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190 Cards in this Set

  • Front
  • Back
• Acidfast rods, sometimes branching filaments but
easily fragmented, irregular staining (beaded).
Mycobacterium
• Cell walls are rich in lipids, waxes.
– Slow growth rate (2-20 hour generation time).
– Resistant to drying, some disinfectants.
– Retain viability in soil and dried feces for many months.
– Killed by sunlight, UV irradiation, and pasteurization.
Mycobacterium
• Reservoir for pathogenic, tuberculous
mycobacteria is _________________.
• Reservoir for pathogenic, tuberculous
mycobacteria is infected animals (parasitic).
• Saprophytic (atypical) mycobacteria are
widespread in __________________.
• Saprophytic (atypical) mycobacteria are
widespread in soil and water (opportunistic).
• Tuberculosis:
• Tuberculosis: an infectious, granulomatous
disease causing tubercles.
– Typically a disease of captivity or domestication,
confining and crowding.
• Pathogenesis of tuberculosis.
• Pathogenesis of tuberculosis.
– Entry via respiratory and intestinal tracts.
– Local multiplication occurs, resistance to phagocytic
killing allows continued intracellular replication.
– Infected cells reach local lymph nodes and may
disseminate.
– Inflammatory and cell-mediated immune reactions
cause accumulation of macrophages (granuloma).
– Caseous necrosis occurs at the center of the lesion and
may proceed to calcification or liquefaction.
– Hematogenous dissemination may produce miliary
tuberculosis, involving multiple tubercle formation.
– Tubercles may enlarge, coalesce and eventually occupy
a sizable portion of the organs.
• Tubercle:
• Tubercle: granuloma with a caseous, necrotic
center that may calcify, may become surrounded
by granulation tissue and a fibrous capsule.
when in capsule not contagious
– Humans are primary host.
– Shed primarily in respiratory discharges.
– Transmitted by aerosols or fomites.
– Lesion found in the lungs and lymph nodes.
• Mycobacterium tuberculosis
Mycobacterium tuberculosis:
Progressive; Limited; Resistant animals
Progressive:primates, dogs, elephants, Canaries, and
Psittacine birds
Limited:cattle and swine
Resistant:birds and cats
– Cattle are the natural host.
– Wild animal reservoirs of agent include badgers in
Europe, brush-tailed opossums in New Zealand, Cape
buffalo in Africa, deer in Europe and North America.
– Excreted in respiratory discharges, feces, milk, urine
and semen.
• Mycobacterium bovis
• Mycobacterium bovis vaccination and treatment/control
– No viable vaccine for use in animals.
– Poorly responsive to treatment, test and eradication.
• Intradermal tuberculin skin test.
– Detect DTH response acquired through infection using
tuberculin or PPD (purified protein derivative).
• Mycobacterium bovis Progressive, Limited, and Resistant animals
Progressive:cattle, sheep, goats,Primates
Deer, elk, bison
Dogs, cats, swine
Llamas, badgers, opossum
Elephants, rhinoceri
Camels,and giraffes
limited:?
Resistant:birds
Current M. bovis concerns
• Michigan White-tailed deer
and other wildlife.
– California, Texas, and New
Mexico.
– 7 black bear, 4 bobcats, 18
coyotes, 2 opossums, 8
raccoons, and 3 red fox,
found to be infected with the
bovine TB organism. The
most likely source of infection
for these animals was
through the consumption of
tuberculous white-tailed deer.
• UK: Badger reservoir, spill-back into cattle.
• New Zealand: Brush-tailed opossums.
• Kruger National Park: infected buffalo with spillover
into predators and other wildlife.
– Poultry are the primary hosts.
– Shed in feces.
– Acquired mainly by ingestion of contaminated food,
water and soil.
– Lesions may be found anywhere, but in birds usually
involve intestines, liver, spleen, and bone marrow.
– Lung lesions are infrequent.
– Some serotypes in environment are opportunistic rather
than contagious diseases.
• Mycobacterium avium
Mycobacterium avium
Progressive, Limited, and Resistant animals
progressive:chickens and other birds
limited: cattle, sheep, goats,Primates
Dogs, cats, Swine, Deer, elk, and bison
Resistant:Psittacines
• Johne’s disease agent
Mycobacterium avium ssp.
paratuberculosis
– Chronic, progressive enteritis characterized by
persistent and progressive diarrhea, weight loss,
debilitation, and eventually death.
– Disease of cattle, sheep, goats and other herbivores.
Mycobacterium avium ssp.
paratuberculosis
• Large numbers of mycobacteria are present in
epithelioid and giant cells in the mucosa of ileum
and colon.
• Mucosa becomes thickened and permanently
corrugated.
Mycobacterium avium ssp.
paratuberculosis
– Chronic, progressive enteritis characterized by
persistent and progressive diarrhea, weight loss,
debilitation, and eventually death.
• Organisms shed in feces, contaminate
environment, transmit primarily to young stock.
Mycobacterium avium ssp.
paratuberculosis
Family:______________
• Smallest and simplest procaryotes.
– Range in size from 0.2 to 0.5 μm.
– Lack genetic ability to form a cell wall, pleomorphic.
• Stain very poorly: lack cell wall and too small to observe.
Family: Mycoplasmataceae
• Mycoplasma, Ureaplasma, (Haemobartonella,
Eperythrozoon now included)
• Occur as commensals on mucous membranes of
the upper respiratory and digestive tracts, genital
tract and bovine udder or cell-associated (RBC).
– Facultatively anaerobic to obligately anaerobic.
– Complex growth requirements for cholesterol, purines,
pyrimidines, etc.
– Form fried-egg-shaped colony.
– Survive for a few days outside the host when protected.
Family: Mycoplasmataceae
• Infections can be endogenous or exogenous.
• Transmission by direct contact, aerosols, eggtransmitted.
• Cytoadherence to mucous membranes.
– Attachment organelle with network of adhesins.
Mycoplasma
• Intracellular localization.
– Potential to fuse with and enter host cells facilitates
latent or chronic infection.
• Cytotoxicity and inflammation.
– Biochemically mediated damage to adjacent host cells.
– Destroy cilia of cells in the respiratory tract.
– Induce cytokine synthesis with pathologic
consequences.
pathogenic mechanisms:
• Infection may be primarily involving body surfaces.
– Respiratory tract, conjunctiva, genital tract, mammary
gland.
• Septicemia
• Serosal surfaces: joints, body cavities.
• Most species have considerable host specificity.
Mycoplasma
– Induce cytokine synthesis with pathologic
consequences.
• Infection may be primarily involving body surfaces.
– Respiratory tract, conjunctiva, genital tract, mammary
gland.
• Septicemia
• Serosal surfaces: joints, body cavities.
• Most species have considerable host specificity.
Mycoplasma
Mycoplasma disease
in Cattle
– Pneumonia, mastitis, abortion.
– Also abortion, otitis media,
conjunctivitis, etc.
Mycoplasma disease
in sheep and goats causes
– Pneumonia, mastitis,
conjunctivitis.
Mycoplasma swine diseases
• Swine diseases

• Polyserositis, arthritis in young pigs.

• Arthritis in young and feeder pigs.

• Enzootic pneumonia.
Mycoplasma in dogs cause
Pneumonia, UTI.
Mycoplasma in rats
• Rats and mice, cats, horses, chickens, turkeys.
– Numerous species causing host specific infections.
– Feline infectious anemia, worldwide. agent
Mycoplasma haemofelis
– Varies from mild anemia without clinical signs to severe
anemia progressing to depression and death.
– Transmission via cat fights, biting arthropods, fleas,
ingestion, transplacental infection reported.
– Deep purple, small coccoid or rod-shaped (0.2 μm)
organisms on erythrocytes.
Mycoplasma haemofelis
– Restricted to dogs.
Varies from mild anemia without clinical signs to severe
anemia progressing to depression and death.
Mycoplasma haemocanis
– Porcine eperythrozoonosis in US.
– Transmitted by biting arthropods and instruments.
– Usually subclinical but occasionally icteroanemia,
embryonic death and abortion.
– Small coccal or ring-forms on erythrocytes.
– Other species (?) reported in several mammals.
• Mycoplasma (Eperythrozoon) suis
• Antimicrobial susceptibility of Mycoplasma family.
– Tetracyclines, chloramphenicol.
– Quinolones, macrolides, lincosamides.
– Anaerobes not susceptible to aminoglycosides.
– Resistant to all cell-wall active agents.
Order: Rickettsiales
• Families:
Rickettsiaceae and Anaplasmataceae
• Minute, obligate intracellular parasites of
eucaryotic hosts (vertebrates, arthropods and
other invertebrates).
– Transovarian and transstadial transmission.
– Transmission to mammals as a result of feeding by an
infected arthropod, etc.
• Rod-shaped, coccoid, pleomorphic.
• Poor survival outside of cells - direct transmission.
• Seasonal occurrence reflecting vector activity.
• Infectious, noncontagious diseases.
Order: Rickettsiales
• Organisms multiply by binary fission in the
cytoplasm (or nucleus) of target cells.
– Endothelium, phagocytic cells, or erythrocytes.
• Toxins: Phospholipase, hemolysins, endotoxin.
– Cell walls contain muramic acid (peptidoglycan).
Order: Rickettsiales
Order: Rickettsiales
• Diagnosis
– Molecular detection
– Serology
– Isolation and identification
Order: Rickettsiales host range,
• Vary from narrow to broad host range, including
some important zoonotic diseases.
Order: Rickettsiales treatment
• Tetracyclines (doxycycline), chloramphenicol,
quinolones.
– Rocky Mountain Spotted Fever, a disease of humans
and dogs, resulting in fever, edema, petechial and
ecchymotic hemorrhages, and neurological signs. agent:_______
Rickettsia rickettsii
fever, edema, petechial and
ecchymotic hemorrhages, and neurological signs.
– Most cases occur in the Eastern US, carried by
Dermacentor andersoni and D. variablilis, seasonal.
Rickettsia rickettsii
– Rocky Mountain Spotted Fever,
– Ticks become infected by horizontal transmission while
feeding, transtadially and vertically by transovarian
passage.
– Replicates in tick midgut, maintained in nature in ticks.
– Ticks attach minimum of 5-20 hours to transmit.
– Incubation period of 2-14 days, targets endothelial cells.
– Serology suggests that most canine infections go
undetected (subclinical).
Rickettsia rickettsii
– Rocky Mountain Spotted Fever,
cattle and other ruminants.
– Fever, anemia, icterus (acute to chronic, incubation up
to 5 weeks).
– Tropical and sub-tropical regions, worldwide.
• Anaplasma marginale
Family: Anaplasmataceae
Anaplasma, Ehrlichia, Neorickettsia
• Ticks, other arthropods, blood-sucking flying
insects, veterinary instruments.
• Infect erythrocytes with a marginal distribution,
small pleomorphic forms (0.2-0.4 μm) in up to 50%
of cells.cattle and other ruminants
Anaplasma marginale,
Ehrlichia: type of infections
– Monocytic or granulocytic infections.
worldwide.
– Reservoir: Canids.
– Brown dog tick (Rhipicephalus sanguineus) is vector.
• Transstadial but not transovarian transmission.
Ehrlichia canis
– Canine monocytic ehrlichiosis
dogs.
Replicates in lymphocytes, monocytes and, rarely, in
neutrophils; vasculitis, thrombocytopenia, leukopenia
and anemia.
– Purple-staining cells or inclusions (morulae) in
monocytes or lymphocytes.
– No vaccine, tick control necessary.
Ehrlichia canis
• Heartwater in domestic and wild ruminants in
Africa and Caribbean.
– Widespread edema, effusions, hemorrhage, pericardial
effusion is inconsistent.
Ehrlichia (Cowdria) ruminantium
– Infects reticular cells, neutrophils, and vascular
endothelial cells, short bacillary forms in cytoplasm.
cattle
• Amblyomma ticks serve as vector.
Ehrlichia (Cowdria) ruminantium
Ehrlichia (Cowdria) ruminantium
• Heartwater in domestic and wild ruminants
• A single isolate from lung, liver, and other tissues
of an aborted bovine fetus isolated in Washington,
1986. Now classified as __________________,
and considered to belong to Chlamydiales.
Ehrlichia (Cowdria) ruminantium
• Heartwater in domestic and wild ruminants
• A single isolate from lung, liver, and other tissues
of an aborted bovine fetus isolated in Washington,
1986. Now classified as Waddlia chondrophila,
and considered to belong to Chlamydiales.
Salmon poisoning in dogs,
coyotes, foxes, bears and
ferrets in Pacific northwest
of US.
Neorickettsia helminthoeca
– Elokomin fluke fever agent is
a milder variant.
• Ingestion of salmon
containing the agent within
the metacercariae of
Nanophyetus salmincola.
– Mature fluke inoculates
agent, 5-7 day incubation.
Neorickettsia helminthoeca
• Parasitizes reticuloendothelial cells of the
lymphoid system, including macrophages.
– Fever, swollen lymph nodes, hemorrhagic enteritis
– Morulae and individual coccal cells in cytoplasm of
macrophages.
• Freeze fish (-20C, 24 hr) or thoroughly cook.
Neorickettsia helminthoeca
• Potomac horse fever in USA (1979) and Europe.
• Equine monocytic ehrlichiosis.
– Fever, leukopenia, usually diarrhea, may progress to
laminitis.
• Present in monocytes, intestinal involvement.
– Morulae in monocytes.
• Transmission: oral ingestion, shed in feces.
• Reservoir?
Neorickettsia (Ehrlichia) risticii
• Seasonal oral ingestion; agent in fresh-water
snails or insects infested with developmental
stages (cercaria or metacercaria) of trematodes.
Neorickettsia (Ehrlichia) risticii
Reservoir of N. risticii
• Insectivorous bats and birds.
– Northern California bats and swallows serve as host for
adult trematodes (Acanthatrium or Lecithodendrium
sp.).
– N. risticii DNA identified by PCR in:
• All stages of life cycle of trematodes (snails, aquatic insects).
• Adult flukes and gastrointestinal tract of insectivores.
• Spleen of bats, liver of swallow.
• Bats and swallows may serve as natural reservoir.
• Seasonal oral ingestion; agent in fresh-water
snails or insects infested with developmental
stages (cercaria or metacercaria) of trematodes.
• Accidental ingestion of snails or insects, feed or
water contaminated with secretions, feces.
– Standing in water with cercaria.
• 100 year history in Uraguay and Southern Brazil.
– Churrío or churrido equino (equine scours).
• Many different strains – some not cross protective
in vaccines.
Neorickettsia (Ehrlichia) risticii
• Q fever in humans: cattle, goats and sheep are
most important reservoirs.
• Worldwide: reported in 125 mammals, birds, fish and 40 ticks.
• Cats and dogs may be reservoirs.
Coxiella burnetii
• Asymptomatic infection, acute influenza-like
illness, chronic endocarditis or hepatitis.
• Occasional abortions, weak offspring or infertility in ruminants
(placentitis and abortion reported in cats).
• Found in milk, urine, feces, birth fluids, placenta, and dust.
• 27 cases during pregnancy: only 5 healthy infants full-term.
• Aerosol (inhalation) transmission, ingestion,
spread by wind, contact with infected animals,
ticks or amoebae, laboratory accidents.
Coxiella burnetii
• Replication in alveolar macrophages; endothelium,
respiratory, renal and serosal epithelium;
fibroblasts.
• Short rods within cells.
Coxiella burnetii
Coxiella burnetii
Biphasic developmental cycle
• Small cell variants (SCV) – 0.2 to 0.5 um.
• Large cell variants (LCV) – > 1.0 um.
• Differences in ultrastructure, antigenicity,
metabolic capability, physical resistance and
protein composition.
• Infective aerosol dose: 1-10 organisms.
• Incubation period: 10-40 days.
• Clinical features:
• Case-fatality rate is low, even without treatment.
• Abrupt or insidious onset: fever, chills, headache,
• Malaise and fatigue lasting for months in up 32% of patients.
Coxiella burnetii
Coxiella burnetii
• Viability and disinfection:
• Increased resistance to heat, dessication, osmotic shock, UV
light, and chemicals (hypochlorite 0.5%, phenolics, lysol, etc.)
• 2% bleach, 30 minute contact with 70% alcohol, quaternary
ammonium disinfectants.
• Obligately parasitic, coccoid bacteria, multiply
within membrane-bound vacuoles in the cytoplasm
of cells of mammalian and avian origin.
• Modified cell wall - glycolipids and protein, familyspecific
LPS.
• Elementary body (EB) is the infectious,
metabolically inactive, extracellular form (200-300
Chlamydia and Chlamydophila
• Relatively resistant, viable for several days.
• Attaches to cell, enters by endocytosis, survives in phagosome.
• Differentiates into RB.
• Reticulate body is the metabolically active,
noninfectious, intracellular form (500-1000 nm).
• Multiplies by binary fission, condense and mature in inclusions.
• After 40 hrs., cause lysis of cells and release of EB’s.
Chlamydia and Chlamydophila
• Persist as subclinical
infections of the respiratory,
gastrointestinal, and genital
tract of birds and mammals.
– Carriers provide prolonged
fecal shedding.
– Transmission by inhalation or
ingestion.
Chlamydia and Chlamydophila
• Infect a broad range of avian and mammalian hosts.
– Disease associations, tissue tropisms, hosts by species.
– Pneumonia, abortion, rhinitis, conjunctivitis, arthritis,
enteritis, no apparent disease (carrier = asymptomatic
infection or nonpathogenic strain).
– Zoonotic infections; but humans have their own endemic
species.
• Conjunctivitis, STD, atherosclerosis, respiratory disease,
Alzheimer’s, arthritis, etc.
Chlamydia and Chlamydophila
Avian chlamydiosis:
Chlamydophila (Chlamydia) psittaci
• Avian chlamydiosis: An acute or chronic infection
of wild and domestic birds causing respiratory,
intestinal, systemic signs, or asymptomic.
An acute or chronic infection
of wild and domestic birds causing respiratory,
intestinal, systemic signs, or asymptomic.
• Entry: pharynx, eye, genital. Bacteremia, infects
brain, eye, genital, intestine, liver, lung, spleen and
kidneys. Transmitted in feces, aerosols, eggs.
Chlamydophila (Chlamydia) psittaci
• 8 serovars, all transmissible to humans.
– Psittacosis: Sporadic disease in humans, other
mammals, and tortoises.
– Ornithosis (pigeons and turkeys).
– Occupational hazards in bird slaughterhouses, other
birds, mammals, worldwide.
• Not associated with abortions, feline infections.
Chlamydophila (Chlamydia) psittaci
• Abortion - Sheep, goats, cattle.
– Enzootic abortion of ewes (EAE), worldwide.
Chlamydophila abortus
• Oral, nasal, genital entry, bacteremic spread.
– Placental colonization, fetal tissues, intestine.
• Women who work with sheep have suffered
sporadic, documented cases of zoonotic abortion.
• Rare cases of abortion in a horse, a rabbit, guinea
pigs, mice, and pigs.
• A distinctive serotype.
Chlamydophila abortus
• Endemic among cats worldwide
• Conjunctivitis, rhinitis, and respiratory problems.
– Also infects genital tissues and joints.
• Asymptomatic persistence not documented.
• Zoonotic infections of humans reported.
• Attenuated live vaccine marketed for cats.
Chlamydophila felis
• Predilection for epithelial cells of mucous
membranes.
• Latent, inactive infections cause persistent
antigenic stimulation leading to chronic
inflammation.
• Diagnosis
– Molecular detection
– Serology
– Isolation and identification
Chlamydiosis
Chlamydiosis Antimicrobial susceptibility:
Antimicrobial susceptibility: Tetracyclines
(doxycycline) and chloramphenicol.
Fungi
• Nonphotosynthetic.
– Live on ______________ in soil, water, on
plants and animals (usually dead and decaying matter).
– May have unique geographic distribution.
• Typical eukaryotic cell structure.
– Rigid cell wall of _________________________.
• Usually ________ or __________.
• ____________ in cell membrane: target of antifungals.
• Unique cell structure, function and differentiation
resulting in sexual and asexual reproduction.
– _____________ features are important identification keys.
Fungi
• Nonphotosynthetic.
– Live on complex organic nutrients in soil, water, on
plants and animals (usually dead and decaying matter).
– May have unique geographic distribution.
• Typical eukaryotic cell structure.
– Rigid cell wall of polysaccharide polymers.
• Usually chitin or cellulose.
• Ergosterol in cell membrane: target of antifungals.
• Unique cell structure, function and differentiation
resulting in sexual and asexual reproduction.
– Morphological features are important identification keys.
Fungi
• Three major morphological groups.
– Yeasts: ovoid, budding cells.
• Typically single-celled, thick cell wall, lacking mycelia, asexual.
– Molds: mass of branching, randomly interlaced
filamentous tubes (hyphae) filled with cytoplasm,
forming a woolly, fuzzy growth (mycelium).
• Hyphae may be septate or aseptate.
– Mushrooms: true fungi that consist of an organized
network of hyphae resulting in regular shaped mycelia.
Fungi • Asexual reproduction:
• Sexual reproduction:
• Asexual reproduction: budding, hyphal extension,
asexual spores (conidia), usual clinical form.
• Sexual reproduction: fusion of gametes,
subsequent division into spores (conidia).
Fungi
• Dimorphism:
a transient adaptation.
– Can grow as either molds or yeast depending on growth
conditions (temperature, nutrients, etc.).
– Drastic changes in metabolism, morphology, antigenic
structure, methods of reproduction
• Special staining/visualization methods for fungi.
– Lactophenol cotton blue stain
– Silver stain
– PAS (Periodic acid-Schiff) stain
– Negative staining
– Potassium hydroxide digest
• Classes or subdivisions of fungi.
– Zygomycetes (Phycomycetes): Aseptate fungi.
– Ascomycetes: Sexual reproductive form.
– Deuteromycetes (Fungi imperfecti): Asexual
reproductive form.
– Basidiomycetes: mushrooms.
Fungi Pragmatic clinical classification.
– Yeasts: those agents primarily observed in this form.
– Dermatophytes: parasitize keratinized structures.
– Dimorphic, systemic fungi.
– Miscellaneous, opportunistic fungi.
• Oval, thin-walled, small budding yeast cells.
• Normal inhabitant of alimentary tract and lower
reproductive tract of most mammals and birds.
• Infections are usually endogenous on mucous
membranes, depend on compromised defenses.
Candida albicans
– Young are especially susceptible.
– Prolonged antibacterial use may predispose.
– Immunocompromised are most susceptible, may
progress to disseminated form.
• Ulceration and fibrinous plaques on membranes.
– Thrush: oral candidiasis and crop mycosis.
Candida albicans
Candida albicans
• Virulence factors:
– Adhesins, secreted proteases and phospholipases, and
morphogenesis (reversible transition between yeast,
pseudohyphae and hyphae).
• Diagnostic characteristics:
– Small budding yeast, with occasional pseudohyphae.
Candida albicans
• Diagnostic characteristics:
– Readily isolated on routine bacteriological agars.
– Germ tube formation when incubated 2-4 hr. in serum.
• Filamentous extension from the yeast cell.
Candida albicans
• Saprophytic, round, yeast (3.5-7 μm) with ability to
form a large polysaccharide capsule (up to 30 μm).
• Worldwide distribution in soil, highest numbers in
pigeon droppings, inside shaded, damp buildings.
• Acquired by inhalation of small, reduced capsule,
environmental yeast -- NOT contagious.
Cryptococcus neoformans
– Deposits in upper respiratory tract or lodges in alveoli.
• Nasal granuloma, can extend locally to the CNS.
• Pulmonary granuloma, can disseminate hematogenously, often
to CNS.
• Antiphagocytic, immunosuppressive capsule elicits
limited inflammatory response.
Cryptococcus neoformans
Round yeast cell; single, pinched-off buds; capsule.
Cryptococcus neoformans
most common systemic
mycosis of cats.
Cryptococcus neoformans
cats – Nasal cavity (80%), pneumonic, meningitis, peripheral
neuritis of optic nerve, granulomatous chorioretinitis.
Cryptococcus neoformans
– Easily cultivated on agar plates.
– Antigen detection in serum, CSF or urine.
• Most mammals susceptible: dogs, horses, humans
• Agent may pass through digestive tract of birds
but rarely infects (inhibited above 39C).
Cryptococcus neoformans
• Aka Pityrosporum
• Saprophytic, lipophilic, monopolar yeasts that
colonize the skin and mucocutaneous regions.
• Frequent colonizer of external ear canal of dogs.
Malassezia pachydermatis
yeast
• Superficial perivascular to interstitial dermatitis
with hyperkerratosis, irregular hyperplasia of the
epidermis and follicular infundibula, epidermal
spongiosis, and lymphocyte exocytosis.
Malassezia pachydermatis
• Change in host immunity, altered skin
microclimate, or disruption in epithelial barrier may
predispose to clinical disease.
– Seborrheic reaction in skin allows the yeast to
proliferate.
Malassezia pachydermatis
• Direct exam: bottle-shaped, small budding cells.
– Bud fission, bud detaches by forming a septum.
Malassezia pachydermatis
• Keratinophilic species of fungi
Dermatophytes
– Able to penetrate all layers of the skin, but generally
restricted to the cornified nonliving keratin layer and
appendages: hair, nails (claws), horn, fur, rarely
feathers.
Dermatophytes
ringworm.
dermatophytosis
• Worldwide distribution as soil saprophytes that
have become highly host-adapted parasites.
– Geophilic still primarily inhabit soil.
– Zoophilic parasitize animals.
– Anthropophilic parasitize humans.
Dermatophytes
Dermatophytes
• Morphology
– Nonparasitic state, including culture, produce septate,
branching hyphae (mycelium) with asexual reproductive
units (either macroconidia or microconidia).
– Parasitic state produces only hyphae and arthroconidia.
Dermatophytes transmission and incubation period
• Transmitted from animals to animals, animals to
humans, humans to humans, humans to animals,
soil to either animals or humans by direct or
indirect contact.
– Conidia survive in hair, on scales and fomites for
months to years.
• Incubation period is usually 1 to 3 weeks.
• Endothrix =
• Endothrix = arthroconidia accumulation within hair (humans).
Dermatophytes
• Pathogenesis
– A _________ enters a defect in the stratum corneum.
– Germination requires _________ and ________ stimuli.
– Develops into __________ branching among cornified
epithelium.
– Portions of mycelium differentiate into _______________.
– Hair invasion begins with germination of a _________
near a follicular orifice.
• Extend along outer root sheaths and invade growing hairs near
the ___________________.
• Grow in outer parts with accumulation of _____________ on the
surface of the hair = ectothrix, characteristic of all significant
animal dermatophytes.
• Endothrix = _____________________________
– Hypertrophy of the _______________ with accelerated
keratinization and exfoliation, producing a scurfy
appearance.
– Infected hair become ___________________.
– Inflammation in area of infection ranges from ________
to _______________ reactions and suppuration.
• Antifungal activity of __________ and ______________ terminates infection.
– Infection may spread beyond area of inflammation,
resulting in ______ of advancing lesion with resolution in
the center = ____________.
Dermatophytes
• Pathogenesis
– A conidium enters a defect in the stratum corneum.
– Germination requires moisture and chemical stimuli.
– Develops into mycelium branching among cornified
epithelium.
– Portions of mycelium differentiate into arthroconidia.
– Hair invasion begins with germination of a conidium
near a follicular orifice.
• Extend along outer root sheaths and invade growing hairs near
the living root cells.
• Grow in outer parts with accumulation of arthroconidia on the
surface of the hair = ectothrix, characteristic of all significant
animal dermatophytes.
• Endothrix = arthroconidia accumulation within hair (humans).
– Hypertrophy of the stratum corneum with accelerated
keratinization and exfoliation, producing a scurfy
appearance.
– Infected hair become brittle and weak, breaks-off.
– Inflammation in area of infection ranges from erythema
to vesiculopustular reactions and suppuration.
• Antifungal activity of serum and body fluids terminates infection.
– Infection may spread beyond area of inflammation,
resulting in “ring” of advancing lesion with resolution in
the center = “ringworm”.
Dermatophytes
• _________ animals are predisposed to infection.
– Lack _____________, skin habitat may differ.
Dermatophytes
• Young animals are predisposed to infection.
– Lack acquired immunity, skin habitat may differ.
Dermatophytes
• Laboratory diagnosis
– Specimen collection from periphery of lesion, pluck hair.
• Use toothbrush to sample asymptomatic animals.
– Wood’s lamp: M. canis may show fluorescence in hair.
– Direct microscopic examination following KOH digestion
for hyphae and arthroconidia.
– Culture using Dermatophyte Test Medium (DTM).
• Dermatophytes usually appear in 7-10 days, changing pH
indicator in agar to red, produce light colored cottony mycelium.
Genera of dermatophytes of veterinary importance
– Microsporum spp.
– Trichophyton spp.
• Macroconidia are few or absent. If present they are elongated
and cigar or pencil-shaped, thin and smooth walls, divided into
many cells by transverse septa.
• Microconidia usually numerous and borne singly along the
hyphae or in grape-like clusters.
Trichophyton spp
Macroconidia are large, thick-walled and divided into many cells
by transverse septa. Tend to be spindle or boat-shaped with
roughened surface.
• Microconidia are relatively few or absent. If present, they are
tear-shaped and borne singly on the hyphae.
Microsporum spp
Ringworm
– 90-98% of cases in cats; irregular patchy alopecia.
– 70% of cases in dogs; classic foci of alopecia with
follicular papules, scales, and crusts.
– Vaccine for treatment and prevention of lesion
development but not for prevention of infection.
• Microsporum canis
ringworm
• Geophilic, 20% of cases in dogs.
Microsporum gypseum
Dermatophyte
Cattle and sheep; discrete, scaling patches of hair loss
with crust formation, some become thickly crusted with
suppuration, winter problem.
Trichophyton verrucosum
Dermatophyte
– Horses; patches of alopecia,
erythema, scaling, and
crusting; “girth itch”.
• Trichophyton equinum
Dermatophytes in horses
• Trichophyton equinum
– Horses; patches of alopecia,
erythema, scaling, and
crusting; “girth itch”.
• Trichophyton
mentagrophytes
• Microsporum equinum
• Microsporum gypseum
Dermatophytes
Environmental control
– Thorough vacuuming and cleaning: no visible hair.
– Washing and disinfection: 1:10 household bleach
solution.
– Discard items that can’t be disinfected.
Systemic mycoses (_______________)
• Most are free-living in nature as ___________, may
have unique geographic or ecologic preferences.
• Entry: primarily by _________.
• Growth in tissues is primarily __________ phase;
nonparasitic growth as _________.
• Lesions tend to be ______________; inadequate
CMI allows dissemination to bone, skin, CNS, or
abdominal viscera.
• Shedding occurs, but very limited contagious risk.
• Diagnosis based on _________________
characteristics of parasitic form.
Systemic mycoses (Dimorphic fungi)
• Most are free-living in nature as saprophytes, may
have unique geographic or ecologic preferences.
• Entry: primarily by inhalation.
• Growth in tissues is primarily yeast phase;
nonparasitic growth as mycelium.
• Lesions tend to be pyogranulomatous; inadequate
CMI allows dissemination to bone, skin, CNS, or
abdominal viscera.
• Shedding occurs, but very limited contagious risk.
• Diagnosis based on unique morphologic
characteristics of parasitic form.
• Coccidioidomycosis, Desert fever, San Joaquin
Valley fever.
• Endemic in the Lower Sonoran Life zones.
– Southwestern US, Mexico, Central and South America.
– Sandy, alkaline soils, high environmental temperatures.
– Low annual rainfall, low elevation.
Coccidioides immitis and C. posadasii
• Grows as mycelium in soil, arthroconidia survive.
– After rainfall, it grows near surface.
– Soil disturbances and wind disseminate spores.
• Most cases occur as a result of residence or travel
in endemic area.
Coccidioides immitis and C. posadasii
• Arthroconidia (<10) inhaled, grow as yeast.
• Spherule undergoes repeated internal divisions to
become filled with endospores.
– Large (10-80 μm), round, double-walled structure.
• Each endospore has the potential to become a
new spherule.
Coccidioides immitis and C. posadasii
Coccidioides immitis and C. posadisii
• Most infections are _______________________________________________: cattle, humans, dogs, cats
• Inadequate ____ allows dissemination of
endospores: _______,_______,_______.
• Others susceptible: horses, llamas, ferrets, etc.
Coccidioides immitis and C. posadisii
• Most infections are inapparent and limited to lung
and hilar lymph nodes: cattle, humans, dogs, cats
• Inadequate CMI allows dissemination of
endospores: dogs, humans, cats.
• Others susceptible: horses, llamas, ferrets, etc.
Coccidioides immitis and C. posadisii
• Dissemination targets:
bones, eyes, heart and
pericardium, testes, brain, spinal cord, visceral
organs.
Coccidioides immitis and C. posadisii
• Diagnostic characteristics:
Yeast: large spherule containing endospores
– Large spherule containing endospores is conclusive.
– Serologic testing is diagnostic and prognostic.
– Do NOT attempt to cultivate.
• Produces highly infectious arthroconidia.
• Drainage contaminating bandages may provide suitable
environment for arthroconidia development.
• Arthroconidia in hyphae
• North American blastomycosis
Blastomyces dermatitidis
• Endemic in Mississippi, Missouri, and Ohio River
valleys, mid-Atlantic states, and the Canadian
provinces of Quebec, Manitoba, and Ontario.
– Sporadic cases observed in other areas.
• Saprophytic mycelium, probably in soil.
– Associated with sandy, acid soil and proximity to water.
Blastomyces dermatitidis
• Susceptible animals.
– Dog (10x humans), cat, horse, ferret, deer, bottlenosed
dolphin, sea lion.
• Acquired by inhalation of spores.
– Enter terminal airway, grow as yeast.
• After established in lungs, may disseminate.
– Skin, eyes, bones, lymph nodes, subcutaneous tissues.
Blastomyces dermatitidis
Blastomycosis
• After established in ______, may disseminate.
–______________________________.
Blastomycosis
• After established in lungs, may disseminate.
– Skin, eyes, bones, lymph nodes, subcutaneous tissues.
– Thick-walled, broad-based budding yeasts (5-20 μm).
– Usually a single bud.
Blastomyces dermatitidis
Blastomyces dermatitidis
• Laboratory diagnosis:
– Thick-walled, broad-based budding yeasts (5-20 μm).
– Serologic testing.
– Culture or PCR on tissue.
– Antigen detection in urine.
• Diagnostic test sensitivity for blastomycosis in canines.
Cytology _______ Budding yeast
Culture ____ [66-91%]
Serology (Antibody) ___ Diagnosed 6%
Cross-reacts
Antigen detection ____ in humans Cross-reacts
Cytology 71-94% Budding yeast
Culture 12%? [66-91%]
Serology (Antibody) 40-95% Diagnosed 6%
Cross-reacts
Antigen detection 93% in humans Cross-reacts
Blastomyces dermatitidis
• Avoid getting _________ when handling a dog with
blastomycosis.
– Accidental percutaneous inoculation results in _______________.
Blastomyces dermatitidis
• Avoid getting bitten when handling a dog with
blastomycosis.
– Accidental percutaneous inoculation results in localized
lesion without dissemination.
• Free-living mycelial stage in soil containing
nitrogen-rich organic matter such as bird and bat
excrement under moist, humid conditions.
Histoplasma capsulatum
• Histoplasmosis:
a chronic, noncontagious,
disseminated, granulomatous disease.
Histoplasma capsulatum region
• Mississippi, Ohio, and Missouri River valleys
Histoplasma capsulatum
• Endemic in central US:__________________________.
– ___________ and ________ regions of the world.
– Isolated from soil in __ states.
Histoplasma capsulatum
• Endemic in central US: Ohio, Mississippi, and
Missouri River valleys.
– Temperate and subtropical regions of the world.
– Isolated from soil in 31 states.
• Produces macroconidia and microconidia in soil.
– Microconidia inhaled into airways.
– Ingestion leading to primary GI disease???
• Microconidia converts to yeast in lung, reproduces
by budding.
• Phagocytized by cells with further intracellular
replication, disseminated by cellular transport.
Histoplasma capsulatum
Histoplasmosis
•diseases
Histoplasmosis
• Acute pulmonary disease.
– Severity correlates with exposure level.
• Granulomatous mediastinitis.
– Enlarged lymph nodes, cough and respiratory distress.
• Progressive disseminated histoplasmosis.
– Generalized disease of reticuloendothelial system (liver,
spleen, lymph nodes), bone marrow, eyes, intestine.
• Equine abortion.
– Placental and fetal infection only.
• Numerous organisms in tissue, contained within
mononuclear phagocytes.
– Single or multiple, small (2-4 μm) round yeast with a
light halo (staining artifact - not a capsule).
Histoplasma capsulatum
Histoplasmosis
• Laboratory diagnosis:
– Numerous organisms in tissue, contained within mononuclear
phagocytes.
• Single or multiple, small (2-4 μm) round yeast with a light halo (staining
artifact - not a capsule).
– Serologic testing.
– Culture on tissue.
– Antigen detection in urine.
• Diagnostic test sensitivity for disseminated histoplasmosis.
Cytology ______ Intracellular yeast
Culture _______
Serology (Antibody) ________ Cross-reacts
Antigen detection _______ Cross-reacts
Cytology 40-57% Intracellular yeast
Culture 82-90%
Serology (Antibody) 67-85% Cross-reacts
Antigen detection 80-95% Cross-reacts
• Infection has been described in many animals, but
is uncommon in all but dogs and cats.
– Most infections are subclinical in dogs, but those with
clinical signs usually have disseminated disease.
– Most infected cats have disseminated disease.
• Avoid high risks for infection: bat guano and
spelunking.
Histoplasma capsulatum
• Sporotrichosis:
an uncommon, sporadic,
chronic granulomatous disease affecting
mostly skin, subcutis, and lymphatics
caused by a dimorphic fungus
• Worldwide distribution, primarily in soils
that are rich in decaying organic matter.
– Also isolated from dead plant materials: rose
bush thorns, sphagnum moss, tree bark, hay
bales.
• Traumatic implantation through skin
results in development of
pyogranulomatous nodules that may
ulcerate and drain, ascend lymphatics
Sporothrix schenckii
• Sporotrichosis: an uncommon, sporadic,
chronic granulomatous disease affecting
mostly skin, subcutis, and lymphatics
caused by a dimorphic fungus.
Sporothrix schenckii
• Infection occurs in humans, horses, dogs and cats
– Also reported in many other species of animals.
• Dissemination is rare in all except
immunocompromised and cats.
– Copious numbers of organisms in tissues of cats.
Sporothrix schenckii
• In tissue, pleomorphic yeast is round, oval or
cigar-shaped and may be found intracellular or
extracellular.
– Very difficult to identify in all but feline tissues.
Sporothrix schenckii
Sporothrix schenckii zoonotic risk
.
Sporothrix schenckii
• Minimal zoonotic risk
except feline to human
transmission: use strict
hygiene, warn handlers.
Subcutaneous mycoses
• In addition to Sporothrix schenckii, 100’s of
species of ___________________ cause
opportunistic infection following ____________________.
– Most have very limited invasive, spread potential.
– May spread to regional lymph node.
• Produce chronic, disfiguring granulomas.
• Diagnosis: __________________________________.
• ___________ is frequently the most effective
treatment.
Subcutaneous mycoses
• In addition to Sporothrix schenckii, 100’s of
species of non-dimorphic molds cause
opportunistic infection following traumatic
implantation.
– Most have very limited invasive, spread potential.
– May spread to regional lymph node.
• Produce chronic, disfiguring granulomas.
• Diagnosis: biopsy to demonstrate broad, ribbonlike
hyphae invading tissue.
• Surgical excision is frequently the most effective
treatment.
• Class of fungi that form
aseptate hyphae and produce
spores in a sac-like structure
known as a sporangium.
• Most are soil organisms that
gain entrance by inhalation or
ingestion (moldy hay).
Zygomycetes
• Invade arterial vessels leading to thrombosis and
infarction, thromboembolic dissemination.
– Granulomatous inflammation in chronic cases.
– Abortion in ruminants due to placentitis and vasculitis.
• Two of the more common genera:
– Mucor and Rhizopus
Zygomycetes
• Ubiquitous saprophytic molds, opportunistic
pathogens depending on impaired,
overwhelmed, or bypassed host defenses.
• Septate hyphae, conidia radiating from
conidiophore.
Aspergillus sp.
• Septate hyphae, conidia radiating
from conidiophore.
– Mycelium in tissues.
– Conidiophore observed only in
aerated body cavities.
Aspergillus sp
Aspergillus sp.
• Several manifestations of
aspergillosis.
Aspergillus sp.
• Several manifestations of
aspergillosis.
– Diffuse infection of airways, air sacs
of birds.
– Sinus infections and disseminated disease in dogs.
– Guttural pouch infection in horses.
• A unicellular eukaryotic organism.
– Originally grouped with the protozoa.
– Number of features in common with fungi.
• No ergosterol.
• Natural reservoir unknown: considered to be
widespread in the environment. Airborne.
– Highly infectious, low virulence.
Pneumocystis sp.
Pneumocystis sp.
• A unicellular eukaryotic organism.
– Originally grouped with the ________.
– Number of features in common with fungi.
• No ___________.
• Natural reservoir unknown: considered to be
widespread in the environment. ____________.
– Highly ___________, low ________.
• Pathogenicity demonstrated for multiple species,
primarily _____________ animals.
• Pneumonia: _______infiltrates. Extrapulmonary
infection reported in a few ____ patients.
• Asymptomatic infection in ____________
humans and mammals.
Pneumocystis sp.
• A unicellular eukaryotic organism.
– Originally grouped with the protozoa.
– Number of features in common with fungi.
• No ergosterol.
• Natural reservoir unknown: considered to be
widespread in the environment. Airborne.
– Highly infectious, low virulence.
• Pathogenicity demonstrated for multiple species,
primarily immunodeficient animals.
• Pneumonia: interstitial infiltrates. Extrapulmonary
infection reported in a few HIV patients.
• Asymptomatic infection in immunocompetent
humans and mammals.
Pneumocystis sp.
Pneumocystis sp.
• Pneumocystis carinii
– P. wakefieldiae – proposed second species in animals.
– P. jirovecii – exclusive agent in humans.
Pneumocystis sp Diagnosis
Diagnosis primarily by direct detection/observation
of agent in tissues.
• Life cycle: forms observed in tissue.
– Trophic form: pleomorphic, 1-5 μm dia., primary
proliverative stage, asexual binary fission.
– Precyst form: 5-8 μm dia., intermediate form and
incompletely differentiated cyst.
– Cyst form: 5-10 μm dia., thick walled, contains 8
sporozoites, collapses after release of spores.
Pneumocystis sp.
Infective stage.
• Drug of choice
• Infective stage unknown.
• Drug of choice: trimethoprim/sulfamethoxazole.
Mycotoxins
• Toxic metabolites of certain fungi that grow on ________.
• Small, ____________, ___________, hydrocarbons.
• Production influenced by substrate (____________),
temperature, moisture, aeration, pH, storage, etc.
– Not all strains of a fungal species produce toxin.
– Toxin may be present without ___________________.
Mycotoxins
• Toxic metabolites of certain fungi that grow on
animal feeds.
• Small, nonantigenic, aromatic, hydrocarbons.
• Production influenced by substrate (plant stress),
temperature, moisture, aeration, pH, storage, etc.
– Not all strains of a fungal species produce toxin.
– Toxin may be present without cultivatable fungi.
Mycotoxins
• ______, or ________ disease: effects may be
cumulative as well as toxin deposition in tissues.
• Lesions of mycotoxicosis depend on the ___________; one or more of the following:
1.
2.
3.
4.
5.
Mycotoxins
• Acute, or chronic disease: effects may be
cumulative as well as toxin deposition in tissues.
• Lesions of mycotoxicosis depend on the specific
toxin; one or more of the following:
– Necrosis and hemorrhage.
– Bone marrow suppression.
– Estrogenic.
– Immune suppression.
– Carcinogenic.
Mycotoxin decontamination and detoxification
Mycotoxin decontamination and detoxification
• Physical cleaning of feedstuff.
• Sort and separate moldy feed ingredients.
– Feed to non-susceptible species.
– Blend with other feed to dilute.
• Chemical detoxification: ammoniation, ozonization.
• Binding agents: add clay, zeolite, granualted
activated carbon to feed.
• Microbiological degradation.
common for queens to transmit to kittens
may cause more serious diseaes in FeLV cats
adhere to surface of RBC
Mycoplasma haemofelis
Antifungals
• Target biochemical differences between ______
and ______ cells.
– Cell membrane active antifungals target __________.
• Polyenes (amphotericin B and nystatin) ____________.
• Imidazoles ______________________.
• Allylamines and thiocarbamates inhibit synthesis (__________ –
________ and _________).
– Inhibit fungal mitosis (_____________).
– Inhibit RNA and protein synthesis (_____________).
– Inhibit cell wall (chitin or glucan) synthesis (_________,
_____________, _____________, _________).
• Antifungal susceptibility testing available in
reference laboratories.
Antifungals
• Target biochemical differences between fungal
and animal cells.
– Cell membrane active antifungals target ergosterol.
• Polyenes (amphotericin B and nystatin) bind to it.
• Imidazoles inhibit synthesis.
• Allylamines and thiocarbamates inhibit synthesis (Terbinafine –
Lamisil and naftifine).
– Inhibit fungal mitosis (griseofulvin).
– Inhibit RNA and protein synthesis (5-flucytosine).
– Inhibit cell wall (chitin or glucan) synthesis (lufenuron,
echinocandins, pneumocandins, cilofungin).
• Antifungal susceptibility testing available in
reference laboratories.
– Fungicidal by binding to ergosterol, causing cell leakage
and cell death.
– Effective against most systemic mycoses agents and
yeasts, variable against opportunitistic fungi.
– Resistance develops slowly and does not reach high
levels, even after prolonged treatment.
• Amphotericin B
– Fungistatic by inhibiting ergosterol synthesis.
– Broad antifungal spectrum of activity: systemic
mycoses, yeast, dermatophytes; variable activity
against opportunistic fungi, bacteria, protozoa,
helminths, etc.
– Very limited acquired resistance.
• Imidazoles
– Miconazole, clotrimazole, ketoconazole, itraconazole,
fluconazole, etc.
– Fungicidal: Deaminated by fungi to 5-fluorouracil,
inhibits RNA and protein synthesis.
– Active only against yeast: Candida, Cryptococcus, etc.
– Resistance emerges rapidly during treatment.
• Flucytosine
– Fungistatic: inhibits mitosis, but action is slow.
– Effective only as a systemic agent against
dermatophytes.
– Resistance is rare.
• Griseofulvin
– Effective for lymphocutaneous sporotrichosis.
• Potassium iodide
Antifungal recommendations for deep/systemic
infections.
Candida
first choice:Amphotericin B, Fluconazole
second choice:Itraconazole
Antifungal recommendations for deep/systemic
infections
Cryptococcus
first choice:Amphotericin B, Fluconazole
second choice:5-flucytosine
Antifungal recommendations for deep/systemic
infections
Coccidioides
first choice:Amphotericin B, Fluconazole
second choice:Keto, Itra
Antifungal recommendations for deep/systemic
infections
Blastomyces
first choice:Amphotericin B, Itraconazole
second choice:Keto, flu
Antifungal recommendations for deep/systemic
infections.
Blastomyces
first choice:Amphotericin B, Itraconazole
second choice:Keto, Flu
Antifungal recommendations for deep/systemic
infections.
Histoplasma
first choice:Amphotericin B, Itraconazole
second choice:Keto, Flu
Antifungal recommendations for deep/systemic
infections
Sporothrix
first choice:Amphotericin B, Itraconazole
second choice:KI
Antifungal recommendations for deep/systemic
infections
Aspergillus
first choice:Amphotericin B, Itraconazole
second choice:Enilconazole
Antifungal recommendations for deep/systemic
infections
Dermatophytes
first choice:Griseofulvin
second choice:Itra, Keto
Prototheca sp.
• _____________ algae
– Found in soil and aqueous habitats worldwide, plant and
animal sources.
• Sporadic cases of bovine _________. Cull.
• Cats: _____________ ___________ and
______________________.
• Dogs: ______________________ ________________.
Prototheca sp.
• Achlorophyllic algae
– Found in soil and aqueous habitats worldwide, plant and
animal sources.
• Sporadic cases of bovine mastitis. Cull.
• Cats: localized infection of the dermis and
subcutis, regional lymphadenopathy.
• Dogs: systemic disease that begins in the GIT and
frequently involves CNS and eyes. Uniformly fatal.
Prototheca sp.
• Diagnosis and identification.
– Round to oval sporangia (7-25 μm dia.), containing 2-20
sporangiospores (internal septation).
– Readily cultivatable on blood agar plates (48 hr.).
Pythium insidiosum
• Aquatic organism – class _____________.
– Often misclassified as “___________.”
– Also described as “________” and swamp _________.
• Differs from true fungi by:
– ____________________.
– ____________________.
– ____________________.
Pythium insidiosum
• Aquatic organism – class Oomycetes.
– Often misclassified as “aquatic fungus.”
– Also described as “leeches” and swamp cancer.
• Differs from true fungi by:
– Producing motile, biflagellate zoospores.
– Cell walls lack chitin.
– Plasma membrane lacks ergosterol.
• Complex life cycle produces a motile zoospore as
the infective stage. Granulomatous lesion.
• Encountered in Gulf Coast states and as far north
as KY, MO, IL, IN, VA, and NJ.
Pythium insidiosum
Pythiosis
• _______ and _______ most commonly affected.
Pythiosis
• Dogs and horses most commonly affected.
– Equine pythiosis:
– Equine pythiosis: Cutaneous and subcutaneous
granulomatous lesions.
• Tumor-like masses with fistules and serosanguinous exudate.
• Kunkers: Stony masses containing viable organisms and
cellular debris.
– Canine pythiosis:
– Canine pythiosis: Cutaneous and gastrointestinal forms.
• Cutaneous lesions typically on limbs and tail.
• GI form: ingestion, granulomatous masses develop within
intestinal wall. Most common form in dogs.
– All forms may include lymphatic and vascular invasion
with metastatic spread
Pythiosis
• Diagnosis:

• Treatment:
Pythiosis
• Diagnosis:
– Direct microscopic examination (septate-hyphae).
– Culture: requires specialized procedures.
– Serology: ELISA.
– PCR-based assays applied to tissue extracts.
– Immunohistochemistry is highly specific for hyphae.
• Treatment:
– Surgical removal of lesions.
– Chemotherapy – poor success.
– Immunotherapy – vaccine.
• Best response with early diagnosis of small
lesions. Chronic cases tend to be unresponsive.
Disinfectants
• _____________ compounds applied to inanimate
surfaces.
– Activity ranges from ________ to ______________.
• Antiseptics are applied to tissues to ___________ or
_____________ microbial infection.
• Factors influencing the action of disinfectants:
– ________________.
– ________________.
– ________________
– ________________.
Disinfectants
• Germicidal compounds applied to inanimate
surfaces.
– Activity ranges from sanitation to sterilization.
• Antiseptics are applied to tissues to suppress or
prevent microbial infection.
• Factors influencing the action of disinfectants:
– Organic material.
– Other physical and environmental factors.
– Concentration and contact time.
– Type and number of microorganisms.
Selecting and evaluating disinfectants
• EPA registration number.
• Indicated use.
– Germicide kills _________.
– General purpose disinfectant kills _________ and
____________.
– Hospital disinfectant kills ____________, _________,
and _____________.
• Hard water and contamination effectiveness.
• Active ingredients = disinfectant.
– Alcohols, aldehydes, acids and alkalies, quaternary
ammonium compounds, phenolics.
Selecting and evaluating disinfectants
• EPA registration number.
• Indicated use.
– Germicide kills Salmonella.
– General purpose disinfectant kills Salmonella and
Staphylococcus.
– Hospital disinfectant kills Salmonella, Staphylococcus,
and Pseudomonas.
• Hard water and contamination effectiveness.
• Active ingredients = disinfectant.
– Alcohols, aldehydes, acids and alkalies, quaternary
ammonium compounds, phenolics.