Positive protein derivative skin test

The use of prophylactic isoniazid therapy for transplant patients with evidence of exposure to M. tuberculosis (those with a positive purified protein derivative skin test) remains controversial. Risk of reactivation and development of clinical tuberculosis is enhanced with posttransplant immunosuppression. Some clinicians believe, however, that the risk of isoniazid-induced hepatotoxicity, especially in liver transplant recipients, in whom the rate of hepatotoxicity has been reported as high as 40%, outweighs the benefits of treatment. High-risk patients who may be considered for isoniazid prophylaxis include those with a positive skin test, those with previously diagnosed tuberculosis who may not have been treated adequately, patients in close contact with individuals with active pulmonary disease, and patients with abnormal chest radiographs consistent with old tuberculosis who have not received prior prophylaxis. " ... 

The nurse is reading this intradermal positive protein derivative (PPD) skin test 72 hours after it was administered. 

Persons with acquired immunodefidency syndrome or those who are positive for the human immunodefidency virus and have a positive tuberculosis skin test or a negative tuberculosis skin test but a history of a prior significant reaction to purified protein derivative (a skin test for tuberculosis)... 

Because of the risks of adverse reaction to the vaccine by persons who had already been exposed to the disease a sensitivity test must be carried out prior to immunization with BCG. A Mantoux skin test assesses an individual s sensitivity to a purified protein derivative (PPD) prepared fi om heat-treated antigens (tuberculin) extracted fiom M tuberculosis. A positive test imphes past infection or past, successful immunization Those with strongly positive tests may have active disease and should be referred to a chest clinic. Many people with active TB, especially disseminated TB, however, sero-convert fiom skin test positive to skin test negative. Results of the skin test must therefore be interpreted with care. 

Infliximab therapy is associated with increased incidence of respiratory infections of particular concern is potential reactivation of tuberculosis or other granulomatous infections with subsequent dissemination. The FDA recommends that candidates for infliximab therapy should be tested for latent tuberculosis with purified protein derivative, and patients who test positive should be treated prophylactically with isoniazid. However, anergy with a false-negative skin test has been noted in some patients with Crohn s disease, and some experts routinely perform chest radiographs to look for active or latent pulmonary disease. Infliximab also is contraindicated in patients with severe congestive heart failure. The significant cost of infliximab is an important consideration in some patients. 

These results were confirmed in the main by Dorset and Henley. A polysaccharide was obtained from Long s synthetic medium after growth of M. tuberculosis, human strain. This polysaccharide showed a positive biuret test for protein, and underwent hydrolysis only with difficulty. D-Arabinose and D-mannose were identified in the hydrolysate. No glycuronic acid could be detected. On hydrolysis, the D-arabi-nose seemed to be liberated before the other constituents. It was concluded from the biological tests that the active principle of tuberculin concerned in eliciting the skin reaction was a protein. This work was repeated with polysaccharides derived from the culture medium of the bovine and avian strains of organisms, and very similar results were obtained. D-Arabinose and D-mannose were also identified in those polysaccharides. 

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