Mycobacteria- Exam III Flashcards
Mycobacteria is a ____ bacterial genus:
acid fast
Mycobacteria have ___ in the cell wall
mycolic acid
Mycolic acid in the ___ of mycobacteria make ____ less effective
cell wall; gram-stain
Describe the gram stain of mycobacteria:
weakly gram positive staining
What is used instead of gram stain in mycobacteria?
acid-fast stain or specific fluorescent detection
Discuss the oxygen requirements of mycobacteria:
obligate aerobe
What two properties of mycobacterium allow them to grow in lung macrophages:
- facultative intracellular growth
- obligate aerobes
What are the reservoirs for mycobacteria?
humans
The basis for diseases caused by mycobacteria is ____ transmission
airborne
As few as ____ cells can result in a mycobacterial infection
10 cells
Mycobacteria was the first organism used in:
koch’s postulates
Describe acid-fast staining:
involves driving a stain into the mycolic acid using a hot carbol fuschin
Basically along the entire surface of the bacterial cell wall structure in mycobacteria:
glycolipids
Glycolipids on the surface of the bacterial cell wall structure in mycobacteria, associate with ____ and cause ____.
mycolic acid; cord formation (adjacent cells stick together)
What is the glycolipids covering the surface of the mycobacterial cell wall referred to as?
cord-factor
What is responsible for the virulence of mycobacteria?
slow cord-like growth
Slow, cord-like growth in mycobacteria results from:
adherence of cell surface lipid mycolic acids with glyco-lipids
While many virulence factors contribute to the virulence of mycobacteria, it is mainly resulting from:
the challenge they provide to the immune repsonse
What do we mean when we say infection with mycobacteria “challenges the immune response”
It obstructs the CD4+ T-cell response in macrophages (delayed type hypersensitivity response)
A disease like leprosy or TB is typically caused by ____ and not ____.
the character of the immune response, not the mycobacteria/toxins themselves
How do the mycobacteria facultatively grow intracellularly in alveolar and other macrophages?
inhibition of phagolysosome fusion
Involves a cell mediated response that will result in a granuloma surrounded by lung tissue and inflammatory leukocytes and contains a central area of necrosis where the nuclei have been destroyed:
CMI to mycobacterium tuberculosis
____ is surrounded by punctate nuclei of lung tissue and inflammatory leukocytes
TB granuloma
What is at the center of a TB granuloma?
central area of necrosis where nuclei have been destroyed
Mycobacteria tuberculosis is a “____” pathogen. Explain
life-long; once infected you may be asymptomatic but never cured
What is the transmission of mycobacterium tuberculosis?
aerosol
Effective ____ is capable of localizing and stopping infection by M. Tuberculosis
Cell-mediated immune response
What is an exception to the idea that an effective cell mediated response is capable of localizing and stopping infection of M. tuberculosis?
young children under 5 years have a high risk for developing progressive TB due to insufficient immune system development/activation
The outcomes of untreated primary TB (for non-immune compromised patients):
____ show no disease (body keeps under control)
____ show clinical TB
____ show progressive systemic disease and death
91%, 6%, 3%
secondary tuberculosis is also known as:
actue/open TB; galloping consumption
Secondary tuberculosis is caused by:
endogenous reactivation of prior infection
While ____, secondary tuberculosis is ____, and ____ is mandatory
rare; VERY contagious; isolation
Endogenous reactivation of prior TB infection is stimulated by:
- stress
- malnutrition
- HIV
Describe what m. tuberculosis disease arises from:
Tissue destruction by our immune defenses and NOT by damage caused by the bacterial infection
In M. Tuberculosis, the repeated attempts to remove foci of infection by lung macrophages causes ____ that impairs lung function
granulomatous lung tissue
Breathing impairment in TB is not due to tuberculosis bacilli but by the:
macrophage-induced tissue destruction
A positive tuberculin test to subdermal PPD (processed protein derivative of the cell wall of the opportunistic intracellular pathogen mycobacterial tuberculosis)
Mantoux reaction
The Mantoux reaction results from a a positive ____ test to ____.
tuberculin; subdermal PPD
What determines where you have a positive or negative TB test?
depends on strength of reaction
Postive TB test =
Strongly positive TB test=
> 10mm redness; >20mm redness
Discuss the possibility of a vaccination against M. tuberculosis
possibility of vaccination with a related mycobacterial species M. Bovis
What species does the M. tuberculosis vaccine come from?
M. bovis
Discuss the type of vaccine created for TB
attenuated vaccine- meaning it is a live bacterium that is
“attenuated” meaning its NOT capable of infection
Name of the TB vaccine:
Bacille Calmette-Guerin (BCG)
The BCG vaccine is a vaccine that protects against:
M. Tuberculosis
The BCG vaccination against M. Tuberculosis has ___ in humans but is ____ in ____ persons
little virulence; infectious; immune-compromised
In what situations might the BCG vaccine for M. Tuberculosis offer some protective immunity?
when given to young children
Why the BCG vaccination discouraged in the US?
gives positive tuberculin test; thus removing an important diagnostic screening tool
M. Leprosy is really dependent in terms of course of disease on:
the genetic makeup of the individual
Describe what occurs when a healthy individual with a healthy immune system encounters M. Leprosy:
CMI conquers disease
Describe what occurs with individuals with a strong Th1-response upon encountering M. Leprosy:
macrophages kill nerves; macula’s and plaques without sensation (this is good prognosis for recovery, and NOT infectious)
In cases where you have a loss of CMI and Th2 response, when encounter with M. Leprosy occurs, what will happen?
CTL lysis an gloss of tissue and nerves
Main symptom of this disease is tissue destruction:
Leprosy
What is the more severe in terms of tissue loss between tuberculoid leprosy & lepramatous leprosy?
Lepromatous leprosy
Between tuberculoid leprosy and lepromatous leprosy which is more widespread with higher bacterial growth?
lepromatous leprosy
Discuss a treatment option for Leprosy:
multidrug therapy: Dapsone + Rifampin + Clofazimine
What is becoming a problem with leprosy treatment?
Drug resistance
Discuss the virulence factors of M. Tuberculosis:
ability to survive and live in lung macrophages
Discuss the clinical features of M. tuberculosis:
pulmonary (& extra pulmonary) tuberculosis
Discuss the treatment for M. Tuberculosis:
Multi-drug therapy (6-12 months)
Discuss the epidemiology for M. Tuberculosis:
Aerosol (person-to-person), all ages but high risk if immune compromised
Discuss the virulence factors of M. Leprae:
ability to survive and live within macrophages
Discuss the clinical features of M. Leprae:
Tuberculoid-to-lepramatous leprosy
Discuss the treatment for M. Leprae:
Multi-drug therapy; 2+ years
Discuss the epidemiology of M. Leprae:
Close physical contact
ALL pathogenic mycobacterial species have:
VERY slow growth rates
What is the gram stain for Nocardia?
Gram positive but poor staining
Nocardia belong to the classification of:
Partially acid-fast
What makes nocardia partially acid-fast?
Presence of mycolic acid in the cell wall
The acid-fast test is used to distinguish nocardia from:
fungal look-alikes
Discuss the virulence factors of nocardia:
opportunistic pathogen- in immunocompromised patients
