staph, strep, gram pos rods, and gram neg diplos Flashcards by Rebekah Beyerlein

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

mannitol salt agar: high salt concentration

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which coagulase tests is the bound coagulase, and free coagulase

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

novobiacibn resistant while other staph are susceptible

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

lemon-yellow colonies

catalase AND oxidase pos

gram pos cocci in tetrads

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

furazolidone disk
- staph susceptible
- micrococcus resistant

bacitracin
- staph resistant
- micrococcus susceptible

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what diseases can GAS cause?

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

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what are the two toxins GAS makes?

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

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

S. pyogenes is susceptible to bacitracin

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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?

has trimethoprim and sulfamethoxazole

GAS and GBS are both RESISTANT

groups C, F, and G are all SUSCEPTIBLE

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

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

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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What four organisms are hippurate pos?

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

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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?

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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what test separates S. viridians from other GDS?

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

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

Gram pos diplococci

normal flora in the upper respiratory tract

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

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

both kinds are alpha hemolytic

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what test is used to identify S. pneumoniae?

S. pneumoniae is optochin “P” disk SUSCEPTIBLE

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

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

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

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)

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

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

they do not usually grow on BAP or chocolate

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

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

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

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

coag neg staph

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

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)

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

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

they will show metachromatic granules after methylene blue treatment

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

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

catalase, motility, and hemolysis for Coryne?

cat pos nonmotile non-beta hemolytic - most Coryne are non hemolytic

how to tell C. diphtheriae from normal Coryne?

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

what is the disease caused Listeria monocytogenes

listeriosis (in neonates, pregnant women, and elderly/immunocompromised people) can cause spontaneous abortions

listeria exhibits what on a wet prep and motility media?

tumbling motility on wet prep umbrella motility on motility media

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

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)

what gram stain and hemolysis pattern does listeria usually have?

gram pos bacilli small gray colonies with small zone of beta hemolysis

what does Erysipelothrix rheusiopathae cause? How to ID it?

causes erysipeloid "red skin lesions" ID: - gram pos pleomorphic non-sporeforming rods - cat neg (- alpha or gamma hemolysis) - nonmotile - and H2S pos

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?

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

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

gram positive bacilli that are beaded/branching N. asteroides most common type they cause mycetomas (chronic tissue and bone disease)

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

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

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

Aracanobacterium haemolyticum

what species are positive for hippurate?

GBS, Campy, Gardenella vaginalis, Listeria

where can you find Listeria (in the environment)?

soil and water

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

HBT medium and vaginalis "V" agar they are beta hemolytic (while lactobacillus is alpha or gamma hemolytic)

what is the gram stain for Neisseria spp?

gram neg diplococci

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

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

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

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

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

true

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

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

all Neisseria are both catalase and oxidase _____

positive :)

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?

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