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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. |