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Questions and Answers
What characteristic of Mycobacteria is responsible for their resistance to staining with commonly used basic aniline dyes?
What characteristic of Mycobacteria is responsible for their resistance to staining with commonly used basic aniline dyes?
Which Mycobacterium strain is included in the Mycobacterium tuberculosis Complex?
Which Mycobacterium strain is included in the Mycobacterium tuberculosis Complex?
What is the typical route of transmission for Tubercle bacilli causing TB?
What is the typical route of transmission for Tubercle bacilli causing TB?
In infected individuals, what can potentially lead to the reactivation of TB?
In infected individuals, what can potentially lead to the reactivation of TB?
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What biological components are typically found in a granuloma formed during TB infection?
What biological components are typically found in a granuloma formed during TB infection?
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What is the purpose of a positive PPD skin test in the clinical diagnosis of primary TB?
What is the purpose of a positive PPD skin test in the clinical diagnosis of primary TB?
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What is the term used to describe the seeding of many organs outside the pulmonary tree with AFB through hematogenous spread?
What is the term used to describe the seeding of many organs outside the pulmonary tree with AFB through hematogenous spread?
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Which organ infection is referred to as Pott disease?
Which organ infection is referred to as Pott disease?
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Which characteristic can be seen in the colonies of Mycobacterium tuberculosis?
Which characteristic can be seen in the colonies of Mycobacterium tuberculosis?
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What is the typical temperature range for the optimal growth of Mycobacterium tuberculosis?
What is the typical temperature range for the optimal growth of Mycobacterium tuberculosis?
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What is the standard treatment duration for pulmonary TB with isoniazid and rifampin?
What is the standard treatment duration for pulmonary TB with isoniazid and rifampin?
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Which type of Mycobacterium is described as a rare cause of mycobacteriosis known as Buruli ulcer?
Which type of Mycobacterium is described as a rare cause of mycobacteriosis known as Buruli ulcer?
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What type of colonies does Mycobacterium marinum form when grown in or exposed to light?
What type of colonies does Mycobacterium marinum form when grown in or exposed to light?
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Which form of tuberculosis is caused by Mycobacterium marinum and occurs when traumatized skin comes into contact with salt water or inadequately chlorinated fresh water?
Which form of tuberculosis is caused by Mycobacterium marinum and occurs when traumatized skin comes into contact with salt water or inadequately chlorinated fresh water?
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What type of colonies do Mycobacterium scrofulaceum form?
What type of colonies do Mycobacterium scrofulaceum form?
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Which Mycobacterium species is implicated in diseases of fish and isolated from aquariums?
Which Mycobacterium species is implicated in diseases of fish and isolated from aquariums?
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What is a common clinical manifestation of Mycobacterium marinum infection in humans?
What is a common clinical manifestation of Mycobacterium marinum infection in humans?
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Study Notes
Mycobacteria Characteristics
- Slender, slightly curved or straight, rod-shaped organisms
- Nonmotile and do not form spores
- Cell wall has extremely high lipid content, resisting staining with basic aniline dyes
- Acid-fastness allows them to resist decolorization with acid-ethanol
Mycobacterium Tuberculosis Complex
- Consists of M. tuberculosis, M. bovis, M. africanum, M. canettii, and M. microti
- M. bovis includes the vaccination strain bacillus Calmette-Guérin
Mycobacterium Tuberculosis (TB)
- Usually a disease of the respiratory tract
- Acquired from persons with active disease who are excreting viable bacilli
- Granuloma formation leads to healing, fibrosis, encapsulation, and calcification
- Potential for reactivation of TB in infected individuals
- Clinical diagnosis: positive PPD skin test, confirmed by stained smear and culture of sputum, gastric aspirates, or bronchoscopy specimens
Extrapulmonary Tuberculosis
- Miliary TB: seeding of many organs outside the pulmonary tree with AFB through hematogenous spread
- Can infect almost any organ of the body
- Manifestations: pleurisy, lymphadenitis, genitourinary TB, skeletal TB (Pott disease), meningitis
Mycobacterium Characteristics
- Colonies are typically raised, with a dry, rough appearance
- Nonpigmented and buff-colored
- Elaboration of cord factor results in characteristic cord formation
- Optimal growth at 35° C to 37° C
- Positive for niacin accumulation, reduction of nitrate to nitrite, and production of catalase
- Grows on thiophene-2-carboxylic acid hydrazide (T2H)
Treatment
- Pulmonary TB: 9-month course of therapy with isoniazid and rifampin
Other Mycobacteria
- Mycobacterium scrofulaceum: causes cervical lymphadenitis in children
- Mycobacterium simiae: isolated from the lymph nodes of monkeys
- Mycobacterium ulcerans (Buruli ulcer): acid-fast cells are long, without beading or crossbanding
- Mycobacterium marinum: implicated in diseases of fish, causes cutaneous infections in humans, and is susceptible to rifampin and ethambutol.
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Description
Explore the characteristics of mycobacteria, focusing on their slender, rod-shaped morphology and unique cell wall with high lipid content. Learn about the acid-fastness property that allows mycobacterial cells to resist staining with basic aniline dyes commonly used in Gram stain.
