ceftriaxone or cefotaxime) or fourth generation cephalosporin (cefepime, ceftazidime) or even meropenem
Empiric antibiotic choice for bacterial brain abscess? What are the expected/most common organisms?
Source: Lung abscess, empyema, bronchiectasis
Fusobacterium Actinomyces Bacteroides Prevotella Streptococci Nocardia
*Penicillin plus metronidazole plus a sulfa (TMP-SMX for Nocardia)
Empiric antibiotic choice for bacterial brain abscess? What are the expected/most common organisms?
Source: Endocarditis
Staphylococcus 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 or fourth generation cephalosporin
Immunocompromised patients
HIV-infected patients
Listeria species
Fungal organisms (Cryptococcus neoformans)
Parasitic or Protozoal organisms (Toxoplasma gondii)
Aspergillus
Coccidioides
Nocardia
*Metronidazole plus a third-generation cephalosporin; antifungal or anti-parasitic agent
How do spinal epidural abscesses occur?
-Contiguous spread from infected vertebrae or intervertebral body disc spaces or hematogenous dissemination from a distant site
Risk factors for an epidural abscess
Prolonged epidural catheter placement Paraspinal glucocorticoid or analgesic injections Diabetes mellitus HIV infection Trauma IVDU Tattooing Alcoholism Acupuncture
Most common organisms causing a spinal epidural abscess
Staphylococcus aureus Gram negative bacilli Streptococci anaerobic organisms rarely fungi
How to diagnose spinal epidural abscess
Clinical: difficult to diagnose because symptoms can be mild or nonspecific and fever is not always present
Diagnostic: MRI, always get two sets of blood cultures, CT guided aspiration for microbiology
Treatment of a spinal epidural abscess
Combination of antimicrobial therapy and surgical drainage; follow-up MRI every 4-6 weeks or with signs of clinical deterioration. Antibiotic choice must have good CNS penetration.
Duration: usually 6-8 weeks or until resolution on follow-up MRI
What is a cranial subdural empyema?
A focal infection or abscess that occurs between the dura mater and arachnoid mater.
What is the management of a cranial subdural empyema?
It is a medical emergency warranting immediate neurosurgical intervention.
What are the inciting factors that can cause a cranial subdural empyema?
Sinusitis, otitis media, mastoiditis
What pathogens are the most common causes of a cranial subdural empyema?
S. pneumoniae, H. influenzae, aerobic and anaerobic Strep species, Staph species (Coag positive and Coag negative), gram negative bacilli, anaerobic species.
Clinical presentation of a cranial subdural empyema?
fever, headache, nausea and vomiting, mental status changes, with history of preceding sinusitis, otitis, meningitis, mastoiditis, or recent neurosurgical procedures or sinus surgeries
Diagnosis of cranial subdural empyema?
MRI, can use CT contrast as an alternative
LP is CONTRAINDICATED if there is a concern for increased intracranial pressure
Treatment of cranial subdural empyema
vancomycin
flagyl
ceftriaxone (penetrates CNS well)
Ultimately a medical emergency that requires immediate evaluation and neurosurgical evaluation
What is the clinical definition of encephalitis?
It is an alteration in mental status lasting 24 hours or more that is associated with two or more of the following: fever, focal neurological deficit, seizure, CSF pleocytosis, abnormal findings on EEG or neuroimaging.
Occurs as a result of a meningitis, encephalomyelitis, but often no cause is found.
What is the most common cause of endemic encephalitis in the U.S.?
HSV-1, usually reactivation of latent virus, infection of the unilateral or bilateral temporal lobes
For HSV encephalitis, how is it diagnosed?
Clinical syndrome with MRI findings of temporal lobe abnormalities.
EEG-periodic lateralizing epileptiform discharges may be present
LP- lymphocytic pleocytosis
PCR-PCR findings of CSF remain positive for up to one week
Treatment of HSV encephalitis
Acyclovir
How does VZV encephalitis occur?
Acute varicella infection or with viral reactivation
What are risk factor for VZV encephalitis
HIV/AIDS or defects in cellular immunity but sometimes can happen in healthy people
How can VZV cause a stroke
VZV can infect cerebral arteries, presenting as an ischemic stroke from a vasculitis rather than encephalitis
How to diagnose VZV encephalitis
VZV in CSF by PCR
When a vasculitis is of concern, or when symptoms are slower, intrathecal VZV antibodies should be measured because VZV PCR results can be negative in these cases
How do you treat a VZV encephalitis or vasculopathy?
Acyclovir
Neuroinvasive West Nile Virus–what is the vector? Ways transmitted? Time of year?
Mosquitos. Usually summer and early fall.
Can also be transmitted via blood transfusion and organ transplantation.
What is the clinical presentation of WNV?
20%-Asymptomatic
Most develop a fever
Severe West Nile: <1% cases. Meningitis, encephalitis, myelitis or some overlap.
Limb weakness (symmetric) or involve a single extremity
Acute asymmetric flaccid paralysis progressing to respiratory failure (like seen with polio)
Viral exanthema or rash
MRI may show focal lesions of the thalami, basal ganglia, and spinal cord
How to diagnose West Nile Neuroinvasive disease?
Clinical suspicion
CSF SEROLOGY to detect IgM to WNV in first week, but titers can remain positive for a year; IgG less helpful
What is one issue for diagnosis of WNV with serology?
Serology has cross reactivity between WNV and other flaviviruses (St. Louis encephalitis virus, Japanese encephalitis virus, yellow fever virus, dengue virus); so caution should be taken when interpreting positive WNV IgG in patients with natural infection or vaccination against the above viruses
How good is PCR for diagnosing west nile virus?
PCR of the serum or CSF are infrequently positive except in immunocompromised patients who may have delayed viral clearance.
Treatment for WNV
Supportive care, monitored in the ICU
Presentation of autoimmune encephalitis
anti-NMDAR antibody
choreoathetosis, psychiatric symptoms, seizures, autonomic instability
*Have a high suspicion for an ovarian teratoma, because that occurs in >50% of cases
What is the treatment of autoimmune encephalitis?
removal of teratoma if present, immunosuppression with glucocorticoids or IVIG.
Immunosuppression because theses are auto-antibodies against NMDAR receptors on neurons
What is the most common form of prion disease in humans?
Cruetzfeldt-Jakob disease
What are the most common causes of CJD in people?
Most cases sporadic
Iatrogenic from surgical contamination or contaminated grafts
What is the clinical presentation of CJD?
disordered cognition
ataxia, spasticity, sensory problems, changes in visual perception
progressive neurological decline resulting in death that occurs rapidly, typically within 6-12 months
What is variant CJD?
It is a novel infectious human prion disease caused by the bovine spongiform encephalopathy agent.
How is variant CJD transmitted?
Consumption of infected beef
Transmission by blood or blood product donors
What is the clinical presentation of variant CJD
motor signs–ataxia, spasticity, myoclonus
psychiatric and sensory signs
dementia and cognitive decline over a brief 6-12 mo period
Different from sporadic CJD in that it occurs in younger people (<70 years old)
