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Positive PPD and chemoprophylaxis for tuberculosis infection
1Department of Family and Preventive Medicine, University of California, San Diego, School of Medicine, USA.
Abstract:
The appearance of an indurated area of 5 mm or more 48 to 72 hours after administration of purified protein derivative (PPD) is considered a positive reaction in persons who have recently had close contact with an individual with active tuberculosis, in persons with radiographic findings consistent with a past history of tuberculosis or in persons with known or suspected human immunodeficiency virus infection. Ten or more millimeters of induration is considered a positive reaction in persons at increased risk of tuberculosis. Induration of 15 mm or more is considered a positive result in all other persons. Candidates for a six-month course of isoniazid include persons under age 35 who are recent converters and have induration of 10 mm or more and persons over age 35 with 15 mm or more of induration. Patients with HIV infection and those with radiographic evidence of previous tuberculosis should receive 12 months of therapy. A regimen of pyrazinamide and either ethambutol, ofloxacin or ciprofloxacin is recommended for contacts of patients with multidrug-resistant tuberculosis.
Insights
Tuberculosis screening using purified protein derivative (PPD) involves measuring induration size. Positive reactions indicate potential tuberculosis infection, guiding treatment decisions for various risk groups.
Area of Science:
- Infectious Diseases
- Immunology
- Public Health
Background:
- Tuberculosis (TB) remains a significant global health concern.
- Accurate screening is crucial for early detection and treatment.
- Purified protein derivative (PPD) testing is a common diagnostic tool.
Purpose of the Study:
- To define positive PPD test reactions based on induration size.
- To outline treatment recommendations for different risk groups.
- To guide management of individuals exposed to or at risk for TB.
Main Methods:
- Administering purified protein derivative (PPD) intradermally.
- Measuring induration diameter 48-72 hours post-administration.
- Classifying reactions based on induration size (5mm, 10mm, 15mm+) and patient risk factors.
Main Results:
- A 5mm+ induration is positive for close contacts, those with TB radiographic findings, or HIV-infected individuals.
- 10mm+ induration is positive for individuals at increased TB risk.
- 15mm+ induration is positive for all other individuals.
Conclusions:
- PPD test interpretation varies by individual risk factors and exposure history.
- Treatment regimens, including isoniazid, pyrazinamide, ethambutol, ofloxacin, or ciprofloxacin, are recommended based on test results and patient profile.
- Specific protocols are advised for HIV-infected patients and contacts of multidrug-resistant TB cases.