CNS Infections- Amoebic & Acute PAM Flashcards
Acute primary amoebic meningoencephalitis
A very rare diseases confined to the CNS that is produced by amoebae (protozoa).
Amoebae possess 2 cellular forms:
- trophozoites- feeding form found in brain and in the environment.
- cyst are the resistant form found in water, never brain (cysts are resistant to freezing water and chlorination)
Naegleria fowleri description
- ubiquitous
- free-living amoebae found in warm, freshwater lakes, puddles, ponds, improperly chlorinated swimming pools and brackish water especially during hot weather summers
Population at risk for acute primary amoebic meningoencephalitis
Children and young adults
-Patients are usually healthy, immunocompetent before disease (but immunocompromised persons are equally susceptible)
Seasonality
Summer: swimming/waterskiing in warm, fresh water
-1/2 of all cases worldwide occur in the US (~1case/y in the US until last year; when 6 cases occurred)
Acute primary amoebic meningoencephalitis (PAM) infections occur when water bearing the agent is _______, the organism is implanted in the _______ from which it invades the CNS through the ________ and can be found in the subarachnoid and perivascular spaces. It is an Inflammatory disease.
forced into the nose (POE)
nasal mucosa
cribriform plate
Fulminate (sudden) course occurs over
2 → 7 days from onset of symptoms to death.
After a short (2 → 4 d) incubation period, patient manifests with signs and symptoms similar to those of ____________.
acute bacterial meningitis and/or encephalitis.
1 → 2 days after symptom first appear, pt. manifests with _______ then _________.
Death occurs 2 → 7 days later due to cardiorespiratory failure and __________.
diffuse encephalitis
coma
cerebral edema
acute primary amoebic meningoencephalitis is difficult to diagnose due to ___________
non-specific symptoms and rapid progression of disease
WILL SEE:
-Peripheral leucocytosis
-Death within a week
Patient history is essential in diagnosis of this disease, warning signs in history are:
- Hyperacute clinical course
- Unrelenting signs and symptoms
- Exposure to fresh water
CSF findings are similar to those of bacterial meningitis except may observe amoeba in CSF (description of CSF)
- Cloudy fluid.
- PMNs predominate.
- Hyperproteinosis (elevated protein levels).
- Hypoglycorrhachia (low glucose).
- Absence of viral, bacterial or fungal agents, NONE detected by staining, culture, PCR, rapid tests, etc
Brain biopsy specimen will reveal
- Positive IFA test with anit-Naegleria fowleri serum
- Clusters of amoebic trophs by H & E stain.
- Intense PMN infiltrate/inflammation in brain parenchyma
Prognosis is _______, with a high mortality, those who survive have ____________.
very poor
catastrophic, irreversible brain damage
Treatment
Amphotericin B - intrathecally and/or intraventricularly
