Mycobacteria Flashcards
What is the most familiar species of Mycobacterium?
- Mycobacterium tuberculosis
- Mycobacterium leprae
What is other name for leprosy?
- Hansen Disease
What is the counterstain for acid fast staining?
- methylene blue
When there is a delay in the processing of the culture specimen, what should be done?
- refrigeration
The inhibitor present in egg-based media
Malachite green
Positive result for nitrate reduction
Red color
Media that enhanced the isolation of isoniazid resistant strain of MTB
Middlebrook 7H11
The positive Niacin reaction is indicated by
Development of yellow color
The optimal growth temperature for M. xenopi
42 degrees celcius
Which strain is used for the fluorescent staining method for the identification of Mycobacteria?
Auramine
What is the average incubation period for slow growing pathogenic Mycobacteria?
2-6 weeks
Mycobacterium tuberculosis is classified as
Nonphotochromogen
MTB reaction for semiquantitative catalase test
> 45 mm bubble column
Mycobacterium tuberculosis is also known as
Koch’s bacillus
Remains a major cause of morbidity and mortality in the world today
Tuberculosis
Other name of Environmental mycobacteria?
Nontuberculous mycobacterium
What is the morphology of mycobacterium?
Gram positive, slender, slightly curved or straight, rod-shaped
Mycobacteria resist staining with
Aniline dyes such as Gram stain
Mycobacteria is resist decolorization with
Acid ethanol
What is the oxygen requirement for mycobacterium?
Strictly aerobic
Fails to grow in vitro
M. leprae
What does a mycobacterium laboratory should have?
Non-recirculating ventilation system
What is the required respiratory protection or mask?
N-95 mask
What is the most important piece of equipment in the microbiology laboratory?
Biological safety cabinet
Negative pressure cabinet
Class I or biological safety cabinet class 1
Vertical laminar flow cabinets
Class II or biological safety cabinet class II
What is the contact time for proper disinfectants?
10-30 minutes
What is the concentration of sodium hypochlorite?
0.1-0.5%
What is the concentration for phenol?
5%
What is the concentration for formaldehyde and for glutaraldehyde?
3-8% and 2%
What is the contact time for formaldehyde and glutaraldehyde?
At least 30 mins
What are the specimen for collection?
- urine
- feces
- blood
- CSF
- respiratory specimens
- tissue biopsies
- aspirations of any tissue or organ
What are the most common specimen for mycobacterium?
Sputum and bronchial aspirates
What is the process of collecting sputum specimen?
- Early morning specimen
- Should be collected on three consecutive days
What is the volume of sputum?
5-10 mL
What is the recommended container?
Sterile, wide-mouth cup with tightly fitted lid
Patients inhale ____to allow them to cough
Nebulized hypertonic saline
This cell wall of mycobacteria makes them somewhat less suceptible to the killing action of the various chemicals
High lipid content
What is the most popular reagent in decontamination?
2-4% sodium hydroxide
Enumerate the agents we can use for Digestion agents
- 4-2% sodium hydroxide
- N-Acetyl-L-Cysteine (NALC)
- Dithiothreitol
What is the colony appearance of mycobacterium in afb staining?
Beaded appearance
Primary stain
Carbolfuschin
Decolorizing agent
Acid alcohol
What is the color of Acid fast organisms?
Red
What is the color of non-acid fast?
Blue
Application of heat with carbolfuschin stain. Tends to provide more consistent results
Ziehl-Neelsen stain
Cold stain. Tergitol is used as a mordant.
Kinyoun stain
What is the positive color for fluorochrome stain or auramine-rhodamine stain
Yellow-orange bacilli
What genus can use AFB stain?
Nocardia spp
Legionella micdadei
Rhodococcus spp
What is the pH level of mycobacteria?
6.5-6.8
What are the three general types of culture media?
- Egg-based media
- Serum Albumin agar media
- Liquid media
What media is most used in clinical laboratory?
Lowenstein Jensen Medium
Enumerate the egg-based media
- lowenstein jensen media
- petragnani media
- American thoracic society media
Rough often exhibit a prominent patterned texture referred to as cording
M. tuberculosis
Variable appearance with glossy whitish colonies often occuring with smaller translucent colonies
M. avium complex
What is the general morphology of mycobacterium?
Smooth and soft or rough and friable appearance
Produce carotene pigment on exposure to light
Photochromogens
Produce pigment in the light or dark
Scotochromogens
Buff or tan colonies
Nonchromogenic or nonphotochromogenic
Posses th enzyme that converts free niacin to niacin ribonucleotide
Niacin accumulation
Culture media of choice for niacin accumulation
Egg agar
What is the negative result of niacin accumulation?
Colorless
The production of nitroreductase which catalyzes the reduction of nitrate to nitrite
Nitrate reduction
What organisms tested positive for nitrate reduction?
- mycobacterium kansasii
- mycobacterium szulgai
- mycobacterium fortuitum
- mycobacterium tuberculosis
What is the reagent of catalase test?
30% hydrogen peroxide
What is the medium used in catalase test and hydrolysis of tween 80?
Tween 80
Production is determined by measuring the height of the column of bubbles when hydrogen peroxide and tween 80 are added to a deep with mycobacterial growth
Semiquantitative catalase test
Who is positive in semiquantitative catalase test?
Mycobacterium tuberculosis
Test to distinguish scotochromogenic and nonphotochromogenic bacteria
Hydrolysis of tween 80
What is the pH indicator of hydrolysis of tween 80?
Neutral red
Positive color of hydrolysis of tween 80
Pink color
Detecting the ability of mycobacteria to split rhe detergent tweeen 80 into oleic acid and polyoxyethylared sorbitol by the presence of enzyme lipase
Hydrolysis of tween 80
Reduction of colorless potassium tellurite to black merallic tellurium
Tellurite reduction test
Positive in tellurite reduction test
Mycobacterium avium
One of the oldest documented communicable diseases
Mycobacterium tuberculosis
Mode of transmission of tuberculosis
Airborne droplets
It is the initial infection.
Positive in PPD
Primary tuberculosis
Detected by measuring nicotinic acid which reacts with cyanogen bromide in the presence of aniline to form a yellow compound
Niacin accumulation
Performed as with the method used for enteronacteriaceae
Nitrate reduction
The mycobacterium is eradicated by the host cellular immune response or walled off in a granuloma in the lung
Primary tuberculosis
Occurs when there is an alteration or suppression of the cellular immune system in the infected host that favors replication of the bacilli and progression to disease
Reactivation tuberculosis
Common presentation in individuals with HIV
Extra pulmonary tuberculosis
Widespread dissemination of mycobacterium tuberculosis via hematogenous spread
Miliary tuberculosis
Skeletal tuberculosis of the skin also referred to as
Pott disease
What is the treatment for TB
9-month course of therapy with isoniazid and rifampin
Produces TB primarily in cattle
Mycobacterium bovis
BCG vaccine
Mycobacterium bovis Calmette-Guerin
Causative agent of hansen disease or leprosy
Mycobacterium leprae
Tissue or test animal for culture
Armadillo or foot pad
What are the 3 types of leprosy
- Tuberculoid leprosy
- Lepromatous leprosy
- Borderline type of leprosy
Diagnostic skin test for M. leprae
Lepromin skin test
What are the two types of lepromin reaction?
- Fernandez reaction
- Mitsuda reaction
Early reaction; reaction after 24-28 gours
Fernandez reaction
3-4 weeks reaction
Mitsuda reaction
Small amount of organisms in skin lesion
BENIGN type
Positive for lepromin skin test
Tuberculoid leprosy
What is other names for tuberculoid leprosy?
Anesthetic or neural leprosy
Abundant organisms in skin lesion
MALIGNANT
negative in lepromin skin test
Lepromatous leprosy
Lion head appearance
Lepromatous leprosy
No manifestation.
Once activated will cause manifestation
Borderline type of leprosy
What are the treatment for leprosy
- dapsone
- clofazimine
- rifampin
What are the four groups of tubercle bacilli?
- Photochromogen
- Scotochromogen
- Nonphotochromogen
- Rapid growers
Color of scotochromogen
Light or dark orange/yellow
What is the growt of scotochromogen?
10-21 days
Who are the members of scotochromogen?
- mycobacterium scotofulaceum
- mycobacterium gordonae
Color of photochromogen
Light orange/ yellow or dark cream/ buff
Growth of photochromogen
20-21 days
Members of photochromogen
- mycobacterium kansasii
- mycobacterium marinum
- mycobacterium simiae
- mycobacterium balnei
Color or nonphotochromogen
Light or dark cream / buff
Growth of Nonphotochromogen
10-21 days
Members of Nonphotochromogen
- mycobacterium avium
- mycobacterium ulcerans
- mycobacterium xenopi
Growth of rapid growers
3-7 days
Members of rapid growers
- mycobacterium fortuitum