LAB

Question 1

Staphylococcus
gram stain/shape:
in clinical specimens generally appear:
catalase:

Answer 1

stain shape: GPC
in clinical specimens generally appear: in clusters (or short chains, pairs and singles)
catalase: positive

Question 2

the most useful way of distinguishing S. aureus from other Staph?

Answer 2

coagulase positive test (after the catalase test distinguishes it from other GPC)

Question 3

Coagulase negative Staph

Answer 3

S. saprophyticus and S. epidermidis

Question 4

S. aureus cases what clinical manifestations

Answer 4

skin abcesses to pneumonia and endocarditis

Question 5

S. epidermidis is often caused by

Answer 5

a cause of baceremia in neutrophenic patients relating to indwelling catheters, shunts and prosthetic devices

Question 6

a common cause of UTIs in young, sexually active women?

Answer 6

S. saprophyticus

Question 7

how do you distinguish between S. saprophyticus and S. epidermitis (both GPC, Cat +, coag negative)

Answer 7

Novobiocin:
S. epidermidis is “Se”nsitive
S. Saprophyticis is resistant

Question 8

Micrococcus

Answer 8

species closely related to Staph that at cat + and coag neg. they are rarely pathogenic, but like S. epidermidis they can infect prosthetic hardware/be difficult to treat in this setting

Question 9

All Strep and Enteroccoci are
Gram stain:
catalase:
in clinical specimens and fluid culture they grow in:

Answer 9

GPC
cat neg
grow in straps or pairs

Question 10

S. pneumoniae (pneumococcus) is a frequent cause of:

Answer 10

pneumonia, meningitis and sepsis

Question 11

S pyogenes, group A strep, is a frequent cause of

Answer 11

pharyngitis, cellulitis, and rheumatic fever

Question 12

S. agalactiae (grp B strep) is a common cause of

Answer 12

neonatal meningitis

Question 13

Enteroccoci are normally found in the

Answer 13

colon

Question 14

unlike Strep, Enterococci can grow in…

Answer 14

hile bile, high salt envts (strep only grows in high bile envt)

Question 15

Enterococcal infections are often associated with

Answer 15

UTIs and GI disorders

Question 16

Haemophilus
size:
Gram stain/shape:

Answer 16

Haemophilus
size: small
Gram stain/shape: pleomorthic gram-neg rods

Question 17

how can you distinguish between different Haemophilus species?

Answer 17

the nutrient growth factors required for them to grow

Question 18

X factor

Answer 18

hemin- comes from blood or its constituents and it’s presence is required for the growth of some Haemophilus and not others

Question 19

V factor

Answer 19

NAD- comes from blood or its constituents and it’s presence is required for the growth of some Haemophilus and not others

Question 20

does H influenzae, the most common Haemophilus pathogen, require factor V, factor X or both for growth? what about the often isolated, but rarely pathogenic H. Parainfluenzae?

Answer 20

H. Influenzae: Both

H. Parainfluenzae: requires only V

Question 21

Neisseria
Gram/shape:
aerobic/anaerobic/other:
oxidase:

Answer 21

Gram/shape: Gram neg diplococci
aerobic/anaerobic/other: strict aerobes
oxidase: positive

Question 22

Nisseria species most difficult to grow. Why?

Answer 22

N. Gonorrhoea, because it thrives in a limited T range and needs ample moisture, CO2 and rich non-acidic medium

Question 23

N mengitidis requires what to grow:

Answer 23

rich media and extra CO2

Question 24

Moraxella:

Gram/shape:

Answer 24

like Nisserai, they’re:
Gram/shape: Gram neg diplococci
aerobic/anaerobic/other: strict aerobes
oxidase: positive

Question 25

Moraxella Catarrhalis, once considered a nonpathogenic Neisseria and a part of normal mouth flora, now appears to be an occasional cause of:

Answer 25

sinusitis and other serious disease

Question 26

how are Neisseria and Moraxella distinguished given that they're both gram neg diploccoci, strict aerobes that are oxidase positive?

Answer 26

sugar fermentation tests

Question 27

Bacitracin is used to distinguish between what and what?

Answer 27

``` Beta-hemolytic Strep (Group A vs Group B) B-Bras Bacitracin B-strep (agalaciae) Resistant A-strep (pyogenes) Sensitive ```

Question 28

most bacteria that can grow aerobically and have a high O2 tolerance posses what in contrast to streptococci or enterococci which are facultative anaerobes that are incapable of using oxygen metabolically

Answer 28

catalase- a heme enzyme that decomposes hydrogen peroxide into H2O and O2

Question 29

S. aureus colonies are the only Staph that usually look...

Answer 29

yellow or beige (as the name aureus implies)

Question 30

How do these look different on an blood agar Alpha-hemolysis: beta hemolysis: Gamma-hemolysis

Answer 30

Alpha-hemolysis: green beta hemolysis: clear Gamma-hemolysis: the absence of any rxn on blood cells in the agar

Question 31

Optochin test

Answer 31

differentiates between S. pneumoniae (susceptible) from other alpha-hemolytic strep (resistant)

Question 32

oxidase test

Answer 32

put test species on a piece of bibulous paper, add a few drops of oxidase reagens, if the culture is oxidase positive, the dye will be oxidized and the colonies will turn pink to red to black

Question 33

Cystein tryptic agar (CTA) differentiates between Nisseria and Moraxella by

Answer 33

because it shows if you can produce acid from metabolizing glucose, maltose, sucrose and lactose. acid production is indicated by the presence of yellow

Question 34

``` S. aureus: cellular morphology: colonial morphology: hemolytic rxn: catalase: identifying tests: ```

Answer 34

``` S. aureus: cellular morphology: GPC in clusters colonial morphology: creamy to yellow hemolytic rxn: Beta catalase: + identifying tests: coagulase ```

Question 35

``` S. epidermidis cellular morphology: colonial morphology: hemolytic rxn: catalase: identifying tests: ```

Answer 35

``` cellular morphology: GPC in clusters colonial morphology: white hemolytic rxn: none catalase: + identifying tests: coag neg, novobiocin sensitive ```

Question 36

``` S. saprophyticus cellular morphology: colonial morphology: hemolytic rxn: catalase: identifying tests: ```

Answer 36

``` cellular morphology: white to yellow colonial morphology: white to yellow hemolytic rxn: none catalase: + identifying tests: coag neg, novobiacin resistant ```

Question 37

``` S. pyogenes (Group A) cellular morphology: colonial morphology: hemolytic rxn: catalase: identifying tests: ```

Answer 37

cellular morphology: gram + cocci in chains colonial morphology: grayish to white translucent hemolytic rxn: Beta catalase: negative identifying tests: bacitracin sensitive

Question 38

``` Group B strep (agalactiae) cellular morphology: colonial morphology: hemolytic rxn: catalase: identifying tests: ```

Answer 38

cellular morphology: gram + cocci in chains colonial morphology: grayish to white translucent hemolytic rxn: Beta catalase: negative identifying tests: bacitracin resistant

Question 39

``` S. pneumoniae cellular morphology: colonial morphology: hemolytic rxn: catalase: identifying tests: ```

Answer 39

S. pneumoniae cellular morphology: gram + cocci in pairs colonial morphology: grayish to white translucent hemolytic rxn: alpha catalase: negative identifying tests: optochin sensitive (unlike all the other alpha hemolytic or viridans grp)

Question 40

``` Non-hemolytic Strep and Enterococcus cellular morphology: colonial morphology: hemolytic rxn: catalase: identifying tests: ```

Answer 40

cellular morphology: gram + cocci in chains colonial morphology: grayish to white translucent hemolytic rxn: non-hemolytic (gamma) catalase: negative identifying tests: bile esculin (+ for gamma strep and enterococcus) and high NaCL (positive growth for enterococcus but not group d strep)

Question 41

``` H influenzae cellular morphology: colonial morphology: hemolytic rxn: catalase: identifying tests: ```

Answer 41

H influenzae cellular morphology: gram + coccobaccili, pleomorphic colonial morphology: gray, translucent, small hemolytic rxn: gamma identifying tests: factor X (hemin) +, Factor V (NAD) +

Question 42

``` H. haemolyticus cellular morphology: colonial morphology: hemolytic rxn: catalase: identifying tests: ```

Answer 42

H. haemolyticus cellular morphology: gram + coccobaccili, pleomorphic colonial morphology: gray, translucent, small hemolytic rxn: beta identifying tests: factor X (hemin) +, Factor V (NAD) +

Question 43

``` H. parainfluenzae cellular morphology: colonial morphology: hemolytic rxn: catalase: identifying tests: ```

Answer 43

cellular morphology: gram + coccobaccili, pleomorphic colonial morphology: gray, translucent, small hemolytic rxn: gamma identifying tests: factor X (hemin) -, Factor V (NAD) +

Question 44

what is the cause? 5 yo w/sore hroat, fever, swollen glands. Redness, edema and grayish white exudate culture: GPC, beta hemolytic, bacitran sensitive

Answer 44

Grp A strep (pyogenes), which can also cause cellulitis and necrotizing fasciitis

Question 45

what is the cause: elderly (79 yo) woman w/ chest pain, difficulty breathing, cough and fever sputum culture: GPC in pairs, alpha hemolysis, optichin sensitive

Answer 45

S. pneumoniae

Question 46

what is the cause: hospitalized pt with urinary catheter dvps a UTI urine culture: GPC in chains, cat neg, bile +, NaCL +

Answer 46

Enterococcus

Question 47

what is the cause: 2 days post surgery, pt notices area around incision = red and swollen and extremely painful culture cloudy fluid from wound: GPC in clusters, cat +, coag +

Answer 47

S aureus-- common on skin and gets in via an encision

Question 48

what is the cause: hospitalized pt with an IV catheter dvps a fever. Skin arnd IV entry site is red and swollen culture from the tip of the catheter: GPC, cat +, coag -, novobiocin -

Answer 48

S. epidermidis-- grows on biofilms on plastics

Question 49

what is the cause: young, sexually active woman dvps abdo pain/dysuria (pain upon peeing) urine culture: GPC, cat +, coag -, novobiocin resistant

Answer 49

S. saprophyticus

Question 50

what is the cause: 23 yo mas with dysuria and urethral discharge discharge = cultured: gram neg diplococci, doesn't ferment maltose, oxidase +

Answer 50

N. gonnhorhea-- diplococci ("the clap")

Question 51

what is the cause: 55 yo w/hist of rheumatic fever who presents with fever, malaise and splinter hemorrhage (sign of endocarditis) culture: GPC, y-hemolytic, bile +, NaCl -

Answer 51

Grp D. strep

Question 52

what is the cause: a bad sinus infection sends an 18 yo pt to doctor culture: GP coccobacilli, gray, translucent, small culture, gamma hemolytic, required factor V and X

Answer 52

H. influenzae

Question 53

HMS student- upper respiratory infection culture: Gram neg, no growth on blood agar, growth on chocolate agar, small gray and translucent, grows around factor V

Answer 53

H. parainfluenzae

Question 54

N gonorrhea is gram neg. diplococci, looks gray, white or yellowish, is y-hemolytic, is oxidase negative and metabolizes which sugars?

Answer 54

just glucose

Question 55

N meningitidis is gram neg. diplococci, looks gray, white or yellowish, is y-hemolytic, is oxidase negative and metabolizes which sugars?

Answer 55

glucose and maltose

Question 56

Moraxella is gram neg. diplococci, looks gray, white or yellowish, is y-hemolytic, is oxidase negative and metabolizes which sugars?

Answer 56

NONE!