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Bacteriology > 5.8 Gram negative aerobic rods > Flashcards

5.8 Gram negative aerobic rods Flashcards

1
Q

Brucella spp. characteristics: gram, shape, stain, environment, nutrition, where they are found

A
  • Small Gram-negative coccobacilli
  • Stain red with acid fast stain (modified Ziehl-
    Neelsen method)
  • Facultative anaerobes, capnophilic (require CO2), have complex nutritional requirements, slow growing
  • Facultative intracellular pathogens
  • Target reproductive organs of variety of
    species
  • Reservoirs and sources of infection: infected animals and their products
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2
Q

important brucella spp.

A

abortus, suis, canis

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3
Q

brucella abortus effects, environmental survival, transmission

A
  • Obligate pathogen of cattle, eradicated in Canada (except Wood Buffalo National Park)
  • Survives in the environment for months
  • Transmission: tissues/liquid of abortion, ingestion, through nasal and oral mucosa, venereal routes, vertical through milk
  • Zoonotic agent
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4
Q

Brucella abortus: pathogenesis

A
  • Can invade epithelial cells allowing mucosal invasion and M cells in intestine
  • Survive intracellularly within phagocytes and nonphagocytic cells; able to block phagosome-lysosomes fusion
    – Causes persistent infection of reticule-endothelial system
  • B. abortus reaches placenta via macrophages → able to use erythritol and multiplies massively in placenta leading to placentitis
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5
Q

brucella abortus life cycle

A

-passed from infected mother to aborted fetus which is a source of infections
-can infect horse but this is a dead end
-can infect wild ungulates
-can be apssed into dairy products and infect people

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6
Q

brucella abortus clinical presentation

A

-abortion between the 5th and 7th month of pregnancy
>infected cows usually abort once, but some may abort during additional pregnancies
-reduced milk production
-calves from infected cows may have latent infections
>infections that are not detected until they become pregnant, abort, or give birth
-decreased fertility, poor conception rates
-occasionally enlarged, arthritic joints
-retained placentas
-birth of weak calves
-stillbirth

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7
Q

Zoonotic potential of brucella abortus: transmission and primary victims

A
  • Transmission by: ingestion, through breaks in the skin, airborne infection (laboratories and abattoirs)
  • Primarily affects consumers of raw milk, farmers, butchers, veterinarians and laboratory personnel
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8
Q

Distribution of Brucella abortus

A

mostly africa, southwest asia, southern europe, south america

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9
Q

Eradication of bovine brucellosis

A
  • Historically, federal test-and-slaughter program in Canada
  • Canadian cattle herds declared Brucella free Sept. 1995
  • Serological testing: Rapid buffered plate test (cheap, not very specific). If +ve, serum agglutination test and complement fixation test ($, less sensitive, more specific)
  • CFIA (with provinces and industry) runs Bovine Surveillance System (BSS) to support Canada’s claim that it is free from brucellosis in cattle
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10
Q

Brucella abortus surveillance

A
  • Pos. serological test → investigation of herd; further
    testing
  • If confirmed infection → CFIA may order quarantine, further testing and/or destruction of infected/exposed animals
  • Producers may get compensation for animals ordered to be destroyed by the CFIA
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11
Q

Brucella suis: where is it found, is it screened, symptoms and species affected

A
  • Occasionally found in North America; more prevalent in South America, Europe and Asia (Wild boars in the USA)
  • Part of CFIA serological screening at slaughter facilities
  • Causes chronic inflammation of the reproductive tracts of sows and boars, stillbirths, neonatal mortality, temporary sterility
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12
Q

brucella suis diagnosis

A
  • Diagnosis: serology (Rose-Bengal plate agglutination, ELISA) → culture/PCR
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13
Q

Brucella canis: where is it found, what disease does it cause?

A
  • May be more prevalent in Canada than originally thought (“puppy mills” and imported dogs), very common in countries with free-ranging dogs (e.g., Mexico)
  • Disease:
  • Chronic, persistent reticuloendothelial infection, bacteremia, vertebral osteomyelitis
  • Abortion late pregnancy; epididymitis, orchitis
  • Transmission to people rare
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14
Q

typical signs of brucella canis in dogs

A

-reproductive problems such as infertility and abortions with few other signs of clinical illness
-abortion

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15
Q

musculoskeletal issue that can be caused by brucella canis

A

-Brucella discospondylitis

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16
Q

important Moraxella spp.

A

Moraxella bovis
Moraxella bovoculi
Moraxella ovis

17
Q

Moraxella bovis shape, aerobe status, gram

A
  • Diplococcus, aerobic, Gram negative
18
Q

disease caused by Moraxella bovis

A
  • Infectious bovine keratoconjunctivitis (IBK, pinkeye)
  • Conjunctivitis → keratitis →ulceration → blindness
  • Animals don’t eat well; welfare and production issues $$$
19
Q

moraxella spp. assoc with pink eye

A

Moraxella bovis
Moraxella bovoculi
Moraxella ovis

20
Q

Moraxella bovis virulence factors

A

Virulence factors:
* RTX haemolysin
* fibrinolysin
* hyaluronidase
* fimbriae (adherence)

21
Q

Moraxella bovis: clinical signs

A

pink eye
corneal ulcer
corneal edema
tearing and blepharospasm

22
Q

Moraxella bovis: treatment, control and prevention

A

Animals carry bacterium in conjunctiva; spread by flies and direct contact from carrier cows
* Control: early diagnosis and treatment with antibiotics (topical); fly control with e.g., insecticide impregnated ear tags
* Prevent predisposing factors: cutting tall grasses; preventing viral infections, avoid dust and ammonia, etc.

23
Q

Pseudomonas aeroginosa gram, air, environment

A
  • Gram negative, strict aerobe, ubiquitous in water and soil
24
Q

Pseudomonas aeruginosa: what kind of pathogen, host, disease

A
  • Opportunistic pathogen with broad host range (plants to
    mammals)→Immunocompromised hosts, burn patients
    • Usually superficial, rarely systemic
25
Q

Pseudomonas aeruginosa virulence factors

A

– Alginate (slime), Elastases, Hyaluronidases
Collagenases, Haemolysins, Exotoxin A

26
Q

should we do susceptibility testing with Pseudomonas aeruginosa?

A

Resistant to many antibiotics and disinfectants→ESKAPE
- Antimicrobial susceptibility testing recommended

27
Q

Pseudomonas aeruginosa Disease in different species

A

Dogs:
Otitis externa; corneal ulcers; wounds, catheter (biofilm)

Horses:
Corneal ulcers; infectious metritis?

Cattle:
Nosocomial mastitis

Sheep:
Fleece rot (rainfall)

Humans:
Corneal ulcers; burn infections; cystic fibrosis

28
Q

Pseudomonas aeruginosa Disease in dogs

A

P. aeruginosa is one of the leading causes of otitis externa in dogs
-can see purulent discharge

29
Q

Pseudomonas aeruginosa Disease in horse

A

P. aeruginosa is a common (~20%) cause of corneal ulcers in the horse

30
Q

Bartonella henselae gram, air, shape

A
  • Gram-negative aerobic coccobacilli
31
Q

Bartonella henselae causes what in humans? other hosts?

A
  • Causes bartonellosis in humans (cat scratch fever)
  • Bacteremia in hosts (e.g. cats)
32
Q

what type of pathogen is Bartonella henselae? where is it found?

A
  • Intracellular pathogen
    – Localize usually RBC, can affect vascular endothelium
    – Since capillaries are found in all tissues, all tissues are susceptible to the inflammatory effects of Bartonella
33
Q

what are the characteristics of Feline bartonellosis? can it have an effect on dogs?

A

self-limiting, transient, febrile illness
* Lasts ~ 48-72 hours
* Rare clinical signs: fever, vomiting, lethargy, red eyes, swollen lymph nodes, and/or decreased appetite
* More common in feral cats, especially kittens

  • Dogs may also present with a wide range of clinical and pathologic abnormalities: fever, endocarditis and myocarditis, granulomatous lymphadenitis, cardiac arrhythmias, granulomatous rhinitis, and epistaxis
34
Q

are cats infected with bartonella henselae able to clear the infection easily? how do they get infected?

A

get infected from flea, often
-most infected cats remain infected for year sor for life

35
Q

human signs of cat scratch fever

A

swollen lymph nodes, bacillary angiomatosis if immunocompromised

36
Q

Bartonella henselae prevention/cure

A
  • “Basic hygiene and flea control”
  • Sensitive to antibiotics that penetrate host cells well e.g., tetracyclines, fluoroquinolones, but….
    – Response to antibiotic treatment is poor; resolves within a few weeks or months so healthy individuals not treated
    – Treatment of infected cats is ineffective; recurs
37
Q

Bartonella henselae diagnostics

A
  • Diagnostics:
    – PCR from blood samples (cats and dogs) – Serology (IFA) (cats and dogs)
38
Q

Acinetobacter spp. type of pathogen, resistances, concerns

A
  • Low grade opportunistic pathogen,
    commensal or environmental organism
  • Naturally resistant to most antimicrobials
  • Acquires resistance genes promiscuously
  • A in the ESKAPE organisms (multidrug resistant hospital-associated pathogens)
  • Emerged as an important nosocomial pathogen in recent years (soldiers returning from Iraq and Afghanistan)
39
Q

What is the clinical relevance of Acinetobacter in animal health?

A

-A. baumannii was the most common species and was significantly associated with systemic infections; deserves attention in clinical practice

-A. baumannii from dogs were more likely to present multidrug resistant phenotypes, highlighting the presence of resistant Acinetobacter in the human environment

Bacteriology (15 decks)

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