Tuberculosis and PPD

Question 1

Definition

Answer 1

Infection due to Mycobacterium tuberculosis

Majority of symptomatic cases due to reactivation of old disease
versus new primary infection

Common cause of fever of unknown origin (FUO)

Question 2

Risk Factors

Answer 2

Immunosuppression
Alcoholism
Pre-existing lung disease
Diabetes
Advanced age
Malnourishment
Living in crowded conditions
Prison
Homelessness
Recent immigration status from developing nations into the US
Health care workers
Sick contacts of known TB patients (i.e. family, friends, coworkers)

Question 3

Miliary tuberculosis

Answer 3

Most severe, often fatal form
Indicates hematologic or lymphatic dissemination

Question 4

Extrapulmonary tuberculosis presentations include

Answer 4

CNS infection
Vertebral body Involvement (Potts Disease)
Renal (most common extrapulmonary site)
GI

Question 5

Symptoms

Answer 5

classically present for prolonged period of time (>3 weeks) and include
Cough
Hemoptysis
Dyspnea
Weight loss
Fatigue
Fever
Night sweats
Cachexia
Hypoxia

Question 6

Physical Exam

Answer 6

Tachycardia
Lymphadenopathy
Crackles/rales
Wheezes
Dullness to percussion

Question 7

Evaluation
Sputum Acid Fast Stain

Answer 7

Leads to presumptive diagnosis because cultures take a few weeks

Question 8

Evaluation
Purified Protein Derivative (PPD)

Answer 8

indicates previous exposure only, not necessarily active infection
Type IV delayed hypersensitivity reaction
May not be present in immunocompromised patients (anergy)

Question 9

Evaluation
CXR

Answer 9

Apical fibrocaseous cavitary lesions
Indicative of reactivation TB with or without cavitation

Ghon Complex
Hilar nodes and lower lobe nodes
Characteristic of primary disease

Multiple, fine, nodular densities
indicative of miliary tuberculosis

Question 10

PPD placement and reading

Answer 10

PPD placement
5 ml injected intradermally on the volar surface of the arm
The transverse induration is measured at 48-72 hours
BCG vaccinations render a patient’s PPD positive for a least one year

Question 11

PPD Reading

Answer 11

Reaction > 5 mm Considered positive in HIV, close TB contacts, CXR evidence

Reaction > 10 mm
Considered positive if homeless, immigrant from or living in developing nation, IVDU, chronic disease, resident of health or correctional institution

Reaction > 15 mm Considered positive in everyone else

Negative reaction with negative
controls Implies anergy from immunosuppression, old age,
malnutriton, and does not rule out TB

Question 12

Differential

Answer 12

Pneumonia, HIV, UTI, lung abscess, lung cancer, Aspergillus fungal ball, spinal tumor

Question 13

Active TB Treatment
Medical Management

Answer 13

Hospital respiratory isolation / directly-observed multi-drug therapy (DOT) for six months

Question 14

Active TB Management
Acute Treatment Phase

Answer 14

Icludes four-drug regimen for X months
Isoniazid (INH)
Must co-administer vitamin B6 (pyradoxine) to prevent peripheral neuritis
Can also cause hepatitis

Pyrazinamide

Rifampin
Turns body fluids orange

Ethambutol
Can cause retrobulbar/optic neuritis
Until drug-susceptibility studies are complete

Question 15

Active TB Management
Chronic Treatment Phase

Answer 15

Rifampin and INH for 6 months

Question 16

Atypical of multi-drug resistant TB Treatment

Answer 16

Medical managment
Supplemental pharmacologic treatment (beyond DOT)

Indications
Atypical or multi-drug resistent TB (MDR-TB)

Question 17

Asymtomatic Postive PPD Treatment

Answer 17

Medical management
Prophylactic INH for 9 months

Indications
Patients with positive PPD without active symptoms who have
CXR suggestive of old infection
Are recent new conversions (<2 years)
Have multiple other high-risk factors

Complications
Liver toxicity; may forgo in patients > 35 because of risk of INH-induced
liver toxicity
Pregnancy is not a contraindication to multi-drug therapy

Question 18

Prognosis

Answer 18

Good to excellent if identified and treated early
Miliary TB is most severe, and often fatal form given systemic dissemination

Question 19

Prevention

Answer 19

all cases ofsuspected or diagnosed TB must be reported to local and state
health authorities for public safety and prevention
Sick contacts must be notified and administered prophylactic treatment to
prevent further spread of diseas

Question 20

Complications

Answer 20

Untreated TB can spread throughout the lungs and to other major organ
systems leading to more advanced presentations (i.e. Potts disease, miliary TB
infection)