BACTE LEC MQ2

What is the general cell size of organisms in the genus Mycobacterium

0.2 to 0.6 µm in width by 1 to 10 µm in length

What structural component makes up an extremely high proportion of the Mycobacterium cell wall

Lipids and mycolic acid (hydroxy methoxy acid)

What is the oxygen requirement for all species in the genus Mycobacterium

Strictly aerobic

What are the motility status and microscopic morphology of Mycobacterium species

Non-motile, plump rods

What special growth requirement is generally needed for culturing slow-growing Mycobacterium species

Whole egg

Why are Mycobacterium species difficult to stain and decolorize once stained

High lipid and mycolic acid content in their cell walls

What primary body systems or disease manifestations are generally associated with Mycobacterium infections

Pulmonary and skin diseases

What are the three main classifications of Mycobacterium species

M. tuberculosis complex, NTM/MOTT (Non-Tuberculous Mycobacteria / Mycobacterium Other Than Tuberculosis), and Non-culturable species

What species are included in the classic/core Mycobacterium tuberculosis complex

M. tuberculosis, M. bovis, M. africanum, M. microti, and M. canettii

What recently recognized animal-associated species belong to the Mycobacterium tuberculosis complex

Mycobacterium caprae, Mycobacterium mungi, Mycobacterium orygis, and Mycobacterium pinnipedii

What are the four Runyon classification categories of Non-Tuberculous Mycobacteria based on growth rate and pigment production

Photochromogens, Scotochromogens, Non-photochromogens, and Rapid growers

Which Mycobacterium species is classified as non-culturable on artificial media

Mycobacterium leprae

What is the typical doubling time for slow-growing Mycobacterium species like M. tuberculosis

24 hours

What is the typical growth timeframe required for rapid-growing Mycobacterium species

3 to 5 days

What is the doubling time or required incubation period before growth is observed in routine slow-growing Mycobacteria cultures

At least 21 days

What is the most common non-sterile specimen submitted for Mycobacterium detection

Sputum

What is the recommended volume for an expectorated or induced sputum sample

5 to 10 mL

How many sputum specimens are recommended for collection per day according to textbook standards versus DOH guidelines

Textbook: 1 specimen per day for 3 days; DOH: 2 specimens in 1 day (1 early morning, 1 random)

Which specimen is preferred for children younger than 3 years, non-ambulatory individuals, or patients unable to produce sputum

Gastric aspirates and washings (gastric lavage)

When and under what condition should gastric aspirate specimens be collected

In the morning after an overnight fast

What is the volume and collection requirement for a urine specimen for Mycobacterium culture

First morning midstream urine specimen, minimum volume of 15 mL

How should non-sterile stool specimens for M. avium complex be stored if processing is delayed by a few hours

Frozen at -20°C

Which patient population commonly submits stool specimens for M. avium complex detection

AIDS patients with disseminated infection

What specimen type and collection conditions are required for detecting Mycobacteremia due to M. avium complex

Sterile blood specimen using SPS, heparin, or citrate anticoagulants

What processing step is applied to sterile body fluid specimens like CSF or tissue before acid-fast staining or culture

Centrifugation to collect sediment

What two sequential steps are required for processing non-sterile specimens prior to Mycobacterium culture

Digestion and decontamination

What is the dual purpose of digestion and decontamination in specimen processing

Digestion liquefies the sample to free trapped organisms; decontamination eliminates normal flora and bacterial contaminants

What is the routine and commonly used digestant and decontaminant agent in laboratories

2%, 3%, or 4% Sodium Hydroxide (NaOH)

What reagent combination is considered the gold standard for Mycobacterium digestion and decontamination

N-acetyl-L-cysteine (NALC) and Sodium Hydroxide (NaOH)

What chemical combination is known as Z-TSP in digestion and decontamination

Benzalkonium chloride (Zephiran) and Trisodium phosphate (TSP)

Which reagent extends the shelf-life of a sputum sample for up to 8 days

1% Cetylpyridinium chloride (CPC) with 1% NaCl

Which decontaminant is specifically used for thin or non-viscous specimens like urine

Sulfuric acid

Which decontaminant reagent at a 0.5% concentration is used for samples likely contaminated with Pseudomonas aeruginosa

0.5% Oxalic acid

Which digestion/decontamination reagent is specifically used for sputum samples from Cystic Fibrosis patients containing M. abscessus

Chlorhexidine

What processing step is performed immediately after adding NaOH to sputum for 15 minutes

Centrifugation to obtain sediment

What are the two main diagnostic uses for the sediment obtained after specimen digestion, decontamination, and centrifugation

1) Acid-Fast Stain screening smear preparation, 2) Inoculation onto culture media

What microscopic criteria defined by Bartlett's scale indicate a true sputum specimen

Presence of >25 PMNs, <10 epithelial cells per low power field, and presence of alveolar macrophages or columnar cells

What patient instructions should be provided prior to sputum collection for Mycobacteria

Brush teeth and gargle with water before collection

What dimension must a blood smear or acid-fast stain smear be for Ziehl-Neelsen or Kinyoun screening

2 x 3 cm or 2 x 5 cm

What is the primary visual difference between the Ziehl-Neelsen and Kinyoun acid-fast staining procedures

Ziehl-Neelsen requires heat (Hot method); Kinyoun does not require heat (Cold method)

What is the microscopic appearance of Acid-Fast Bacilli (AFB) using carbolfuchsin staining methods

Red/pink rods against a blue background

What AFB count corresponds to a report of "0" on the National DOH Ziehl-Neelsen/Kinyoun reporting scale

No AFB seen in 300 visual fields

What AFB count corresponds to a report of "1-9/100 fields" on the National DOH reporting scale

1-9 AFB seen per 100 visual fields (Exact count reported)

What AFB count corresponds to a DOH report of "1+"

10 to 99 AFB per 100 visual fields

What AFB count corresponds to a DOH report of "2+"

1 to 10 AFB per OIF in at least 50 visual fields

What AFB count corresponds to a DOH report of "3+"

More than 10 AFB per OIF in at least 20 visual fields

According to CDC Table 26-2, what is the quantitative report for 0 AFB seen under Fluorochrome (x450) or Carbolfuchsin (x1000)

0 / No acid-fast bacilli seen

According to CDC Table 26-2, what quantitative report is given for 1-2 AFB seen in 300 fields (Fluorochrome) or 1-2 in 70 fields (Carbolfuchsin)

Doubtful acid-fast bacilli seen; resubmit another specimen

According to CDC Table 26-2, what field count range defines a "1+" quantitative result under Carbolfuchsin (x1000)

1-9 AFB in 10 fields

According to CDC Table 26-2, what field count range defines a "2+" quantitative result under Carbolfuchsin (x1000)

1-9 AFB per field

According to CDC Table 26-2, what field count range defines a "3+" quantitative result under Carbolfuchsin (x1000)

4-36 AFB per field

According to CDC Table 26-2, what field count range defines a "4+" quantitative result under Carbolfuchsin (x1000)

36 AFB per field

What five key characteristics are used to classify and identify species under the genus Mycobacterium

1) Growth rate, 2) Colony morphology, 3) Incubation temperature, 4) Photoreactivity/pigment production, 5) Biochemical test results

What ingredient is added to egg-based media to inhibit contaminating organisms

Malachite green

What is the primary disadvantage of using egg-based media like Lowenstein-Jensen

Prolonged growth time (6 to 10 weeks) and opacity (cannot easily detect early pigment)

Which egg-based media is routine for non-sterile specimens

Lowenstein-Jensen (LJ) Media

Which egg-based media is less inhibitory and recommended for sterile specimens

American Thoracic Society (ATS) Media

Which egg-based media contains higher concentrations of malachite green and is most inhibitory for heavily contaminated specimens

Petragnani Media

Which egg-based media is specifically recommended for Mycobacterium avium

Wallenstein Medium

What are the primary advantages of clear, agar-based media over egg-based media for Mycobacteria

Clear media allows easy examination of colonies, detects pigment early, supports faster growth (10-12 days), and serves as an alternative for AST

What agar-based media contains dextrose for mycobacterial growth

Middlebrook 7H10

What chemical supplement is added to Middlebrook 7H11 agar to enhance growth

Casein hydrolysate

Name three examples of selective mycobacterial culture media containing antibiotics

Gruft Modified Lowenstein-Jensen, Selective Middlebrook 7H11, and Mitchison Selective 7H11

Name four liquid or automated culture media used for rapid Mycobacterium detection

BACTEC 12B/13A, Septi-Chek, Middlebrook 7H9, and Dubos Tween Albumin broth

What required media, reagent/indicator, and positive/negative colors define the Niacin Test

Media: Lowenstein-Jensen; Reagents: Cyanogen bromide and Aniline (or impregnated strip); Positive: Yellow; Negative: No color change

Which Mycobacterium species is characteristically Niacin positive

Mycobacterium tuberculosis

What positive and negative controls are used for the Niacin Test

Positive Control: Mycobacterium tuberculosis; Negative Control: Mycobacterium intracellulare

What media, reagents, and color changes occur in the Nitrate Reduction Test

Media: Sodium Nitrate Broth; Reagents: Sulfanilic acid and alpha-naphthylamine (or N,N-dimethyl-1-naphthylamine); Initial Positive: Red; Initial Negative: No color

What step and reagent confirm a true negative result in the Nitrate Reduction Test

Addition of zinc dust/powder; Positive for unreduced nitrate (true negative test): Red; Negative for unreduced nitrate (true positive test): No color change

Which Mycobacterium species is characteristically Nitrate Reduction positive

Mycobacterium tuberculosis

What positive and negative controls are used for the Nitrate Reduction Test

Positive Control: Mycobacterium tuberculosis; Negative Control: Mycobacterium intracellulare

What media, reagent, and positive result color define the Iron Uptake Test

Media: Lowenstein-Jensen; Reagent: 20% Ferric ammonium citrate; Positive: Rusty brown color; Negative: No color change

Which Mycobacterium species is characteristically positive for the Iron Uptake Test

Mycobacterium fortuitum

What media, reagents, and positive color change define the Arylsulfatase Test

Media: Phenolphthalein media; Reagents: 2N Sodium carbonate; Positive: Pink/red; Negative: No color change

What incubation duration for the Arylsulfatase test specifically detects rapid growers like M. fortuitum

3-day Arylsulfatase test

What positive and negative controls are used for the Arylsulfatase Test

Positive Control: Mycobacterium fortuitum; Negative Control: Mycobacterium intracellulare

What media, reagent, and positive reaction define the Pyrazinamidase Test

Media: Pyrazinamidase agar; Reagent: 1% Ferrous ammonium sulfate; Positive: Pink/red band in 4 days; Negative: No color band

Which Mycobacterium species is characteristically Pyrazinamidase positive

Mycobacterium tuberculosis

What temperature and duration are required to heat colonies prior to adding 30% H2O2 in the Heat Stable Catalase Test

68°C for 20 minutes

What reagent is used in the Heat Stable Catalase Test, and what indicates a positive result

30% H2O2; Positive: Bubbling; Negative: No bubbling

Which Mycobacterium species is Heat Stable Catalase positive, and which is negative

Positive: Mycobacterium gordonii; Negative: Mycobacterium tuberculosis

What height of bubble column defines a positive result in the Semiquantitative Catalase Test

Height greater than 45 mm (>45 mm)

Which Mycobacterium species yield a semiquantitative catalase result of >45 mm

Mycobacterium gordonii and Mycobacterium kansasii

What substrate and pH indicator are used in the Tween 80 Hydrolysis Test, and what is the positive color change

Substrate: Tween 80 Media; Indicator: Phenol red; Positive: Pink/red; Negative: Amber/no color change

How many days does it take for Mycobacterium kansasii versus Mycobacterium tuberculosis to hydrolyze Tween 80

M. kansasii: 3 days (Rapid positive); M. tuberculosis: 10 to 20 days

What reagent is used in the Tellurite Reduction Test, and what constitutes a positive result

Potassium tellurite; Positive: Smooth, fine black precipitate ("smoke-like" action); Negative: Gray clumps

Which Mycobacterium species is characteristically positive for Tellurite Reduction in 3 days

Mycobacterium avium complex

What concentration of NaCl broth is used in the Salt Tolerance Test, and what indicates a positive result

5% NaCl broth; Positive: Turbidity/growth; Negative: Clear/no growth

Which Mycobacterium species is characteristically Salt Tolerance positive

Mycobacterium fortuitum

What chemical is used in the T2H/TCH Susceptibility Test, and which species is inhibited by it

Thiophene-2-carboxylic acid hydrazide (T2H); M. bovis is sensitive (growth inhibited); M. tuberculosis is resistant (growth occurs)

Which selective/differential agar without crystal violet is used to identify the M. fortuitum-chelonae complex

MacConkey agar without crystal violet

What media, indicator, and positive color change define the Urease Test for Mycobacteria

Media: Urea agar or urea broth; Indicator: Phenol red; Positive: Pink/red/fuchsia; Negative: No color change (yellow/amber)

Which Mycobacterium species is characteristically Urease positive

Mycobacterium tuberculosis

What are two common synonyms for Mycobacterium tuberculosis

Koch's bacillus and Tubercle bacillus

What are the two main virulence factors produced by Mycobacterium tuberculosis

Cord factor (Trehalose 6,6'-dimycolate) and Sulfatides

What special inclusions can be demonstrated in M. tuberculosis cells, and what are their physical dimensions

Much granules; length 1 to 4 µm, diameter 0.2 to 0.6 µm

What physical parameter (temperature and time) kills M. tuberculosis in boiling water

Boiling for 10 minutes

How long must M. tuberculosis be exposed to direct sunlight to be killed

20 to 30 hours of direct sunlight

How long must M. tuberculosis be exposed to 5% phenol to be completely killed

24 hours

What is the characteristic colony morphology of M. tuberculosis on Lowenstein-Jensen media

Tan or buff, rough, dry, warty, "cauliflower-like" granular colonies