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Microbiology > Lecture 13: Actinomyces, Nocardia, Dermatophilus and Corynebacterium > Flashcards

Lecture 13: Actinomyces, Nocardia, Dermatophilus and Corynebacterium Flashcards

1
Q

are actinobacteria gram negative or positive

A

Positive

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2
Q

What are the different lifestyles of actinobacteria

A
  1. Free living saprophytes (in soil)
  2. Mutualists
  3. Commensals
  4. Pathogens
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3
Q

What is the cell morphology of actinomyces

A

Typically rods or filaments, often branching

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4
Q

Actinomyces are ___ or ___ anaerobes

A

Facultative or obligate

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5
Q

T or F: actinomyces are capnophilic

A

True

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6
Q

identify species

A

Actinomyces spp

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7
Q

What is the primary habitat for actinomyces in mammals

A

Oral mucosa and tooth surfaces, MM of nasopharynx, urogenital tract, and intestinal tract

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8
Q

What is the cause of actinomyces

A

Traumatic inoculation of resident bacteria into susceptible tissues

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9
Q

Actinomyces is typically a ___infection

A

Polymicrobial

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10
Q

Pathogenicity of actinomyces ___with mixed infections

A

Increases

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11
Q

What is the pathogens is of actinomyces

A

Pyogranulomatous reactions, suppurative inflammation surrounded by granulomatous elements, fistulous tracts secrete purulent exudate- which contains sulfur granules made up of club colonies

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12
Q

Sulfur granules are useful in dx which organism

A

Actinomyces spp

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13
Q

what are these and what organism spp is likely

A

Sulfur granules, actinomyces spp

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14
Q

What does Actinomyces Bovis cause in cattle

A

Lumpy jaw, suppurative lesions of soft tissue and bone, abscesses

Osteomyeltitis—> tooth dislodgment, inability to chew, mandibular fractures

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15
Q

Cow presents with tooth dislodgement, inability to chew, and mandibular fractures, and lumpy jaw. What is likely bacterial cause

A

Actinomyces Bo is

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16
Q

What does Actinomyces suis cause in swine

A

Mastitis (lumpy udder) and ventral SQ lesions in sows

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17
Q

What causes A. Suis in sows

A

Traumatic inoculation during suckling and weaning

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18
Q

what is likely cause

A

Actinomyces bovis

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19
Q

What is likely cause

A

A. Suis

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20
Q

What does A. Bovis cause in horses

A

Mandibular lymphadenopathy (mimics strangles), fistulous withers and poll evil, skin nodules

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21
Q

What actinomyces species typically effects dogs and cats

A

A. Viscous

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22
Q

What does A. Viscous cause in dogs and cats

A

SQ abscesses, thoracic infections (pyothorax, pneumonia), abdominal and retroperitoneal infections

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23
Q

what is likely cause

A

A. Viscous

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24
Q

How do you dx actinomycis

A
  1. Clinical presentation
  2. Lumpy jaw- rads
  3. Exudates/ aspirates containing sulfur granules, club colonies
  4. PCR
  5. MALDI-TOF
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25
Q

What are these and what species does this indicate

A

sulfur granules, club colonies—> Actinomyces

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26
Q

What is tx for actinomycosis

A
  1. Surgery- drainage, excision and debridement of lesions
  2. Prolonged antibiotics- penicillin
  3. Bovine lumpy jaw- sodium iodide IV with antibiotics, debridement of bone lesion
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27
Q

What is the appropriate treatment of lumpy jaw from A. Bovis

A

Sodium iodide IV with antibiotics
Debridement of bone lesion followed by lavage with iodine solution

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28
Q

How can you prevent actinomycosis

A
  1. Good oral care
  2. Limit amount of rough forage fed
  3. Protect pets from grass awns
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29
Q

Dermatophilus congolensis is a ___anaerobe

A

Facultative

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30
Q

T of F: dermatophilus congolensis is capnophilic

A

True

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31
Q

Dermatophilus is a ___ parasite commonly found in cattle, sheep and horses

A

Obligate

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32
Q

How is dermatophilus congolensis transmitted

A

Direct contact, fomites, biting arthropods

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33
Q

What is the main reservoir for Dermatophilus congolensis

A

Asymptomatic chronically infected hosts

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34
Q

What is the pathogens is of D. Congolensis

A
  1. Trauma/ persistent wetting facilitates invasion of epidermis and hair follicles
  2. Virulence factors: enzymes (keratinases) increase epidermal permeability
  3. Infected epidermis and neutrophil exudate—> scab and crusting skin lesion
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35
Q

What is dermatophilosis

A

Exudative dermatitis with formation of scabs/crusts

36
Q

The following was removed from dairy cow and histo performed what is cause

A

Dermatophilus congolensis

Histo: alternating bands of keratinized epidermal cells and inflammatory cells

37
Q

What are the predisposing factors for dermatophilosis

A
  1. Prolonged wetting from rain—> lesions on dorsum and head
  2. Trauma from thorny scrub—> lesions on face and legs
  3. Arthropod bites
38
Q

What is the lesion progression for dermatophilosis

A

Papules—> exudate—> paintbrush lesions of matted hair—> lesions form scab

39
Q

Cow spent long time in rain and developed these lesions, what is likely cause

A

Dermatophilus congolensis

40
Q

What bacteria could have caused this scab to form on horse

A

D. Congolensis

41
Q

What are the treatment options for mild cases of Dermatophilosis

A

Grooming and isolation in dry quarters

42
Q

What are the treatment options for severe causes of dermatophilosis

A

Antibiotics- penicillin-streptomycin

43
Q

What is a treatment option for horses following dermatophilosis

A

Topical treatment with povidone iodine following grooming

44
Q

What hemolysis is seen with dermatophilus congolensis

A

Beta-hemolysis

45
Q

What spp have branching filaments that fragment into rods and cocci and are partially acid fast

A

Nocardia spp

46
Q

Nocardia spp are ___aerobes

47
Q

Nocardia spp are ___ so widespread in soil and water

A

Saprophytes

48
Q

What are the routes of infection for Nocardia spp

A

Trauma to skin, inoculation of teat canal, inhalation, ingestion

49
Q

What is Nocardiosis characterized by

A

Suppurating lesions with various granulomatous features, sanguinopurulent exudates

50
Q

What is the pathogens is of Nocardia

A

Suppurating lesions with sanguinopurulent exudates, lymph nodes may be involved, hematogenous spread

51
Q

what spp is this

A

Nocardia spp

52
Q

Pathogenic Nocardia are facultative ___organisms so they grow and survive inside ___

A

Intracellular, phagocytes

53
Q

What virulence factors protect Nocardia against being killed by phagocytes

A

Superoxide dismutase and catalase

54
Q

What species is this

A

Nocardia (growing inside macrophage)

55
Q

What does nocardiosis cause in dairy cattle

A

Mastitis
Can cause pneumonia, abortion (rare)

56
Q

What does nocardiosis cause in swine

A

Pneumonia, abortion, lymphadentitis (rare)

57
Q

What does nocardiosis cause in horses

A

Pneumonia, pleuritis, systemic abscesses, cutaneous-subcutaneous lesions, abortion (rare)

58
Q

What does nocardiosis cause in cats and dogs

A

Utaenous and SQ lesions (often with abscesses), regional lymphadentitis, pulmonary nocardiosis with cough, hemoptysis, respiratory distress, mucopurulent oculonasal discharge

59
Q

What is likely cause

A

Nocardiosis

60
Q

How can you dx nocardiosis

A
  1. Gram positive, partially acid fast bacilli
  2. Culture and ID
61
Q

Why do you do both a gram stain and acid fast when identifying nocardiosis

A

Differentiate between actinomyces

62
Q

what species is this

63
Q

What is tx for nocardiosis

A
  1. Debridement and drainage of lesions
  2. Prolonged trimethoprim-sulfonamides
64
Q

What shape are corynebacterium

A

Pleomorphic

65
Q

Corynebacterium are ___anaerobes and aerobes

A

Facultative

66
Q

Where are corynebacteria found

A

Skin and mucous membranes (commensals)

67
Q

How does corynebacterium pseudotuberculosis colonize

A

Via skin trauma

68
Q

What is pathogens is of C. Pseudotuberculosis

A
  1. Facultative intracellular pathogen (survives in phagocytes)
  2. Spreads to draining LN
  3. Virulence factors phospholipase D, cell wall lipids enhance invasion
  4. Abscess form in LN
69
Q

T or F: corynebacterium pseudotuberculosis can be a chronic infection that can persist for hosts life

70
Q

What does C. Pseudotuberculosis cause in sheep and goats

A

Caseous lymphadentitis

71
Q

What is the external form of C. Pseudotuberculosis

A

Abscess form in superficial LN, skin, subcutis

72
Q

What is the internal form of C. Pseudotuberculosis

A

Abscess form in internal organs and LN

73
Q

The external form of C. Pseudotuberculosis is more common in goats or sheep? And where are abscess

A

Goats- abscesses in head/neck regions

74
Q

The internal form of C. Pseudotuberculosis is more common in goats or sheep? And what is it associated with

A

Sheep, associated with weight loss, and ill thrift (thin ewe syndrome)

75
Q

What does the external form of C. Pseudotuberculosis cause in horses

A

Abscesses in pectoral region or along ventral midline of abdomen

76
Q

goat presents with these abscesses. What is likely cause

A

C. Pseudotuberculosis external form

77
Q

Sheep has these abscesses in liver, what is likely cause

A

C. Pseudotuberculosis, internal form

78
Q

What are the vectors for external form of C. Pseudotuberculosis in horses

A

Horn fly, stable fly

79
Q

What does the internal form of C. Pseudotuberculosis cause in horses

A

Abscess in liver, kidney, spleen and lungs, weight loss, fever, depression colic

80
Q

Which form of C. Pseudotuberculosis in horses has a high case fatality rate (30-40%)

A

Internal form

81
Q

Horse presents with severe limb swelling and cellulitis with multiple draining ulcerative lesions along lymphatics, in both hind limbs. What is this and what is cause

A

C. Pseudotuberculosis causing ulcerative lymphangitis

82
Q

Horse presents with pectoral abscess with exudates, what is likely cause

A

C. Pseudotuberculosis, external form

83
Q

How can you diagnose C. Pseudotuberculosis

A
  1. Abscess contents
  2. culture and ID
  3. Internal form: rads and ultrasound, serological tests to detect antibodies against PLD and cell wall antigens
84
Q

How can you diagnose internal C. Pseudotuberculosis

A

Radiographs, ultrasounds, serological tests to detect antibodies against PLD and cell wall antigens

85
Q

What is tx for Caseous lymphadentitis caused by C. Pseudotuberculosis in sheep and goats

A

Abscess is thick walled so refractory antimicrobial therapy:
1. Long term (4-6wks) systemic antibiotics (penicillin G + rifampin)
2. Intralesional tulathromycin

86
Q

What is the treatment for horses with lymphangitis and internal abscesses due to C. Pseudotuberculosis

A

Long-term IV antibiotics—> penicillin G and cephalosporins

Microbiology (31 decks)

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