chapter 22: microbial diseases of the nervous system Flashcards
central nervous system
brain and spinal cord
peripheral nervous system
all nerves that branch off from the brain and spinal cord
meninges
trilaminar membrane system that protects brain and spinal cord
subarachnoid space
holds CSF
blood brain barrier
restrictive capillary system that protects the brain and spinal column from invasion by potentially toxic compounds and microbes
meningitis
inflammation of the meninges
encephalitis
inflammation of the brain
meningoencephalitis
inflammation of the meninges and the brain
bacterial meningitis symptoms
fever, headache, stiff neck, often followed by nausea and vomiting; convulsions and coma
viral meningitis
most common, aseptic meningitis, mild disease
three species responsible for most cases of bacterial meningitis
streptococcus pneumoniae, neisseria meningitidis, haemophilus influenzae type B (nearly eliminated due to HiB childhood vaccine)
all three pathogens responsible for meningitis are
encapsulated, to avoid phagocytosis and can grow in the blood stream; and, can invade the meninges reaching the CSF
bacterial meningitis
serious life-threatening disease develops rapidly and requires prompt medical intervention
antibiotics for bacterial meningitis
antibiotic therapy given by intravenous adminstration
diagnosis for bacterial meningitis
spinal tap
H. influenzae
small gram negative aerobic rod, misnamed when incorrectly identified as cause for influenza, common member of throat flora; occasionally enters blood stream and bad stuff begins
carbohydrate capsule in H. influenzae
aids in avoiding phagocytosis and survival
Antigenic Type B
most common in children where risk is high, disease occurs in primarily children under 4, by age 5, children typically immune due to cross immunity to other agents, HiB vaccine given at 6mo has nearly eliminated this childhood disease
streptococcus pneumoniae
common inhabitant of nasopharynx, gram + encapsulated diplococci, responsible for about 3000 cases of meningitis annually in the US., most frequent among children 1 month-4 years old, 30% mortality in children, 80% in elderly. starts with case of pneumonia of otitis media and progresses
leading cause of bacterial meningitis
streptococcus pneumoniae since HiB is on decline
factors which lead to progression of streptococcal meningitis
are part microbial, part host, antibiotic therapy depending upon sensitivity tests
Meningococcal Meningitis
caused by Neisseria meningitis, aerobic gram negative cocci, polysaccharide capsule important to virulence, very invasive organism, highly contagious, has 5 main capsule types, vaccine directed against 4/5, 5th on its way
Meningococcal meningitis common to which areas of the body?
nose and throat of carriers, without causing disease; 10% of the population constitutes reservoir of infection
meningococcal meningitis typically begins as
a throat infection, leading to becteremia and eventually meningitis; can cause death in a few hours after symptoms
meningococcal meningitis is most common in
children under the age of 2, sporadic adult cases, usually associated with crowded stressful environments: dorm life, military barracks, etc.
survivors of meningococcal meningitis typically have
deafness or brain impairment
Tetanus etiologic agent
Clostridium tetani
clostridium tetani
gram positive, spore-forming obligate anaerobic rod; common in soil-spores are ubiquitous in soil and animal fecal waste
all symptoms of tetanus are caused by
potent neurotoxin: Tetanus Toxin or Tetanospasmin