BacT week 6

Question 1

acid fast-partial bacteria

Answer 1

corynebacterium, rhodococcus, nocardia

Question 2

acid fast bacteria

Answer 2

mycobacterium

Question 3

Corynebacterium key characteristics

Answer 3

gram + pleomorphic bacteria. Aerobes or facultative anaerobes. short mycolic acids in cell wall.
Pathogenic strains are non-motile
Commensals found on mucus membranes, some species in environment. Often host-specific.
Opportunistic pathogens causing mainly pyogenic infections. Tissue trauma allows for establishment of pathogenic bacteria
Tend to survive in macrophages and cause chronic granulomatous disease

Question 4

External lipid coat (mycolic acids) virulence factor

Answer 4

Corynebacterium. protection from hydrolytic enzymes in host phagocytes

Question 5

exotoxin phospholipase D (PLD) virulence factor

Answer 5

Corynebacterium. Hydrolyze cell membranes to cause increased vascular permeability

Question 6

Diphtheria toxin virulence factor

Answer 6

Corynebacterium. interferes with protein synthesis in cells

Question 7

corynebacterium important species

Answer 7

C. pseudotuberculosis. Has 2 types: non-nitrate reducing and nitrate reducing.
Non = sheep/goats, causes caseous lymphadenitis
Nitrate reducing = horses, cattle. Causes ulcerative lymphangitis, abscesses

Question 8

Caseous lymphadenitis

Answer 8

chronic pyogranulomatous infection of the LNs. Abscessation/enlargement of superficial or internal LNs. Infection spread by pus from ruptured abscesses/nasal/oral secretions.
Caseous necrosis of the LNs
Organism can survive for long periods in the environment.
Internal abscessation –> thin ewe syndrome
3 month incubation period
Not hot or painful
economic losses

Question 9

Caseous lymphadenitis diagnosis

Answer 9

CS (abscess, weight loss), culture purulent material, radiographs/ultrasounds for internal abscesses
Serology - synergistic hemolysin inibition test (for PLD antibodies). Positive titers can indicate recent exposure, vaccination, resolved infection, active infection. Low titer does not rule out disease, do REPEAT samples

Question 10

Caseous lymphadenitis control

Answer 10

not curable!
Only treat animals with emotional/genetic value
Isolate animals to easily-disinfected area. drain abscesses, surgical excision if possible. Iodine/bleach/chlorhex to disinfect. Use systemic antibiotics
Ideally, cull infected animals.
Commercial vaccine for sheep and goats (not recommended in flocks that have never had CL)

Question 11

Ulcerative lymphangitis (pigeon fever, dry-land distemper)

Answer 11

Infectious, inflammatory condition of the cutaneous lymphatic system in lower limbs and chronic abscesses in pectoral and ventral region. swelling of chest or abdomen, fever, loss of appetite, lameness, deep subQ external abscesses.
Common in dry areas (cali)
Seasonal patterns 0 more prevalent in autumn and early winter.
Flies play a role in transmission
Bacteria enter through skin abrasions

Question 12

Ulcerative lymphangitis treatment and prevention

Answer 12

T = long-term systemic antibiotic therapy with topical treatment
P = isolation of infected horses, fly control and good sanitation

Question 13

Contagious bovine pyelonephritis

Answer 13

inflammation of the urinary bladder that may ascend to the ureters to cause kidney infection.
Caused by C. renale group of bacteria
Reservoir: vulva, vagina in clinically normal carrier cows
Contributing factors: parturition stress, peak lactation, high protein diet, trauma to bladder/urethra
CS: fever, anorexia, painful urination, ammoniac odor of urine, acute ab pain, decreased rumen contractions and milk production

Question 14

Murine pseudotuberculosis

Answer 14

lungs: suppurative pneumonia
Kidney, liver, heart: nodular lesions
Joints: arthritic lesions of pedal extremities
LNs: hyperplasia

Question 15

Rhodococcus characteristics

Answer 15

occur as cocci or rods. aerobic soil saprophyte. non-motile. salmon-pink colonies. weakly acid-fast.
Opportunistic pathogens in young foals (under 6 months). facultative intracellular pathogen - survive in macrophages

Question 16

R. equi risk factors

Answer 16

dry wether, high foal density, poor grass cover on paddocks, large number of horses on the farm

Question 17

vapA virulence factor

Answer 17

R. equi. promotes surival in non-activated macrophages. encoded by plasmid

Question 18

capsular polysaccharides virulence factor

Answer 18

R. equi. slows phagocytosis

Question 19

Mycolic acids virulence factor

Answer 19

R. equi. slows phagocytosis

Question 20

Suppurative bronchopneumonia in foals

Answer 20

bronchopneumonia and lung abscessation in foals 1-4 months of age. Infection occurs mostly within the first 2 weeks of life.
CS: fever, anorexia, diarrhea, cough, dyspnea
Hard to detect - slowly progressive
polysynovitis, intestinal and mesenteric abscesses, ulccerative colitis
Significant economic impact - mortality, prolonged treatment, prophylaxis expenisve

Question 21

Suppurative bronchopneumonia diagnosis

Answer 21

thoracic auscultation and percussion- crackles and wheezes w/ asymmetric distribution
Ultrasonography of the thorax - nodular long lesions
Cytological exam of respiratory secretion - neutrophilic leukocytosis
Culture of transtracheal or broncheoalveolar wash samples

Question 22

Suppurative bronchopneumonia treatment and prevention

Answer 22

T = prolonged Tx, combination therapy of macrolide antibiotics and rifampicin. Supportive therapy.
P = hyperimmune serum, colostrum, dust control, no vaccine!

Question 23

Nocardia general characteristics

Answer 23

pleomorphic bacteria. Cocci or rods with long branching filaments. strict aerobes. facultative intracellular bacterium. Non-motile, non-spore forming. partial acid-fast
Ubiquitous in soil and water, usually non pathogenic for immunocompetent individuals.

Question 24

Nocardiosis forms in dogs

Answer 24

thoracic, cutaneous and disseminated

Question 25

Nocardiosis forms in cattle

Answer 25

mastitis

Question 26

Canine nocardiosis

Answer 26

thoracic form - fibrovascular proliferative reaction on pleura and accumulation of sanguinopurulent fluid in thoracic cavity Cutaneous form - ulcer or granulomatous swelling disseminated form - non-specific clinical signs depends on organ system affected Infection mainly via inhalation, through skin wounds or ingestion Classic sulfur granules in exudate

Question 27

Bovine nocardial mastitis

Answer 27

chronic mastitis with multifocal fibrosis in affected glands. white clots intermittently in the milk. outbreaks associated with dry cow therapy. control is difficult but nocardial mastitis is usually sporadic occasional systemic reaction

Question 28

Actinomyces general characteristics

Answer 28

gram +, club-shaped rods and filamentous branching bacT. Facultative or strict anaerobes, require CO2 (capnophilic). Non-spore forming, non motile. Characteristic colonies growing in the centre of lesions surrounded by macrophages (sulfur granules). Outer perimeter of lesion looks granulomatous. Actinomyces are commensals of the oral cavity, colonize nasopharynx and oral mucosa

Question 29

actinomyces pathogenesis

Answer 29

disrupted oral mucosa, spread by direct extension to bones, chronic infection with bone lysis

Question 30

Lumpy jaw in cattle (actinomyces)

Answer 30

Pyogranulomatous osteomyelitis. granulomatous lesions involving the mandible, maxillae and other bony tissues of the head Bone infection causes facial distortion, loose teeth and dyspnea. Predisposition = trauma in the oral cavity

Question 31

Lumpy jaw diagnosis

Answer 31

CS: swelling of jaw with fistulous tracts discharging purulent exudate microscopic exam with crushed granules from aspirates of unopened lesions culture purulent material (capnophilic!) radiograhy can be used to determine degree of bone destruction

Question 32

Lumpy jaw treatment and control

Answer 32

treatment: susceptible to penicillin G and iodine, long term treatment with high dose penicillin, can be excised surgically if small and circumscribed long-term therapy may fail as these lesions are chronic and walled off Control: minimize risk of injury, remove foreign bodies

Question 33

Dermatophilus general characteristics

Answer 33

gram +, filamentous branching bacteria, aerobic, motile asexual zoospores (create hyphae). Has a tram track appearance. Hyphae penetrate into living epidermis and subsequently spread in all direction causing inflammation only can attack abnormal/reduced skin barrier Causes infection of traumatized/persistently wet skin with formation of scabs and crusts obligate pathogen

Question 34

Dermatophilus acute vs chronic infection

Answer 34

acute - 2-3 weeks long, heals spontaneously | Chronic - cornification of epithelium --> scabs --> moisture enhances proliferation and zoospore release

Question 35

dermatophilosis pathogenesis

Answer 35

filaments colonize hair follicles and penetrate skin layers, inflammatory cell layer is formed under infected epidermis and keratinizes --> scab and crust formation --> accumulation of cutaneous keratinized material forming a wart like lesion and matted hair

Question 36

Dermatophilosis diagnosis

Answer 36

CS, detection in stained smears or histology of scabs, cytology of fresh crusts with Giemsa

Question 37

dermatophilosis treatment

Answer 37

parenterally administered anti-b's, topical treatments less effective but may include chlorhex or iodine

Question 38

dermatophilosis control

Answer 38

isolate clinically affected cows, provide shelter during prolonged rainfall, clear grazing areas of thorny plants, reduce tick infestation, prophylactic tetracycline use in endemic areas, control of intercurrent diseases

Question 39

Trueperella general characteristics

Answer 39

gram + pleomorphic, facultative anaerobic and capnophilic, non-motile and non spore forming. found on mucosal membranes in GIT, UGT, resp tract in cattle and swine. Opportunistic pathogen of cattle/sheep/swine. Suppurative infection, prevalence is sporadic and governed by precipitating stress/trauma

Question 40

Pyolysin

Answer 40

hemolytic toxin, cytotoxic for neutrophils and macrophages, dermatonecrotic and lethal for lab animals found in trueperella

Question 41

Summer mastitis

Answer 41

caused by trueperella. mastitis of non-lactating cows and heifers during summer months. synergistic action with other bacteria. Transmission via the head fly (hydrotea irritans). affected area is swollen, hard, painful and hot. Udder secretion is thick and clotted with green/yellow pus

Question 42

Trueperella diagnosis

Answer 42

smear and gram stain of purulent material | necropsy and isolation of bacteria

Question 43

Trueperella treatment

Answer 43

penicillin G! reports of resistance

Question 44

Trueperella prevention

Answer 44

prevent primary cause, no efficient vaccine

Question 45

Actinobaculum

Answer 45

actinobaculum suis - gram + rods, anaerobes, non-motile, non-spore forming Commensal organism in preputial diverticulum of boars, not in UGT of healthy sows, transmitted via coitus porcine cystitis, pyelonephritis, anorexia, arched back, dysuria, haematuria Potentially fatal (renal failure)