Mycobacteria Overview Quiz

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Questions and Answers

What is the main cause of human tuberculosis in developed countries?

Mycobacterium tuberculosis (correct)

Non-tuberculous mycobacteria

Mycobacterium bovis

Mycobacterium marinum

Which characteristic does NOT describe Mycobacterium?

Spores forming (correct)

Non-motile

Aerobic

Very thin rods

What is the estimated percentage of infected individuals who actually develop tuberculosis?

25-30%

15-20% (correct)

35-40%

5-10%

What is a common mode of transmission for tuberculosis?

Inhalation of a single viable organism Signup and view all the answers

What is the prevalence of tuberculosis in the Philippines?

About 1 million active cases Signup and view all the answers

Which of these mycobacteria is associated with drug-resistant tuberculosis?

Mycobacterium tuberculosis Signup and view all the answers

Which category does Mycobacterium bovis belong to?

Mycobacterium tuberculosis complex Signup and view all the answers

In what state is tuberculosis particularly dangerous for immune-compromised individuals?

Pulmonary phase Signup and view all the answers

What unique component is found in the cell wall of Mycobacterium?

N-glycolyl muramic acid Signup and view all the answers

What characteristic makes Mycobacterium difficult to stain?

High lipid content Signup and view all the answers

Which strain of Mycobacterium bovis is used for immunization against tuberculosis?

Bacillus Calmette-Guerin (BCG) Signup and view all the answers

What is the property of Mycobacterium that allows them to resist decolorization with acidified alcohol?

Acid Fastness Signup and view all the answers

What occurs after the initial infection with Mycobacterium tuberculosis?

Subsequent organ involvement Signup and view all the answers

Which symptom is NOT commonly associated with pulmonary tuberculosis?

Nausea Signup and view all the answers

How do Mycobacterium bacilli typically enter the body?

Ingestion of infected milk Signup and view all the answers

What type of immune response does the BCG vaccine aim to elicit?

Cell-mediated immunity Signup and view all the answers

What is the most likely reason some patients develop miliary tuberculosis?

Poorly functioning cellular immunity Signup and view all the answers

What describes Mycobacterium's classification in terms of Gram staining?

Generally considered gram-positive Signup and view all the answers

Which of the following organs can be involved in tuberculosis infection aside from the lungs?

Cervical lymph nodes Signup and view all the answers

What immune response takes place when the body tries to eliminate Mycobacterium tuberculosis?

Delayed hypersensitivity response Signup and view all the answers

What is a common presenting symptom of miliary tuberculosis?

Night sweats Signup and view all the answers

How is tuberculosis primarily diagnosed?

Tuberculin test Signup and view all the answers

What do granulomas in the lungs primarily consist of?

Macrophages and lymphocytes Signup and view all the answers

Which of the following is NOT a common symptom of primary active tuberculosis?

Loss of taste Signup and view all the answers

What is a disadvantage of the PPD test for tuberculosis?

It lacks 100% sensitivity and specificity Signup and view all the answers

What is indicated by a positive reaction to the PPD skin test?

Exposure to Mycobacterium tuberculosis Signup and view all the answers

What does the term 'miliary' refer to in tuberculosis?

Disseminated disease Signup and view all the answers

Which system can be affected by tuberculosis leading to meningitis?

Nervous system Signup and view all the answers

What does tissue necrosis caused by the hypersensitivity reaction in tuberculosis result in?

Low granuloma formation with caseous material Signup and view all the answers

How are T-cells and macrophages involved in tuberculosis infection?

They help phagocytize the bacteria in the lungs Signup and view all the answers

What is NOT a possible outcome when Mycobacterium antigen concentration is high?

Development of larger granulomas Signup and view all the answers

Which test simulates proteins found in M. tuberculosis for diagnostic purposes?

PD test Signup and view all the answers

Which statement accurately describes the transmission of NTMs?

NTMs are not usually transmitted from person to person. Signup and view all the answers

What is true regarding the isolation of NTM organisms?

Isolation of NTMs may not be associated with disease. Signup and view all the answers

Which factor can complicate the interpretation of an NTM culture?

Nodular or fibrotic changes on chest X-ray. Signup and view all the answers

What does recent contact with an active TB patient suggest regarding NTMs?

NTMs may also be present and complicate diagnosis. Signup and view all the answers

What is a notable characteristic of NTMs regarding their pathogenic potential?

Pathogenic potential varies greatly among different NTM species. Signup and view all the answers

What does the PD Test specifically assess?

Responses to multiple antigens Signup and view all the answers

What characteristic makes the PD Test less subject to reader bias?

The test can be performed in a single visit Signup and view all the answers

What key feature distinguishes the results of the PD Test from the effects of BCG vaccination?

Results are unaffected by previous BCG vaccination Signup and view all the answers

What reaction is observed in an infected individual after the PD Test?

Delayed hypersensitivity reaction Signup and view all the answers

Which of the following best describes induration measured after the PD Test?

Firmness resulting from immune cell influx Signup and view all the answers

Approximately how many species of non-tuberculous mycobacteria (NTMs) are currently recognized?

130 species Signup and view all the answers

What is the primary mode of transmission for Mycobacterium tuberculosis?

Inhalation of infectious aerosols Signup and view all the answers

In which areas can non-tuberculous mycobacteria (NTMs) sometimes colonize healthy individuals?

Skin, respiratory, and gastrointestinal tracts Signup and view all the answers

Study Notes

Mycobacteria

Tuberculosis is a highly curable but prevalent disease.
It's the leading killer among infectious diseases in the Philippines.
Many drug-resistant cases exist.
Mycobacterium belong to a genus of aerobic, non-spore-forming, non-motile microorganisms.
They are rod-shaped (0.2-0.6 μm x 1-10 μm) and may branch.
Cell walls contain unusual N-glycolyl muramic acid (instead of N-acetyl).
High lipid content creates a hydrophobic permeability barrier.
Acid-fastness is a crucial property of mycobacteria, not usually stained by gram staining.
Gram positive
Mycobacteria generally grow slower than most human pathogens (20-36 hours for division).
Colonies form visibly in 2-60 days.

Major Groups of Mycobacteria

Mycobacteria are divided into two groups, based on differences in epidemiology and disease association.
Mycobacterium tuberculosis complex: includes M. tuberculosis, M. caprae, M. bovis, M. microti, M. bovis BCG, and M. canettii, M. africanum, and M. pinnipedii.
Nontuberculous mycobacteria (NTM): all species not in the complex.

Mycobacterium tuberculosis Complex

Pathogenesis (M. tuberculosis): inhalation of a viable organism often leads to infection. The disease usually develops years later due to immune system breakdown.
In some, infection becomes systemic and affects multiple organs.
Pathogenesis (M. bovis): ingestion of infected cow's milk can lead to infection, and the M. bovis strain BCG is used for vaccination.
BCG: attenuated strain of M. bovis, is used to immunize against tuberculosis.

Signs and Symptoms of Tuberculosis

Symptoms can vary from asymptomatic to acutely symptomatic, often include lung-related signs or symptoms.
General common presenting symptoms of pulmonary tuberculosis include low-grade fever, night sweats, fatigue, loss of appetite, and weight loss.

Diagnosis of Tuberculosis

Tuberculin test (PPD): measures delayed hypersensitivity to tuberculin and is often used to diagnose TB infection; however not 100% accurate.
QuantiFERON-TB Gold: new test approved by the FDA to diagnose latent or current TB infection.

Nontuberculous Mycobacteria (NTM)

130 recognized species.
Ubiquitous in the environment.
Infections are rarely transmitted person-to-person.
1959, Runyon's system classifies them into four groups (I-IV) based on growth characteristics and pigment production.
Runyon group I (Photochromogens): require light for pigmentation.
Runyon group II (Scotochromogens): produce pigment in the dark.
Runyon group III (Nonphotochromogens): do not produce pigment under any condition.
Runyon group IV (Rapid growers): exhibit rapid growth(visible in less than 7 days).

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Description

Test your knowledge on mycobacteria, particularly tuberculosis and its health implications. This quiz covers their characteristics, classification, and the major groups within the Mycobacterium genus. Learn about their unique properties and the challenges posed by drug-resistant strains.