Exam 1 Meningitis- Prunuske Flashcards
What are clinical symptoms of meningitis?
Fever and headache; Less commonly: nuchal rigidity (stiff neck), photophobia, rash (Gram- Bacteria), upper respiratory symptoms, anorexia, nausea, vomiting, diarrhea, altered mental state
What is the source of most meningitis?
Through blood, CSF and trauma to the cranium
Give an overview for the management of meningitis
History and physical, blood culture (start empiric treatment), Neuroimaging of altered mental state, papilladema, Lumbar puncture- ID organism, switch to definitive treatment
What are routine tests to run on a sample of CSF?
WBC w/ differential, RBC count, glucose, protein, gram stain, bacterial culture
What are the findings of CSF of a bacterial meningitis?
Increased pressure, Increased WBC count, more PMNs, Increased protein, decreased glucose
What are findings of a viral meningitis in CSF sample?
increased WBC, increased lymphocytes and monocytes, slight increase in prtn, normal glucose
What is a big difference between aseptic and normal meningitis in terms of symptoms?
Aseptic does not have neck stiffness and altered mental state
When is the most common time to have aseptic meningitis?
highest during first year of life.
What is the treatment for viral meningitis?
supportive therapy and recover on their own, can be fatal in neonatal period
What are most viral meningitis caused by?
Enterovirus (RNA viruses), less commonly: HSV2, arthropod-borne viruses, HIV
What are the 2 common enteroviruses?
Coxsackie and ECHO virus
What is the genome organization of enteroviruses (coxsackie and ECHO)
ssRNA + sense, naked (non-enveloped)
What are most common symptoms of septic meningitis?
Fever, stiff neck, irritability and neurological dysfunction (cranial nerve dysfunction), acute onset and progression
What are the main bacterial causes of septic meningitis?
S. pneumoniae (pneumococcal), Neisseria meningitidis (meningococcal), Haemophilus influenza type B
What is the first empiric treatment of septic meningitis? When should you start it?
Ceftriaxone of cefotaxime. IMMEDIATELY
What are other agents and their treatments that some patients may be at risk of causing meningitis?
MRSA (vancomysin), HSV-2 (acyclovir), Listeria (ampicillin)
What is the mechanism of cetriaxone (3rd gen cephalosporin)
Binds to penicillin binding proteins (transpeptidases) to inhibits cell wall synthesis. Broad, can be inactivated by beta-lactamases
What is the most common cause of meningitis in under 2 mo old
Group B strep
What is the most common cause of meningitis in 11-17 year olds?
N. meningitidis
What is the most common cause of meningitis in adults?
S. pneumoniae
List steps of development of bacterial meningitis
1)Mucosal colonization of nasopharynx 2)invasion and multiplication in blood stream 3)/4) cross into CSF, 5) release of inflammatory cytokines in CSF by astrocytes and microglia 6) Increased permeability of BBB, 7) Diapedesis of leukocytes into CSF, 8) edema and increased intracranial pressure, 9) neuronal injury including hearing loss (Cranial nerve 8)
What are the virulence factors of Neisseria meningitidis?
Capsule, IgA protease, Pili, endotoxin, outer membrane proteins
What are the virulence factors of Haemophilus influenzae?
Capsule, IgA protease, Pili, endotoxin, outer membrane proteins
What are the virulence factors of Streptococcus pneumoniae?
Capsule, IgA protease
Is listeria gram- or gram+?
Gram+
What does LPS cause when an Gram- organism infects an individual?
a rash that does not fade with pressure
How does LPS affect macrophages?
activates them leading to release of NO (causes hypotension and shock) and IL-1 (fever) and can activate disseminated intravascular coagulation leading to purpuric skin rash
What are the microscopic characteristics of Neisseria meningitidis?
Gram- diplococcus
What do most oubreaks of N. meningitidis occur?
during winder or early spring, associated with overcrowding
What is the prophylactic treatment of N. meningitidis?
Ceftriaxone
What are the microscopic characteristics of S. pneumoniae?
Gram positive diplococci (lancet shaped)
How is S. pneumoniae transmitted?
respiratory droplets
In patients with S. pneumoniae infection, what is meningitis secondary to?
paranasal sinusitis and otitis media
What patients most commonly get meningitis caused by S. pneumoniae?
> 2 months old
What vaccine should patients with sickle cell anemia get to protect against meningitis?
S. pneumoniae
What are the microscopic characteristics of Hemophilus influenza Type B?
Gram- “Coccoid” rod
What are the most common groups to be infected with Hemophilus influenza type B?
infants and young children (2 months-10 years)
What is Group B strep also known as?
Streptococcus agalactiae
Where is GBS commonly found?
gastrointestinal and genitourinary tract flora
When are infants most commonly infected with GBS?
in utero or during vaginal delivery
What is done to prevent transmission of GBS from mothers to infants?
Prophylactic Penicillin G drip during delivery
What is the tree of Streptococcus agalactiae (GBS)?
Gram+ cocci, Bacitracin resistant, catalase negative, CAMP reaction
Can E. coli K1 strain have beta lactamases? What should you do?
Yes- switch to carbapenem if ceftriaxone is not enough
What does the K1 strain of E. coli do?
is has LPS that prevents fusion with the lysosome
What are the microscopic characteristics of Listeria monocytogenes?
Gram+ rod
Who does listeria monocytogenes usually infect?
Immunosuppressed, older adults, newborns
How do people commonly get infected with listeria?
Eating contaminated foods- unpasteurized milk, cheese, and deli meats
What are common symptoms of listeria meningitis?
Fever, headache, diarrhea, no nuchal rigidity.
What are the virulence factors of listeria?
Internalin induces phagocytosis by epithelial cells of intestine, phospholipase and listeriolysis O allow escape from vacuole, actin tails allow spread between adjacent cells
What is the therapy for listeria meningitis?
Ampicillin and gentamicin for 3 weeks
What causes chronic meningitis?
Mycobacterium tuberculosis, Syphillus, Leptospira, and Lyme disease (B. burgdorferi), Fungi (Cryptococcus neoformans, Coccidioides).
What is the treatment of Mycobacterium tuberculosis?
Rifampin, Isoniazid, pyrazinamide, ethambutol (RIPE)
What are the microscopic characteristics of Mycobacterium tuberculosis
Gram- cocci in rods
What is the mechanism of rifampin?
Inhibits DNS-dependent RNA polymerase induces the formation of drug-metabolizing enzymes including CYP450
What is the mechanism of Isoniazid
Inhibits mycolic acids (component of mycobacterial cell wall). Acetylation by the liver varies genetically and fast acetylators may require higher dose
What is the mechanism of Ethambutol
inhibits cell wall synthesis by binding to arabinosyl transferase
What is the treatment of Cryptococcus neoformans?
Liposomal amphoteracin B and Flucytosine, followed by fluconazole for 3-12 months
What is the mechanism of Amphoteracin B?
Binds ergosterol and creates holes in fungal membranes
What is the mechanism of Flucytosine?
Taken up and converted to 5-fluorouracil, interfering with DNA and RNA synthesis
What is the mechanism of Fluconazole?
Binds Fungal p-450 enzyme and blocks production of ergosterol
Besides viral infections, what else can cause aseptic meningitis?
TMP-SMX (abx)
What does N. meningitidis contain that helps it mimic brain spingolipids?
lipo oligosaccharides
What usually causes the rash in patients with bacterial meningitis?
The LPS on the gram- bacteria (Listeria and N. meningitidis are gram-)
T/F: Streptococcus pneumoniae is the most common cause of meningitis in people older than 2 mo old
True
T/F: Streptococcus agalactiae (GBS) is most common cause of meningitis in new borns
True
