5.8 Gram negative aerobic rods Flashcards
Brucella spp. characteristics: gram, shape, stain, environment, nutrition, where they are found
- 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
important brucella spp.
abortus, suis, canis
brucella abortus effects, environmental survival, transmission
- 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
Brucella abortus: pathogenesis
- 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
brucella abortus life cycle
-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
brucella abortus clinical presentation
-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
Zoonotic potential of brucella abortus: transmission and primary victims
- 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
Distribution of Brucella abortus
mostly africa, southwest asia, southern europe, south america
Eradication of bovine brucellosis
- 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
Brucella abortus surveillance
- 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
Brucella suis: where is it found, is it screened, symptoms and species affected
- 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
brucella suis diagnosis
- Diagnosis: serology (Rose-Bengal plate agglutination, ELISA) → culture/PCR
Brucella canis: where is it found, what disease does it cause?
- 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
typical signs of brucella canis in dogs
-reproductive problems such as infertility and abortions with few other signs of clinical illness
-abortion
musculoskeletal issue that can be caused by brucella canis
-Brucella discospondylitis
important Moraxella spp.
Moraxella bovis
Moraxella bovoculi
Moraxella ovis
Moraxella bovis shape, aerobe status, gram
- Diplococcus, aerobic, Gram negative
disease caused by Moraxella bovis
- Infectious bovine keratoconjunctivitis (IBK, pinkeye)
- Conjunctivitis → keratitis →ulceration → blindness
- Animals don’t eat well; welfare and production issues $$$
moraxella spp. assoc with pink eye
Moraxella bovis
Moraxella bovoculi
Moraxella ovis
Moraxella bovis virulence factors
Virulence factors:
* RTX haemolysin
* fibrinolysin
* hyaluronidase
* fimbriae (adherence)
Moraxella bovis: clinical signs
pink eye
corneal ulcer
corneal edema
tearing and blepharospasm
Moraxella bovis: treatment, control and prevention
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.
Pseudomonas aeroginosa gram, air, environment
- Gram negative, strict aerobe, ubiquitous in water and soil
Pseudomonas aeruginosa: what kind of pathogen, host, disease
- Opportunistic pathogen with broad host range (plants to
mammals)→Immunocompromised hosts, burn patients- Usually superficial, rarely systemic
Pseudomonas aeruginosa virulence factors
– Alginate (slime), Elastases, Hyaluronidases
Collagenases, Haemolysins, Exotoxin A
should we do susceptibility testing with Pseudomonas aeruginosa?
Resistant to many antibiotics and disinfectants→ESKAPE
- Antimicrobial susceptibility testing recommended
Pseudomonas aeruginosa Disease in different species
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
Pseudomonas aeruginosa Disease in dogs
P. aeruginosa is one of the leading causes of otitis externa in dogs
-can see purulent discharge
Pseudomonas aeruginosa Disease in horse
P. aeruginosa is a common (~20%) cause of corneal ulcers in the horse
Bartonella henselae gram, air, shape
- Gram-negative aerobic coccobacilli
Bartonella henselae causes what in humans? other hosts?
- Causes bartonellosis in humans (cat scratch fever)
- Bacteremia in hosts (e.g. cats)
what type of pathogen is Bartonella henselae? where is it found?
- 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
what are the characteristics of Feline bartonellosis? can it have an effect on dogs?
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
are cats infected with bartonella henselae able to clear the infection easily? how do they get infected?
get infected from flea, often
-most infected cats remain infected for year sor for life
human signs of cat scratch fever
swollen lymph nodes, bacillary angiomatosis if immunocompromised
Bartonella henselae prevention/cure
- “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
Bartonella henselae diagnostics
- Diagnostics:
– PCR from blood samples (cats and dogs) – Serology (IFA) (cats and dogs)
Acinetobacter spp. type of pathogen, resistances, concerns
- 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)
What is the clinical relevance of Acinetobacter in animal health?
-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
