53 terms

Infectious Agents Final Exam

Describe the invasiveness of Lepto.
Lepto can penetrate intact mucosa of the alimentary tract, eye and genitalia, or abraded/moist skin after contact with contaminated urine, water, food, or coitus.
What is the natural habitat of Lepto?
The lumen of the proximal convoluted tubules (in latent or chronic carriers).
Describe the Lepto vaccine.
Bacterin for 1-6 serovars. Killed vaccine. Should vaccinate 2-3 times per year.
Can the Lepto vaccine clear a carrier state?
No, but it will prevent abortion and acute clinical signs.
How is the Lepto carrier state treated?
Streptomycin, 25 mg/kg
What serologic test is performed to test for Lepto, and what are you looking for?
Microscoptic agglutination/lysis test (MALT). A standard suspension of each Lepto serovar is used, with a serum dilution from the test subject added. A positive test shows a pellet of clumped lysed cells at the bottom of the tube.
What do direct tests detect?
The organism itself.

Examples: Culture, Direct fluorescent antibody
What do indirect tests detect?
Antibodies to the organism.
How are the anaerobes classified?
Gram reaction
Ability to form spores
Name the anaerobic GP cocci.
Name the anaerobic GN rods.
Name the anaerobic GP rods.
Name the anaerobic GP spore-forming rod.
T of F: Obligate anaerobes outnumber facultative anaerobes by >1000:1.
What are the synergistic requirements of Bacteroides spp.?
Other bacteria supply Bacteroides spp. with Vit. K.
What are the synergistic requirements of B. asaccharolyticus?
Uses succinate supplied by Klebsiella to cause severe spreading lesions.
What are the synergistic requirements of various facultative anaerobes and obligate anaerobes?
Facultative anaerobes remove oxygen and release reducing substances to provide a better environment for obligate anaerobes. In return, obligate anaerobes produce leukotoxins and remove opsonins and complement.
What are the cultural requirements for submitting specimens for anaerobic culture?
Specimens that might be contaminated with normal flora should not be cultured.

Acceptable specimens:
- Aspirates from enclosed lesions or body sites normally sterile
- TTA or lung aspirates
- Uterine aspirates
- Abscess/deep wound aspirates
- Tissue obtained from deep infections during debridement
- Sequestra, bone biopsies, or nearby soft tissue
- Aspirates from occeous bullae or frontal sinuses
What is the only known obligate anaerobe that can survive in urine?
Actinobaculum suis (formerly Eubacterium suis)
Do you sensitivity test for anaerobes?
No, anaerobes have predefined antimicrobial sensitivities.
What are the predefined sensitivities for anaerobes?
Penicillins, chloramphenicol, clindamycin, and metronidazole are the most common. Some cephalosporins are effective against anaerobes.
What does Clostridium perfringens, toxin type A cause?
Food poisoning
Enterotoxemia in cattle and lambs
Canine hemorrhagic gastroenteritis
What does Clostridium perfringens, toxin type C cause?
Enteritis necroticans (Pigbel) in humans
What does Clostridium difficile cause?
Pseudomembraneous colitis
What does Clostridium septicum cause?
Abomastitis (braxy, bradshot) in sheep
Malignant edema
Gangrenous dermatitis of the head in chickens
What does Clostridium spiroforme cause?
Diarrhea in weaned rabbits
What does Clostridium colinum cause?
Ulcerative colitis in fowl
What do Fusobacterium and conjunction with other bacteria cause in cattle?
Bovine Liver Abscess
What does Fusobacterium necrophorum in conjunction with B. nodosus cause?
Footrot in sheep
What does Bacteroides melanogenicus cause?
Pyometras in dogs and cats
What does Clostridium chauvoei cause?
Blackleg in cattle
What does Clostridium sordelli cause?
Sudden death syndrome (SDS) in cattle and sheep
What does Clostridium novyi cause?
Gas gangrene in cattle and sheep
Infectious hepatitis (Black disease) in cattle and horses
What is used to treat gastrointestinal Campylobacter?
What does Campylobacter fetus venerealis cause?
Bovine genital campylobacteriosis
Classic infertility syndrome
What does Campylobacter fetus fetus cause?
Bovine genital campylobacteriosis

Can sometimes cause Classic infertility syndrome
What does Campylobacter jejuni cause?
Mild to severe hemorrhagic enteritis
Possibly hepatitis
How do Rickettsial diseases differ?
Arthropod vector
Localization within host cell
Clinical manifestations
Appearance/distribution of rash
How are Rickettsial diseases similar?
Disease processes
Symptoms (rash, headache, fever, thrombosis, death due to DIC)
What does Rickettsia exist in the body?
What are the differences between elementary bodies and reticulate bodies with Chlamydia?
Elementary bodies are spore-like, relatively metabollically inactive states. Infective agent. When an elementary body infects a host cell, it forms a reticulate body that is adapted for intracellular growth.
T or F: Rickettsial organisms are obligate intracellular pathogens.
What is unique about Rickettsial cytoplasmic membranes?
They are very permeable.
Where are Rickettsial organisms found in the host cell?
Cytoplasm or nucleus
Can Rickettsial organisms be cultured on artificial media?
No, must be cultured in cell lines or chicken eggs.
What is the causative agent of Rocky Mountain Spotted Fever?
Rickettsia ricketsii
What are the signs of Rocky Mountain Spotted Fever in dogs?
Possible red rash
Fever 5 days after tick bite
Petechial and hemorrhages on exposed mucosa
Vasculitis causing edema in extremities including scrotum and prepuce
Describe Chlamydia elementary bodies.
0.3-0.4 um spore-like bodies, metabolically inactive, adapted for extracellular survival.

Infects cells when they are phagocytosed.
What air-borne, spore-like bacteria is always found in sheep?
Coxiella burnettii
What is the vector for canine erlichyosis?
Tick (Brown dog tic, Rhipicephalus sanguineus -- E. canis; Ixodes spp. -- E. ewingii)
Which Chlamydia spontaneously resolves?
Chlamydiophila felis (Feline chlamydiosis)
How is Chlamydiophala abortus prevented in cattle?
Antibiotic treatment is the most practical means of control.

Quarantine of affected animals and proper disposal of infective material.
How is Anaplasma transmitted?
Ixodes spp. ticks