Exam 4- Chapter 22 Flashcards
1
Q
Cryptococcus neoformans Meningitis (Cryptococcosis)
A
- Soil fungus associated with pigeon and chicken droppings
- Transmitted by the respiratory route through dried contaminated droppings
- In the immunocompromised, it spreads through blood to the CNS
- Mortality of up to 30%
- Treatment: amphotericin B and flucytosine
2
Q
Haemophilus influenzae Meningitis
A
- Gram-negative aerobic bacteria; normal throat microbiota
- Can enter the bloodstream
- Pathogenicity due to capsule antigen type b
- Occurs mostly in children (6 months to 4 years)
- Prevented by the Hib vaccine
- Accounts for 45% of bacterial meningitis cases; 6% mortality
3
Q
Neisseria meningitidis Meningitis (Meningococcal Meningitis)
A
- Gram-negative aerobic cocci with a capsule
- Six serotypes associated with the disease
- Forty percent of people are healthy nasopharyngeal carriers
- Begins as a throat infection, rash, and bacteremia
- Mortality of 9–12% with antibiotic therapy; 80% without
- Outbreaks common in dorms and military barracks
- Vaccination protects against serogroups A, C, Y, and W, but not B
4
Q
Streptococcus pneumoniae Meningitis (Pneumococcal Meningitis)
A
- Gram-positive encapsulated diplococcus
- Seventy percent of people are healthy nasopharyngeal carriers
- Also causes pneumonia and otitis media
- Most common in children (1 month to 4 years)
- Mortality: 30% in children, 80% in the elderly
- Prevented by conjugated vaccine
5
Q
Diagnosis and Treatment of the Most Common Types of Bacterial Meningitis
A
- Sample CSF via a spinal tap or lumbar puncture (Pathogens in CSF do not survive storage or changes in temperature)
- Latex agglutination tests
- Chemotherapy initiated before diagnosis (Broad spectrum third-generation cephalosporins)
6
Q
Listeriosis
A
- Caused by Listeria monocytogenes
- Gram-negative aerobic rod
- Usually foodborne and asymptomatic
- Meningitis more common in the immunocompromised
- Can invade the bloodstream, causing sepsis
- Reproduces in phagocytes
- Spread phagocyte-to-phagocyte
- Infects pregnant women, crossing the placenta and leading to stillbirth
7
Q
Botulism
A
- Caused by Clostridium botulinum
- Gram-positive, endospore-forming, obligate anaerobe
- Intoxication comes from ingesting the botulinal exotoxin (Specific for the synaptic end of the nerve; Blocks release of the neurotransmitter acetylcholine, causing flaccid paralysis)
- Death usually comes from respiratory or cardiac failure
8
Q
Type A toxin (botulism)
A
- Fatality: 60–70%
- Heat-resistant and proteolytic
9
Q
Type B toxin (botulism)
A
-Fatality: 25%
10
Q
Type E toxin (botulism)
A
- Produced by organisms in marine and lake sediments
- Less heat-resistant than other strains
11
Q
Infant botulism
A
- C. botulinum growing in the intestines of infants due to a lack of intestinal microbiota
- Associated with honey
12
Q
Wound botulism
A
-growth of C. botulinumin wounds
13
Q
Botulism treatment and prevention
A
- Treatment with respiratory assistance and antitoxins
- Prevented with proper canning and the use of nitrites in foods
14
Q
Rabies
A
- Caused by the rabies virus
- Genus Lyssavirus
- bullet shape (Single-stranded RNA; easily develops mutants)
- Usually transmitted by the saliva of an animal bite
- Can also cross mucous membranes
- In the United States, silver-haired bats are the most common cause
- Initial symptoms: muscle spasms of the mouth and pharynx; hydrophobia
- Virus multiplies in the skeletal muscles and travels through the PNS to the brain cells, causing encephalitis (Average incubation of 30 to 50 days; Forms Negri bodies in the brain stem)
15
Q
Furious (classical) rabies
A
animals are restless, then highly excitable
