Key Terminology & Definitions - Bacteria & Fungi

Question 1

Mycobacteria

Answer 1

Nonmotile, non spore-forming, aerobic or microaerophilic pleomorphic coccobacilli, gram positive but are hard to stain due to abundant lipid

Question 2

Mycobacterium avium

Answer 2

Most commonly causes mycobacteriosis in birds, but sometimes cattle, pigs, horses, sheep, primates

Question 3

Mycobacterium tuberculosis

Answer 3

Mostly seen in humans but sometimes pigs, primates, dogs, cats, cattle, psittacine birds

Question 4

Mycobacterium bovis

Answer 4

Persists in soil, can remain infective for weeks - high doses needed for oral transmission so environmental contamination is not an important means of transmission

Question 5

Tuberculoid granuloma

Answer 5

Dynamic structure, prevents spread to other sites + hosts, cell-mediated response kills infected macrophages + forms caseous centre, bacteria in granulomas can remain dormant for long periods until something disturbs immune response

Question 6

Tubercle

Answer 6

Classic gross lesion, circumscribed, often encapsulated, pale, yellow-white nodule, granulomatous inflammation and central caseous necrosis +/- mineral, large ones can liquefy and resemble abscesses, fibrosis inc w/ time + more forms in animals w/ greater resistance

Question 7

Purified protein derivatives

Answer 7

Can produce delayed type IV hypersensitivity reactions in a sensitised animal (used in intradermal skin tests) to detect mycobacterium bovis

Question 8

Mycoplasma sp.

Answer 8

Smallest self-replicating organisms, small genome, no cell wall , protein and lipid-rich plasma membrane, variation in surface antigens allows evasion of immune response, refractory to many antibiotics, obligate parasites with specific host and tissue tropisms, don’t survive in environment for lone, need close contact to spread

Question 9

Enzootic

Answer 9

Low level of disease, constantly present in a population

Question 10

Mycoplasma hyopneumoniae

Answer 10

Common, chronic, non-fatal disease of young pigs (grower-finishers), high morbidity + low mortality, usually non-productive coughing, poor growth + feed conversion, adheres to cilia, causes loss of cilia (+ 2^y effects), can predispose to fatal multifactorial pneumonia, plays role in porcine respiratory complex

Question 11

PRRS

Answer 11

Porcine reproductive and respiratory syndrome (arterivirus)

Question 12

Mycoplasma bovis

Answer 12

Carried and shed in secretions of respiratory, genital tracts and mammary glands, infection via direct contact with nasal secretions/milk in calves, high morbidity, low mortality, enzootic pneumonia of young calves, chronic pneumonia + polyarthritis in feedlot beef cattle, plays roles within bovine respiratory complex

Question 13

Mycoplasma mycoides ssp. mycoides SC

Answer 13

Contagious bovine pleuropneumonia (CBPP), notifiable disease, small colony type, endemic to Africa (low incidence due to vaccine campaigns), variable clinical signs, morbidity + mortality, adults more susceptible than young, virulence also affected by strain, predisposing factors e.g. crowding, stress co-infection, virulence dec during outbreaks as is spreads through animals

Question 14

Organising centres

Answer 14

Changes in interlobular septa, medial proliferation, look like vasculitis, blood vessel surrounded by proliferation of connective and inflammatory cells bounded by a peripheral zone of necrotic cells

Question 15

Type I organising centres

Answer 15

More proliferative cells (inflammatory) in central zone

Question 16

Type II organising centres

Answer 16

Proliferative cells are scarce and peripheral zone is relatively larger (immune system overwhelmed)

Question 17

Mycoplasma ovipneumoniae

Answer 17

Atypical non-progessive chronic pneumonia, chronic, non-fatal disease in sheep and goats, affects all ages, usually young < 6 m/o, multifactorial disease triggered by stress, crowding, poor air quality, or host, reduced growth, chronic soft cough, nasal discharge, animals recover if management improved, lesions persist at least 7 months after recovery

Question 18

Mycoplasma caprricolum spp. capripneumoniae

Answer 18

Contagious caprine pleuropneumonia, notifiable disease, goats, endemic to Africa, Middle East, India, high morbidity + mortality, lethargy, dyspnoea, fever, coughing, polyarthritis in young goats

Question 19

Agalactia

Answer 19

An absence or failure of the secretion of milk

Question 20

Mycoplasma agalactiae

Answer 20

Notifiable disease, can cause respiratory signs, contagious agalactia, adults = mastitis, agalactia, +/- arthritis, keratitis, youngstock = pneumonia, pleuropneumonia, chronic bronchopneumonia, fibrinosuppurative, polyarthritis, septicaemia

Question 21

Mycoplasma equirhinis

Answer 21

Can rarely cause clinical signs in sports horses

Question 22

Mycoplasma cynos

Answer 22

Most pathogenic part of multifactorial shelter respiratory disease

Question 23

Feline mycoplasmas

Answer 23

M, felis, M. gatiae, M. arginini, may contribute to more complex disease

Question 24

Aspergillus fumigatus

Answer 24

Ubiquitous environmental fungus, factors predisposing to disease following inhalation unclear

Question 25

Exopthalmos

Answer 25

Inflammation behind eyes associated w/ infection in sinuses/nose -> pushes eye forward

Question 26

Mycotic rhinitis

Answer 26

Mostly Aspergillus fumigatus, can distort nasal bones, extend into adjacent tissues causes

Question 27

Pulmonary aspergillosis

Answer 27

Uncommon, usually haematogenous spread drom colitis (embolic), look for septate branching hyphae at lesion edges

Question 28

Blastomyces dermatidis

Answer 28

Thermally dimorphic fungus - infectious, non-contagious disease of dogs and humans, primarily in North America, dimorphic fungus, grows as a mould in environment and yeast at body temp (once inhaled), likes acidic sandy soil especially if recently disturbed (fungi)

Question 29

Cryptococcosis

Answer 29

Most common systemic mycosis of cats (+ dogs, horses, cattle, humans), sporadic, non-contagious disease, often causes chronic nasal disease, may cause ulcerative skin lesions, ocular disease, pneumonia, brain lesions, ascending mastitis in cows, filamentous form in environment, once spores inhaled they disseminate haematogenously

Question 30

Cryptococcus neoformans

Answer 30

Temperate climates, found in soil + bird droppings, most common in dogs, usually requires immunosuppression for lesions

Question 31

Cryptococcus gattii

Answer 31

Most common in cats, causes disease in immunocompetent animals

Question 32

Coccidioidomycosis (Valley Fever)

Answer 32

Coccidiodes immitis or Coccidiosis posadasii - infect all mammals, dogs most common, endemic to SW US, central and South America, dimorphic fungus, mould like hot, dry conditions, infection by inhaling spores, infection more common than disease, respiratory distress, draining skin, nodules (cats)

Question 33

Pneumocystis carinii

Answer 33

Sporadic disease of pigs, foals, dogs, usually requires immunosuppression, attaches to type I pneumocytes via cell wall glycoprotein A, cell-mediated immune response important to control, two forms (uninucleate trophic form, binary fission and thick-walled, multinucleate form, sexually) (fungi)

Question 34

Entomopthoromycosis

Answer 34

Chronic nasal or cutaneous disease of horses, sheep, rarely cattle, all saprophytic (live in environment) fungi of tropical and subtropical climates, lesions most commonly in nostrils can form obstructive and invasive masses, sheep - ethmoid conchae most affected, ulcerating, cavitating granulomas with coral-shaped granules (fungi)

Question 35

Dichotomous branching

Answer 35

Forking at 45 degree angles

Question 36

Conidium

Answer 36

Type of asexual reproductive spore of fungi (kingdom Fungi) usually produced at the tip or side of hyphae

Question 37

Sporangia

Answer 37

Capsule structure - where reproductive spores are produced and stored

Question 38

Endosporulation

Answer 38

Rupture of sporangia, released endospore to start a new cycle

Question 39

Oomycete

Answer 39

Fungal-like organisms phylogenetically related to algae

Question 40

Pythium insidiosum

Answer 40

Produces similar lesions to Entomopthoromycosis, aquatic, fungus-like oomycete in horses, cattle, sheep, lots of eosinophils, thick-walled hyphae, infrequently septate (clinical finding = entomophthoromycosis, needs to be cultured/PCT or IHC to tell apart from entomophoromycosis - will have less hyphae, causes Swamp cancer syndrome

Question 41

Rhinosporidium seeberi

Answer 41

Not really a fungus - an aquatic protist parasite, mostly humans and dogs, mostly wet tropical environments, infection via exposure to contaminated water, lesions = unilateral soft, pink nasal polys, bleed easily

Question 42

Mortierella wolfi

Answer 42

In cows, acute fatal mycotic pneumonia secondary to placental infection, fibrinonecrotic pneumonia within a few days of parturition or abortion, due to haematogenous spread as the placenta detaches (embolic pattern in lungs), rare outside New Zealand (fungi)

Question 43

Emmonsia sp.

Answer 43

Adiasporomycosis, mostly wild rodents but sometimes domestic animals, dimorphic fungus related to blastomycosis, granulomatous lesions in lungs, sometimes lymph nodes, diagnosed by finding large (300 μm), spherical, uninucleate adiaspores, thick PAS-positive wall (magenta satining), does not endosporulate

Question 44

Histoplasma capsulatum

Answer 44

Fungi, causes pulmonary lesions, found in contaminated soil

Question 45

Mucor and Rhizopus sp.

Answer 45

Fungi that can be opportunists in cows, caseous necrosis or granulomatous inflammation