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Microbiology > RT3 > Flashcards

RT3 Flashcards

1
Q

viral agents that cause infectious pharyngitis (strep throat)

A

Rhinovirus
Adenovirus
Coronavirus

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2
Q

bacterial agents that cause infectious pharyngitis (strep throat)

A 
Strep pyogenes (usuallyGroupA β‐Strep) 
Corynebacterium diphtheriae
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3
Q

signs and symptoms of strep throat/infectious pharyngitis

A
  • Throat pain
  • Difficulty swallowing
  • Red and swollen tonsils, sometimes with white patches or streaks of pus
  • Tiny red spots on the soft or hard palate — the area at the back of the roof of the mouth
  • Swollen, tender lymph glands (nodes) in the neck
  • Fever
  • Headache
  • Rash
  • Stomachache and sometimes vomiting, especially in younger children
  • Fatigue
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4
Q

why must you test specifically for strep throat to diagnose it

A

one can have all the signs and symptoms and not have a true strep throat infection – more likely to get these symptoms from a viral infection or less likely from other illnesses

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5
Q

can you tell by looking into the mouth if the cause of an infectious pharyngitis is bacterial or viral

A

no you cannot tell by looking so one must do a point of care test to be sure

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6
Q

viral agents that cause bronchiolitis

A

Adenovirus
Influenza Virus
Respiratory Syncitial Virus

think AIR through the bronchioles

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7
Q

bacterial agents that cause bronchiolitis

A

Bordetella pertussis

Mycoplasma pneumonia

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8
Q

what are the assays used for the microbial agents of bronchiolitis

A

you do a swab to use the assay

for the viral AIR agents
Adenovirus: PCR, antigen detection
Influenza virus: virus isolation
Respiratory syncitial virus: antigen detection

for the bacterial agents
bordatella pertussis: culture, DFA, serology, PCR
mycoplasma pneumonia: acid fast, culture

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9
Q

respiratory bacteria by definition have what type of oxygen requirements

A

aerobes and facultative anaerobes

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10
Q

how do you culture media for respiratory bacteria

A

get a routine sputum specimen and you can use either a blood, chocolate, or macconkeys agar

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11
Q

significance of using chocolate and mcconkey agar

A

chocolate agar - blood agar that has been heated to break open RBCs and release their content

mcconkeys: for selection and differentiation

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12
Q

what pathogens required special growth media that is not standard and what agar do they use

A

bordatella pertussis: bordet- gengou

c. diphtheria: tinsdale agar

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13
Q

characteristic of streptococci

A

small, gram positive, cocci in shape, metabolized through fermentation with lactic acid production, facultative anaerobe (but actually have all the qualities of aerotolerant anaerobe - grow in presence of oxygen, metabolize via fermentation, have only superoxide dismutase)

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14
Q

clinical syndrome of streptococci pyogenes

A

pharyngitis (strep throat)

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15
Q

describe the name streptococci pyogenes

A

Group A streptococcus according to Lancefield classification

pyogenes = induce of pus formation due to leukocidin production (leukocidin destroys leukocytes which will make pus)

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16
Q

how are streptococci classified

A

based on 16s rRNA sequencing

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17
Q

streptococci are classified by groups based on

A

polysaccharides (major cell wall carbs)

there’s group A –> W though there is no I or J

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18
Q

example of streptococci that does not have a carb group

A

S. pnuemonia

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19
Q

lab identifications of streptococci

A
  • 􏰀Gram Positive Spheres in chains (Older cultures become Gram Variable)
  • 􏰀Lack catalase (facultative anaerobes)
  • 􏰀Growth enhanced by CO2
  • 􏰀Nutritionally fastidious (􏰀Normal culture medium = Blood agar (BA) 􏰀Yeast extract + peptone +5% blood)
20
Q

streptococcal have large amounts of virulence factors which is not all expressed by all strain. what determines this variability?

A

transduction mediated gene transfer or transformation

21
Q

describe s. pyogenes on blood agar

A
  • where there is production of streptolysin S, there is beta hemolysis (tot destruction of erythrocytes) making the plate transparent
  • sensitive to bacitrain so no growth where this antibiotic is present
22
Q

clinical syndrome of corynebacterium diphtheria

A

severe pharyngitis (diphtheria)

23
Q

physical features of corynebacterium diphtheria

A

gram positive, club shaped, nonsporeforming rods that are pleomorphic with chinese letter arrangement

24
Q

what does corynebacterium diphtheria looks like on a gram stain

A

purple
irregular in shape
rod shaped
one end is thicker than the other

25
Q

why is corynebacterium diphtheria unusual in developed countries

A

because of DPT vaccine – the D component is diphtheria toxoid

26
Q

where are endemics and outbreaks of diphtheria seen

A

endemics - subtropical and tropical areas

outbreak - places with breakdown in health infrastructure

27
Q

pathogenesis of corynebacterium diphtheria

A

organism is non invasive and does not enter the bloodstream but the toxin that it releases enters the blood stream and invades tissues

organism grows in a biofilm on the surface of the pharynx while its necrotizing toxin kills the tissue that it gets to

28
Q

main virulence factor of diphtheria

A

the diphtheria exotoxin

29
Q

how are the genes for diphtheria toxin acquired

A

via lysogenic conversion

30
Q

complication of diphtheria

A

pharyngitis can be so severe that it blocks the airway –> suffocation

bull neck, pseudomembranous

31
Q

what three tests can be done to see if you grew diphtheria toxin on the blood agar aka testing for toxigenicity

A

Elek, EIA, PCR

32
Q

Elek, EIA, PCR – which is more effective and which is more probable (cheaper to use)

A

more effective - PCR

Elek test is cheaper, quicker, simpler

33
Q

explain what positive elek test would look like

A

beneath the filter paper that has the antitoxin, there will be lines of precipitin (at angles) indicating presence of diphtheria toxin

34
Q

viral agents of infectious sinusitis and otitis media

A

Rhinovirus
Adenovirus
Coronavirus

35
Q

if you see viral agent in an infectious sinusitis and otitis media, what type of infection is it mostly

A

it is mostly an exogenous infection

36
Q

bacterial agent of infectious sinusitis and otitis media

A 
Streptococcus pneumoniae 
Haemophilus influenzae (part of normal flora)
37
Q

if you see bacterial agent in infectious sinusitis and otitis media, what type of infection is it mostly

A

it is mostly an endogenous infection

38
Q

clinical syndromes of haemophilus influenzae

A

otitis media, pneumonia, epiglottis

39
Q

what is haemophilus influenzae the most common cause of

A

swelling of epiglottis and supraglottic tissue

40
Q

describe physical features of haemophilus influenzae

A

gram negative, pleomorphic, facultative anaerobe, normal component of normal flora, IgA proteases

41
Q

does h. influenza cause influenza

A

no

42
Q

pathogenesis of h. influenzae

A

it is gram neg bacteria so it has LPS which impairs ciliary function

it has a pili

also has a non-pilus adhesins –> P-2 outer membrane protein; attaches to sialic acid-containing mucin oligosaccharides

43
Q

what is the h. influenzae antiphagocytic capsule composed of

A

Polyribose Ribitol Phosphate (PRP)

44
Q

how do you culture and diagnose h. influenzae

A

catalase: positive
coagulase: negative
culture with chocolate agar with X and V growth factors

45
Q

what do the X and V factor do

A 
X = acts as hemin
V = acts as NAD
46
Q

what other haemophilus require both X and V factor

A

none just h. influenza

Microbiology (39 decks)

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