Quiz on Mycobacterium Characteristics with Flashcards

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Questions and Answers

What is the primary component of the cell wall of Mycobacterium tuberculosis?

Teichoic acid

Peptidoglycan

N-glycolylmuramic acid (correct)

Lipopolysaccharide

What is the optimal pH range for the growth of Mycobacterium tuberculosis?

7.0 - 7.5

5.5 - 6.5

7.5 - 8.0

6.5 - 6.8 (correct)

Which of the following is NOT a characteristic of Mycobacterium tuberculosis?

Aerobic

Spore-forming (correct)

Motile

Catalase positive

What is the generation time of Mycobacterium tuberculosis?

>12 hours Signup and view all the answers

Which of the following is a rapid-growing mycobacterium?

Mycobacterium fortuitum Signup and view all the answers

What is the optimal temperature for the growth of Mycobacterium tuberculosis?

35-37°C Signup and view all the answers

What is the primary means of transmission of Mycobacterium tuberculosis?

Inhalation of airborne droplet nuclei Signup and view all the answers

Which of the following is a common symptom of tuberculosis in the spine?

Severe back pain Signup and view all the answers

What is the primary method of diagnosis for pulmonary tuberculosis?

Tuberculin test Signup and view all the answers

Which of the following is a risk factor for developing tuberculosis?

Malnourished patients Signup and view all the answers

What is the characteristic feature of Miliary tuberculosis?

Millet-seed-like granuloma formation in various organs Signup and view all the answers

What is the term used to describe the sulfates attached to the disaccharide (trehalose) in Mycoside Cord Factor?

Sulfides Signup and view all the answers

Which of the following Mycobacterium species has been isolated from tuberculosis patients in both immunocompetent and immunocompromised individuals?

Mycobacterium microti Signup and view all the answers

What is the primary function of the most common virulence factor for M.tuberculosis?

Activating the protective cellular immune system Signup and view all the answers

What is the characteristic appearance of rough colonies of M.tuberculosis?

Curved strands of bacilli exhibiting 'cording' Signup and view all the answers

What is the purpose of the BCG strain of Mycobacterium bovis?

To vaccinate newborns against tuberculosis Signup and view all the answers

What is the mode of transmission of Mycobacterium bovis to humans?

Through contaminated milk from infected cows Signup and view all the answers

What is the characteristic of Mycobacterium bovis growth on Egg-based media?

Slow growing, small, and non-pigmented Signup and view all the answers

What is the primary function of albumin in serum agar-based media?

to protect AFB against toxic agents in the culture media Signup and view all the answers

Which medium is specifically designed for heavily contaminated specimens?

Petragnani medium Signup and view all the answers

What is the name of the oxygen sensor used in the MGIT 960 system?

Fluorescence quenching-based oxygen sensor Signup and view all the answers

Which of the following inhibitory agents is NOT used in Middlebrook 7H11 medium?

Trimethoprim lactate Signup and view all the answers

What is the primary advantage of the BACTEC 12B system?

Reduced processing time for the isolation of AFB Signup and view all the answers

What is the name of the test used for extrapulmonary specimens?

XPERT MTB/RIF test Signup and view all the answers

Which of the following species of Mycobacterium is known to produce yellow to orange pigmented colonies even without light exposure?

M. xenopi Signup and view all the answers

What is the most common site of colonization by Mycobacterium avium complex?

Gastrointestinal tract Signup and view all the answers

What is the growth rate of Mycobacterium xenopi?

10-21 days Signup and view all the answers

Which biochemical test is variable in Mycobacterium avium complex?

Pyrazinamidase Signup and view all the answers

What is the major species of Mycobacterium avium complex?

M. avium and M. intracellulare Signup and view all the answers

Study Notes

Mycobacteria General Characteristics

Mycobacteria are aerobic, slow-growing, and non-spore forming bacilli
They are non-motile, catalase positive, and non-encapsulated
They produce granules, and their cell wall contains N-glycolylmuramic acid and mycolic acid
They are obligate aerobes, with growth enhanced by increased CO2
They have a pH requirement of 6.5-6.8 and a generation time of over 12 hours
Some species are slow growers, taking over 2 weeks to incubate, while others are rapid growers, taking around 3 days

Mycobacterium Tuberculosis Complex

The complex includes M. tuberculosis (Koch's bacillus), M. bovis, M. africanum, M. canetti, M. microti, and M. pinnipedii and M. caprae
M. tuberculosis is a slow-growing, non-spore forming, non-motile, and non-encapsulated bacterium
It is an obligate aerobe, with a pH requirement of 6.5-6.8 and a generation time of over 12 hours
It can cause tuberculosis, which is typically diagnosed through a positive tuberculin test

Non-Tuberculous Mycobacteria (NTM)

NTM includes slow-growing and rapid-growing mycobacteria
Slow-growing NTM includes M. avium complex, M. gordonae, M. kansasii, M. marinum, M. terrae complex, M. ulcerans, and M. xenopi
Rapid-growing NTM includes M. fortuitum, M. chelonae, and M. abscessus subsp. abscessus

Biochemical Tests

Positive tests for Mycobacterium include niacin, nitrate reduction, and pyrazinamidase
Negative tests for Mycobacterium include urease, thiophene-2 carboxylic acid (T2H) inhibition test, and catalase test

Mycobacterium Microti

M. microti is a slow-growing, non-spore forming, non-motile, and non-encapsulated bacterium
It has been isolated from tuberculosis patients in both immunocompetent and immunocompromised individuals
It is found in rodents and is considered an agent of tuberculosis in animals

Mycobacterium Pinnipedii and Caprae

M. pinnipedii and M. caprae were first isolated from animals, and further studies showed that they can also be transmitted to humans

Tuberculosis is a potentially fatal form of disseminated TB characterized by millet-seed-like granuloma formation in various organs
It arises from a primarily pulmonary infection that spreads hematogenously
Common sites of infection include the spleen, lungs, bone marrow, kidneys, adrenal glands, and eyes
Miliary tuberculosis is a potentially fatal form of disseminated TB

Virulence Factors

Virulence factors for Mycobacterium include sulfides, mycoside cord factor, and wax D
The most common virulence factor for M. tuberculosis is a complicated mycoside that acts as an adjuvant and activates the protective cellular immune system

Mycobacterium Bovis

M. bovis is an attenuated strain used for vaccination
It is acquired by humans through the ingestion of contaminated milk from infected cows
It can also be transmitted through exposure to different animals
Culture: Egg-based media, slow growing, small, smooth, rounded, and non-pigmented

Screening for Pulmonary PTB in Adults

Lowenstein-Jensen medium is the most commonly used medium for screening
American Thoracic Society medium is used for CSF and BM
Petragnani medium is used for heavily contaminated specimens
Wallenstein medium is used for M. avium complex
Serum agar-based media (transparent media) are mainly composed of bovine albumin, glycerol, malachite green, oleic acid, and B-catalase
The purpose of albumin is to protect AFB against toxic agents in the culture media

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Description

Test your knowledge of Mycobacteria, including Mycobacterium tuberculosis complex. Learn about their characteristics, cell wall composition, and growth requirements.

Mycobacteria: General Characteristics

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