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Microbiology > Microbiology: Exam 2 > Flashcards

Microbiology: Exam 2 Flashcards

1
Q

All Enterobacteriaceae

A
  • Gram negative
  • Ferment glucose
  • Reduce nitrates to nitrites
  • Oxidase negative (except plesiomonas)
  • Motile at body temp (except for Kleb, Shigella, Yersina)
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2
Q

MacConkey agar differentiates..

A

lactose fermentation

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3
Q

EMB agar differentiates..

A

lactose fermentation of enteric bacilli

positive = purple
E. coli = greenish hue

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4
Q

HE agar differentiates..

A

lactose and sucrose fermentation

most non pathogens = orange
pathogens = green/blue color (salmonella = black)

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5
Q

XLD agar differentiates

A

sucrose, lactose, and xylose fermentation

Yellow colonies: E. coli, Citrobacter
Red or colorless colonies: Shigella. (salmonella = black center)

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6
Q

E. Coli

A
  • pink colonies on Mac plates (because it ferments lactose)
  • sex pilli/fimbriae
  • beta hemolysis
  • O,H,K antigens
  • IMVC = ++–
  • TSI: A/A
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7
Q

O antigen

A

heat stable antigen located in LPS

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8
Q

H antigen

A

flageller antigen

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9
Q

K antigen

A

capsular antigen

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10
Q

5 types of E. coli

A
  1. Enteropathogenic: infant diarrhea in children less than a year old. no blood in stool, just mucus.
  2. Enterotoxigenic: Traveler’s diarrhrea. toxins that lead to hyper secretion of fluids
  3. Enteroinvasive: very similar to shigella. blood in stool. damage to intestinal mucosa.
  4. Enterohemorrhagic: conditions include hemolytic uremic syndrome, colitis, fatality. bloody diarrhea without WBC (differentiates from Shigella). O157:H7 Shiga toxin.
  5. Enteroadherent: UTI’s and diarrheal disease <- mostly in children
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11
Q

O157:H7 toxin

A

E coli
detected on SMAC plate
doesn’t ferment sorbitol

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12
Q

Uropathogenic E. coli

A

most common cause of UTI’s

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13
Q

Kleb, Enterobacter, Serratia, Pantoea, Cronobacter, and Hafnia are all…..

A

IMVC –++ <— Few exceptions

Wound, pneaumonia, and UTI infections

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14
Q

Klebsiella

A

non-motile.
TSI: A/A

K. pneaumoniae has capsule
K. oxytoca = Indol +

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15
Q

Enterobacter

A

TSI: A/A

E. cloacae- doesn’t produce lysine decarboxylase (only one)

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16
Q

Pantoea

A

similar to Kleb (differentiate by motility, Pantoea is motile)
lysine, ornithine, and arginine negative

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17
Q

Serratia

A
  • ONPG positive (means slow lactose fermentor)
  • DNAse positie
  • highly resistant to antimicrobials
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18
Q

Hafnia

A

BEER

linked to gastroenteritis

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19
Q

Proteaus

A
  • produce swarming on lab media. STINKS
  • phenylalanine deaminase positive
  • urease positive

P. mirabilis- most common. indole negative. ornithine decarboxylase positive. TSI: K/A with H2S

P. vulgaris- TSI: A/A. sometimes produces H2S. indole positive. ornithine decarboxylase negative.

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20
Q

Edwardsiella

A

E. tarda is only pathogen
Indole positive.
TSI: K/A with H2S

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21
Q

Citrobacter

A

C. freaudnii- nosocomial UTI’s, endocarditis.

to differentiate from Salmonella: Citrobacter hydrolyzes urea but not decarboxylate lysine and Salmonella does the opposite

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22
Q

IMVC test

A

(I)ndole production
(M)ethyl red test aka MR
(V)oges-Proskauer test aka VP
(C)itrate production

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23
Q

Salmonella

A
  • colorless colonies with black centers (H2S- except for S. paratyphi A)
  • TSI: K/A
  • negative for most tests.
  • virulence factors- fimbriae for adhesion
  • can cross GI tract into bloodstream
  • toxins
  • O,H antigens
  • has a capsular antigen similar to K
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24
Q

Subgroup 1 Salmonella

A

human infections

how to differentiate:
S. typhi- ornithine decarboxylase negative
S. paratyphi- lysine decarboxylase negative
S. choleraesuis- trehalose fermentation negative

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25
Q

Salmonella infections

A
  • Food poisoning with vomitting/diarrhea (do not use anti-diarrheal) caused by bacteria itself. need large [bacteria].
  • can be carrier state in gall bladder

-Typhoid fever: flu-like symptoms and then constipation. can enter lymphatic & vascular system. engulfed by monocytes but then released. invades gall bladder and Peyer’s patches. can lead to necrosis. found in blood/urine first and then stool.

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26
Q

Shigella

A
  • non-motile.
  • TSI: K/A
  • resistant to stomach acid
  • low [bacteria] for infections
  • Shiga toxin

S. sonnei is ONPG and ornithine decarboxylase positive

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27
Q

Types of Shigella

A

Group A: S. dysenteriae- most serious. developing countries
Group B: S. flexneri- 2nd most common in US. gay male sex.
Group C: S. boydii- developing countries
Group D: S. sonnei- most common in US. usually non-fatal, less severe symptoms

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28
Q

Shigella infections

A

dysentery- most severe. shedding of intestinal mucosa, blood in stool, ulcers, tenesmus (rectal prolapse)

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29
Q

Yersina

A

TSI: K/A. CIN agar can differentiate.

Y. pestis- safety pin appearance on Gram stain. Class A bioterrorism agent. transmission through rodent bites.

Y. enterocolita- most common. contact with pigs, dogs, cats. survives in cold temperatures. motile at 25 degrees, not 37. stimulates appendicitis. ornithine decarboxylase positive.

Y. pseudotuberculosis- ingestion of fecal material. motile at 25 degrees.

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30
Q

Carb Utilization test

A

-lactose degradation- used to ID enteric pathogens.
consists of glucose and galactose
2 enzymes: beta-galactoside and permease
-slow fermentators don’t have permease

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31
Q

Oxidation fermentation

A
  • oxidation- utilizes carbs aerobically
  • fermentation- utilizes carbs anaerobically
  • asacchrolytic- doesn’t utilize carbs
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32
Q

O/F Basal Media

A

helps classify as either oxidizer or fementator
two tubes- one aerobic, one anaerobic. can be any sugar

+ for fermentator- yellow throughout both tubes
+ for oxidizer- aerobic tube is yellow, anaerobic is green
- for carb use- both green

33
Q

TSI slant

A
  • lactose and sucrose in 10:1 ratio to glucose
  • black precipitate = ferrous sulfate
  • phenol red = pH indicator
  • no fermentation = red (K/K)
  • can create gas bubbles

-glucose fermentation: A/A then K/A after 24 hours.
if still A/A after 24 hours: either lactose or sucrose.
on MAC plate: if clear colony then its sucrose.

34
Q

ONPG test

A

tests for slow lactose fermentators

turns yellow for positive rxn

35
Q

Methyl-Red and Voges Proskauer test

A

MR: glucose->pyretic acid->mixed acid ferm (4.4)
PV: glucose->butylene glycol ferm->diacetyl + KOH + alpha-naphthol

red = positive for both tests

36
Q

Decarboxylase test

A

tests ability of enzymes to remove carboxyl group (COOH) from lysine, ornithine, arginine.

dihydrolase: arginine -> ornithine

37
Q

LIA Slant

A

deamination or decarboxylation of lysine.

deamination = reddish color
decarboxylation = purpleish color
38
Q

Deaminase test

A

removes amine group from amino acids

PAD tests- produces phenylpyruvic acid. add 10% Ferric chloride. green = positive

39
Q

Citrate utilization

A

citrate used as sole carbon source

blue = positive

40
Q

gelatinase production

A

loss of gelling.

+ = liquefaction

41
Q

indole tests

A

breaks tryptophan down into indole.

add Ehrlich’s reagent (PDAB) or Kovac’s. red = positive

42
Q

NO3 reduction

A

two reagents: Sulfanilic acid and NNDN.
red on 1st step OR gas production w/o red = + for reduction to NO2
next add zinc, if red still..then negative (zinc forced the run)

43
Q

Oxidase

A

purple = positive

be able to recognize that the really long enzyme name is associated with this test

44
Q

Urease

A

hydrolyze urea to ammonia, water, and CO2

bright pink = positive

45
Q

Vibrios

A
  • found in fresh, brackish, and salt water
  • causes epidemics
  • Gneg straight rods. curved in clinical specimens.
  • string test positive.
  • catalase/oxidase positive
  • Vibriostat disk (O/129) sensitive
  • halophilic (except for V. cholerae & V. mimicus)
46
Q

Vibrio species

A

V. cholerae- O1, O139 antigens. El Tor biogroup. causative agent of cholera . rice water stool- watery diarrhea with flecks of mucus (caused by toxins) fluid loss.

V. parahaemolyticus- associated with seafood (oysters). heat stable hemolysin. Gastroenteritis

V. vulnificus- raw undercooked seafood. wound infections, GI, sepsis. lactose positive (only one)

V. alginolyticus- most frequent, least pathogenic

47
Q

TCBS agar

A

yellow: V. cholerae and V. alginolyticus
green: V. parahaemolyticus and V. vulnificus

48
Q

Aeromonas

A
  • oxidase positive
  • mesophilics are motile
  • psychrophillics are non motile
  • beta hemolysis
  • indole positive
  • string test negative
  • resistant to vibriostat disc
49
Q

Plesiomonas

A
  • glucose & inositol fermentating
  • oxidase positive (unlike enterobacteriaciae)
  • facultatively anaerobic
  • motile via polar flagella
  • cold-blooded animals (zoo keepers)
  • sensitive to vibriostat disc (unlike aeromonas)
  • can’t grow in high salt (unlike vibrios)
  • positive for ornithine/lysine decarboxylase and arginine dihydrolase
50
Q

Campylobacter

A
  • microaerophillic- 5% O2 is optimal. likes to grow @ 42 degrees.
  • oxidase/catalase positive.
  • looks like seagull wings
  • darting motility
  • direct contact with animals & improperly cooked poultry

C. jejuni: #1 cause of diarrheal illness worldwide
C. fetus: can cause animal abortions

51
Q

Helicobacter

A

H. pylori colonizes 20-40% of adults

  • microaerophillic
  • urease positive (rapid color change on Christenen’s urea medium)
  • causes stomach cancer/ulcer formation
  • corkscrew motility
  • Campy BAP, skirrow agar?
52
Q

All Non-Fermentators (glucose)

A
  • G neg rods
  • doesn’t ferment sugars, only oxidizes them
  • generally oxidase positive
  • TSI: K/K
  • prefer moist environments (fluids in hospitals)
  • can withstand treatment with chlorhexidine
  • sepsis, wound infections, meningitis, osteomyelitis
53
Q

Pseudomonas aeruginosa

A
  • grape-like odor, blue-green pigment on SBA
  • variable on MAC plate
  • beta hemolysis
  • oxidase positive
  • arginine dihydrolase positive
  • grows at 42 degrees (hot tub syndrome)
  • citrate positive
  • acetamide utilization
  • Exotoxin A- similar to diphtheria toxin by blocking protein synthesis
  • nosocomial UTI’s/bacteremia, pneaumonia, Cystic Fibrosis pts
54
Q

P. stutzeri

A

wrinkly leathered colonies

55
Q

Acinetobacter

A
  • found in the environment and hospitals (ventilators, catheters, humidifiers)
  • oxidase and catalase negative
  • coccobacilli
  • on MAC plate: non-lactose fermenter, purplish hue. non-hemolytic

A. baumanii: glucose oxidizer. resistant to antibiotics
A. lwoffii- glucose negative. less virulent

56
Q

Stentrophomonas

A

almost entirely nosocomial. also in environment

S. maltophilia: rough lavender-green colonies with ammonia odor.
on MAC: NFL. DNAse positive. lysine decarboxylase positive

57
Q

Burkholderia Cepacia

A

-nosocomial. pneumonia especially with CF pts
-oxidase is weak/slow positive (can be variable)
-on SBA: non-wrinkly yellow-green colonies
motile
-ONPG and lysine decarboxylase positive
-utilizes glucose, lactose, maltose, and mannitol
-arginine dehydrolase negative (this is how you differentiate this from pseaudomonas)
-OFPBL & BCSA agars are selective for this organism

58
Q

Flavobacteriaceae

A
  • contaminant of hospital equipment
  • indole, gelatin hydrolysis, oxidase, and DNAse positive
  • non motile

Elizabethkingia meningoseptica: no growth on MAC plate. meningitis and septicemia of newborns, especially neonates.

59
Q

Shewanella

A

brown-tan colonies on SBA

H2S on TSI

60
Q

Haemophilus & Pasteurella are both..

A
  • part of the family Pasteurellaceae
  • G neg rods
  • non-motile
  • oxidase/catalase positive
  • reduces nitrate to nitrite
61
Q

Haemophilus

A
  • parasite in mucous membranes
  • hemolysis, dies rapidly on plates
  • requires X factor (hemin), V factor (NAD) or both (if its called para_____ then it only requires V factor.
  • wont grow on MAC but will on CAP with bacitracin
62
Q

H. influenzae

A

-satellitism around S. aureus
required X and V. neg for porphyrin
virulence: capsule, IgA protease, LPS, adherance factors
- Serotype B (HiB) = #1 cause of meningitis in children that aren’t vaccinated

63
Q

H. aegyptius

A
  • causes pink eye and Brazilian purpuric fever

- required X and V

64
Q

H. ducreyi

A
  • STI. extremely fastidious (needs to culture for 7 days)
  • chancroid, painful lesions
  • requires just X
  • nastaaaaaay
65
Q

H. aphrophilus

A

endocarditis

66
Q

Culturing haemophilus

A

Mueller Hinton agar with X & V strips

67
Q

porphyrin test

A

if it doesn’t require X factor, thats a positive result (pink-red-orange color)

68
Q

HACEK

A 
(H)aemophilus
(A)citnobacillus
(C)ardiobacterium
(E)ikerella
(K)ingella
  • all normal flora of oral cavity
  • endocarditis
  • increase CO2
  • Gneg rods but won’t grow on MAC
69
Q

A. acitomycetemocommitans

A

star formation at center of colonies

70
Q

C. hominis

A
  • infects aortis valve the most

- pitting on agar

71
Q

E. corrodens

A
  • human bite and fight wounds

- bleach like odor, pits agar

72
Q

K. kingae

A

isolates of children <3yo- affects bones and joints

73
Q

Capnocytophaga

A
  • Gneg rods that may fusiform (thick in center, thinner at ends)
  • producing gliding motility
74
Q

Pasteurella myltocida

A
  • bipolar staining (safety pin appearance)
  • no growth on MAC
  • exposure from cat/dog bites/scratches
  • weak acid fermentation
75
Q

Brucella

A
  • different types of Brucella can be differentiated by growth on agars with different dyes
  • brucellosis, undulant (persistant) fever
  • contact with animals and their products
  • catalase/oxidase positive
  • H2S and urease positive within 2hours
76
Q

Franscisella

A

requires cysteine for growth

rabbit fever

77
Q

Legionella

A
  • inhalation of aerosols (no person to person contact)
  • epidemics via air conditioners
  • can live within macrophages
  • pneaumonia, legionnaire’s disease, pontiac fever caused by L. pneaumophili
  • aquatic sources
  • wont Gstain well, no growth on SBA
  • requires L-cystein
  • grows on BCYE agar
78
Q

Bordatella

A
  • B. pertussis & B. parapertussis cause whooping cough
  • Pertussis toxin- interferes with signal transduction
  • breathing in aerosols, very contagious
  • specimens are best from nasopharynx on calcium alginate or Dacron swabs
  • Regen-Lowe transport medium
  • Bordet-Gengou agar: smooth silver pinpoint colonies resembling mercury droplets

Microbiology (26 decks)

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