The last final shit Flashcards
Actinomyces, Nocardia, Dermatophilus
Gram +, nonmotile, rod to coccobacillus that show branching. Non-spore forming and look like fungi.
Actinomyces characteristics
commensal. From mucous membrane wounds or gaining entry to tissues. Cause opportunistic and chronic infections that grow slowly along anatomic barriers. Suppurative granulomas. Sulfur granules of bacteria embedded in tissue and look like cheese in pus.
Nocardia characteristics
soil-borne. Inhalation or wounds. Non-contagious, granulomatous exogenous infections.
Dermatophilus
obligate. Direct contact or inanimate objects. Not highly pathogenic.
Actinomyces bovis location
Oral cavity mostly in cattle. Enters through mucosal membrane wounds in the Upper digestive tract. Grow under anaerobic conditions and cause abscesses.
What is A. bovis infection characterized as and what’s the layman term
Development of indurated, granulomatous, suppurative lesions involving bone and soft tissue. Also called Lumpy jaw.
A. bovis infection in pigs
Abscesses of liver, may cause chronic granulomatous suppurative mastitis. Common in people, lesions involve upper torso.
How do you identify A. bovis?
Examine pus granules. Add sodium hydroxide, crush, make Gram stain, can see + branching.
Disease from A. viscosus and A. israelii
Oral cavity, pyothorax
Nocardia asteroides
Begins as nodule which rupture and spread. Chronic and progressive characterized by suppurative granulomatous lesions.
Cattle-Mastitis with fistulous draining tracts
Dogs/cats-localized with mycetomas, or lymph node infection or both. Ulcerations, halitosis, lesions in oral cavity for dogs
Infrequent in horses
Humans-pulmonary and SQ form. CNS one is fatal
Diagnosis and treatment of N. asteroides
Gram stain or partial acid fast stains. Grows on unenriched plates and BA. Slow growth, irregular colonies. Need debridement and lesion drainage, use sulfa-tri, tetracycline. May need for 12 weeks
Nocardia farcinica
In cattle, severe mycetoma involving SQ lymphatic spread. May be concurrent with mycobacterium. Called bovine farcy.
Dermatophilus congolensis location
Aerobic, Gram +, filamentous. Found in epidermis. Widely prevalent in cattle. Looks like crusts or scabs.
What happens in severe infections of D. congolensis?
Death of calves, sheep, goats. Mycotic dermatitis, can be seen in 3 forms: lumpy wool, face and scrotum, lower leg and foot that is strawberry foot rot. Abscesses involve subcutis and muscles
Diagnosis and treatment of D. congolensis
Smears from scabs with distilled water and can see coccoid bacteria with segmenting filaments. Small rough, grey white colonies can be seen in a day. When cleared, infection does not re occur. Need penicillin AND streptomycin. or tetracycline and chloramphenicol.
Mycobacteria
slender and slightly curved, unique cell wall with high lipid content. Has mycolic acids, waxes, and glycolipids. Retain carbol-fuschin dye so are acid fast. Trehalose dimycolate and LAM in wall too.
How does Mycobacterium cell wall differ from others and benefit the bacteria?
Resist dehydration, acid or alkali inactivation, common antibiotics, disinfectants, environmental factors. Resistant to host macrophage clearance and lead to chronic infections. All because of unique unusual waxy cell wall
What are the three forms of Mycobacterium species?
Non-pathogenic, obligate pathogenic that require host environment for replication, potentially pathogenic needing any environment but can cause disease in immunosuppressed people.
What are the four groups of MYcobacteria?
1) Photochromogens-grow slowly and produce yellow light when incubated in light, cause tubercular-like lesions and mild disease. 2) Scotocromogens-grow slowly, yellow orange pigment when no light, like the species in tap water. 3) Non-chromogens-very clow growing, pathogenic, no pigment, avium species and cat leprosy. 4) Saprophytes-rapid growth, non-pigmented, mastitis pathogens, lesions restricted to skin and lymph nodes
Pathogenic mechanisms of Mycobacterium
Intracellular survival, humoral and cell-mediated survival not effective at clearing. Skin test assesses if there is a cell mediated, delayed hypersensitivity reaction where most tissue damage is from Th1.
What are the clinical forms of illness from Mycobacterium?
Pulmonary tube fibrous connective tissue capsule-granulomatic lesions in lungs, caseous necrosis at the center that may calcify or liquefy; generalized tuberculosis-granulomatic lesions at many sites; leprosy-cutaneous granulomatous disease.
Diagnosis of Mycobacterium
Examine smear after acid fast. Most common is tuberculin skin test, examine infiltration of macrophages and lymphocytes near antigen inoculation site. Can be from AGID, ELISA, CF detect antibodies. Definitive diagnosis requires isolation in culture or nucleic acid based detection.
Johne’s disease
Caused by M. avium paratuberculosis. Occurs in ruminants and can survive over a year in soil. Diarrhea and lose weight rapidly, wasting disease. Infected at young age but not seen until adults. More in northern dairy areas. Primary site is ileum of small intestine. Results in necrotic granuloma formation, poor absorption of nutrients. Starts when infected animal enters herd, drink milk from animal. Test fecal samples, DNA analysis of feces, blood test for antibodies.
What are the four strategies employed to control infection in a herd for Johne’s?
Newborns raised in clean environment, fed milk free of disease, identify and remove adult infected animals, move animals to new location.
Crohn’s disease
Humans, chronic diarrheal disease with no cause and no cure. No connection between this and Johne’s, may be from same bacteria.
M. tuberculosis complex infections
Each member is zoonotic, bovine TB was cause of human TB. Use BCG vaccine not in US and pasteurize milk. Transmitted by aerosol. Use streptomycin but treatment in food animals not likely.
Hansen’s disease or leprosy
Caused by M. leprae, affects nerve and skin in cooler areas. Exposure to infected armadillos, through milk or nasorespiratory route.
Cat leprosy
M. lepraemurium, localized skin infection with acid fast bacilli, granulomatous nodules. From rats.
M. avium in birds
Present in soil, water, bird droppings, can replicate outside host. Inhalation from environment can cause. Causes TB in AIDS people. Common in swine, responsible for econ lesions. Granulomas in lymph nodes of head. Dogs and cats resistant.
General characteristics of Spirochetes
Long, slender, spiral shaped, varying number of axial filaments within the periplasmic space. extracellular.
Borrelia characteristics
micro-aerophilic, obligate, vector-borne pathogenics.
Leptospira characteristics
Pathogenic and free living. 2 periplasmic flagella. Hooked appearance. Pass through water system. need aeration and grow in soft agar.
Brachyspira
obligate anaerobic.
Antigenic variation
Way to avoid host immune mechanisms, make large immunodominant surface antigens, switch antigen before all wiped out, follow a certain order. Borrelia replace outer membrane protein coats in response to immune response.
Diagnosis, treatment, and control for Borrelia
Direct microscopic exam, dark field looking for spiral bacteria. Tick bite with bulls-eye rash is Lyme disease. Tetracycline. Inactivated whole cell antigen vaccine and recombinant outer membrane protein based vaccines.
Lyme disease
Transmitted by Ixodes, bulls eye rash with nonspecific symptoms. Disease manifests in CNS signs, cardiac abnormalities. Late disease is swelling of joints and pain. rarely fatal. Based on clinical signs and ELISA. Common arthropod borne disease. causes acute or subacute arthritis in dogs. Joint swelling and shifting lameness in dogs. Skin biopsy for dogs.
Avian/Fowl Borreliosis
B. anserina, causes intravascular hemolysis, emaciation, fever. Isolate sick birds and detick. Treat with tetracyclines. Green diarrhea, not in heart and brain.
Relapsing fever
Borrelia; recurrence of high temps and fever every few days, during which spirochetes can be seen but not when temp is normal. Pathogen changes surface proteins. Tick borne (rodents) or louse borne (other humans). Use doxy for this
