Mycobacterium & NTM 🫁 Flashcards by James Sandoval

aka Koch’s bacillus

Mycobacterium tuberculosis

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Major virulence factor of Mycobacterium tuberculosis

cord factor

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Mycobac generation time?

> 12hrs - grows slowly bc of their hydrophobic cell surface

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Mycobac pH requirement on (culture media)

6.5-6.8

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2 GROUPS OF MYCOBACTERIA:

Mycobacterium tuberculosis complex (MTC)
Nontuberculosis mycobacteria (NTM, MOTT)

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Mycobacterium tuberculosis major virulence factor

cord factor

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Which of the following is (are) fluorescent stain(s) used in the detection of the mycobacteria?

a. Auramine-rhodamine
b. Kinyoun’s
c. Ziehl-Neelsen
d. Both b and c

Auramine-rhodamine

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A nonpigmented mycobacterium is isolated that reduces nitrate
to nitrite and is niacin-positive. You should suspect:

a. M. kansasii
b. M. xenopi
c. M. tuberculosis
d. M. avium complex

c. M. tuberculosis

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The causative agent of Hansen disease:

a. Is highly contagious
b. Readily grows on most mycobacterial media
c. Grows best at core body temperature (37°C)
d. None of the above

d. None of the above

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The skin test for tuberculosis:

a. Detects antibodies to mycobacterial antigens
b. Detects a cell-mediated immune response to mycobacterial
antigens
c. Uses the bacillus of Calmette-Guérin strain as the antigen
source
d. Both a and b

b. Detects a cell-mediated immune response to mycobacterial
antigens

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what are the MYCOBACTERIUM TUBERCULOSIS COMPLEX ??

(TBACM)

Mycobacterium tuberculosis
Mycobacterium bovis
Mycobacterium africanum
Mycobacterium canetti
Mycobacterium microti

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It has the longest replication time among the
mycobacteria (20-22 hours)

Mycobacterium tuberculosis

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ID:

Culture: slow growing, buff in color raised and
dry – “cauliflower colonies”, rough colonies
exhibit “cording”
(curved strands of bacilli)

Mycobacterium tuberculosis

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ID:

Biochemical tests:
o** (+)** niacin and nitrate reduction😌
o growth on T2H
o (-) 68°C catalase test 😉
o It is inhibited by nitroimidazopyran (NAP)

Mycobacterium tuberculosis

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✍️Macrophage destroys intracellular mycobacteria

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Part 1/2

✍️MTB does not produce toxin.

The pathologic features of TB are the result of hypersensitivity reaction to mycobacterial antigen.

Which causes :
⬇️ Antigen
⬆️ Hypersensitivity

✅Granuloma
✅Calcification - as granuloma healing occurs - with scar formation as a reminder of the past infection.

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Part 2/2 (MTB)

⬆️ Antigen
⬆️ Hypersensitivity reaction:

✅Tissue necrosis – from enzymes of degenerating macrophages
✅No granuloma formation
✅ Necrosis – caseous material at the primary lesion

✍️After healing, the bacilli are not totally eradicated and will stay in granulomas for months or
years

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✍️Overall, children account for most cases of miliary TB, but it is also a common form of
TB in HIV-infected individuals

✍️ Miliary TB:
seeding of many organs outside pulmonary tree

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✅It is also known as tuberculosis spondylitis or skeletal TB of the spine

✅It is a grave form of tuberculosis caused by the invasion of M. tuberculosis into the
spinal vertebrae

Pott’s disease

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💊Anti-TB drugs
Primary drugs:

RIPES

Rifampin (Rifampicin)
Isoniazid
Pyrazinamide
Ethambutol
Streptomycin

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💉Anti-TB drugs
Secondary drugs:

✅ Injectable drugs: Amikacin, Capreomycin, Kanamycin

✅Fluoroquinolones: Ciprofloxacin, Ofloxacin, Levofloxacin, Moxifloxacin

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How long is the TB treatment process?

(6 months) since slow grower…

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✍️MULTIDRUG RESISTANT MYCOBACTERIUM TUBERCULOSIS (MDR-TB)

Happens when :

✅Happens if the patient is on multidrug therapy and fails to complete the course of medication

✅Acquired by spontaneous mutation as a result of inappropriate use of antimicrobial drugs and
lack of patient compliance

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Primary MDR-TB is resistant to?

Rifampin and Isoniazid

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Extensively drug-resistant tuberculosis (XDR-TB) is resistant to?

Resistance to Rifampin and Isoniazid + Fluoroquinolones + one of the injectable drugs

What mycobacterium spp. is the TB vaccine derived from?

Mycobacterium bovis

It produces TB in cattle, dogs, cats, swine, parrots, and humans

Mycobacterium bovis

Mycobacterium bovis mode of transmission

✅ingestion of contaminated milk from infected cows ✅exposure to infected animals and their carcasses

resembles “water droplets” in Middlebrook media

Mycobacterium bovis

ID Biochemical tests: o (-) niacin and nitrate reduction🦠 o No growth in the presence of T2H o (-) 68°C catalase test

Mycobacterium bovis

Associates with human cases of TB in tropical Africa

Mycobacterium africanum

✅Smooth strain of M. tuberculosis and grows more rapidly (6 days) ✅First human isolate was from a cervical lymph node and from AIDS patient with mesenteric tuberculosis ✅Biochemical test: (+) niacin and reduced nitrate to nitrite

Mycobacterium canetti

✅ Isolated from TB patients in both immunocompetent and immunocompromised individuals

Mycobacterium microti

also known as MOTT?

NONTUBERCULOSIS MYCOBACTERIA (NTM)

✅Chronic pulmonary disease resembling TB is the usual clinical presentation ✅Found in soil and water ✅Opportunistic pathogens

NONTUBERCULOSIS MYCOBACTERIA (NTM) AKA MOTT

☀️💡Photochromogen color

Nonpigmented (dark) Yellow pigment (light) M. kansasii M. asiaticum M. marinum M. simiae

🌃☀️Scotochromogen color

Yellow to orange pigment in dark,, , but will intensify when exposed to constant light source . M. gordonae M. szulgai M. scrofulaceum M. flavescens M. xenopi

✍️Non-photochromogen spp.

M. avium complex M. ulcerans M. terrae complex M. gastri M. haemophilum

✍️Rapid Growers spp. - Pigment variable

M. fortuitum M. chelonae M. smegmatis M. phlei M. abscecuss M. mucogenicum

✍️Group 1-2-3 are slow growers!!! Group 4- rapid growers - sila smegmatis etc.

Group I – Photochromogen Group II – Scotochromogen Group III – Non-photochromogen

1. aka “Wood pigeon bacilli” 2. rapid grower or slow grower?

1. M. avium subsp. SILVATICUM 2. slow grower

✅Causative agent of Johne’s disease (inflammatory bowel disease) ✅Also isolated from bowel mucosa of patients with Crohn’s disease

Mycobacterium subsp. paratuberculosis

Also known as the “Yellow bacilli” 🔬Microscopy: long rods with distinct cross-banding -----------“Shepherd’s crook”--------------

Mycobacterium kansasii (Photochromogenic colonies)

AKA "Buruli ulcer" - painless nodule under the skin after previous trauma that does not heal

Mycobacterium ulcerans

* Previously known as M. aquae, also known as: ------- “Tap water bacillus”-------

Mycobacterium gordonae -CONTAMINATES TAP WATER

✅can be either non-photochromogen or scotochromogen ‼️ ✅Recovered from hot and cold-water taps, especially water storage tanks of hospitals, and from birds ✅First isolated from African toad

Mycobacterium xenopi

LEPROSY / HANSEN DISEASE causative agent

Mycobacterium leprae

✅cause of crippling of the hand ✅ERYTHEMA NODOSUM LEPROSUM

LEPROSY / HANSEN DISEASE by: M. leprae

🦠Bacteria ID: ✅Aerobic, acid-fast rods ✅CANNOT be cultured in vitro. Can only be cultured in certain animals : -🐁Mouse footpad - Armadillo - 🙈Monkeys

Mycobacterium leprae

REMEMBER! ✍️Mycobacterium leprae ✅Leprosy ✅Hansen disease ✅Armadillos ✅Erythema nodusum leprosum

leprae

✍️Calcified granulomas are generally considered a sign of past or latent TB infection, as they indicate **that the body has walled off the active infection** and the ** disease is no longer active or contagious. ** **(RANKE'S COMPLEX)**

✍️Calcified granulomas are generally considered a sign of past or latent TB infection, as they indicate that the body has walled off the active infection and the disease is no longer active or contagious. (RANKE'S COMPLEX)

in MTB why is Cord factor the mot important virulence factor?

✅inhibits neutrophil migration and damages mitochondria ✅may be responsible for release of tumor necrosis factor ➡️ "cachexia"

✍️Specimens for Mycobact

✅sputum, ✅gastric lavage, ✅urine ✅bronchoscopy specimens, ✅fecal specimens ✅body fluids: (pleural, pericardial, peritoneal, synovial, CSF), blood, wound, skin lesion aspirates, or tissue

term used - removal of normal microbiota or other bacterial contaminants from sputum specimen

Decontamination

The term that involves splitting of the sulfide bonds in mucin that may trap mycobacteria, liquefying mucus of sputum

Digestion

✍️* After decontamination, mycobacteria are concentrated by centrifugation ✍️* Over treatment with decontamination agents may result in fewer positive cultures ✍️* Failure to isolate mycobacteria from patient with signs and symptoms of disease may indicate overtreatment of decontamination

---SPECIMEN COLLECTION AND HANDLING----

The most common decontamination agent on sputum - Serves as both a decontaminant and digestant

* 2-4% NaOH ✍️* N-Acetyl-L-Cysteine and NaOH -Both a decontaminant and a digestant agent -NALC is also known as dithiothreitol – a digestion agent

stain more sensitive than carbol fuchsin 🔬(+) result: bright yellow-orange bacilli against a dark background

Auramine-Rhodamine Flurochrome

✍️INTERPRETATION OF STAINING RESULTS:✍️

✅ View a minimum of 300 fields before a slide is called negative. ✅ AFB can be transferred from one slide to another via immersion oil - stained bacilli can float off the slide and can contribute to a false-positive of the next slide. ✅ If at least 2 of the first 3 sputum direct smears are positive, then 3 specimens are often sufficient to confirm diagnosis. ✅ If none or only 1 of the first 3 sputum smear is positive, additional specimens are needed for culture confirmation.

AKA: Mantoux Test ✅It detects a patient’s cell-mediated immune response to the bacterial antigens in a type IV hypersensitivity reaction ✅This test does not differentiate active disease from infection ✅A reactive (+) result indicates past environmental exposure to M. tuberculosis or a previous tuberculosis vaccination ✅Presence of hard, dense, raised wheal (induration) that is 10 mm or larger after 48 hours

TUBERCULIN SKIN TEST -Uses Tuberculin purified protein derivative (PPD)

most commonly used biochemical test to identify MTB

Niacin Accumulation (Nicotinic acid) Test -95% of M. tuberculosis isolates produce free niacin ✅(+) result: Yellow – indicates accumulation of free niacin

* Detects the production of nitroreductase, which converts nitrate to nitrite

Nitrate Reduction Test (+) result: Red color forms ✅Positive: M. tuberculosis, M. kansasii, M. szulgai, M. fortuitum

Heat-stable catalase is a catalase that is resistant to heat at ________? cooled and reacted with hydrogen peroxide ✅ (+) result: column of bubbles with a height of more than ⬆️45 mm

68°C for 20 minutes Negative: o M. tuberculosis complex o M. gastri o M. haemophilum o M. marinum

Used to differentiate between the species of non-photochromogens and scotochromogens

Tween 80 Hydrolysis ✅(+) result: Pink color due to unbound neutral red (from amber color to pink)

* It detects the ability of mycobacteria to convert ferric ammonium citrate to an iron oxide Useful in distinguishing M. chelonae from other rapid growing NTM

Iron Uptake

✍️Growth on MacConkey Agar without Crystal Violet *✅M. fortuitum-chelonae complex can grow on MacConkey agar without crystal viole

✅Most rapid test for identification of common mycobacterial species

Nucleic Acid Hybridization Test ✅For M. tuberculosis complex, M. avium complex, M. intracellulare, M. kansasii, M. gordonae ✅ Required inoculum: single colony (1 mm diameter)

- Designed to detect M. tuberculosis complex bacilli directly from the patient specimens

Direct Nucleic Acid Amplification Test

BACTE ID *✅ It invades peripheral nerve and skin cells, and becomes obligately intracellular parasite *✅ Mostly found in Schwann cells that surround peripheral nerve axons and in mononuclear phagocytes *✅🔬Microscopy: rod shape exhibiting “cigar pocket/pocket fence” arrangement

Mycobacterium leprae

appears as “cigar pocket/pocket fence” arrangement

Mycobacterium leprae

✍️HANSEN’S DISEASE/LEPROSY Transmission: ✅ inhalation ✅ with infected skin ✅ arthropod bite ✅ through breast milk ✅ vertical transmission

🐋

* 2 Forms of Leprosy?

1. Tuberculoid Leprosy - localized (+) Lepromin test 2. Lepromatous Leprosy - systemic * (-) Lepromin test

Mycobacterium & NTM 🫁 Flashcards

Mycobacterium tuberculosis and Non-Tuberculosis Mycobacteria (72 cards)