CNS Infections Flashcards
CSF profile (WBC/predominant cells/protein/glucose) for normal hosts
<5/lymphocytes/20-60/45-80
CSF profile (WBC/predominant cells/protein/glucose) for bacterial meningitis
1000-5000*/neutrophils/100-500/<45
*may be lower if very early or partially treated
CSF profile (WBC/predominant cells/protein/glucose) for viral encephalitis
5-500/lymphocytes/20-60 (normal)/45-80 (normal)
CSF profile (WBC/predominant cells/protein/glucose) for fungal meningitis
100-500/lymphocytes/increased (100-500)/<45
Symptoms of meningitis vs encephalitis
Meningitis: fever/nuchal rigidity/photophobia
encephalitis: fever, altered mental status, hallucinations, seizures
4. Common clinical signs of encephalitis in adults include headache, fever, malaise, nuchal rigidity, altered mental status, and nausea and vomiting
Dexamethasone use in acute bacterial meningitis
administering dexamethasone 0.15 mg/kg every 6 hours for up to 96 hours, with the first dose administered 10–20 minutes before, or at least concomitant with, the first dose of antimicrobial therapy. Can d/c if cultures do not show Strep pneumo
Common causes of viral encephalitis
HSV, West Nile, enteroviruses
encephalitis. HSV-1 causes dis- ease in adults as a result of genital or rectal HSV infection, whereas HSV-2 usually occurs in newborns because of their passage through the vaginal canal of mothers with active HSV.
Diagnosing suspected HSV encephalitis
- A PCR for HSV should be done for all patients thought to have encephalitis. In addition, if the initial
test is negative, repeat testing should be completed in 3–7 days in patients with compatible symptoms or
temporal lobe localization on MRI or CT. It is important to establish the diagnosis of HSV encephalitis
because withholding treatment can result in a mortality rate of almost 70%.
Empiric management of encephalitis
Acyclovir 10–20 mg/kg intravenously every 8 hours should be initiated in all patients with suspected encephalitis (Figure 1). Therapy duration should be 14–21 days for HSV encephalitis. Both relapse and mortality in neonates decrease when the 20-mg/kg intravenous dose is given every 8 hours for 21 days.
No benefit has been shown with adding adjunct corticosteroid therapy to acyclovir therapy; therefore,
this is not recommended
Most common causes of encephalitis in US
the most commonly identified etiologies in the United States are herpes simplex virus, West Nile virus, and the enteroviruses, followed by other herpesviruses.
Viral encephalitis CNS findings
In patients with viral encephalitis, CSF analysis typically reveals a mild mononuclear pleocytosis, although a polymor- phonuclear cell predominance may initially be seen if the sam- ple is obtained early in the course of illness; encephalitis.
CSF protein concentration is generally mildly or moderately elevated
A decreased CSF glucose concentration is un- usual in viral encephalitis and suggests disease caused by bac- teria (e.g., L. monocytogenes and M. tuberculosis), fungi, or pro- tozoae (e.g., Naegleria species).
Utility of CSF PCR for HSV encephalitis
The utility of PCR assays for the diagnosis of herpes simplex encephalitis (usually caused by herpes simplex virus type 1 in adults) has been reliably demonstrated, with reported sensitivities and specificities of 96%–98% and 95–99%, re- spectively, in adults [61]; CSF PCR results are positive early in the disease course and remain positive during the first week of therapy,
An initially negative CSF PCR result for herpes simplex virus may become positive if the test is repeated 1–3 days after the initiation of treatment
in undiagnosed cases in which patients have clinical fea- tures of herpes simplex encephalitis or temporal lobe lesions on neuroimages, consideration should be given to repeating the PCR for herpes simplex virus 3–7 days later on a second CSF specimen. In this instance, a negative CSF PCR result may allow discontinuation of acyclovir therapy
Empiric therapy for encephalitis
acyclovir (10 mg/kg intravenously every 8 h in children and adults with normal renal function; 20 mg/kg intravenously every 8 h in neonates) should be initiated in all patients with suspected encephalitis as soon as possible, pending results of diagnostic studies.
