EXAM 3 CNS Infections Dr. Cluck Flashcards
Objectives
list common organism causing CNS infection
-appropriate drugs and formulations -> especially for ACUTE bacterial meningitis
-drugs for chemoprophylaxis
-who needs chemoprophylaxis and who doesn’t!
What is the definition of meningitis?
inflammation of the membrane that covers the brain and the spinal cord, and the CSF that is in contact with that membrane
Bacterial meningitis is considered a medical emergency –> should be treated ASAP
Gram-positive bacterial organisms causing CNS infections
Strep pneumonia (+)
Streptococcus agalactiae (+) (Group B strep) - 35% in neonates
Staph aureus (+)
Listeria monocytogenes (+)
Gram-negative bacterial organisms causing CNS infections
Neisseria meningitis (-)
Haemophilus influenza (-)
Enterobacterales (-)
Which organism causes the majority of CNS infections?
Strep pneuomonia (+)
Which organism is known to cause CNS infections in neonates?
Streptococcus agalactiae (+) (Group B strep)
-also listeria and E.coli
-when seen in adults they often have other risk factors
Which bacterial organisms are likely to be hospital-acquired?
Staph aureus (+)
Enterobacterales (-)
Which bacterial organisms are likely to be community-acquired?
Strep pneumonia (+)
Streptococcus agalactiae (+)
Neisseria meningitis (-)
Haemophilus influenza (-)
Listeria monocytogenes (+)
Which viral pathogens may cause CNS infection?
-Enteroviruses
-HIV
-HSV 1-> encephalitis
-HSV 2 -> meningitis
Which other pathogens may cause CNS infection?
Fungal (Cryptococcal) -> patients often immunocompromised (fe AIDS with low CD4 count)
-Parasitic/Protozoal: Naegleria fowleri
Which parasitic organism causes CNS infection?
Naegleria fowleri
-brain-eating ameba
often seen when people use Neti-pods with tap water (the water should be boiled)
What are the general risk factors for CNS infections?
Immunosuppressive states
-HIV
-malingnancy (cancer)
-transplantations
When to consider vaccination against encapsulated organisms?
in case of asplenia or splenectomy
-S. pneumo
-Haemophilus influenzae
-Neisseria meningiditis
What are the risk factors for a S. pneumoniae CNS infection?
-Pneumococcal pneumonia
-sinusitis
-otitis media
-Alcoholism
-diabetes
-Asplenia/splenectomy
-Cochlear implants (ear, passage way to get into the CNS)
-S. pneumo bacteremia (S. pneumo in the blood)
-> consider Pneumococcal meningitis and treating with Ceftriaxone 2g IV q12h at least until meningitis is ruled out
What are the risk factors for N. meningitis CNS infection?
-Complement deficiencies
-Nasopharyngeal carrier
What are the risk factors for Group B streptococcus (S. agalactiae) CNS infection?
neonates
What are the risk factors for L. monocytogenes CNS infection?
-neonates (< 1 month of age)
-pregnant women !!!
->60y of age (immunosenescence)
What are the risk factors for H. influenzae CNS infection?
-Lack of vaccination !!!
-diabetes
-splenectomy
-chronic alcoholism
-multiple myeloma
-immund deficiency
What are the risk factors for Enteric gram-negative bacilli (hospital-acquired)?
chronic and debilitating diseases
-poorly controlled diabetes
-cirrhosis, alcoholism
-chronic UTI
neurosurgical procedures, particularly craniotomy
-> patient comes back with symptoms (febrile)
-> consider gram-negative Staph aureus, gram-negatives (but rare)
What are the risk factors for Strep pneumo?
-most common
-patients often with contiguous focus or foci (concomitant endocarditis, PNA, sinusitis)
-non-resistant stereotypes are more drug-resistant (what are the stereotypes?)
-> Ceftriaxone and Vancomycin
What are the risk factors for N. meningitis?
often in children in young adults (college age)
->patients living close promixity (dorms, base camps)
-Serotype B, C, and Y most often in US
Which vaccine protects against Serotype B N. meningitis?
Trumenba and Bexsero
What are the risk factors for Group B Strep ( Strep agalactiae)?
half of cases in the first month of life
adults may be affected by GBS meningitis, likely have risk factors
What are the risk factors for Listeria monocytogenes?
-use of TNF-alpha inhibitors (infliximab) - BIOLOGICS
-certain foods (cheese, deli meats, franks, cantaloupes!)
-pregnancy (200x greater risk)
Clinical Presentation of patients with meningitis
Fever
strong headache
altered mental status (AMS)
nuchal rigidity (stiff neck)
rash (not so often)
-> presentation depends on patients age, etiology agent (organisms), immune status, area of brain that is involved
What is the gold standard for meningitis diagnosis?
Lumbar puncture (caution with increased cranial pressure) -> culture CSF -> PCR
->antimicrobial should not be delayed, given it too early may hinder diagnosis since it sterilizes the CSF within hours
When is the CSF indicative for a meningitis infection?
turbid or cloudy CSF fluid could be indicative of an infection
-bloody: traumatic tap
-other indicators: CRP, procalcitonin, CSF lactate
-> not often used
Common CSF findings
(not on exam?)
-elevated WBC >1000 per mm3
-predominance of PMNs (neutrophils)
-low CSF to glucose ration
Which physical exams may be indicative of meningitis?
Brudzinski’s sign
Kernig’s sign
-> indicative of meningeal irritation if positive
-LOW sensitivity
Which antimicrobials penetrate the CNS regardless of inflammation?
Sulfonamides
Metronidazole (great when anaerobs are involved)
Chloramphenicol
Trimethoprim
Rifampin
Isoniazid
-> they are usually not used, they use ß-lactams
Which antimicrobials penetrate the CNS with inflammation?
Penicillin G
Ampicillin/sulbactam
Ceftriaxone
Cefuroxime
Imipenem
Meropenem
Ciprofloxacin
Levofloxacin
Moxifloxacin (best penetration of the FQs)
and more
if there are newer drugs on the EXAM the answer is wrong, bc there is not enough data that supports sufficient CNS penetration
What are the antimicrobials of choice for meningitis?
Ceftraixone 2g q12h !!!
Meropenem 2g q8h (needs dose adjustment in renal impairment)
Which drug may be used for Listeria?
Ampicillin/Gentamicin -> despite having low CNS penetration (data suggest lower mortality risk)
-> could use Meropneme instead in case of allergy
Meropenem alone covers all community acquired diseases
Ceftriaxone/ampicillin
Which drugs have low CNS penetration?
Aminoglycosides
1st gen cephalosporin (cefazolin) -> use nafcillin instead
2nd gen cephalosporin
Clindamycin
Ketaconazole
Itraconazol
How should CNS infection be treated empirically?
3rd/4th gen cephalosporin (ceftriaxone, ceftizidim, cefepime) + Vancomycin +/- rifampin
Vancomycin: to cover penicillin-resistant Strep penumo or elevated MIC to cephalosporin
Rifampin: not seen in praxis (due to DDIs) expert opinion
add Aminoglycoside + Gent in patients who at risk for Listeriosis (homemade cheese, deli meats, elderly)
-> de-escalate once culture and sensitivity come back
What is the duration of therapy?
7 days: (probably 10 d)
N. meningitidis
H. influenza
10-14 days:
Strep pneumo
14-21 days-
Strep agalactiae
21 days:
Aerobic negatives
Listeria (more than 21 days)
What is the role of Corticosteroids in CNS infection?
adjunct drug - Dexamethasone
when used it should be given with the first dose of antimicrobials, bc some antimicrobials need inflammation for penetration
Treatment Aseptic meningitis
supportive care, self-limiting
-initially the gram stain is negative, but still infectious
-causing organism: enteroviruses, west-nil virus
-drug-induced:
(IV immunoglobulins (IVIG),
NSAIDs
TMP-SMX
Which organism may cause Aseptic meningitis?
-enteroviruses (most common 85%)
-west-nil virus
-Herpes simplex (HSV 1 and 2)
-Spirochetes (T- palladium and B.burgdorferi)
-Fungal - Cryptococcus neoformans and Coccidioides immitis
-Tuberculous meningitis
Who needs meningitis prophylaxis?
-patients who are exposed to patients with confirmed N. meningitidis or H. influenza
-Rule: >8h and <3ft
When is chemoprophylaxis not needed?
when exposed to patients with Strep penumo
-> no data to support use of chemoprophylaxis
Meningitis prophylactic agents
-Ciprofloxacin 500 mg x1 dose (drug of choice)
-Rifampin 600 mg q12h x4 doses (different dosing with H. influenza, often DDI with rifampin)
-Ceftriaxone 250 mg IM x1 dose
-Azithromycin 500 mg x1 dose (alternative)
-> need prophylaxis regardless of immune state (also if they have been vaccinated)
Which organism causes Encephalitis?
inflammation of the brain parenchyma
-caused by
Herpesviruses (VZV, CMV, HHV-6)
HSV-1
Arboviruses (West Nile Virus, St. Louis)
Enteroviruses
-HSV commonly affects the brain focally (on one area) -> personality changes, seizures, decreased level of consciousness
