Mycobacterium Flashcards
What kind of bacteria are Mycobacterium?
Mycolic acid, gram + rods, acid fast +, aerobic, facultative intracellular pathogen
What is the importance of Mycobacterium?
Human and bovine tuberculosis
What kind of infections do Mycobacterium cause?
Chronic granulomatous infections
What are 2 virulence factors of Mycobacterium?
- Mycolic acid containing cell wall lipids
2. Cell protein antigens
T/F: Under optimum conditions, obligate pathogens can survive in a contaminated environment for extended periods
True
T/F: Many species of Mycobacterium are soil and water saprophytes that can opportunistically infect susceptible hosts
True
What are 4 important disease caused by Mycobacterium?
- Mammalian tuberculosis
- Avian tuberculosis
- Leprosy
- Johne’s disease
Which two Mycobacterium are in the tuberculous group and form caseous granulomas?
- M. tuberculosis
2. M. bovis
Which Mycobacterium is in the tuberculous group and forms non caseous granulomas?
M. avid complex
Which immune response is important in the destruction of bacilli?
Cell mediated immune response
What type of hypersensitivity is caused by Mycobacteria?
Type IV or Delayed type hypersensitivity
What is the classic lesion of tuberculosis?
Tubercles
What are the characteristics of tubercles?
Granulomas with epithelioid macrophages (hard) or caseous necrosis (soft) surrounded by multinucleate giant cells
What re elements of a tubercle?
Activated macrophages/epithelioid cells
Lymphocytes
Fibrosis
+/- Mineralization
+/- Coagulative/caseous/liquefactive necrosis
Who is the main reservoir for tuberculosis?
Humans
Is TB a treatable and curable disease?
Yes
T/F: Drugs are always used in combination to treat tuberculosis
True
What are 5 problems of TB treatment?
- Combo drug therapy needed
- Limited single drug activity
- Developed drug resistance
- Need prolonged treatment
- Poor drug distribution in walled off lesions
What is multi drug resistant TB (MDR-TB)?
Resistant to at least isoniazid and rifampin
What is extensively drug resistant TB (EDR-TB)
Resistant to isoniazid and rifampin, plus fluoroquinolone and at least one of three injectable second-line drugs
What does Mycobacterium bovis cause?
Zoonotic TB
What is the main portal of entry for M. bovis?
GI tract
What kind of host range and distribution does M. bovis have?
Wide host range and geographic distribution
What kind of infection does M. bovis cause in cattle?
Bovine tuberculosis
What is the most common transmission model of M. bovis in cattle?
Aerosol
What are some lesions of M. bovis?
Enlarged regional lymph nodes and generalized wasting in advanced disease stage
How would you DX bovine tuberculosis?
Tuberculin test
Direct acid fast
Culture
DNA-based methods / PCR
Clinical disease + histopathology
What is a tuberculin hypersensitivity skin test?
Screening test in caudal tail fold; read reaction at injection site 72 hours after
What type of lesions would be seen with Tb?
Caseous necrosis
Granulomatous inflammation
Multinucleate giant cells
Macrophages and lymphocytes
Is therapy for TB in cattle recommended?
No
Are there vaccines for TB in cattle?
No
What disease does M. avian subsp. paratuberculosis cause?
Johne’s disease or paratuberculosis
What is Johne’s disease?
A chronic, progressive granulomatous enteritis
Who is the primary host for Johne’s disease?
Ruminants (cattle)
If you suspect Johne’s infection in mother, what should happen to the calf?
Remove from mother and feed colostrum
What is the “iceberg effect” for paratuberculosis?
If one clinical animal is detected, many cases of subclinical animals exist
What are the symptoms of Johne’s disease?
Diarrhea and weight loss bc there is no absorption of nutrients due to caseous granulomas in mucosa
What is the main DX method for paratuberculosis?
Serology-Ab detection
What are two ways to detect host response to paratuberculosis infection?
- Humoral Immune response
2. Cell mediated immune response - Johnin hypersensitivity skin test
Why are vaccines for Johne’s disease restricted?
Vaccines highly reactive
T/F: M. paratuberculosis has a role in Human Crohn’s disease
True
What does Mycobacterium avian complex (MAC) cause?
Avian tuberculosis
How can MAC spread?
Wide spread in soil, water, including treated municipal tap water
What does Mycobacterium ulcers cause?
Buruli ulcer
What does Mycobacterium leprae cause?
Leprosy or Hansen’s disease
What is the only know animal reservoir for M. leprae?
Nine banded Armadillo in southern US
What is tuberculoid leprosy?
Few acid positive bacilli in lesion
What is lepromatous leprosy?
No cell mediated response, severe disease with numerous acid fast + bacilli
What does Mycobacterium lepraemurium cause?
Feline and murine leprosy
What is seen with feline and murine leprosy?
Granulomatous dermatitis panniculitis
Leproid granulomas
What is seen in DX of M. lepraemurium?
In geimsa or gram stain, will see negative stained bacilli
How would you TX Leprosy in dogs?
Doxycycline can be effective
What kind of host response is seen with Saprophytic Mycobacterial spp?
Granulomatous pyogranulomatous host response
What is seen with Saprophytic Mycobacterial spp?
Chronic, non-healing cutaneous lesions and lack of response to common antimicrobial treatments
