Principles of infectious disease Flashcards
What is present in the wall of a gram + bacteria that is not present in a gram negative bacteria?
thick peptidoglycan layer
teichoic acid in wall
T/F: Spores are metabolically active.
false
How does bacterial infection cause fever?
endotoxin activates macrophages to release IL-1 and TNF, causing fever
Name 5 common zoonotic bacteria.
Borrelia burgdorferi, Brucella, Francisella tularensis, Yersinia pestis, Pasteirella multocida
Enterobaceriaceae: describe O, K, and H antigens
O - somatic, polysaccharide of endotoxin
K - capsular, related to virulence
H - flagellar, found in motile species
What kind of bacteria form spores and when?
certain gram + rods when nutrients are limited
Where is beta-lactamase in bacteria? What does it do?
periplasm of gram - bacteria
enzyme hydrolyzes beta-lactam antibiotics, conferring resistance
What molecule is specific to gram - bacterial cell membranes?
LPS
What are exotoxins and endotoxins, chemically speaking?
exotoxins tend to be polypeptides, while endotoxins are usually lipopolysaccharides
How could bacterial infection cause hypotension?
endotoxin induces macrophages to release nitric oxide -> vasodilation, hypotension
can also activate alternate complement pathway C3a, causing hypotension
Which organisms have exotoxin that acts by ADP ribosylation?
Corynebacterium diphtheriae, Escherichia coli, Vibrio cholerae, and Bordetalla pertussis
What helps organisms adhere to indwelling catheters?
glycocalyx (composed of polysaccharide)
Name the dominant normal flora on the teeth.
strep. mutans
Being in a newborn nursery is a risk factor for which two pathogens?
CMV and RSV
Name the dominant normal flora in the oropharynx.
strep. viridans
Name the dominant normal flora in the vagina.
Lactobacillus, E. coli, group B strep.
What disinfecting procedure kills spores?
autoclaving
Which pathogen is most associated with total parenteral nutrition?
Candida albicans
Where do bacteria keep their exotoxin or endotoxin genes?
exotoxin genes on plasmids or bacteriophages
endotoxin genes on bacterial chromosomes
T/F: we can vaccinate against exotoxins and endotoxins
false
we have toxoid vaccines against exotoxins for diseases like tetanus, botulism and diphtheria, but there are no vaccines against endotoxins
T/F: Spores are highly resistant to destruction by heat and chemicals.
T
Gram for gram, which is more fatal: exotoxin or endotoxin?
exotoxin
Name the dominant normal flora in the colon.
Bacteriodes fragilis > E. coli
How is catalase a virulence factor?
it degrades H2O2, an antimicrobial product of PMNs
Name the dominant normal flora of the nose.
Staph. aureus
Are vaccines available for encapsulated bacteria?
yes
What are two of the most common causes of nosocomial infections?
E. coli (UTI) and Staph. aureus (wound infection)
What are spores made of? What do they protect from?
keratin-like coat, dipicolinic acid
provide resistance to dehydration, heat and chemicals
What is the major surface antigen of gram + cell walls and which two cytokines does it induce?
teichoic acid - unique to gram + bacteria
induces TNF and IL-1
Spores have ___ acid in their core.
dipicolinic
What are the two pathogens most commonly associated with urinary catheterization?
E. coli, Proteus mirabilis
What is the most likely pathogen when a water source (water aerosols) is involved?
Legionella
Name four organisms with IgA proteases.
Strep. pneumoniae, N. meningitidis, N. gonorhoeae, H. influenzae
What pathogen is often found on respiratory therapy equipment?
Pseudomonas aeruginosa
What is the main virulence factor of encapsulated bacteria and how does it confer virulence?
polysaccharide capsule is antiphagocytic
Which has greater heat stability: endotoxin or exotoxin?
endotoxin
Name the dominant normal flora in the skin.
Staph. epidermidis
How might a bacterial infection cause disseminated intravascular coagulation?
endotoxin can activate Hageman factor which initiates coagulation cascade, causing DIC
