Exam 2 Flashcards
Mycobacterium stain what?
Gram positive, acid fast positive, ROD SHAPE. do NOT have an outer membrane
What contributes to acid fast staining?
Mycolic acid
What type of infection does mycobacterium cause?
chronic granulomatous infections
What are the virulence factors of mycobacterium
- Lipid rich (mycolic acid containing) cell wall
- Lipoarabinomannan- inhibits phagosome-lysosome fusion
- Cell protein antigens
True or False - under optimum conditions obligate pathogens can survive in a contaminated envior for extended periods
True
How is TB transmitted
inhalation and ingestion
Pathogenesis of TB
- Cell mediated immune response is important in the destruction of bacilli. If bacilli survive, infected macrophages are killed following stimulated release of macrophage- derived cytotoxins and enzymes. Type IV hypersensitivity or delayed type hypersensitivity-> which leads to tissue destruction.
- Caseous necrosis and mineralization followed by liquefaction and cavity formation resulting from enzymatic action. Rupture of these granulomas allows dissemination.
What does TB lesions consist of
- Granulomas
- Epithelioid macrophages
- Caseous necrosis
- multinucleated giant cells (Langhan’s cell)
What are the primary drugs for TB?
-Isoniazid, Rifamycins, Ethmanbutol, Pyrazinamide
What are the secondary drugs for TB?
-Aminoglycosides, Fluoroqunilones
Why is Mycobactrium bovis important?
- Causes zoonotic TB
- Ingestion, inhalation and less frequently by contact with mucous membranes and broken skin
- Wide host range
- GI tract is the main portal of entry
What are some clinical signs of M. bovis?
- Enlarged regional lymph nodes and generalized wasting (cachexia) are seen in advanced disease stages. Pulmonary forms may be associated with chronic cough.
- Larger stages firm, nodular lesions are evident in target organs and associated lymph nodes
M. bovis transmission
- Aerosol transmission most common among cattle
- May be shed in milk, prior to widespread pasteurization resulted from drinking/handling contaminated milk
- Can enter body at any site (badgers transmission through skin wounds)
M. bovis diagnostic test
- Tuberculin hypersensitivity skin test
- Rare: Imaging techniques, culture
- Post mortem exam/histo-> granulomatous lesions in lymph nodes and major organs
Tx for M. bovis
- Not recommended for animal esp. infected cattle
- Testing and culling of infected animals
- For humans, combo antimicrobial agents used
What is Mycobacterium avium subsp. Paratuberculosis = Johne’s disease
- A chronic, progressive granulomatous enteritis
- Primary host-ruminants (cattle)
- Excretion of organism through milk
Pathogenesis of Mycobacterium avium subsp. Paratuberculosis = Johne’s disease
- infection through ingestion of contaminated material milk or in utero
- Localizes macrophages in the intestine, local LN
- Develops granulomatous enteritis, cachexia
Diagnosis of Paratuberculosis (johne’s disease)
- Detection of host response to infection
- Humoral immune response: ELISA or agar gel
- Cell mediated immune response: Hypersensitivity skin test
- Acid-fast stain
- Culture
- PCR
What is Mycobacterium leprae
- Leprosy or Hansen’s disease
- Chronic granulomatous debilitating disease
- Transmission from shedding through nose not from the skin
What is Mycobacterium lepraemurium
- Feline and murine (rodent) leprosy
- Solitary or multiple cutaneous nodules or ulcerated lesions
- Very fastidious organism
- Granulomatous dermatitis and panniculitis
Campylobacter, helicobacter and lawsonia all have what in common?
- All have typical gram-negative cell wall
- All are opportunistic, extracellular pathogens
- Except Lawsonia intracellularis -> obligate intracellular pathogen
Characteristics of Campylobacter
- Curved motile gram negative rods (seagull shaped)
- Microaerophilic (require low O2 to grow)
- Inhabit the GI tract or lower genital tract
- Difficult to isolate; needs special culture requirements
Characteristics of Campylobacter jejuni
- Major cause of intestinal illness and diarrhea in humans and animals
- Poor hygiene and management
- Young animals
- Infection by ingestion of contaminated materials
What bacteria is associated with subsequent Guillain-Barre syndrome
Campylobacter jejuni
C. jejuni infection is associated with
Superficial erosive colitis, ileitis and fluid loss, apparently with invasion of bacteria since bacteremia is a common event in C. jejuni enteritis.
Diagnosis and treatment of C. jejuni
Diagnosis: culture of feces, PCR
Treatment: Self-limiting diarrhea illness, macrolides, fluoroquinolones in severe cases
Characteristics of Campylobacter fetus subsp. venerealis
- obligate animal parasite
- subclinical infection is preputial crypts of bulls
- transmission at breeding -> organisms migrate to the uterus and fallopian tubes following estrus
- Breeding/artificial insemination with infected bull or semen
Pathogenesis of Campylobacter fetus subsp. venerealis
-Endometritis and salpingitis (infection/inflammation of fallopian tubes) or varying severity may cause transient infertility and early embryonic death
Diagnosis of Campylobacter fetus subsp. venerealis
-Detect organism in smegma, preputial washes or semen
Characteristics of Campylobacter fetus subsp. fetus
- commensals in the intestinal tract of cattle and sheep
- Causes ovine genital campylobacteriosis
- Sheep > ingestion through contaminated food/water > bacteremia > inflammation of placenta and abortion
- Cattle: occasional abortion
Characteristics of Helicobacter spp.
- small, spirally curved gram-negative rods
- microaerophilic, and some require hydrogen
- motile (bipolar flagella)
- pathogenic and commensals present in the gastric mucosa and intestine
Characteristics of Helicobacter pylori
- Gram negative microaerophilic bacterium in the stomach
- Causes gastric ulcers
- Associated with gastric neoplasms
Virulence factors and pathogenesis of H. pylori
-adhesins, flagella, endotoxin and extracellular urease, mucinase, vacuolating cytotoxin, catalase/SOD
Helicobacter hepaticus and helicobacter bilis are what?
mouse pathogens involved in hepatic necrosis, nonsuppurative hepatitis, heptocellular tumors
Heliobacter mustelae is involved in what
hypergastrinemia and peptic ulcers in ferrets
Characteristics of Lawsonia intracellularis
- Small, spirally curved gram-negative rod
- Lawsonia are intracellular bacteria which replicate in the apical cytoplasm of enterocytes- obligate intracellular pathogen
- Associated with porcine proliferative enteropathy
- Causes reduced weight gain and proliferative hemorrhagic enteropathy
- Mainly seen in weaner pigs and yearling foals
Characteristics of Spirochetes
- Gram negative bacT
- Slender, helically coiled, spiral organisms, move with corkscrew or flexing motion
- Darkfield microscopy
- Tight/loose coiled morphology due to flagella (axial filaments/endoflagella) located in periplasmic space
T/F Leptospira is saprophytes
True- saprophytes are free living in water
Describe the characteristics of a Leptospira infection
- Pathogenic species maintained in the renal tubules or reservoir animals
- Reservoir animals excrete the bacteria through urine and contaminate envior.
- Pathogenic species survive for a short period in ponds, rivers, surface water, moist soil and mud
- Direct contact with urine or contaminated water results in infection
What is the natural habitat of lepto
Proximal convoluted tubules of kidney (sometimes genital tract)
Virulence factors of Lepto
- Cell associated: Endoflagella, outer membrane proteins, LPS (different from other gram negative bacT)
- Extracellular: Hemolysins, protein cytotoxins
What are the types of pathology of Lepto?
- Acute and chronic inflammation of various organs most notably the liver and kidneys
- During bacteremia phase, intravascular hemolysis petechial hemorrhages and DIC
- Jaundice (hepatitis)
- Nephritis (acute, chronic interstitial nephritis)
- Placentitis and abortion
- Mastitis
Describe leptospirosis in dogs
- acute febrile illness
- Renal or hepatic injury, uveitis, pulmonary hemorrhage, abortion
- Clinical signs: PU/PD, Dehydration, vomiting, diarrhea, lethargy, abdominal pain
- Signs of hepatic and renal failure, including icterus
- Bleeding abnormalities and DIC
What is the gold standard test for Lepto?
Microscopic agglutination test
How does the Microscopic agglutination test work?
MAT- measures antibody titers to leptospira serovars using an agglutination test which uses live leptospira serovars
What is leptospira borgpetersenni serovar hardjo
it is host adapted in cattle resulting in reproductive failure due to early embryonic death and repeat breeding
What are the most common causes of equine lepto
Serovars Pomona and Grippotyphosa
Characteristics of Borrelia
- Gram negative
- Loosely coiled spirochete commonly cause arthropd (tick-borne) infections
- Linear Chromosome
What Borreli causes lyme disease in North America
B. burgdorferi
What happens after the tick ingest blood for lyme disease
After tick ingest blood, spirochete up-regulated expression of an outer surface protein, which is essential for virulence in mammals
What are the borrelia virulence factors
- LPS
- Antigenic variation in major outer surface lipoproteins
- Ability to hide out in L forms,
Lyme disease pathogenesis
- After inoculation into the skin, spirochetes multiple to highest numbers in the skin and disseminate via the blood stream
- Skin rash (erythema migrans) is often the first sign of infection in human beings
- Organism spread through the blood to joints, brain, nerves, eyes, heart, liver, kidney
Characteristics of Brachyspira hyodysenteriae
- Anaerobic spirochete agent of swine dysentery
- Obligate parasite of colon in pigs
- Survives relatively poor in enviornment
How is Brachyspira hyodysenteriae transmitted?
- Fecal-oral
- Asymptomatic carrier pigs
- Mechanical vectors (boots, coveralls, vehicles)
How do you diagnosis Brachyspira
- Direct staining and observation of loosely coiled spirochetes in clinical specimens
- Anaerobic culture
- PCR
- Histopathology and silver staining
- This condition must be differentiated from salmonellosis
What does Treponema pallidum cause ?
Causes syphilis a sexually transmitted disease in humans
What is Papillomatous digital dermatitis (PPD)
- “Hairy Heel Warts”
- Growing cause of lameness in cows
- Economic loss, decreased milk production
How do you treat Papillomatous digital dermatitis (PPD)
- Spraying feet of dairy cattle with AB (tetracycline or lincomycin) solutions while they are milking -> most cost effective
- Formaldehyde foot baths
Characteristics of Treponema paraluis- cuniculi
- Rabbit syphilis or vent disease in rabbits
- Perineal and facial lesions
- Epidermal hyperplasia with erosions, ulcers
- Increased susceptibility
- Spread by direct or venereal contact
What is Rickettsia
Rickettsia are arthropod transmitted parasites of blood cells or endothelial cells and may cause persistent infections
- Small obligate intracellular bacteria
- Gram negative coccibacilli
- Reside in an arthropod host
- Rodents and small mammals can act as reservoirs
Treatment for Rickettsia
Tetracycline, Doxy, Chloramphenicol, Enrofloxacin
Transmission of Rickettsia rickettsia
-Dermacenter and Rhipicephalus sanguineous
Pathogenesis of Rickettsia rickettsia
Organism invades and replicates in edothelial cells of small blood vessels, initiating platelet activation, intravascular coagulation and progressive necrotizing vasculitis.
Clinical signs of Rickettsia rickettsia
Fever, depression, anorexia, subq edema, petechiation of mucous, myalgia and stiff gait.
Treatment for Rickettsia rickettsia
Tetracycline therapy
Characteristics of Anaplasmataceae
- Parasites of haematopoietic (bone marrow derived cells) of vertebrate host
- Transmitted by either invertebrate host, (trematode=neorickettsia) or by a vector (tick)
- Can be zoonotic
Who transmits anaplasma phagocytophilum
Ixodes (deer) tick
what does Anaplasma phagocytophilum cause
- Causes canine granulocytic ehrlichiosis: found in neutrophils in the host
- Necrotizing small vessel vasculitis
- Disease: febrile illness and neutropenia, thrombocytopenia, rarely shock
what does Anaplasma phagocytophilum cause in horses
Usually mild subclinical limb edema, icterus, ataxia, may be rapidly fatal (DIC)
what transmits Anaplasma platys
Rhipicephalus sanguineous (brown dog tick)
What does Anaplasma platys cause?
- infectious cyclic thrombocytopenia
- Infects platelets leading to thrombocytopenia
- Often asymptomatic
- Fever, and acute infections may result in petechial and ecchymosis
What is the principal target cell for Anaplasma marginale
Erythrocytes
What does anaplasma marginale cause in ruminants
Cause anaplasmosis in ruminants
What are the clinical signs of anaplasma marginale
Fever, anemia, icterus
What is the vector for Anaplasma marginale
Ticks (boophilus), biting flies, blood contaminated fomites.
What does Ehrlichia canis cause?
Canine monocytic ehrlichiosis (CME)
What does Ehrlichia ewingii cause?
Granulocytic ehrlichiosis in people and dogs in North America
What does Neorickettsia risticii cause?
Potomac Horse Fever
- Infects enterocytes and monocytes
- Fever, anorexia, profound leukopenia, severe diarrhea, laminitis, abortion
What does Neorickettsia helminthoeca cause?
Causes salmon poisoining in dogs
-infects monocytes and macrophages
What type of bacteria is Chlamydia
Obligate intracellular parasite
Disease of chlamydia include what?
Enteritis, abortion, polyarthritis, polyserositis, conjunctivitis, pneumonia
Why is Chlamydia psittaci important?
It is a zoonotic pathogen and reportable disease
Why is Mycoplasma different from other bacteria?
- Small free living bacT
- No cell wall -> no gram stain
Mycoplasma colonies often have what type of appearance
“fried-egg appearance”
Characteristics of Mycoplasma hyopneumoniae
- Enzootic pneumonia of swine
- Mostly spread direct contact, chronic non-productive, unthrifty appearance, decrease weight gain
What is the most virulent mycoplasm in cattle
Mycoplasma mycoides subsp. mycoides
Is Mycoplasma mycoides subsp. mycoides reportable?
Yes
Which myoplasma is contagious bovine pleuropneumonia
Mycoplasma mycoides subsp. mycoides
What does mycoplasma bovis cause?
- upper resp. tract bronchopneumonia, seen in cattle with feedlot pneumonia
- Mastitis, Arthritis
True or False - Ureaplasma diversum can be normal commensal organisms of the lower urogenital tract
TRUE
Why is M. capricolum sbsp. capripneumoniae important
Contagious caprine pleuropneumonia caused a reportable disease in USA
What are two reportable avian mycoplasmas
M. gallisepticum and M. synoviae
What does M. gallisepticum cause?
chronic respiratory diseases in chicken and turkeys
What does Mycoplasma felis of horses cause?
pleural effusion, also predisposes to secondary S. zooepidemicus, then anaerobe colonization of effusion
What does mycoplasma edwardii cause in dogs?
Meningoencephalitis
What type of drugs do you NOT use to treat mycoplasma edwardii
Do not use cell wall active drugs
Mycoplasma hemofelis is formerly known as what
Hemobartonella felis
What is the principal target cell of Mycoplasma hemofelis
Erythrocytes
What is L- form bacteria
are strains of bacteria that lack cell walls.
Characteristics of fungi
- Free-living microorganisms
- Majority are saprophytes and non-pathogens
- Heterotrophs
- Reproduce asexually by fragmentation, budding, and through spores
- Cell membrane contain sterols
- Plant-like cell wall (glucan, mannan,chitin NOT cellulose)
Unicellular fungi is called what?
Yeast
Multicellular fungi is called what?
Mold
Mold has what structures?
Mold has hyphae and fruiting bodies which contain spores
What is groups of hyphae called?
mycelium
The main element of the vegetative or growing form is the what?
Hyphae
Fungi can be divided by cross walls called what?
Septa
Define mycelium
Filamentous mass of hyphae
What are the diseases caused by fungi?
- Fungal infections: fungus invade the tissue and induce its pathogenic effect
- Mycotoxicoses: fungal contamination or growth on food material leads to accumulation of toxins and when consumed induce severe disease
- Allergies: Inhaled fungal spores induce hypersensitivity and allergy
How does immunity to fungal infections work?
- Immunity is mainly cell-mediated
- Antibodies usually produced but are NOT protective
- Most lesions are granulomatous
Define Phaeohyphomycosis
a mycotic infection of humans and lower animals caused by a number of dematiaceous (brown-pigmented) fungus.
Define Chromoblastomycosis
a mycotic infection of the cutaneous and subcutaneous tissues characterized by the development in tissue of dematiaceous rounded sclerotic bodies.
Define Zygomycosis
any infection due to a member of the zygomycetes. These are primitive, fast growing, terr
Define Mycetoma
Is a mycotic infection of humans and animals caused by a number of different fungi and actinomycetes characterized by draining sinuses, granules and tumefaction.
Characteristics of dermatophytes
- Superficial mycosis (ringworm or tinea)
- Fungal parasites of keratinized epithelium of skin and nails
- Cross species infection very common
- Zoonotic disease
- Highly contagious
Describe what the classical ring worm lesion looks like
Slowly expanding, circular area of alopecia and desquamated epithelium. Central hair regrowth, inflamed edge. Often multiple different size lesions
What are the two dermatophytes we learned about for dogs and cats?
- Microsporum canis
- Microsporum gypsium
What is Kerion?
Nodular (kerion) lesions caused by dermatophytes, localized, or generalized folliculitis and often with furunculosis
What is pseudomycetoma
a subcutaneous nodule caused by microsporum canis (image of a Persian cat)
How do you diagnosis ring worm?
- Clinical species ID of dermatophyte assist in controlling infections that may a family pet etc.
- Woods lamp detection of fluorescence is used for detecting M. canis infection
True or false- Sample collection for ring worm should be collected from the periphery of the lesion or combing with a tooth brush
TRUE
What is microsporum gallinae and what does it often effect
- Avian ringworm of favus
- often affects the comb and wattles, but may invade feather follicles.
