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Tuberculosis Flashcards

1
Q

Mycobacteria are

A

rod-shaped aerobic bacilli that multiple slowly, every 18 to 24 hours in vitro.

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2
Q

Mycobacteria are responsible for two diseases:

A

tuberculosis, mostly caused by M. tuberculosis, and leprosy due to M. leprae.

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3
Q

Mycobacterial infections classically result in the formation of

A

slow- growing, granulomatous lesions that cause tissue destruction anywhere in the body.

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4
Q

Define Pulmonary tuberculosis (PTB)

A

TB involving the lung parenchyma or the trachea-bronchial tree. Miliary TB is classified as PTB because there are lesions in the lungs.

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5
Q

Extrapulmonar y tuberculosis (EPTB)

A

TB involving organs other than the lungs (e.g., pleura, lymph nodes, abdomen, genitourinary tract, skin, joints and bones, meninges).
A patient with both PTB and EPTB should be classified as a case of PTB.

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6
Q

What questions are required to ask during TB symptom screening ?

A

Do you have a cough1?
o Is it productive?
o If productive, are there streaks of blood?
• Do you have fever?
• Have you lost weight?
• Do you have night sweats?
• Do you have chest pains?

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7
Q

Which co-morbid conditions and lifestyle habits that can predispose a patient to TB:

A

• HIV
• Smoking
• Alcohol and substance abuse
• Diabetes
• Undernutrition

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8
Q

C-reactive protein (CRP) is

A

C-reactive protein (CRP) is an acute-phase protein and a biomarker of conditions associated with inflammation. This tool should only be used for TB screening among adults and adolescents living with HIV in combination with symptom screening. If either is positive, a person should be considered a presumptive TB patient.

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9
Q

What are the recommended diagnostic tools in Zambia ?

A

• GeneXpert® MTB/RIF or Ultra (Cepheid)
• TruenatTM (Molbio Diagnostics)
• TB loop-mediated isothermal amplification (LAMP)
• Smear microscopy
• Lateral flow urine lipoarabinomannan assay (LF-LAM)
vitro
Acid-fast bacilli(AFB)smear and culture using sputum

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10
Q

Tuberculosis is

A

A bacterial infection caused by mycobacterium tuberculosis

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11
Q

Latent tuberculosis infection is

A

That state in which the bacillus is present in the body but is asymptomatic

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12
Q

TB is caused by tubercle bacilli, which belongs to the genus

A

Mycobacterium

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13
Q

M. Tuberculosis complex comprises

A

M. Tuberculosis, M bovis ( cow breasts) , M africanum, M javis (bird droppings) , M homonis

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14
Q

Bacillus is an

A

Aerobe, loves oxygen, it may spread to any organ in the body but is more common in those with higher oxygen tension such as lungs, kidneys and brain

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15
Q

Three populations of the M tuberculosis organism

A

1 . Actively growing extracellular bacilli (in pulmonary cavities with liquefied casesous debris - this is the population in which drug resistance develops rapidly)
2 . Slow growing or intermittently growing bacilli (in macrophages- intracellular environment is acidic and many drugs are not active in these conditions)
3 . Slower growing bacilli (in solid caseous material- environment is neutral ph; compromised drug penetration due to poor blood supply.

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16
Q

Which drug is bactericidal against all 3 populations of M. Tuberculosis, most effective sterilising drug and makes short course possible?

A

Rifampin

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17
Q

Which drugs are bactericidal against extracellular bacilli?

A

Isoniazid, streptomycin and other amino-glycosides

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18
Q

Which drug is bactericidal against intracellular bacilli

A

Isoniazid

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19
Q

Which drug is bactericidal against intracellular bacilli and works well in an acidic ph

A

Pyrazinamide

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20
Q

Based on the location of the infection, two types of tuberculosis are seen, such as:

A

➢ Pulmonary tuberculosis
➢ Extrapulmonary tuberculosis

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21
Q

What is Pulmonary tuberculosis ??

A

This is a type of - tuberculosis which is seen in the lungs.

22
Q

What is Extrapulmonary tuberculosis ?

A

This is a type of TB that Occurs in organ systems other than the lungs. The most common sites are lymph nodes, pleura, bone and joints, urogenital tract, and meninges.

23
Q

Constitutional symptoms of TB include:

A

➢ Tiredness
➢ Headache
➢ Weight loss
➢ Fever (usually appears in the late afternoon/evening, is low-grade at the onset and becomes high-grade with the progression of the disease)
➢ Night sweats and
➢ Loss of appetite

24
Q

Respiratory symptoms of TB include:

A

➢ Voice hoarseness
➢ Dry or productive cough lasting more than 2 weeks
➢ Haemoptysis (the coughing up of blood) is often the presenting symptom
➢ Dull aching chest pain due to tuberculosis pleurisy (inflammation of the pleurae) or pneumothorax (air/gas trapped in the thoracic cavity), especially during inspiration

25
Q

Unique features of the TB bacteria.

A

● The slow growing organisms
● The dormant
● Lipid rich cell wall
● Facultatively intracellular
These are frequently developing drug resistance on monotherapy.

26
Q

For initial empiric treatment of TB, start patients on a 4-drug regimen with;

A

isoniazid, rifampin, pyrazinamide, and either ethambutol or streptomycin. Once the TB isolate is known to be fully susceptible, ethambutol (or streptomycin, if it is used as a fourth drug) can be discontinued.

27
Q

Initial phase

A

Rifampin (R) , isoniazid (H) , pyrazinamide (Z) and ethambutol (E) for 2 months

28
Q

Continuation phase

A

4 months of rifampin and isoniazid

29
Q

A longer period of treatment than standard 6 months is needed for?

A

Meningeal TB where there is direct spinal cord involvement

30
Q

What is the significance concurrent use of the 4 drugs in the initial phase?

A

To reduce the bacterial population as rapidly as possible and limits the development of resistant organisms.
With in 2-3 weeks of the start of therapy, even smear-positive patients become non-infectious

31
Q
A

Is defined as active TB affecting any of the following:
• Lungs
•Pleural cavity
•Mediastinal lymph nodes
•Larynx

32
Q

Active meningeal TB should be treated with ?

A

2HREZ/10HR

33
Q

The most common indications for use of steroids are:

A

• TB meningitis
• TB pericarditis
• TB Immune Reconstitution Inflammatory Syndrome
• Massive pleural effusion
• Massive lymphadenopathy with pressure effects
• Severe hypersensitivity reactions to anti-TB drugs
Rarely:
• Hypoadrenalism
• Renal tract TB (to prevent ureteric scarring)
• TB laryngitis with life-threatening airway obstruction

Note: Steroids doses must be tapered, and not be stopped abruptly.
The most used drug is dexamethasone, prednisolone

34
Q

—————— is a prodrug activated by a mycobacterial catalase–peroxidase (KatG).

A

Isoniazid

35
Q

Which drug is particularly effective against rapidly growing bacilli and is also active against intracellular organisms?

A

Isoniazid

36
Q

——————is the most serious adverse effect associated with isoniazid.

A

Hepatitis

37
Q

Peripheral neuropathy (manifesting as paresthesia of the hands and feet) appears to be due to a relative —————.

A

pyridoxine deficiency . This can be avoided by supplementation of 25 to 50 mg per day of pyridoxine (vitamin B6)
(While using isoniazid)

38
Q

———————-is bactericidal for both intracellular and extracellular mycobacteria, including M. tuber- culosis, and NTM, such as M. kansasii and Mycobacterium avium complex (MAC). It is effective against many gram-positive and gram-negative organisms and is used prophylactically for
individuals exposed to meningitis caused by meningococci or Haemophilus influenza .————— also is highly active against M. leprae.

A

Rifampin

39
Q

——————blocks RNA transcription by interacting with the β subunit of mycobacterial DNA-dependent RNA polymerase.

A

Rifampin

40
Q

Which drug causes the following adverse effect: urine, feces, and other secretions have an orange-red color, so patients should be forewarned. Tears may even stain soft contact lenses orange-red.

A

Rifampin

41
Q

——————-must be enzymatically hydrolyzed by pyrazinamidase to pyrazinoic acid, which is the active form of the drug.

A

Pyrazinamide

42
Q

Which drug causes uric acid retention is common but rarely pre- cipitates a gouty attack ?

A

Pyrazinamide

43
Q

—————-inhibits arabinosyl transferase—an enzyme important for the synthesis of the mycobacterial cell wall.

A

Ethambutol

44
Q

The most important adverse effect of ethambutol is?

A

optic neuritis, which results in diminished visual acuity and loss of ability to discriminate between red and green. The risk of optic neuritis increases with higher doses and in patients with renal impairment. Visual acuity and color discrimination should be tested prior to initiating therapy and periodically thereafter.

45
Q

Uric acid excretion is decreased by _____________, and caution should be exercised in patients with gout.

A

ethambutol

46
Q

What is peritheral neuropathy?

A

Peripheral neuropathy happens when the nerves that are located outside of the brain and spinal cord (peripheral nerves) are damaged. This condition often causes weakness, numbness and pain, usually in the hands and feet. It also can affect other areas and body functions including digestion and urination.

47
Q

How does Isoniazid cause Peripheral neuropathy?

A

Isoniazid(INH)inhibits the enzyme pyridoxine phosphokinase; this enzyme is necessary to activate pyridoxine to pyridoxal 5’ phosphate, the cofactor in many “pyridoxine-dependent” reactions. Functional pyridoxine deficiency is the likely mechanism of INH-induced peripheral neuropathy.

48
Q

How do ethambutol cause Optic Neuritis?

A

Ethambutol toxic optic neuropathy are mitochondrial dysfunction and metal chelating effects on the retinal ganglion cells.
Ethambutol-induced optic neuropathy is most commonly characterized by bilateral symmetrical loss of vision, but it may also occur successively in both eyes. Ethambutol may influence retinal photoreceptor cells and retinal ganglion cells.

49
Q

What is the connection between HIV and TB?

A

TB is an opportunistic infection (OI). OIs are infections that occur more often or are more severe in people with weakened immune systems than in people with healthy immune systems. HIV weakens the immune system, increasing the risk of TB in people with HIV.

50
Q

Wh en an individual has TB and HIV,What do you treat first?

A

The first priority for HIV-positive TB patients is to initiate TB treatment, followed by co-trimoxazole and ART to prevent what we call IRIS(Immune reconstitution inflammatory syndrome)

51
Q

What is IRIS?

A

Patients with TB/HIV co-infection may experience a temporary exacerbation of symptoms or radiographic manifestations after initiation of ART. This phenomenon is called Immune Reconstitution Inflammatory Syndrome (IRIS). There are two types of IRIS: paradoxical and unmasking:
• This paradoxical reaction in HIV-infected patients with TB is a result of immune reconstitution. This occurs because of the initiation of ART in a patient with a known TB diagnosis and already on anti-TB drugs. An exacerbation of TB symptoms occurs following ART initiation.
• Unmasking IRIS occurs in patients who have undiagnosed TB disease, with symptoms emerging after initiating ART.
Symptoms and signs may include:
• Fever, worsening respiratory symptoms
• Worsening constitutional symptoms, such as weight loss and night sweats
• Lymphadenopathy
• Worsening of CXR findings
• Expanding central nervous system lesions on CT scan
Management of TB IRIS
• Do a thorough clinical evaluation to exclude other causes, particularly DR- TB and other opportunistic infections.
• Patients should continue TB treatment without change unless MDR-TB is diagnosed, or drug-drug interactions are suspected.
• If MDR-TB is diagnosed, switch to second-line ATT.
• When unmasking IRIS is diagnosed, initiate TB treatment.
• Temporal interruption of ART may be recommended if life-threatening
complications of IRIS develop, but it should be restarted when the patient is
stabilized.
• Administer prednisone (0.5–1.0 mg/kg/day) for moderate to severe cases.

Immune reconstitution inflammatory syndrome (IRIS) is a condition seen in some cases of HIV/AIDS or immunosuppression, in which the immune system begins to recover, but then responds to a previously acquired opportunistic infection such as TB when therapy is not initiated,with an overwhelming inflammatory response that paradoxically makes the symptoms of infection worse.

Flash Cards (20 decks)

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