Mycobacterial infections

Question 1

What are mycobacteria?

Answer 1

Aerobic and non-motile bacteria, cell wall thicker than many other bacterial species

e.g Mycobacterium tuberculosis, mycobacterium leprae

Non-TB mycobacteria = resp disease, lymphadenitis, skin disease, disseminated disease

Question 2

Discuss the process/stages/types of TB

Answer 2

Primary infection = contained by immune system

Primary pleural effusion = fluid between layers of tissue that line lungs/chest cav

Disseminated to produce miliary TB = spread from lungs to other parts of body through blood or lymph system

Disseminated to produce CNS TB

Question 3

How is TB diagnosed?

Answer 3

Mantoux TB skin test = identifies latent infection

X-ray

Question 4

What is the infectious form of TB?

Answer 4

Pulmonary TB = non-infectious 2wks after daily standard short-course therapy

Req infection control, cont infection control in = HIV positive, extensive cavitation, smear positive and high risk of drug resistance, laryngeal TB

Question 5

What are the signs and symptoms of TB?

Answer 5

Productive cough, chest pain, haemoptysis

Systemic
- Fever, chills, night sweats
- easy fatigability, anorexia, weight loss

Question 6

How many people exposed to TB get infected?

Answer 6

only 10-30% –> 90% become latent other 10% active TB

Treatment can cure, untreated = 50% die in 5 years, 25% recover, 25% remain sick

Question 7

When is chemoprophylaxis considered in TB?

Answer 7

Patients w. HIV
Recent TB converters
Patient <30 yrs of age w/ no known TB contact
Immunosuppressed

Question 8

What are the signs and symptoms of latent TB?

Answer 8

shaking chills, hypotension, acute resp distress

Question 9

When is short course TB therapy indicated/suitable?

Answer 9

organism is susceptible

Question 10

What is the standard short term treatment for TB? (Inc duration)

Answer 10

Isoniazid, rifampicin = 6months

Pyrazibamide, ethambutol = 2 months

Question 11

How long is miliary or CNS TB treated?

Answer 11

Treated for 12 months

Question 12

What additional drugs are used to treat TB? (Other than short term therapy)

Answer 12

Prednisone/prednisolone (speed resolution of TB pleural effusion)

Early death have been attributed to adrenal insufficiency (inc catabolism of endogenous corticos) secondary to enz induction by rifampicin

Question 13

When is corticosteroid use indicated in TB treatment?

Answer 13

TB pericarditis
TB meningitis
Very ill patients

Question 14

What measures improve TB treatment adherence?

Answer 14

Patient/family education

Close consistent follow up

Directly observed therapy(DOT)

Question 15

Why is TB treatment adherence important?

Answer 15

Reduce transmission, risk of relapse

Prevent drug resistance

Satisfactory treatment outcomes

Question 16

What drugs affects plasma levels if rifampicin?

Answer 16

Warfarin
Corticosteroids
Certain antiretrovirals
Oral contraceptives

Question 17

Why does rifamycin interact with many drugs?

Answer 17

it is an inducer of CYP450 enz

Question 18

Does TB treatment change w/ pregnancy?

Answer 18

No, standard therapy is given

BF (not discouraged) = give pyridoxine (vitamin) to babies on days that mother receives isoniazid

Question 19

What are nontuberculous mycobacteria (NTM)?

Answer 19

environmental organisms that occasionally cause respiratory, cutaneous or disseminated infection

rarely person-person

treatment is prolonged and difficult

Question 20

What pulmonary diseases are caused by myocbacteria?

Answer 20

Cavity/fibrotic upper lobe disease (similar to TB)

Hypersensitivity pneumonias

Question 21

What other disease can NTM cause?

Answer 21

Disseminated disease = immunocompromised patients, w/ HIV infections w/ low DC4 cell count

Leprosy, Avium (like TB), barnsdale ulcer, fish tank granuloma