Intro To Infectious Diseases Flashcards
What is a bacteria associated with meningitis?
Neisseria meningitidis
What side effect does prednisone do to the body?
Immunosuppression
What can cause encephalitis?
Herpes Abscesses (tumor) (strep and staph) Ammonia build up tumor Lupus Hemmorhage Drugs
What area does meningitis involve?
The subarachnoid space
What area does encephalitis involve?
Diffuse parenchyma
What are does an abscess involve?
Some focus point
What are the four common symptoms of meningitis and how often does a Px have them?
95% of Pxs have 2 out of: Headache Fever Nuchal (neck) rigidity Altered mentality
What is the most common cause of meningitis?
Viral
What is the most life threatening cause of meningitis?
Bacterial
What causes of meningitis usually only happen when the Px is immunocompromized?
Fungal and protozoan
What is one of the most important virulence factors that allow organisms to survive?
Capsule virulence factors so they can stay in the blood stream longer
What are the main symptoms of encephalitis?
Fever, headache, and altered mental status
Motor and sensory deficits not seen in meningitis
Progression leads to seizures, speech disturbances, lethargy, and coma
What percentage of cases of encephalitis have an unknown etiology?
33% - 66%
What are some none viral causes of encephalitis?
Entrovirus
Arbovirus
Herpes virus
Rabies virus
What are some none viral causes of encephalitis?
Rickettsia
Mycoplasma
Acute disseminated encephalomyelitis (ADEM)
What are symptoms of an abscess?
More focal neurological symptoms
Fever
Headache
Seizure
What is the most common cause of encephalitis?
Streptococci
What are some other bacteria that can cause a brain abscess?
Pseudomonas
Haemophilus
Staph
Bacteriodes
When do mycobacterium, fungi, or parasites cause abscesses?
When the Px is immunocompromized
How do you distinguish between
Encephalitis vs. Encephalopathy?
-itis -pathy
Headache common. Uncommon
Fever common. Uncommon
Inflammation. No inflammation
High WBC. Normal WBC
What are some causes of encephalopathy?
Build up of a drug or some metabolic product
Are infections of the CNS common?
No
What are important innate immune cells in the CNS?
Astrocytes and Microglia
How does the rabies virus get into the brain?
Retrograde axonal transport
What bacteria can be passed from a mother to a fetus through food?
Listeria
What is the mortality rate for Listeria?
25%
What diagnostic test do you do if you want to confirm Listeria infection?
Blood culture before treatment
Lumbar puncture
Imaging for abscess to avoid herniation
How do you identify an organism?
Gram stain
PCR
What properties of an antibiotic for Listeria would be good?
Gets into the brain (small)
Bacteriocidal
What class is primarily used for brain infections?
3rd generation cephalosporins
Small lipophilic
Low affinity for plasma binding proteins
Include dexamethasone for decreasing inflammation
What is the treatment for Listeria?
Ceftriaxone + ampicillin
By inhibiting Transpeptidation of peptidogylcan
What is the spectrum for 3rd generation cephalosporin ceftriaxone?
For streptococci and more serious gram - infections. Can cross BBB
Also gram +
Worried about allergies
Inactivation by beta-lactamases
What are major side effects of beta lactams?
Seizures since it crosses the BBB
Why would you do neuroimaging?
Look for an abscess, herniation
Where is a lumbar puncture done?
Between L3/4
What are routine tests done on a lumbar puncture?
WBC with diff RBC Glu concentration Protein concentration Gram stain Bacterial culture
What percent of CSF and blood cultures are positive?
40 and 60 respectively
What levels help differentiate between viral and bacterial meningitis?
Elevated protein, decreased glucose, and increase polymorphonuclear leukocytes
What stain is Listeria?
Gram positive
Intracellular
What is the normal WBC for CSF?
0-5
What’s is a typical WBC for someone with bacterial meningitis?
100-20000
Average is about 800
What is PMN?
Polymorphonuclear leukocytes-Granulocytes
What is a normal PMN for bacterial meningitis?
> 80% PMN
What is the typical WBC for someone with viral meningitis?
5-500
Average 50
What is the typical PMN for viral meningitis?
Greater than 50 L
Less than 20 PMN
What does a very high CSF protein indicate?
Bacterial meningitis while viral is lower but still high
What do you see in CSF glucose for bacterial meningitis?
Low glucose because bacteria use glucose while viruses don’t
What type of bacteria is Listeria?
Rod (gram positive)
What are some virulence factors for Listeria?
Internalin - induces phagocytosis (intracellular)
Phospholipase - escape from vacuole
Listeriolysin - escape from vacuole
Actin tail - facilitate pseudopod
Why do you use gentamicin and what does it do?
It is an aminoglyacide and inhibited ribosomes
Ampicillin helps it get into the cell
Gentimicin is added once listeria is found
