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Microbiology > Gram Positive Bacilli > Flashcards

Gram Positive Bacilli Flashcards

1
Q

General Characteristics of Corynebacterium

A
  • free living saprophytes (water, soil, air), usual flora of animals and humans
  • diphtheriae is the most significant pathogen, others typically only in ICPs
  • falcultative, gram-positive, non spore-forming rods, have Babe-Ernst granules
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2
Q

C. diphtheriae Virulence factors

A
  • exotoxin - diphtheria toxin (only produced by some strains), inversely proportional to available iron
  • can use IgG to block toxin
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3
Q

Fragments of Corynebacterium diphtheriae

A
  • A: active fragment is cytotoxic, inhibits protein synthesis
  • B: binds to specific cell membrane receptors, mediates entry of fragment A
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4
Q

Infections of Corynebacterium diphtheriae

A
  • Respiratory infection, droplets spray, aerosol, or hand-to-mouth contact, unimmunized people are susceptible
  • incubation 2-5 days, fever, malaise, sore throat, inflammatory response and tissue necrosis, tough gray-white pseudomembrane
  • systemic infection when toxin is absorbed in bloodstream, affects kidneys, heart and nervous system
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5
Q

Treatment of diphtheria

A
  • administer antitoxin, produced in horses
  • antiboitics to clear infection, penicillin or erythromycin
  • vaccine available
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6
Q

Cutaneous diphtheria

A
  • prevalent in the tropics

- infection occurs at site of abrasion

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7
Q

Culturing diphtheria

A
  • Loeffler’s serum agar: demonstrates pleomorphism and metachromatic granules (Babe-Ernst)
  • Cysteine-tellurite blood agar (CTBA): modified Tinsdale media, selective and differential, brown or grayish to black around colonies
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8
Q

Identification of Corynebacterium diphtheriae

A
  • identification by fermentation reactions, urease

- toxigenicity testing: must have toxin, Elek test, PCR

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9
Q

C. amycolatum

A

most frequently recovered, common on skin, opportunistic, joint infections, endocarditis, sepsis (ICPs)

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10
Q

C. jeikeium

A

infection from catheters or prosthetic vavles, endocarditis

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11
Q

C. psuedodiphtheriticum

A

opportunistic, usually endocarditis

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12
Q

C. psuedotuberculosis

A

contact with sheep, dermonecrotic toxin

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13
Q

C. striatum

A

rare infections, normal flora

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14
Q

C. ulcerans

A

mastitis in cattle, contact with animals or unpasteurized milk

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15
Q

C. urealyticum

A

urinary pathogen, highly urease positive

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16
Q

Characteristics of Coryneform

A
  • speciated if found in normally sterile site, or if it’s the prominent organism of a specimen
  • may require urine samples if predominant
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17
Q

Most significant pathogen of Corynebacterium group

A

C. diphtheriae

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18
Q

Major virulence factor of C. diphtheriae

A

exotoxin

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19
Q

toxigenic fragments

A
  • A: active fragment, cytotoxic, inhibits protein synthesis

- B: binds to specific cell membrane receptors, mediates the entry of fragment A

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20
Q

C. diphtheriae on Loeffler’s serum agar

A

metachromatic granules (Babes-Ernst granules)

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21
Q

C. diphtheriae on CTBA

A

brown to grayish black around colonies

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22
Q

confirm identification of C. diphtheriae

A

urease from fermentation reactions

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23
Q

toxigenicity testing of C. diphtheriae

A

Elek test

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24
Q

Major virulence factors of Listeria monocytogenes

A
  • the hemolysin Listeriolysin O (hemolytic and cytotoxic)

- p60 surface protein (induces phagocytosis b/c of increased adhesion to mamalian cells)

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25
Q

Major identifiers of Listeria

A
  • grows at 4C, catalase positive

- umbrella motility at 25C, tumbling motility

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26
Q

transmission of E. rhusiopathiae

A

occupational exposure (animals like sheep)

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27
Q

identification of E. rhusiopathiae

A

catalase negative and TSI positive (H2S production)

28
Q

identification of Arcanobacterium

A

catalase negative, narrow zone of beta hemolysis, produces black dot under colonies

29
Q

Nocardia

A

aerobic, weakly acid-fast, gram-variable, morphologically resemble fungi

30
Q

N. cyriaciageorgica and N. farcinica

A

cause confluent bronchopneumonia, no sulfur granules

31
Q

N. braziliensis

A

causes actinomycotic mycetomas (cutaneous infection), sulfur granules present

32
Q

Actinomadura

A

colonies can be red, resemble Nocardia but non-acid-fast

have a molar tooth appearance after 2 week incubation

33
Q

Rhodococcus

A

salmon-pink colonies, zig-zag growth

34
Q

Streptomyces

A

smell woodsy w/ waxy, heaped colonies

35
Q

Bacillus anthracis

A
  • agent of anthrax, nonhemolytic on SBA
  • identification: nonhemolytic on SBA, medusa head or egg whites, non-motile, produces lecithinase, string of pearls morphology
36
Q

Virulence factors of Bacillus anthracis

A

protein exotoxin (EF, LF and PA)

37
Q

Infections cause by Bacillus anthracis

A

most are cutaneous, pulmonary infection (“woolsorter’s disease”), GI anthrax, Injectional anthrax

38
Q

Bacillus cereus

A

motile (flagella), hemolysin positive

39
Q

Rothia dentocariosa

A
  • normal oral flora

- bacteremia, endocarditis, wound infection, eye infection

40
Q
  • gram-positive, non spore forming rods

- found in nature, can be in produce, dairy, processed meat

A

characteristics of Listeria monocytogenes

41
Q

Listeriolysin O (hemolytic and cytotoxic), phospholipase C, catalase, superoxide dismutase, surface protein p60

A

virulence factors of Listeria monocytogenes

42
Q
  • adults: penetration of the intestine
  • ICP/elderly: septicemia, meningitis, endocarditis
  • Pregnant women: premature labor, spontaneous abortion
  • newborn: meningitis
A

infections of L. monocytogenes

43
Q
  • grow at cold temperature, catalase positive
  • hippurate hydrolysis negative
  • umbrella motility at 25C, tumbling motility
  • CAMP test block
A

identification of L. monocytogenes

44
Q
  • ampicillin or penicillin G

- TMP-SMZ (sulfa drugs) if penicillin allergy

A

treatment of L. monocytogenes

45
Q
  • gram-positive, non spore forming
  • in nature worldwide, found in animals
  • infection through occupational exposure (hands/fingers, self-limiting)
A

E. rhusiopathiae characteristics

46
Q
  • cell surface antigens, endothelial cell adherence

- enzymes

A

E. rhusiopathiae virulence factors

47
Q
  • catalase negative, TSI positive (H2S)

- requires CO2, SBA or CA, alpha hemolysis

A

E. rhusiopathiae identification

48
Q

pharyngitis, cellulitis

A

Infections of arcanobacterium

49
Q
  • low virulence
  • catalase negative, narrow beta hemolysis
  • black dot under colony
  • treat with erythromycin
A

arcanobacterium

50
Q
  • stains gram-variable
  • causes bacterial vaginosis, observe clue cells, treat with clindamycin
  • use human blood bilayer tween agar
A

Gardnerella vaginalis

51
Q
  • aerobic, weakly acid-fast, gram-variable
  • morphologically resemble fungi
  • found in the environment, affect ICPs
A

Nocardia

52
Q
  • bronchopneumonia, no sulfur granules

- high mortality rate

A

N. cyriaciageorgica and N. farcinica

53
Q
  • cutaneous infection

- sulfur granules

A

N. braziliensis

54
Q
  • wet mounts, branching filaments
  • parafin bait test, substrate hydrolysis/utilization
  • antimicrobial susceptibility
A

identification of Nocardia

55
Q

treatment of Nocardia

A

resistant to penicillin, susceptible to sulfnoamides

56
Q

red colony, molar tooth appearance, non acid-fast

A

actinomadura

57
Q

zig-zag growth, salmon-pink colony

A

Rhodococcus

58
Q
  • waxy, heaped colonies

- smell woodsy, branching with chains and spores

A

Streptomyces

59
Q
  • found in livestock, acquired by contamination of food or a wound
  • large spore-forming bacilli, nonhemolytic
A

Bacillus anthracis

60
Q
  • polypeptide capsule

- potent exotoxin (edema factor, lethal factor, protective antigen)

A

virulence factors of B. anthracis

61
Q
  • cutaneous (black eschar)
  • respiratory (woolsorter’s disease)
  • GI infection
  • injectable infection
A

infections of B. anthracis

62
Q

nonhemolytic, medusa head or beaten eggwhites, nonmotile, produces lecithinase, string of pearls when exposed to penicillin

A

identification of B. anthracis

63
Q

treatment of B. anthracis

A

most susceptible to penicillin

64
Q

Food poisoning (diarrheal syndrome, emetic form), infections of the eye, septicemia, meningitis, etc.

A

infections of B. cereus

65
Q
  • exotoxin (enterotoxin), pyogenic toxin

- spores, enzymes, beta-lactamase

A

virulence factors of B. cereus

66
Q

aerobic, beta hemolytic, motile, spores, hemolysin positive

A

identification of B. cereus

67
Q

treatment for B. cereus

A

vancomycin (eye infection), clindamycin and gentamycin combo

Microbiology (26 decks)

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