Page 196 - Review of Medical Microbiology and Immunology ( PDFDrive )

mebooksfree.com
mebooksfree.com
mebooksfree.com

mebooksfree.com
mebooksfree.com
mebooksfree.com
mebooksfree.com mebooksfree.com mebooksfree.com among Native Americans, African Americans, and Native 185 mebooksfree.com
mebooksfree.com
mebooksfree.com
CHAPTER 21 Mycobacteria
bovis also causes tuberculosis in humans. Mycobacterium
Alaskans.
bovis is found in cow’s milk, which, unless pasteurized, can
cause gastrointestinal tuberculosis in humans. The disease
tuberculosis occurs in only a small number of infected
Pathogenesis
individuals. In the United States, most cases of tuberculosis
are associated with reactivation in elderly, malnourished
shown in Figure 21–2. It describes primary tuberculosis
men. The risk of infection and disease is highest among
which typically results in a Ghon focus in the lower lung.
socioeconomically disadvantaged people, who have poor
Primary tuberculosis can heal by fibrosis, can lead to pro-
housing and poor nutrition. These factors, rather than An overall scheme of pathogenesis by M. tuberculosis is
gressive lung disease, can cause bacteremia and miliary
mebooksfree.com
mebooksfree.com
mebooksfree.com mebooksfree.com Primary tuberculosis Infection with Mycobacterium tuberculosis mebooksfree.com mebooksfree.com
genetic ones, probably account for the high rate of infection

Nonimmune host
(usually child)

mebooksfree.com mebooksfree.com Delayed (HIV, malnutrition) Severe bacteremia hematogenous mebooksfree.com mebooksfree.com
Death mebooksfree.com
Tuberculin skin mebooksfree.com
Ghon focus
(usually lower
lobes)

Progressive
Heals by fibrosis
Lymphatic or
lung disease
dissemination
Miliary
hypersensitivity
in several organs
(Latent tuberculosis)
test positive Death tuberculosis Dormant tubercle bacilli
mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com
Reactivation in
adult life

Cavitary lesion
(usually upper
lobes)

mebooksfree.com mebooksfree.com mebooksfree.com Extrapulmonary tuberculosis mebooksfree.com mebooksfree.com
mebooksfree.com
• CNS (parenchymal tuberculoma or meningitis)
• Vertebral body (Pott’s Disease)
• Lymphadenitis • Renal • GI • Adrenals

FIGURE 21–2
Pathogenesis by Mycobacterium tuberculosis. (Reproduced with permission from Le T, Bhushan V, and Sochat, M. First Aid for the USMLE
Step 1. 25th ed. New York: McGraw-Hill, 2015.)

mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com