Chapter 202 Tuberculosis

Question 1

If untreated, the disease may be fatal

Answer 1

within 5 years in 50–65% of cases.

Question 2

(the bovine tubercle bacillus—characteristically resistant to pyrazinamide, once an important cause of TB transmitted by unpasteurized milk, and currently the cause of a small percentage of human cases worldwide)

Answer 2

M. bovis

Question 3

(the “vole” bacillus, a less virulent and rarely encountered organism)

Answer 3

M. microti

Question 4

(a bacillus infecting seals and sea lions in the Southern Hemisphere and recently isolated from humans)

Answer 4

M. pinni- pedii

Question 5

(isolated from banded mongooses in southern Africa),

Answer 5

M. mungi

Question 6

(a rare isolate from East African cases that produces unusual smooth colonies on solid media and is considered closely related to a supposed progenitor type).

Answer 6

M. canetti

Question 7

is due mainly to the organisms’ high content of mycolic acids, long-chain cross-linked fatty acids, and other cell-wall lipids.

Answer 7

Acid fastness

Question 8

content (65.6%) is indicative of an aerobic “lifestyle.”

Answer 8

high guanine-plus-cytosine

Question 9

The most infectious patients have cavitary pulmonary disease or, much less commonly, laryngeal TB and produce sputum containing as many as

Answer 9

105–107 AFB/mL.

Question 10

Bacilli, however, may persist for years before reactivating to produce _____, which, because of frequent cavitation, is more often infectious than is primary disease.

Answer 10

secondary (or postprimary) TB

Question 11

Clinical illness directly following infection is classified as ____ and is common among children in the first few years of life and among immunocompromised persons.

Answer 11

primary TB

Question 12

The incidence among women peaks at

Answer 12

25–34 years of age.

Question 13

About 2–4 weeks after infection, two host responses to M. tuberculosis develop: a

Answer 13

1. macrophage-activating CMI response

2. tissue-damaging response.

Question 14

is a T cell–mediated phe- nomenon resulting in the activation of macrophages that are capable of killing and digesting tubercle bacilli.

Answer 14

macrophage-activating response

Question 15

is the result of a delayed-type hypersensitivity (DTH) reaction to various bacillary antigens; it destroys unactivated macrophages that contain multiplying bacilli but also causes caseous necrosis of the involved tissues

Answer 15

tissue-damaging response

Question 16

these areas are most commonly involved in primary TB.

Answer 16

middle and lower lung zones

Question 17

The lesion forming after initial infection is usually peripheral and accompanied by transient hilar or paratracheal lymphadenopathy, which may or may not be visible on standard chest radiography

Answer 17

Ghon focus

Question 18

The Ghon focus, with or without overlying pleural reaction, thickening, and regional lymphadenopathy, is referred to as the

Answer 18

Ghon complex

Question 19

postprimary TB is probably most accurately termed adult-type TB because it may result from endogenous reactivation of distant LTBI or recent infection (primary infection or reinfection)

Answer 19

Also referred to as reactivation or secondary TB,

Question 20

It is usually localized to the apical and posterior segments of the upper lobes, where the substantially higher mean oxygen tension (compared with that in the lower zones) favors mycobacterial growth.

Answer 20

Post primary or adult type disease

Question 21

Hemoptysis, however, may also result from rupture of a dilated vessel in a cavity

Answer 21

(Rasmussen’s aneurysm) or from aspergilloma formation in an old cavity.

Question 22

Hemoptysis develops in ____ of cases, and massive hemoptysis may ensue as a consequence of the erosion of a blood vessel in the wall of a cavity.

Answer 22

20–30%

Question 23

Most common site of gastric TB

Answer 23

Terminal ileum and cecum