Exam 1 Nervous system infectious disease Flashcards
Name major defenses of nervous system
bony casing of the brain and spinal cord, CSF provides cushion, BBB
What are microglial cells derived from?
monocyte cells that are resident macrophages in CNS
Describe microglial cells
inflammatory macrophages that participate in the innate immune response to a pathogen and activate T lymphocytes via antigen presentation
What TLRs do microglial cells express?
TLR2 and TLR9
What major pathogens does TLR2 detect?
Peptidoglycans, lipoproteins, gram-positive bacteria, trypanosomes, mycobacteria/other bacteria
What major pathogens does TLR9 detect?
HSV, bacterial DNA, dinucleotides, malaria parasite heme product
What are the normal biota of the CNS?
It’s a sterile environment
What is the worst form of meningitis?
Bacterial
Define meningitis
Inflammation of the meninges
What is the way to diagnose meningitis?
lumbar puncture, CSF is gram-stained and potentially cultured
What are common symptoms of meningitis
photophobia, headache, painful and/or stiff neck, fever, increased WBC in CSF
What is the treatment for N. meningitidis
ceftriaxone
What should you begin treatment for with a patient with meningitis
N. meningitidis because it’s so serious- ceftriaxone immediately
What are the major causes of bacterial meningitis
N. meningitidis, S. pneumoniae, H. influenzae, L. monocytogenes
What are the fungal causes of meningitis?
C. neoformans, Coccidioides immitis
What is viral meningitis called?
aseptic meningitis
Describe Neisseria meningitidis meningitis
Gram (-) diplococci, epidemic form, most acute, starts in upper respiratory
Describe Streptococcus pneumoniae meningitis
Most common community-based meningitis, acquired often secondary to other problems (decreased immune system), will become a problem if infected via systemic issue without a spleen
Describe Haemophilus influenzae meningitis
Gram (-),Human only, starts as respiratory infxn
Describe Listeria monocytogenes meningitis
Gram (+), immunocompromised patients
Describe Cryptococcus neoformans meningitis
Fungal, chronic, reservoir: birds (pigeons), often occurs in urban areas
Describe Coccidioides immitis meningitis
Fungal, usually found in SW USA, can cause osteomyelitis
What is the usual cause of neonatal/infant meningitis?
infection of the fetus by the mother in utero or during passage through the birth canal (most common). Most commonly GBS (S. agalactiae and E. coli K1 strain)
What individuals does meningitis prefer to infect?
Individuals with immature immune systems (premature babies)
What are the most common neonatal/infant causes of meningitis?
Streptococcus agalactiae, Cronobacter sakazakii, E. coli
Describe Streptococcus agalactiae
Group B strep, found in 10-30% of female reproductive tracts, most common cause of infant meningitis, TREATMENT: IV antibiotics during birth
Describe E. coli strain that causes meningitis in infants
K1-strain usually affecting premature babies, 20% mortality
Describe Cronobacter sakazakii causing meningitis
Gram (-) bacilli, most commonly in environment, outbreaks usually associated with contaminated infant formula, mortality as high as 40%
Describe meningoencephalitis
Encephalitis that involved meninges which are closely connected
What usually causes meningoencephalitis?
Two amoebas: Naeglaria fowleri and acanthamoeba, can also be caused by accidental parasites
How are individuals usually infected with N. fowleri?
found in warm bodies of water that usually are forced into the nasal cavity and infect the olfactory nerve
How are individuals usually infected with Acanthamoeba?
infects through a break in the skin
What almost always causes acute encephalitis?
Almost always a viral infection
What are the most common viral causes of acute encephatlits?
Arboviruses and herpesviruses
What are the most common symptoms of acute encephalitis?
Behavior changes, confusion, decreased consciousness and seizures
What is the empiric treatment for acute encephalitis? What are you trying to treat?
Acyclovir to treat HSV-1 and HSV-2
What are the main arboviruses that cause acute encephalitis in north america?
St. Louis encephalitis, Eastern equine, western equine, la crosse, west nile
What strains of herpesvirus cause acute encephalitis?
1 and 2, but less commonly vericella
What viruses cause acute encephalitis?
HSV-1, HSV-2, VZV, JC virus (immunocompromised individuals)
What are major causes of post-infectious encephalitis?
Measles, other childhood rash-associated diseases. Usually infect about 2 weeks after clearing initial system
What is the most common cause of subacute encephalitis?
TOXOPLASMA gondii. Other causes: measles virus (subacute sclerosing panencephalitis), prions.
What is the average incubation of rabies?
1-2 months, depends on the wound site and inoculation dose
What are symptoms of rabies infection?
fever, headache, vomiting, fatigue and other nonspecific symptoms
What are acute symptoms of rabies?
agitation, disorientation, seizures and twitching. Followed by hydrophobia and progressively worse neurological symptoms
What kind of virus is the causative agent of rabies?
ssRNA (-) virus, class V
What are the major reservoirs of rabies virus?
wild animals, raccoons, skunks, coyotes, foxes and bats
What is the mode of transmission of rabies?
Virus present in saliva enters body through wound from a bite
How do you diagnose rabies?
Observation of tissue sample from rabid animal or postmortem human exam using immunological tests
What is the tell-tale sign of rabies under microscope?
Negri bodies in cytoplasm of nerve cells
What is the treatment of those infected with rabies?
Passively immunized with rabies immune globulin (injected both IM and at site of bite. Patient is then given immunization with inactivated rabies virus prep
Describe infection by polio virus
Poliomyelitis; acute enteroviral infection of spinal cord that causes neuromuscular paralysis.
Describe tetanus infection and how it causes its effects
Clostridium tetani (gram + endospore-forming rod) releases a toxin that causes swelling in vegetative cell
What is the treatment of tetanus?
immunoglobulin against toxin and Penicillin G to kill bacteria
Describe the treatment of tetanus and how it works
Immunoglobulin will kill all toxins, will not dislodge any toxins, but as long as you treat the bacteria during acute symptoms you can survive
What causes death during tetanus?
paralysis of respiratory muscles
What is the difference between tetanus and botulinum poisoning?
Tetanus causes muscle rigidity, botulinum causes flaccid paralysis
What is the treatment to botulism?
Immunoglobulin against toxin, toxin vaccines
How does the botulinum toxin assert its effects?
Decreasing release of acetylcholine
Is E. coli gram+ or gram-?
Gram- bacillus
Is streptococcus agalactiae gram+ or gram-?
Gram+ cocci
Is Cronobacter sakazakii gram+ or gram-? how are people most commonly infected with it?
Gram- bacillus; most commonly in contaminated baby formula powder
