Source: Peloquin CA, Namdar R.
Tuberculosis. In: DiPiro, JT, Talbert RL, Yee GC, Matzke GR, Wells BG,
Posey LM. Pharmacotherapy: A Pathophysiologic Approach. 8th ed. http://accesspharmacy.com/content.aspx?aid=8003007.
Accessed July 23, 2012.
- Communicable infectious disease
- May produce silent, latent infection, as well as progressive,
- Caused by Mycobacterium tuberculosis, a
- Transmitted by coughing or sneezing.
- Primary infection initiated by alveolar implantation of M. tuberculosis in droplet nuclei small
enough (1–5 mm) to escape ciliary epithelial cells of upper
respiratory tract and reach alveolar surface.
- Progression to clinical disease depends on:
of M. tuberculosis organisms inhaled
- Virulence of these organisms
- Host’s cell-mediated immune response
- Bacilli ingested by pulmonary macrophages, where they are
killed or continue to multiply.
- Macrophages form granulomas to contain organisms.
- M. tuberculosis can spread through
bloodstream to infect any tissue or organ; most commonly infects
posterior apical region of lungs.
- Cell-mediated immunity occurs as well as delayed-type hypersensitivity.
- After 1–3
months, tuberculin skin test will be positive.
- ~90% of patients who experience primary disease have
no further clinical manifestations other than positive skin test
alone or in combination with radiographic evidence of stable granulomas.
- Primary progressive disease seen in ~ 5% of patients
- Reactivation disease develops in ~10% of patients,
with nearly half of these cases occurring within 2 years of infection.
- Most cases of TB
in United States believed to result from reactivation.
- Occasionally, massive inoculum of organisms may be introduced
into bloodstream, causing widely disseminated disease and granuloma
formation known as miliary TB.
- Globally, 2 billion people infected and 2–3 million
people die from TB each year.
- Isolate patients to prevent spread of active disease.
- Members of high-risk groups should be tested for TB infection
and educated about disease (Table 1; Column 1 at highest risk for
TB, followed by those in Column 2).
Table 1. Criteria for
Tuberculin Skin Test Positivity by Risk Group ||Download (.pdf)
Table 1. Criteria for
Tuberculin Skin Test Positivity by Risk Group
|Reaction ≥5 mm of Induration||Reaction ≥10 mm of Induration||Reaction ≥15 mm of Induration|
Recent contacts of TB case patients
Recent immigrants (i.e., within last 5 years) from high-prevalence countries
Injection drug users
Persons with no risk factors for TB
|Fibrotic changes on chest radiograph consistent with prior
TB||Residents and employeesa of the following high-risk
congregate settings: prisons and jails, nursing homes and other
long-term care facilities for the elderly, hospitals and other healthcare
facilities, residential facilities for patients with AIDS, and homeless
|Patients with organ transplants and other
immunosuppressed patients (receiving equivalent of prednisone for
Mycobacteriology laboratory personnel
Persons with the following clinical conditions that place
them at high risk: silicosis, diabetes mellitus, chronic renal failure,
some hematologic disorders (e.g., leukemias and lymphomas), other
specific malignancies (e.g., carcinoma of head or neck and lung),
weight loss 10% of ideal body weight, gastrectomy, and jejunoileal
Children younger than 4 years or infants, children, and adolescents exposed
to adults at high risk...