Lesson 9: The Mycobacteria Flashcards
Identify the bacteria:
Rod-shaped
Non-motile
Non-encapsulated
Non-spore forming
Strictly aerobic
Catalase (+)
Produces Much’s granules (inclusion bodies)
Mycobacteria
What is the inclusion body of Mycobacteria?
Much’s granules
Repels the action of gram-stain that is the reason why Mycobacterium is stained with acid fast staining
Mycolic acid
What is the mordant for Mycobacteria when using acid-fast stain?
Heat
Heating is the principle of what technique?
Ziehl-Neelssen Technique
Cold method uses “detergent” which is the principle of?
Kinyoun method
Stains are difficult to be decolorized in mycobacteria because of the presence of?
Mycolic acid
3 major groups of Mycobacteria
Mycobacterium tuberculosis complex
Non-tuberculous mycobacteria (NTM)
Mycobacterium leprae
Classification of Mycobacterium based on PHOTOREACTIVITY
produce carotene pigment upon exposure to light
Photochromogens
Classification of Mycobacterium based on PHOTOREACTIVITY
produce carotene pigment in light or dark
Scotochromogen
Classification of Mycobacterium based on PHOTOREACTIVITY
No pigment; these colonies are a buff color
Nonphotochromogenic
M. tuberculosis complex (5)
M. tuberculosis
M. bovis
M. africanum
M. microti
M. canetti
Photochromogens (3)
M. kansasii
M. marinum
M. simiae
Scotochromogens (3)
M. scrofulaceum
M. szulgai
M. gordonae
Nonphotochromogens (4)
M. avium complex
M. xenopi
M. mamoense
M. paratuberculosis
Rapid Growers (3)
M. fortuitum
M. chelonae
M. abscessus
Primarily a pathogen of the respiratory tract and once called “Consumption”
Mycobacterium tuberculosis
2 Types of Tuberculosis
Primary Tuberculosis
Extrapulmonary Tuberculosis
A test for Mycobacterium tuberculosis where it detects patient’s cell-mediated immune response to bacterial antigens
PPD Test (Purified Protein Derivative Test) / Mantoux / Tuberculin Skin Test / TB Skin test
Method for detecting Mycobacterium tuberculosis
Blood test
Measure person’s immune reactivity to specific mycobacterial antigens
Interferon-Gamma Release Assays
Identify the bacteria:
Primarily in cattle, dogs, cats, swine, parrots, and human
Slow grower
Nonpigmented
Similar to M. tuberculosis
Small, granular, rounded “WHITE COLONIES” with irregular margins
Mycobacterium bovis
MOTT stands for?
Mycobacteria other than Tubercle Bacillus
MOTT is also known as?
NTM/Non-Tubercle Bacillus
It is an opportunistic pathogen in patients with liver disease, immunocompromised, percutaneous trauma
NTM/Non-Tubercle Bacillus
It causes leprosy
Mycobacterium leprae
Other name of Leprosy
Hansen’s Disease
Identify the bacteria:
Infection of the skin, mucous membranes, and peripheral nerves
Most cases are from warm climates
Bacteria infect the cooler areas of the body (ears, nose, eyebrows, fingers, toes)
Causes leprosy
Mycobacterium leprae
Sputum specimen that is the method of choice (self couching)
Spontaneous
Sputum specimen with aerosol saline (facilitates coughing)
Induced
For sputum specimen in Mycobacteria, what type of cough or sputum is needed?
Deep cough or expectorated sputum induced by nebulization
True or False
Bronchial washing or lavages can be collected as specimen for Mycobacteria
True
It is the specimen of choice for detection in children and infants
Should be processed within 4 hours
Gastric Lavage/Aspirates
Gastric Lavage/Aspirates contain this substance that can neutralize the acidity of the gastric lavage in order to not kill the mycobacteria
Sodium carbonate
It is used to recover mycobacterium that may have been swallowed during the night
Only used when patient is unable to produce a good quality sputum specimen
Gastric aspirates
Ideal for isolation of mycobacteria
Urine
Why is 24-hour urine specimen not ideal for Mycobacteria?
Because of dilution and high concentration
What is the preferred urine specimen?
First morning midstream
Minimum required urine volume for urine specimen of mycobacteria?
15 mL
Can pooled urine be collected?
Yes, but it most not exceed 12-24 hours
What type of specimen uses Lidocaine to obtain airway mucosal anesthesia?
Bronchoscopy specimen
It is used in Bronchoscopy specimen to obtain airway mucosal anesthesia
Lidocaine
Can stool/fecal specimens be submitted for mycobacteria?
Yes, as long as it does not have a preservative
Effect of contaminants in fecal specimens can cause what type of results?
False-negative results
Stool specimens is primarily collected from AIDS patients to determine what type of Mycobacterium?
Mycobacterium avium complex (MAC)
These are centrifuged for concentration of sediments first before inoculating for culture
Body fluids
It is a test used for the detection of Mycobacteria in the blood
Interferon-Gamma assay
Specimen from non-sterile site is mixed with an agent that will kill non-mycobacterium bacteria
These common decontamination agents are?
Sodium Hydroxide (NaOh) - most common
Oxalic acid (used with Ps. aeruginosa)
Benzalkonium chloride + Trisodium phosphate (Zephiran)(used for the presence of Pseudomonas)
Liquefying mucus enables the mycobacterium to contact and use the nutrients in the agar medium
These common digestion agents are?
N-acetyl-L-cysteine (NAC) + 2% NaOH = Most common
Trisodium phosphate (Z-TSP) with Zephiran
Dithiothreitol (DTT) + 2% NaOH (sputolysin)
Purpose of NAC as a digestion agent is to split what?
To split the disulfide bonds
2% Sodium Hydroxide (NaOH) acts as what?
Antimicrobial agent
3 Types of sterile specimens
CSF
Synovial Fluid
Biopsy Tissue
For concentration of Mycobacteria, after decontamination and digestion, it is centrifuged for how many minutes?
15 minutes at 3000g
It uses heat to drive the color into the lipids of the cell wall
Decolorized with “acid-alcohol”
Ziehl-Neelsen method
More sensitive type of Acid Fast Stain
Auramine-Rhodamine Fluorochrome Stain
After staining with Acid-Fast, a minimum of ____ OIF are examined
300 OIF
For hot and cold method, a primary stain is used and it is liquid soluble and contains “phenol”. What is the type?
Carbolfuchsin stain
Carbolfuchsin stain contains this substance that helps the stain penetrate the cell wall
Phenol
What is the counterstain used in Ziehl-Neelsen Method?
Methylene Blue
3 Types of Media used for Mycobacterium
Egg-Based with Malachite Green(Lowenstein-Jensen Medium)
Agar Based
Liquid Media
Agar based media for Mycobacteria which promotes early growth and is “serum based”
Middlebrook 7H10 and 7H11 agar
Liquid Media for Mycobacteria
Middlebrook 7H9 Broth
Laboratories with large volumes of Mycobacterium cultures use an automated reader which is used for blood, body fluids, and bone marrow.
BACTEC
BACTEC broth contains what labeled substrate?
14C
It contains “saponin” to liberate intracellular organisms
Advantages include yielding isolated colonies, quantification of mycobacteria, shorter recovery time
Isolator-Lysis Centrifugation System
Non-tuberculosis Mycobacteria (NTM) can be a slow grower or a rapid grower, which groups are which?
Group 1,2,3 = slow grower
Group 4 = rapid grower
Group 1 of NTM
Photochromogens
Group 2 of NTM
Scotochromogens
Group 3 of NTM
Nonphotochromogens
Group 4 of NTM
Rapid Growers
Growth rate of Rapid Growers
Colonies in <7 days
Growth rate of Slow Growers
Colonies in >7 days
Temperature range for Mycobacteria culture
20-42C
Identify the bacteria
Slow grower
Think, flat, spreading and friable with a rough appearance colony
“Cord” formation
Growth at 35-37C (BT)
Colonies are NOT photoreactive
Mycobacterium tuberculosis
Common antibiotics for Mycobacterium tuberculosis (5)(RIPES)
Rifampin
Isoniazid
Pyrazinamide
Ethambutol
Streptomycin
