JH IM Board Review - Infectious Disease VI Flashcards
Meningitis - Definition:
Inflammation of the LEPTOMENINGES = Tissue surrounding the brain and spinal cord.
Aseptic meningitis is defined as:
Meningeal inflammation with an absence of bacteria on CSF exam and culture.
Some pathogens may cause chronic meningitis, in which symptoms are present for …?
4 or more weeks.
==> Cryptococcal meningitis (Rarely in seemingly healthy individuals).
==> TB meningitis.
In meningitis, unlike encephalitis, …?
Brain function is normal.
==> Mental status changes and seizures can occur.
Meningitis - PEx may reveal signs of meningeal irritation, but these findings occur in less than …?
5% of patients.
==> Kernig = Pain in the back is elicited with passive extension of the knee while the hip is flexed.
==> Brudzinski = Passive flexion of the neck results in spontaneous flexion of the hips and knees.
Meningitis - Dx:
- Blood cultures should be obtained IMMEDIATELY.
- Dx relies on exam of the CSF.
- Neuroimaging with CT or MRI is only needed in select situations before performing a LP.
- If neuroimaging is needed, empiric abx (and dexamethasone if indicated) should be started BEFORE scanning.
Bacterial meningitis - Empirical Tx - <1month:
Ampicillin + cefotaxime OR Ampicillin + aminoglycoside.
Bacterial meningitis - Empirical Tx - 1month-50yr:
Vanco + 3rd gen cephalosporin (ceftriaxone or cefotaxime).
Bacterial meningitis - Empirical Tx - >50yr:
Ampicillin (to cover Listeria spp.) + Vanco + 3rd gen cephalosporin.
Bacterial meningitis - Empirical Tx - Penetrating head trauma, post-neurosurgery, CSF shunt:
Vanco + Cefepime, ceftazidime, or meropenem.
Meningitis - Tx - Role of adjunctive dexamethasone:
Recommended in adults with suspected or proven pneumococcal meningitis.
==> 1st dose IDEALLY given 10-20min before the first dose of abx.
==> If not given before the first dose of abx, then give concomitantly with the 1st dose.
==> Dosing: 0.15mg/kg IV every 6h for 2-4 days.
Common etiologic agents causing acute bacterial meningitis in adults - S.pneumo:
- MC etiologic agent in the USA.
- Mortality 19-26%.
- Sometimes associated with other foci of infection (eg pneumonia, endocarditis).
Common etiologic agents causing acute bacterial meningitis in adults - S.pneumo - Tx:
Vanco + 3rd gen cephalosporin until antimicrobial susceptibility is known.
==> Some experts add rifampin if dexamethasone is given.
Common etiologic agents causing acute bacterial meningitis in adults - N.meningitidis:
- Affects mostly children and young adults.
- Patients with terminal complement deficiency are at increased risk.
- Maculopapular rash progresses to petechiae on the trunk, extremities, and mucous membranes.
Common etiologic agents causing acute bacterial meningitis in adults - N.meningitidis - Tx:
3rd gen cephalosporin.
==> Switch to penicillin G or ampicillin once confirmed to be highly sensitive.
N.meningitidis - Chemoprophylaxis:
Rifampin (or ciproflox or ceftriaxone) recommended for household contacts, day care center members, those directly exposed to oral secretions.
Common etiologic agents causing acute bacterial meningitis in adults - H.flu:
- Mostly occurs in children.
- Disease in adults usually associated with:
==> Sinusitis, otitis media, pneumonia, sickle cell disease, splenectomy, DM, immunodeficiency, head trauma with CSF leak, or alcoholism.
Common etiologic agents causing acute bacterial meningitis in adults - H.flu - Tx:
3rd gen cephalosporin.
Common etiologic agents causing acute bacterial meningitis in adults - Listeria:
- Disease of neonates, older adults, and immunocompromised (incl. poorly controlled diabetics and pregnant women).
- Outbreaks associated with contaminated produce, coleslaw, milk, cheese.
- Associated with hematologic malignancy, steroid use, iron overload.
Common etiologic agents causing acute bacterial meningitis in adults - Listeria - Tx:
Ampicillin (or PCN G) +/- aminoglycoside.
Common etiologic agents causing acute bacterial meningitis in adults - S.aureus:
Usually seen after head trauma, in post-op settings, or when hardware is present.
Common etiologic agents causing acute bacterial meningitis in adults - S.aureus - Tx:
Nafcillin or oxacillin (if methicillin-susceptible).
==> Vanco +/- rifampin (if methicillin-resistant).
Causes of aseptic meningitis - Categories:
- Viral.
- Bacterial.
- Fungal.
- Miscellaneous infections.
- Non infectious diseases.
- Drugs.
Causes of aseptic meningitis - Viral:
- Enteroviruses.
- Mumps.
- Echovirus.
- Poliovirus.
- Coxsackie.
- HSV.
- CMV.
- VZV.
- Arbo.
- Acute HIV.
- Influenza.
Causes of aseptic meningitis - Bacterial:
- TB.
- Rickettsiae.
- Syphilis.
- B.burgdorferi.
Causes of aseptic meningitis - Fungal:
- Cryptococcus.
- Coccidioides.
- Histoplasma.
- Candida.
- Molds (aspergillus, exserohilum).
Causes of aseptic meningitis - Miscellaneous infections:
- Toxo.
- Malaria.
- Whipple.
- Leptospira.
Causes of aseptic meningitis - Noninfectious disease:
- Brain tumors.
- Sarcoidosis.
- Lupus.
- Meningeal carcinomatosis.
Causes of aseptic meningitis - Drugs:
- TMP-SMX.
- Ibuprofen.
- Carbamazepine.
Encephalitis frequently occurs with …?
MENINGITIS ==> Meningoencephalitis.
MYELITIS ==> Encephalomyelitis.
In pts who had a recent viral illness or vaccination and who present with encephalitis, consider …?
A diagnosis of acute disseminated encephalomyelitis (ADEM).
West Nile virus may be associated with …?
FLACCID WEAKNESS + Reduced or absent reflexes.
Encephalitis - Dx - CSF PCR:
- HSV.
- CMV.
- EBV.
- VZV.
- JC virus.
- West Nile virus.
- Enteroviruses.
Encephalitis - Dx - CSF serology is useful for …?
Detection fo ARBOviruses.
Encephalitis - Dx - Serum +/- CSF serologic testing and PCRs can help diagnose:
Tick-borne + Spirochetal disease.
Encephalitis - Dx - Brain Bx when?
ONLY needed in pts who continue to deteriorate on acyclovir and who have a negative Dx workup.
Encephalitis - Dx - CSF culture is useful for:
- Fungal.
- Mycobacterial.
- Bacterial.
causes of encephalitis.
Encephalitis - Dx - Perform respiratory viral panel testing if …?
There is a suspicion of resp. viral disease.
Encephalitis - Dx - MRI?
ALWAYS. If not possible, then CT.
Indications for head CT before LP when acute bacterial meningitis is suspected - Immunocompromised host:
- HIV/AIDS.
- Transplant patient.
- Patient on immunosuppressive medications.
Indications for head CT before LP when acute bacterial meningitis is suspected - Hx of CNS disease:
- Mass lesion.
- Stroke.
- Focal infection.
Indications for head CT before LP when acute bacterial meningitis is suspected - Papilledema:
Especially if no venous pulsations.
Indications for head CT before LP when acute bacterial meningitis is suspected - New-onset seizure:
Onset within 1 week of presentation.
Indications for head CT before LP when acute bacterial meningitis is suspected - Focal neurologic deficit:
- Dilated nonreactive pupil.
- Ocular motility abnormalities.
- Abnormal visual fields.
- Gaze palsy.
- Arm or leg drift.