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Flashcards in Microbiology: Exam 2 Deck (78):
1

All Enterobacteriaceae

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

2

MacConkey agar differentiates..

lactose fermentation

3

EMB agar differentiates..

lactose fermentation of enteric bacilli

positive = purple
E. coli = greenish hue

4

HE agar differentiates..

lactose and sucrose fermentation

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

5

XLD agar differentiates

sucrose, lactose, and xylose fermentation

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

6

E. Coli

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

7

O antigen

heat stable antigen located in LPS

8

H antigen

flageller antigen

9

K antigen

capsular antigen

10

5 types of E. coli

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

11

O157:H7 toxin

E coli
detected on SMAC plate
doesn't ferment sorbitol

12

Uropathogenic E. coli

most common cause of UTI's

13

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

IMVC --++ <--- **Few exceptions**

Wound, pneaumonia, and UTI infections

14

Klebsiella

non-motile.
TSI: A/A

K. pneaumoniae has capsule
K. oxytoca = Indol +

15

Enterobacter

TSI: A/A

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

16

Pantoea

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

17

Serratia

-ONPG positive (means slow lactose fermentor)
-DNAse positie
-highly resistant to antimicrobials

18

Hafnia

BEER
linked to gastroenteritis

19

Proteaus

-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.

20

Edwardsiella

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

21

Citrobacter

C. freaudnii- nosocomial UTI's, endocarditis.

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

22

IMVC test

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

23

Salmonella

-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

24

Subgroup 1 Salmonella

human infections

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

25

Salmonella infections

-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.

26

Shigella

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

S. sonnei is ONPG and ornithine decarboxylase positive

27

Types of Shigella

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

28

Shigella infections

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

29

Yersina

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.

30

Carb Utilization test

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

31

Oxidation fermentation

-oxidation- utilizes carbs aerobically
-fermentation- utilizes carbs anaerobically
-asacchrolytic- doesn't utilize carbs

32

O/F Basal Media

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

TSI slant

-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

ONPG test

tests for slow lactose fermentators
turns yellow for positive rxn

35

Methyl-Red and Voges Proskauer test

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

red = positive for both tests

36

Decarboxylase test

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

dihydrolase: arginine -> ornithine

37

LIA Slant

deamination or decarboxylation of lysine.

deamination = reddish color
decarboxylation = purpleish color

38

Deaminase test

removes amine group from amino acids

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

39

Citrate utilization

citrate used as sole carbon source
blue = positive

40

gelatinase production

loss of gelling.
+ = liquefaction

41

indole tests

breaks tryptophan down into indole.
add Ehrlich's reagent (PDAB) or Kovac's. red = positive

42

NO3 reduction

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

Oxidase

purple = positive

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

44

Urease

hydrolyze urea to ammonia, water, and CO2
bright pink = positive

45

Vibrios

-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

Vibrio species

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

TCBS agar

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

48

Aeromonas

-oxidase positive
-mesophilics are motile
-psychrophillics are non motile
-beta hemolysis
-indole positive
-string test negative
-resistant to vibriostat disc

49

Plesiomonas

-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

Campylobacter

-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

Helicobacter

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

All Non-Fermentators (glucose)

-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

Pseudomonas aeruginosa

-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

P. stutzeri

wrinkly leathered colonies

55

Acinetobacter

-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

Stentrophomonas

almost entirely nosocomial. also in environment

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

57

Burkholderia Cepacia

-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

Flavobacteriaceae

-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

Shewanella

brown-tan colonies on SBA
**H2S on TSI**

60

Haemophilus & Pasteurella are both..

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

61

Haemophilus

-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

H. influenzae

-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

H. aegyptius

-causes pink eye and Brazilian purpuric fever
-required X and V

64

H. ducreyi

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

65

H. aphrophilus

endocarditis

66

Culturing haemophilus

Mueller Hinton agar with X & V strips

67

porphyrin test

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

68

HACEK

(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

A. acitomycetemocommitans

star formation at center of colonies

70

C. hominis

-infects aortis valve the most
-pitting on agar

71

E. corrodens

-human bite and fight wounds
-bleach like odor, pits agar

72

K. kingae

isolates of children <3yo- affects bones and joints

73

Capnocytophaga

-Gneg rods that may fusiform (thick in center, thinner at ends)
-producing gliding motility

74

Pasteurella myltocida

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

75

Brucella

-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

Franscisella

requires cysteine for growth
rabbit fever

77

Legionella

-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

Bordatella

-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