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Infectious Agents > Gram Positive Rods > Flashcards

Gram Positive Rods Flashcards

1
Q

What are 4 bacteria that are gram-pos rods?

A
  • erysiopelothrix
  • corynebacteria
  • rhodococcus
  • listeria
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2
Q

Erysiopelothrix rhusiopathiae (E. insidisa)

A

Non-motile, non-spore forming, non-acid fast, incomplete hemolysis

  • catalase neg
  • produce H2S on TSI
  • survives in soil
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3
Q

Erysiopelothrix is found in up to _____

A

50% of pigs

- major source is carrier animals = pigs carry in tonsils and lymphatics

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4
Q

Erysiopelothrix is resistant to

A

Chemicals, and to drying, pickling, salting, smoking

is a non-spore forming bacterium!

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5
Q

4 forms of disease caused by erysiopelothrix

A
  • acute septicemia
  • urticarial cutaneous lesions (diamond skin)
  • vegetative endocarditis
  • arthritis
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6
Q

Joint ill in lamb

A

Wound infections in sheep that lead to polyarthritis, caused by erysiopelothrix

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7
Q

Wound infections in dogs leads to

A

Rheumatoid arthritis and heart valve endocarditis

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8
Q

Erysiopelothrix is an _________ of butchers, fish handlers, and veterinarians

A

Occupational disease

- erypsipeloid and local wounds can lead to fatal septicemia or joint/heart valve infection

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9
Q

Development and severity of erysiopelothrix infection depends on ______

A

Virulence of strain and resistance of host

  • stress
  • age 3-18 months
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10
Q

What are 3 routes of exposure for erysiopelothrix?

A
  • oral
  • cutaneous
  • respiratory
  • could also inseminated hens with contaminated sperm*
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11
Q

________ occurs in acute septicemia

A

Vascular disturbances

- starts as hyaline thrombosis and progresses to fibrinous thrombosis by 4 days

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12
Q

Erysiopelothrix causes ______ accumulation in joints, heart valves, and arteries

A

Fibrin

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13
Q

What is the virulence factor for erysiopelothrix?

A

Neuraminidase (enzyme)

  • removes N-acetylneuraminic acid (sialic acid) from substrates (RBCs, mucin, fibrinogen, leukocytes, thrombocytes)
  • leads to anemia, leukopenia, and thrombocytopenia
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14
Q

Antineuraminidase antibodies are _____

A

Protective

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15
Q

Clinical signs of erysiopelothrix infection in swine

A
  • acute: fever, anorexia, depression, death in 2-3 days
  • stiff gait, urticarial cutaneous lesions, diamond skin lesions (non-specific), possible abortion
  • subacute: less severe than acute, with possible recovery
  • chronic: lameness, possibly a sequal to acute, subacute, or unrecognized infection
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16
Q

Diagnosis of erysiopelothrix

A
  • acute: blood smears from live animals, liver/spleen/heart blood from necropsy
  • chronic: affected skin, heart, joint fluid
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17
Q

Erysiopelothrix immunity

A
  • Humoral!!!
  • hyperimmune antiserum: short term, passive protection
  • bacterins: short duration
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18
Q

Erysiopelothrix vaccine

A

EVA (erysipelas vaccine avirulent)

  • live vaccine, same for swine and birds
  • injectable, aerosol, or oral
  • prevents septicemia, but not chronic form
  • cannot be given with antibiotics!!
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19
Q

Erysiopelothrix treatment

A

Penicillin is best drug

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20
Q

Rhodococcus equi

A

Chronic suppurative bronchopneumonia of foals

  • 2 weeks to 5 months, peaks at 4-6 weeks old
  • too young to develop a vaccine
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21
Q

R. equi characterization

A

Extensive lung abscessation and ulcerative enteritis and mesenteric lymphadenitis
- summer or enzootic pneumonia

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22
Q

Route of entry for R. equi

A

Inhalation of pathogentic R. equi in dust

- is also carried in the GIT of gregarious birds

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23
Q

Environmental requirements of R. equi

A
  • is an aerobe that accumulates in feces in soil

- ammonia accumulation in environment inhibits normal defense system of respiratory tract (allows for easy infection)

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24
Q

_____ may follow pneumonia

A

Enteritis

  • via swallowing of infected sputum
  • ingestion leads to microscopic enteritis, no diarrhea
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25
Q

R. equi is common in the feces of _____

A

Herbivores and swine

- is not usually in the normal flora

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26
Q

Pathogenesis of R. equi

A
  • survives, multiplies, kills alverolar macrophages leading to caseous necrosis and lung destruction
  • pyogranulomatous response
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27
Q

R. equi is an _____

A

Facultative intracellular parasite

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28
Q

Virulence factors of R. equi

A
  • capsular polysaccharides are antiphagocytic and resistant to complement
  • exoenzymes: cholesterol oxidase and phospholipase C
  • cell wall mycolic acid facilitates intracellular survival
  • plasmid encoded Vap A protein that interferes with phagolysosome formation
29
Q

Host factors that facilitate R. equi infection

A
  • clinical disease is related to immunocompetency of foals —> foals that produce no detectable IFN-gamma are at risk of developing pneumonia
  • decline in colostral antibody
30
Q

Diagnosis of R. equi

A

Collect specimens from:

  • nasal discharge
  • bronchial wash
  • feces
  • intestine
  • mesenteric lymph nodes
  • blood
31
Q

Treatment of R. equi

A

Lipid soluble antibiotics that penetrate bacteria

  • erythromycin with rifampin***
  • 80% survival rate if treated early with no lasting damage
32
Q

Corynebacterium

A

Opportunistic urinary tract commensal of cattle

33
Q

What are the 3 species of Corynebacterium?

A
  • C. pilosum: mild, cystitis only
  • C. renale: chronic cystitis and ascending pyolonephritis
  • C. cystitidis: chronic pyelonephritis and most severe cystitis
34
Q

Corynebacterium is most common in _____

A

Mature cows due to short urethra of females

- predisposed to by pregnancy and parturition

35
Q

Corynebacterium is spread by ______

A

Bull and urine

36
Q

Virulence factors of corynebacterium

A
  • pili: adherence to host cells
  • urease: produces toxic ammonia and inactivates complement
  • renalin (exoprotein): lyses host cell membrane
37
Q

Diagnosis of corynebacterium

A

Urine

- stain and culture

38
Q

Treatment of corynebacterium

A
  • large doses of penicillin

- remissions are common (reculture)

39
Q

C. (ovis) pseudotuberculosis

A

Facultative intracellular pathogen

  • sheep/goats: caseous lymphadenitis
  • horses: ulcerative lymphangitis and folliculitis
  • other hosts: chronic lymphadenitis and abscesses
40
Q

C. pseudotuberulosis usually follows ____

A

Wound infections in adults

- shearing, docking, castration, earbiting, headbutting

41
Q

Canadian horsepox

A

C. psudotuberculosis infection in horses that presents as folliculitis with mildly pururitic skin lesions
- progresses from nodules to alopecia and crusts with underlying pus

42
Q

Pigeon’s fever

A

C. pseudotuberculosis in horses with slowly enlarging, localized and nonpainful abscesses

43
Q

Virulence factors of C. pseudotuberculosis

A
  • phospholipase D: increase vascular permeability, facilitate dissemination, inhibition of chemotaxis
  • cell wall lipid and mycolic acid: facilitate intracellular survival
44
Q

Treatment of C. pseudotuberculosis

A

Penicillin (works on skin lesions only) and trimethoprim/sulfonamide

45
Q

Is there a vaccine for C. pseudotuberculosis?

A

Crude vaccine: austrailan whole cell bacterins (is being evaluated in US sheep)

46
Q

C. diptheria

A

Human pathogen, carried in throat

  • exotoxin and temperate phage
  • subunit toxin inhibits protein synthesis
47
Q

C. bovis

A

Commensal of bovine udder (20% of quarters)

- mild neutrophil response may protect against pathogens

48
Q

C. suis

A

Cystitis and ascending pyelonephritis in sows

  • anaerobe carried in prepuce and preputial diverticulum of 60-80% of boars
  • transmitted during mating
49
Q

C. ulcerans

A

Mastitis in cows

  • mild to severe pharyngitis in people
  • causes caseous lymphadenitis in sheep/goats
50
Q

C. haemolyticum

A

Pharyngitis and skin infection in people

51
Q

C. kutscheri (murium)

A

Carried by normal experimental mice and rats

- caseous tuberculosis-like focal lesions in lungs and other organs

52
Q

Listeria

A

Slender, nonsporing, gram-pos rod, palisades in young cultures

  • motile at room temp, but not at 37 C
  • best grown on blood agar
53
Q

What are the pathogenic forms of listeria?

A
  • L. monocytogenes

- L. ivanovii

54
Q

L. monocytogenes

A

Resistant to freezing and high salt concentrations

  • may survive pasteurization
  • grows within 4-44 C or 39 to 111 F, and pH of 5-9
55
Q

Environmental requirements of L. monocytogenes

A

Saprophyte in nature, soil, water, feces, sewage

- latent, healthy carriers shed it in feces and milk during stress

56
Q

What are the 2 natural reservoirs on L. monocytogenes?

A

Soil and mammalian GIT

57
Q

Transmission of L. monocytogenes

A

Animal to animal via fecal-oral route

58
Q

Listeriosis

A

Primarily a winter/spring disease of feedlot or housed ruminants

  • less acidic pH of silage enhances growth
  • outbreaks occur after feeding spoiled silage
  • remove silage to stop the spread
59
Q

Disease of L. monocytogenes

A
  • meningoencephalitis is most common form of listeriosis in ruminants
  • septicemia is common in monogastrics (inclu. young ruminants)
  • abortion/stillbirth are common in septicemia
60
Q

L. monocytogenes pathogenesis

A

Facultative intracellular pathogen

  • entry thru alimentary tract (Peyer’s patch)
  • interaction between Internalin A and E-cadherin, Internalin B and Met mediates internalization
  • multiplies in epithelial cells and phagocytes
61
Q

____ and ____ mediates internalization into host cells

A

InlA and InlB

62
Q

Escape from phagosome by ____ and _____

A

Listeriolysin O (LLO) and phospholipases (PLCs)

63
Q

ActA

A

Actin polymerization into filamentous actin

64
Q

Encephalitis or meningoencephalitis affects

A

Sheep, cattle, goats, and pigs

65
Q

______ of all domestic animals is susceptible

A

Uterus

66
Q

Cell mediated immunity from listeria

A

Infected animals develop both DTH and acquired CMI at same time
- mediated by T cells and activated macrophages

67
Q

Diagnosis of listeria

A
  • sample of lumbosacral CSF
  • specimen from brain or aborted fetus
  • confirmed only by isolation and identification of L. monocytogenes (cold enrichment for up to 12 weeks)
68
Q

Why is serology not used for listeria diagnosis?

A

Many healthy animals have high Listeria titers

69
Q

Treatment of listeria

A

Tetracylines or penicillin/ampicillin with aminoglycoside

  • antibiotics have no use against the neurologic form
  • remove silage
  • only have experimental bacterins and attenuated vaccines

Infectious Agents (44 decks)

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