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Microbiology > staph, strep, gram pos rods, and gram neg diplos > Flashcards

staph, strep, gram pos rods, and gram neg diplos Flashcards

1
Q

what is the media used that is selective and differential for staph spp.? What does it contain that makes it this way?

A

mannitol salt agar: high salt concentration

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2
Q

which coagulase tests is the bound coagulase, and free coagulase

A

slide coagulase = bound coagulase (also called “clumping factor”)

tube = free coagulase (that forms a complex with coagulase reacting factor in the plasma)

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3
Q

after catalase pos and coagulase neg tests, what differs S. saprophyticus from other coag neg staph? (and the results)

A

novobiacibn resistant while other staph are susceptible

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4
Q

micrococcus is a what color usually? What is the catalase and oxidase result, and what is the gram stain?

A

lemon-yellow colonies

catalase AND oxidase pos

gram pos cocci in tetrads

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5
Q

what are two disk tests to differ micrococcus and staph spp.?

A

furazolidone disk
- staph susceptible
- micrococcus resistant

bacitracin
- staph resistant
- micrococcus susceptible

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6
Q

what diseases can GAS cause?

A

pharyngitis, strep throat, scarlet fever, erysipelas, TSS, rheumatic fever and acute glomerulonephritis

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7
Q

what are the two toxins GAS makes?

A

streptolysin O and S
- O is oxygen liable
- S is oxygen stable

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8
Q

GAS are almost always ______ to bacitracin “A” disk?

A

S. pyogenes is susceptible to bacitracin

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9
Q

what are the two microbial agents in an SXT disk, and how does this disk show if strep is group A, B, C, F, G?

A

has trimethoprim and sulfamethoxazole

GAS and GBS are both RESISTANT

groups C, F, and G are all SUSCEPTIBLE

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10
Q

GBS causes what two things? Why do we test pregnant women for this?

A

neonatal sepsis and meningitis

pregnant women can pass it to their baby during birth since S. agalactiae is normal female urogenital flora (but can cause UTIs too)

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11
Q

what is one test done one blood plates to ID GBS?

A

CAMP test: streak vertical line of S. aureus down plate and horizontal (but not touching) of suspected GBS to it, and an arrow of hemolysis is made when “beta-lysin” from S. aureus meets the “CAMP factor” from GBS

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12
Q

What four organisms are hippurate pos?

A

GBS, listeria spp., garderella vaginalis, and some Campy spp.

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13
Q

GDS hemolysis looks like what on a blood plate?

What’s one test where both enterococci AND nonetnerococcci are both positive? What is the test that differentiates the two?

A

GDS: alpha or gamma hemolysis

All GDS: pos for bile esculin (black precipitate)

6.5% salt tolerance:
- enterococci pos
- nonenterococci neg

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14
Q

what test separates S. viridians from other GDS?

A

most GDS are pos for bile esculin while S. viridians is not

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15
Q

what is the gram stain of S. pneumoniae (“pneumococcus”) that makes it different from other strep? Where is normal flora in the body?

A

Gram pos diplococci

normal flora in the upper respiratory tract

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16
Q

what are the two morphologies on media that S. pneumo exhibit?

A

mucoid colonies, or umbilicated (doughnut shaped). The umbilictaed ones are autolysins

both kinds are alpha hemolytic

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17
Q

what test is used to identify S. pneumoniae?

A

S. pneumoniae is optochin “P” disk SUSCEPTIBLE

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17
Q

What is the other test to ID S. pneumoniae other than the optochin disk test?

A

bile solubility: either broth or plate methods
- sodium deoxycholate and sodium taurocholate speed up the autolysing behavior of S. pneumoniae

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18
Q

what is the test to distinguish the 80 types of pneumococci?

A

quelling reaction: the pneumococci types have different polysaccharide capsules, so by antigen-antibody reaction, the capsules begin to swell (if there’s a match between the pneumococci and the antibody they’re mixed with)

18
Q

what are satelliting strep? Do they usually grow on BAP or chocolate?

A

nutrient deficient, nutritionally variant, strep that depend on
- thiol
- pyridoxal
- vitamin B

they do not usually grow on BAP or chocolate

19
Q

what is the BAP hemolysis pattern of enterococcus, and how to ID?

A

usually show (alpha or) gamma hemolysis, but NOT beta

pos for:
- bile esculin
- 6.5% salt
- PYR disk POSITIVE (pink)

20
Q

what is a common bacteria that pose a risk for infection in people who have indexing medical devices (cathaters/heart valves/ect)?

A

coag neg staph

21
Q

(what is the gram stain for bacillus spp.? And how to tell B. anthracis from B. cerus?)

A

they’re all large, boxy gram pos rods with endospores

B. anthracis: non-hemolytic, nonmotile (and oxidase and catalase pos)

B. cerus: beta hemolytic and motile

(Bacillus grow well on BAP)

22
Q

Corynebacterium spp. gram stain and what do this spp show when stained with methylene blue?

A

gram pos rods in clubs, V-L formation, palisades

they will show metachromatic granules after methylene blue treatment

23
Q

what is a media that is selective and differential for Corynebacterium?

A

Telluride medium / tinsdale agar (many normal flora are inhibited by tellurite, while Coryne is not. Make grey-black colonies)

24
Q

catalase, motility, and hemolysis for Coryne?

A

cat pos

nonmotile

non-beta hemolytic
- most Coryne are non hemolytic

25
Q

how to tell C. diphtheriae from normal Coryne?

A

Has toxin. do an ELEK test
- filter paper with diptheriae antitoxin interacts with diphtheria toxin and creates a precipitate, showing positivity for the test

26
Q

what is the disease caused Listeria monocytogenes

A

listeriosis (in neonates, pregnant women, and elderly/immunocompromised people)

can cause spontaneous abortions

27
Q

listeria exhibits what on a wet prep and motility media?

A

tumbling motility on wet prep

umbrella motility on motility media

28
Q

listeria is positive for five tests. what are they? which of them differentiate listeria from GBS?

A

catalase, CAMP, hippurate, bile esculin, and motile at 25ºC

GBS is neg for catalase, motility, and bile esculin

(also GBS is gram pos cocci while listeria is GPB)

29
Q

what gram stain and hemolysis pattern does listeria usually have?

A

gram pos bacilli

small gray colonies with small zone of beta hemolysis

30
Q

what does Erysipelothrix rheusiopathae cause? How to ID it?

A

causes erysipeloid “red skin lesions”

ID:
- gram pos pleomorphic non-sporeforming rods
- cat neg
(- alpha or gamma hemolysis)
- nonmotile
- and H2S pos

31
Q

name the pinpoint colony that is normal flora in the female genital area. What is the gram stain, and how to differ it from G. vaginalis?

A

Lactobacillus is gram pos chains of rods, while G. vaginalis is short gram pos rods not in chains

32
Q

what is the gram stain for Nocardia spp.? What is the most common type of Nocardia? What does this spp. cause in humans?

A

gram positive bacilli that are beaded/branching

N. asteroides most common type

they cause mycetomas (chronic tissue and bone disease)

33
Q

True or false: Nocardia are partially acid fast (with Kunyon stain)

A

true: reddish-purple filaments mean a positive result (while blue means negative)

34
Q

what spp. is small gram bacilli/rods that are beta hemolytic, catalase neg, nonmotile, cause pharyngitis, and identified by the reverse CAMP test?

A

Aracanobacterium haemolyticum

35
Q

what species are positive for hippurate?

A

GBS, Campy, Gardenella vaginalis, Listeria

36
Q

where can you find Listeria (in the environment)?

A

soil and water

37
Q

what two media are made for G. vaginalis? What is the hemolysis for G. vaginalis that helps differ it from Lactobacillus

A

HBT medium and vaginalis “V” agar

they are beta hemolytic (while lactobacillus is alpha or gamma hemolytic)

38
Q

what is the gram stain for Neisseria spp?

A

gram neg diplococci

39
Q

what media is made for N. gonorrhoeae? Why? What diseases does this bacteria cause?

A

Modified Thayer Martin (or Martin-Lewis) because they have the nutrients this fastidious organism needs, as well as having antimicrobial agents for pretty much every other bacteria

causes gonorrhea (STD)

in women: cervicitis, PID, salpingus, endometritis, and peritonitis

in men: acute urethritis, prostatitis, and epididymitis

in neonates: conjunctivitis

40
Q

what are the CTA sugar test results for N. gonorrhoeae, N. meningitidis, and N. lactamica? What do neg and pos results look like?

A

N. gonorrhoeae: glucose only

N. meningitidis: glucose and mactose

N. lactamica: glucose, maltose, and lactose

neg: red (no color change)
pos: yellow from acid formation

41
Q

True or false: Neisseria meningitidis is part of the normal flora of the upper respiratory tract

A

true

42
Q

what is the disease caused by N. meningitidis? What about the severe form?

A

meningitis: bacteria from URT get into bloodstream and spread to the meninges (the proactive layers surrounding the brain and CNS)\

severe meningococcemia: waterhouse-friderichsen syndrome

43
Q

all Neisseria are both catalase and oxidase _____

A

positive :)

44
Q

Just like Neisseria spp, M. catarrhalis is oxidase positive, catalase positive, gram neg diplococci.

Other than the Thayer Martin agar, how can you differentiate the two?

A

M. catarrhalis is both butyrate esterase test and DNAse test POSITIVE, while Neisseria is neg for both

Microbiology (9 decks)

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