Microbiology - Meningitis Flashcards
What is meningitis?
Inflammation of the meninges (whereas encephalitis is inflammation of the brain).
How does meningitis typically present? (4 main)
Headache
Fever
Nuchal Rigidity
Altered Mental Status
Nausea, vomiting, photophobia can also be seen.
What are the three subdivisions of meningitis? Timing?
Acute - SX w/in 24 hrs
Subacute - SX w/in days-weeks
Chronic - SX present for > 4 weeks
What is the pathophysiology of meningitis as seen in a) Strep Pneumonia b) Neisseria meningitidis and c) Haemophilus influenza
Pneumonia and Neiserria spread by normal flora of nasopharynx which invade bloodstream.
Haemophilus spread by respiratory droplets to nasopharynx.
They all have a polysaccharide capsule (avoid phagocytosis and complement). Infect the choroid plexus (which produces CSF) - SX will be caused by inflammatory response due to LPS/teichoic acids - increased cytokines and chemokines will be released.
What is the pathophysiology of meningitis as seen in Strep agalactiae (Group B Strep - GBS)?
(-) cause of meningitis in adults, (+) cause of meningitis in neonates. Colonize genitourinary tract - vaginal carriage is up to 30% in pregnant women. Passed to neonate during birth (MCC of MENINGITIS IN NEONATES)
What is the most common cause of meningitis in neonates? When does early onset disease present vs late onset?
Strep. agalactiae (Group B Strep).
Early onset: In first 7 days
Late onset: 1 week to 3 months after birth
What is the pathophysiology of meningitis as seen in Listeria monocytogenes? Where do they replicate?
Infection is caused by consuming contaminated food. They replicate in phagocytes.
Who is at risk to get listeria?
Pregnant women can pass to their children (in utero or during birth) and immunocompromised (old age, disease, etc - CMI deficient)
What is the presentation of early vs. late onset disease in neonates (Listeria)? Timing of each?
Early onset disease (seen in the first 7 days) - the severe form presents with Granulomatosis infantiseptica (abscesses and granulomas) and there is a HIGH MORTALITY RATE.
Late onset disease (appears 1-3 weeks after birth) and the neonate presents with meningitis or meningoencephalitis with septicemia.
How do you diagnose meningitis? What will be increased/decreased in ________?
Lumbar puncture is done (blood samples are second best). The CSF should have an INCREASE in the following:
INCREASED:
Pressure
WBC
Protein
DECREASED:
GLUCOSE
What physical SX would help you differentiate meningitis caused by Neisseria meningitidis from other causes?
Nonblanching petechial or purpuric rash
What is the treatment for meningitis? General tx? Specific tx?
Give empiric antibiotics w/in 60 minutes of presentation to emergency department.
General: START EMPIRIC ANTIBIOTICS IMMEDIATELY!
Specific: 3rd or 4th generation CEPHALOSPORIN (3rd gen - ceftriaxone or cefotaxime - can cross the BBB) + VANCOMYCIN
How does Neisseria meningitidis stain (gram stain)? Is it aerobic or anaerobic?
GN Diplococcus. Aerobic
Where is Neisseria meningitidis usually found? How does it spread?
Found: common in nasopharynx
Spread: respiratory droplets
Time frame for Neisseria meningitidis?
Causes disease in susceptible individual in less than 4 days.
What are Neisserias two virulence factors? (2)
Pilli - allow for colonization
Polysaccharide capsule
Note: Think DIPLOCOCCI = 2 cocci = 2 virulence factors and 2 diseases (meningitis and septicemia)
What are the two most common diseases caused by Neisseria meningitidis? (2)
Meningitis and Septicemia (meningococcemia)