Mycobacteria Flashcards
4 NTM that can give false positive with an IGRA test?
1) M. kansasii (human)
2) M. marinum (human)
3) M. szulgai
4) M. flavescence
3 TB antigens used by the Quantiferon Gold IGRA test?
1) ESAT-6
2) CFP-10
3) TB7.7
In IGRA testing what is phytohemagglutin (PHA)?
The positive control (mitogen)
Name 1 spore forming mycobacterium?
M. marinum
Pigment classifications of mycobacterium?
Nonchomogen
Photochromogens
Stotochromogen
Definition of rapid growing mycobacteria?
Grow in 7 days or less on solid LJ media from subculture
What is in LJ media?
Malachite green Eggs Gylcerol Starch Asparagine Magnesium citrate
8 members of the Mycobacterium tuberculosis complex?
1) M. tuberculosis
2) M. bovis
3) M. bovis BCG
4) M. africanium
5) M. microti
6) M. caprae
7) M. canettii
8) M. pinnipedii
5 groups of persons with greater risk factor for progression from latent TB to active TB?
1) HIV
2) Underlying medical conditions
3) Infected in the past 2 years
4) Children <4 years old
5) Persons with fibrotic or cancerous lesions on CXR
Difference in treatment between M. tuberculosis and M. bovid?
M. bovis is intrinsically resistant to Pyrazinaminde
3 drugs used in the treatment of M. leprae?
1) Dapsone
2) Rifampin
3) Clofazimine
2 principle manifestations of leprosy?
1) Anesthetic skin lesions
2) Peripheral neuropathy
How is leprosy transmitted?
Shedding from the nose - prolonged and intimate contact with a person with multibacillary disease (lepromatous)
What is the preferred decolorizer for M. leprae?
10% sulphuric acid (it’s less acid fast than TB)
10 clinically relevant slow growing mycobacterium species? (not TB)
- M. avium Complex
- M. genavense
- M. haemophilum
- M. kansasii
- M. malmoense
- M. marinum
- M. simiae
- M. szulgai
- M. ulcerans
- M xenopi
MAC disease in
- Men
- Women
- Children
Men = Upper lung fibrocavitary disease (like TB) Women = Lady Windermere Syndrome (nodular bronchiectasis) Children = Lymphadenitis
2 species in MAC?
1) M. avium
2) M. intracellulare
2 growth characteristics of Mycobacterium marinum?
1) Requires 30 degrees
2) Photochromogenic
Name 1 NTM that can synthesize niacin?
M. simiae
M. szulgai temperature dependant chromogens?
25 degrees = photochromogenic
37 degress = scotochromogenic
3 laboratory practices for TB lab?
1) Restricted access
2) Negative pressure with directional airflow
3) PPE
4 recommendations for respirators for M. tuberculosis?
1) Filter particles 0.3 um in size, 95% efficiency at 50 L/min flow
2) Fit tested for no more than 10% face seal leakage
3) Available in at least 3 different sizes
4) Fit checked by the person wearing it each time
3 effective disinfectants for the TB lab?
1) Amphyl (phenol-soap mixture)
2) 0.05-0.5% sodium hypochlorite
3) UV light
Steps in case of a TB laboratory accident (spill)
1) Personnel should hold their breath
2) Make sure BSC are on
3) Turn off centrifuges
4) Leave the area ASAP
5) Keep door closed for 30 min prior to going in to clean up
Criteria for shipping dangerous goods?
1) Rigorous packing
2) Appropriate labels
3) Documentation of hazardous contents of the box
4) Training of workers in the transportation chain
3 NTM organisms that grow optimally at 30 degrees?
1) M. marinum
2) M. haemophilum
3) M. ulcerans
Optimal contamination rate in TB samples?
3-5%
4 methods to decrease the contamination rate of mycobacterial samples?
1) Increase the strength of the alkali treatment
2) Use a selective media
3) Make sure specimens are completely digested
4) Use an alternate digestion/decontamination procedure for problem specimen types
Fluorescent dye used to stain mycobacterium?
Auramine O +/- rhodamine B
4 species other than M. tuberculosis that can have cording?
1) MAC
2) M. gordonae
3) M. chelonae
4) M. marinum
1 NTM that does not grow on LJ media?
M. genavense
What atmosphere are mycobacterium incubated in for isolation?
5-10% CO2
3 limitations of TST testing?
1) Can not distinguish TB from BCG
2) Unknown predictive values
3) Cross reactions with NTM
6 Digestion-Decontamination methods for mycobacterial samples
1) NALC-NaOH
2) NaOH
3) Oxalic Acid
4) CPC
5) Zephiran-Trisodium Phosphate
6) Sulfuric Acid
Pigmentation (Y/N) for
- MAC
- M. gordonae
- M. kansasii
- M. marium
- M. ulcerans
Yes to all except M. ulcerans is non pigmented
3 slow growing mycobacteria (besides TB) that can reduce nitrate?
1) M. kansasii
2) M. simiae
3) M. szulgai
3 Nucleic acid tests for direct testing for mycobacteria and type of test they are?
1) AMTD (TMA of rRNA)
2) GeneXpert (RT PCR, amplification of rhoB)
3) Hain MTBDRplus (PCR amplification + Line Probe assay)
Optimal growth temperature of:
- M. haemophilum
- M. marinum
- M. xenopi
M. haemophilum = 25-30
M. marinum = 30
M. ulcerans = 30
M. xenopi = 40-45
2 paper test strips that are positive for M. tuberculosis?
1) Nitrate
2) Niacin
For what mycobacteria is 16S rRNA sequencing not discriminatory?
M. marinum M. ulcerans M. chelonae M. absessus M. kansasii M. gastri
For what mycobacteria do the Accuprobe DNA probes detect?
MTB Complex
MAC
M. gordonae
M. kansasii
3 methods for genotyping M. tuberculosis strains?
1) IS6110 RFLP Typing
2) Spoligotyping
3) MIRU-VNTR Typing (Mycobacterial interspersed repetitive units)
2 methods for genotyping Slowly Growing NTMs?
1) PFGE
2) rep-PCR (Repetitive-unit sequence based PCR)
2 antimicrobial susceptibility test methods for Slowly Growing NTM?
11) Broth microdilution
2) Broth macrodilution
CLSI recommends antimicrobial susceptibility testing for what 3 slowly growing NTM organisms?
1) M. kansasii
2) M. marinum
3) MAC
What drugs should be reported for M. kansasii?
Rifampin and Clarithromycin
if Rif resistant then test the whole panel
What drugs should be tested for MAC?
Only Clarithromycin
2 testing methods for M. tuberculosis for antimicrobial susceptibility?
1) Agar proportion
2) Broth based (commercial) systems
What drugs should be tested for TB if resistant to rifampin, or any 2 other primary drugs?
1) Ethambutol (higher concentration)
2) Capreomycin
3) Ethionamine
4) Amikacin
5) p-aminosalicylic acid
6) Rifabutin
7) Streptomycin
8) Levofloxacin
List the 6 groups of rapid growing mycobacterium with pigment characteristics
1) M. fortuitum group - No pigment
2) M chelonae/absessus group - No pigment
3) M. mucogenicum group - No pigment
4) M. smegmatis group - Late pigment
5) M. neoaurum - Early pigment
6) M. mageritense/M. wolinskyi
Temperature for primary isolation of RGM?
28-30 degrees
Of the 3 clinically relevant RGM
- Polymyxin B resistance
- Cefoxitin Resistance
Polymyxin B: M. chelonae/absessus no zone
Cefoxitin: M. chelonae no zone
Macrolide resistance for the RGM?
M. abscessus and M. fortuitum have erm gene
M. cheloae does not
Preferred aminoglycoside for M. chelonae and M. abscessus?
M. abcessus = Amikacin
M. cheloae = Tobramycin
2 methods for genotyping RGM strains?
1) PFGE
2) RAPD-PCR (Randomly Amplified Polymorphic DNA PCR)
What drug should not be reported for M. abscessus/cheloae?
Imipenem (results are not reproducible)
3 reasons why IGRA use is cautioned in children less than 5 years of age?
1) Data is limited
2) Children can rapidly progress to severe disseminated disease
3) 5 mL of blood is required which may be excessive in small children
