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BACT211 (LECTURE) > WEEK 7: MYCOBACTERIA > Flashcards

WEEK 7: MYCOBACTERIA Flashcards

1
Q
  • Non-motile, non-spore forming slender, slightly curved or straight, rod- shaped organisms that have tendency to clump
  • The cell wall has extremely high lipid content; thus, mycobacterial cells resist staining with commonly used basic aniline dyes, such as those used in the Gram stain, at room temperature.
  • take up dye with increased staining time or application of heat but resist decolorization with acid-ethanol
  • This characteristic is referred to as acid fastness—hence, the term AFB
  • are strictly aerobic, but increased carbon dioxide (CO2) will enhance the growth of some species.
A

Mycobacteria

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2
Q

Mycobacterium tuberculosis Complex (5)

A

M. tuberculosis
M. bovis
M. africanum
M. canettii
M. microti

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3
Q

The primary source of BCG (Bacillus CalmetteGuérin) vaccine

A

M. bovis

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4
Q

A PPD skin test is reactive if the induration is?

A

20mm

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4
Q

are acquired from persons with active disease who are excreting viable bacilli by
coughing, sneezing or talking.

A

Tubercle bacilli

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5
Q

is usually a disease of the respiratory tract

A

TB

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6
Q

an unexplained pleural effusion with mononuclear pleurocytosis, manifests as cough, fever, and chest pain, resembling the presentation
of bacterial pneumonia

A

Pleurisy

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6
Q

an organization of lymphocytes, macrophages, fibroblasts, and capillaries.

A

granuloma

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6
Q

refers to the seeding of many organs outside the pulmonary tree with AFB through hematogenous spread

A

Miliary TB

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6
Q
  • TB is usually a disease of the respiratory tract.
  • Tubercle bacilli are acquired from persons with active disease who are excreting viable bacilli by coughing, sneezing or talking.
  • hard tubercle or granuloma may be formed
  • The granuloma is an organization of lymphocytes, macrophages, fibroblasts, and capillaries.
  • With granuloma formation, healing occurs, as well as fibrosis, encapsulation, and
    calcification, with scar formation as a reminder of the past infection.
  • In infected individuals, there is a potential for reactivation of TB.
  • Clinical diagnosis of primary TB: positive PPD skin test.
    diagnosis is confirmed by stained smear and culture of sputum, gastric aspirates, or bronchoscopy specimens.
A

Mycobacterium tuberculosis

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7
Q

Skeletal TB of the spine is referred to as?

A

Pott disease

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7
Q
  • Colonies are typically raised, with a dry, rough
    appearance.
  • The colonies are nonpigmented and classically described as being buff-colored
  • Optimal growth occurs at 35° C to 37° C.
  • Positive for niacin accumulation
  • reduction of nitrate to nitrite
  • Production of catalase
  • Grows on thiophene-2-carboxylic acid hydrazide
    (T2H)
A

Mycobacterium tuberculosis

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8
Q

➢ 21 days of incubation at 37° C.
➢ niacin-negative
➢ do not reduce nitrate
➢ do not grow in the presence of (T2H)
thiophene-2-carboxylic acid hydrazide

A

Mycobacterium bovis

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8
Q
  • Miliary TB refers to the seeding of many organs
    outside the pulmonary tree with AFB through hematogenous spread.
  • Almost any organ of the body can be infected by
    M. tuberculosis
  • Pleurisy, an unexplained pleural effusion with
    mononuclear pleurocytosis, manifests as cough, fever, and chest pain, resembling the presentation of bacterial pneumonia.
  • Lymphadenitis
  • Genitourinary TB
  • Skeletal TB of the spine is referred to as Pott disease.
  • Meningitis
  • Cerebrospinal fluid (CSF) examination usually reveals an elevated protein level, decreased glucose level, and a predominance of lymphocytes
A

Extrapulmonary Tuberculosis

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9
Q

TRUE OR FALSE

Almost any organ of the body can be infected by
M. tuberculosis.

A

TRUE

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10
Q
  • TB primarily in cattle but also in other ruminants,
    as well as in dogs, cats, swine, parrots, and
    humans.
  • The disease in humans closely resembles that
    caused by M. tuberculosis and is treated similarly.
A

Mycobacterium bovis

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11
Q
  • Vank’s disease
  • resistant to at least two of the most powerful first anti-TB drugs, INH and RMP
A

MDR-TB

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12
Q

M. bacteremicum
M. canariasense
M. cosmeticum
M. monacense
M. neoaurum

M. mageritense/M. wolinskyi Group

M. mageritense
M. wolinskyi

A

Early Pigmented

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12
Q

resistant to INH and RMP plus any fluoroquinolones and at least one injectable second line drugs (amikacin, kanamycin, or capreomycin)

A

XDR-TB

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12
Q
  • atypical mycobacteria or mycobacteria other than
    tuberculosis (mott)
  • found in the environment that colonize the skin,
    respiratory tract and gi of healthy individuals
  • chronic pulmonary disease resembling tb
  • non transmissible from person to person
  • aids contributed to incidence to ntm disease
A

Non-tuberculous Mycobacteria

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13
Q

M. bohemicum
M. celatum
M. genavense
M. haemophilum
M. heidelbergense
M. interjectum
M. intermedium
M. kansasii
M. lentiflavum
M. malmoense
M. marinum
M. scrofulaceum
M. simiae
M. szulgai
M. terrae complex (M. arupense, M. heraklionense, M. kumamotense)
M. ulcerans
M. xenopi

A

Slow Growers (Other than Mycobacterium avium
Complex)

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13
Q
  • M. intracellulare
  • environmental saprophytes and have been
    recovered from soil, water, house dust, and other
    environmental sources
  • is a cause of disease in poultry and
    swine - Zoonotic
  • the cells are short, coccobacillary, and uniformly stained, without beading or banding
  • production of a heatstable catalase and the ability
    to grow on media containing 2 μg/mL of T2H
A

Mycobacterium avium complex

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13
Q
  • M. fortuitum Group

M boenickei
M. brisbanense
M. fortuitum
M. houstonense
M. neworleansense
M. peregrinum
M. porcinum
M. senegalense
M. septicum
M. setense

  • M. chelonae/M. abscessus Group

M. abscessus subsp. abscessus
M. abscessus subsp. bolletii
M. chelonae
M. franklinii
M. immunogenum
M. salmoniphilum

  • M. mucogenicum Group

M. aubagnense
M. mucogenicum
M. phocaicum

  • M. smegmatis Group

M. goodii
M. smegmatis

A

Rapid Growers

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14
Q

NTM colonies that
develop pigment
on exposure to
light after being
grown in the dark
and take longer
than 7 days to
appear on solid
media

are slow-growing NTM that produce colonies that require light to form pigment.

A

I. Photochromogens

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14
Q

NTM colonies that
develop pigment
in the dark or light
and take longer
than 7 days to
appear on solid
media

are slow-growing NTM that produce pigmented colonies whether grown in the dark or the light.

A

II. Scotochromogen

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14
Q
  • chronic pulmonary disease and cervical lymphadenitis
  • resistant to isoniazid, streptomycin, p-aminosalicylic acid, and rifampin and susceptible
    to ethambutol and cycloserine.
  • short coccobacillus without cross bands on
    acid-fast–stained smears.
  • Colonies are smooth glistening, and opaque, with
    dense centers
A

Mycobacterium malmoense

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14
Q

NTM colonies that
are nonpigmented
regardless of whether they are grown in the dark
or light and take
longer than 7 days to appear on solid media

are slow-growing NTM that produce unpigmented colonies whether grown
in the dark or the light.

A

III. Nonphotochromogens

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15
Q

NTM colonies that grow on solid media and take fewer than 7 days to appear

A

IV. Rapid growers

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15
Q
  • Causative agent of Johne disease, an intestinal
    infection occurring as a chronic diarrhea in cattle,
    sheep, goats, and other ruminants.
  • very slow growth rate (3 to 4 months)
  • Needs mycobactin-supplemented medium for
    primary isolation
A

Mycobacterium avium subsp. paratuberculosis

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15
Q
  • cause of disseminated infections in patients with
    AIDS
  • enteritis and genital and soft tissue infections
  • Middlebrook 7H11 agar supplemented with
    mycobactin.
  • heat-stable catalase, pyrazinamidase, and urease
  • positive
A

Mycobacterium genavense

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16
Q
  • a multidrug regimen of isoniazid, rifampin, and
    ethambutol is currently recommended
  • long rods with distinct crossbanding
  • colonies appear smooth to rough, with characteristic wavy edges and dark centers when grown on Middlebrook 7H10 agar
  • Colonies are photochromogenic
  • With prolonged exposure to light, most strains
    form dark red crystals of β–carotene on the surface
    of and inside the colony.
  • strongly catalase-positive
  • hydrolyze Tween 80 in 3 days
  • strong nitrate reduction
  • Pyrazinamidase production
A

Mycobacterium kansasii

17
Q
  • Submandibular lymphadenitis, subcutaneous nodules, painful swellings, ulcers progressing to abscesses, and draining fistulas are often the clinical manifestations.
  • A unique characteristic of this organism is its requirement for hemoglobin or hemin for growth.
  • chocolate (CHOC) agar, Mueller-Hinton agar with
    5% Fildes enrichment, and Löwenstein-Jensen (LJ)
    medium containing 2% ferric ammonium citrate.
    Middlebrook 7H10 agar with an X factor disk
  • Optimal growth temperature is 28° C to 32° C; little or no growth occurs at 37° C.
  • cells are strongly acid-fast, short, occasionally
    curved bacilli without banding or beading, and
    arranged in tight clusters or cords
A

Mycobacterium haemophilum.

17
Q
  • cervical lymphadenitis in children
  • resistant to isoniazid, streptomycin, ethambutol,
    and p-aminosalicylic acid when tested in vitro.
  • The organism grows slowly (4 to 6 weeks) at incubation temperatures ranging from 25° to 37° C
A

Mycobacterium scrofulaceum

17
Q
  • isolated from the lymph nodes of monkeys
  • Colonies on Middlebrook 7H10 agar are thin,
    transparent or tiny, and filamentous
A

Mycobacterium simiae

17
Q
  • is a rare cause of mycobacteriosis, also referred to as Buruli ulcer
  • acid-fast cells are long, without beading or
    crossbanding
A

Mycobacterium ulcerans

17
Q
  • has been implicated in
    diseases of fish and isolated from aquariums.
  • Cutaneous infections in humans occur when traumatized skin comes into contact with salt water
    or inadequately chlorinated fresh water containing
    the organism.
  • tender red or blue-red subcutaneous nodule, or
    swimming pool granuloma, usually occurs on the
    elbow, knee, toe, or finger
  • susceptible to rifampin and ethambutol, resistant
    to isoniazid and pyrazinamide, and partially
    resistant or intermediate to streptomycin
  • Cells of _______ are moderately long to long
    rods with cross barring.
  • is photochromogenic; young colonies
  • Colonies grown in or exposed to light develop a
    deep yellow color.
  • Growth is optimum at incubation temperatures of
    28° C to 32° C.
  • none reduces nitrate or produces heat-stable
    catalase
  • The organisms hydrolyze Tween 80 and produce
    urease and pyrazinamidase.
A

Mycobacterium marinum

18
Q
  • recovered from hot and cold-water taps (including
    water storage tanks of hospitals)
  • susceptible to the quinolones (ciprofloxacin,
    ofloxacin); some isolates are susceptible to vancomycin, erythromycin, or cefuroxime
  • Colonies on Middlebrook 7H10 agar are small,
    with dense centers and filamentous edges.
  • cornmeal-glycerol agar reveals distinctive round
    colonies with branching and filamentous extensions;
    aerial hyphae are usually seen in rough colonies.
  • Young colonies grown on cornmeal agar have a
    bird’s nest appearance, with characteristic stick-like
    projections.
A

Mycobacterium xenopi

18
Q

seen in patients with cystic fibrosis (CF)

A

M. abscessus

18
Q

have been associated with a variety of infections of the skin, lungs, bone, central
nervous system, and prosthetic heart valves.

A

M. chelonae

18
Q
  • M. abscessus subsp. abscessus (formerly M.
    abscessus), M. chelonae, and M. fortuitum.
  • M. chelonae have been associated with a variety
    of infections of the skin, lungs, bone, central
    nervous system, and
    prosthetic heart valves.
  • M. abscessus seen in patients with cystic fibrosis
    (CF)
  • tap water is an important reservoir
  • positive 3-day arylsulfatase test, no reduction of
    nitrate, and growth on MacConkey agar without
    crystal violet
A

Mycobacterium chelonae–Mycobacterium abscessus Group

19
Q
  • M. ____, M. peregrinum, and an unnamed third species.
  • isolated from water, soil, and dust
  • associated with localized cutaneous infections
  • Middlebrook 7H11 agars after 1 to 2 days of
    incubation colonies with branching filamentous
    extensions and rough colonies with short aerial
    hyphae.
  • pleomorphic, ranging from long and tapered to
    short, thick rods partially acid-fast
  • positive 3-day arylsulfatase test and reduction of
    nitrate
A

Mycobacterium fortuitum Group

19
Q
  • contains two species, M.
    smegmatis and M. goodie.
  • M. smegmatis has been implicated in rare cases
    of pulmonary, skin, soft tissue, and bone infections.
  • cells are long and tapered or short rods with irregular acid fastness. Occasionally rods are curved with branching or Y-shaped forms; swollen, with deeper staining, beaded, or ovoid forms are sometimes seen.
  • Colonies appearing on egg medium after 2 to 4 days are usually rough, wrinkled, or coarsely folded; smooth, glistening, butyrous colonies may also be
    seen.
  • negative arylsulfatase reaction, positive iron
    uptake, ability to reduce nitrate, and growth in the
    presence of 5% NaCl and on MacConkey agar without crystal violet
A

Mycobacterium smegmatis Group

20
Q

appear to be more commonly diagnostic than washing or biopsy, possibly because of an inhibitory effect on the mycobacteria by lidocaine used in adults during bronchoscopy or
of dilution of the specimen with saline

A

Brushings

21
Q
  • this is recommended because children have difficulty producing sputum
  • should be obtained in the morning after an overnight fast
A

gastric aspiration

22
Q

specimen should be neutralized with ________ _______ or another
buffer to pH __.0 as soon as possible after specimen collection.

A

sodium carbonate, 7.0

23
Q

stool patients with AIDS, who may be at risk for developing disseminated mycobacterial disease resulting from ____________ _________ _______

A

Mycobacterium avium complex

24
Q

0 (1) to liquefy the sample through digestion of the
proteinaceous material

0 (2) to allow the chemical decontaminating agent to contact and kill the nonmycobacterial organisms

A

Digestion and Decontamination of Specimens

25
Q

Usual concentration 2%, 3%, or 4%—serves as a digestant and decontaminating agent

A

Sodium Hydroxide

26
Q

0 A combination of a liquefying agent, such as N-acetyl-L-cysteine (NALC) or dithiothreitol, plus NaOH is commonly used.

0 Treatment with mucolytic agents such as NALC splits mucoprotein, allowing greater sedimentation

A

N-Acetyl-L-cysteine

27
Q
  • Another digestant-decontamination benzalkonium chloride
    (Zephiran) combined with trisodium phosphate (Z-TSP).
  • TSP liquefies sputum rapidly
  • shortens the exposure time and effectively
    destroys many contaminants, with little bactericidal effect on the
    tubercle bacilli.
A

Benzalkonium Chloride

28
Q

5%, is used to decontaminate specimens contaminated with Pseudomonas aeruginosa, such as sputum specimens from patients with Cystic fibrosis.

A

Oxalic Acid

29
Q

The conventional acid-fast staining methods (2)

A

Ziehl-Neelsen and Kinyoun stains

30
Q

In Ziehl-Neelsen and Kinyoun stains, what is the primary stain, decolorizing agent, and counterstain?

A

carbolfuchsin
acid-alcohol
methylene blue

31
Q

staining procedure involves the application of heat with the carbolfuchsin stain

A

Ziehl-Neelsen

32
Q

acid-fast stain is a cold stain

A

Kinyoun

33
Q

what is the minimum amount of field before a slide is called negative?

A

300 fields

34
Q

replication time of M. tuberculosis

A

20 to 22 hours

35
Q

Most pathogenic mycobacteria require how many weeks of incubation?

A

2 to 6 weeks

36
Q

growth of M. tuberculosis is enhanced by an atmosphere of?

A

5% to 10% CO2

37
Q

Mycobacteria require a pH between?

A

6.5 and 6.8

38
Q

does not grow on media used routinely to isolate mycobacteria and requires extended incubation (6 to 8
weeks)

A

M. genavense

39
Q

fails to grow on artificial media.

A

M. leprae

40
Q

Serum albumin agar media, such as Middlebrook 7H10
and 7H11 agars

A

Agar-Based Media

41
Q

also contains 0.1% casein
hydrolysate, which improves the recovery of isoniazid-
resistant strains of M. tuberculosis

A

Middlebrook 7H11 medium

42
Q

TRUE OR FLASE

Mycobacterium spp. grow more rapidly in solid
medium

A

FLASE (LIQUID MEDIA)

43
Q

2 nonselective liquid media used for subculturing
stock strains

A

Middlebrook 7H9 broth and Dubos Tween albumin

44
Q

have a variable appearance, with glossy whitish colonies
often occurring with smaller translucent colonies

A

Colonies of Mycobacterium avium complex

45
Q

most commonly used biochemical test for the identification of MTB

A

niacin

46
Q

In Iron Uptake, what color does the colonies appear in a positive reaction?

A

rusty brown

47
Q

The test is most useful in
distinguishing M. chelonae, which is generally negative

A

Iron Uptake

48
Q

Most members of the genus Mycobacterium possess this
enzyme

A

arylsulfatase

49
Q
  • Detection of urease activity can be used to distinguish
    M. scrofulaceum, urease-positive, from M. gordonae,
    urease-negative.
  • A pink to red color is indicative of a positive reaction.
A

Urease

49
Q
  • is a precursor in the synthesis of chloramphenicol.
  • selectively inhibits the M. tuberculosis complex
A

NAP

50
Q

this organism is susceptible to lower concentrations of T2H than MTB

A

M. bovis

51
Q
  • High salt concentration (5% NaCl) in egg-based media (e.g., LJ) inhibits the growth of most mycobacteria.
  • M. flavescens, M. triviale, and most rapidly growing Mycobacterium spp. are exceptions that do grow in the presence of 5% NaCl.
A

Sodium Chloride Tolerance

52
Q

has been used for many years to determine an
individual’s exposure to M. tuberculosis

A

tuberculin skin test

BACT211 (LECTURE) (18 decks)

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