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Opportunistic Infections: Tuberculosis

Basic Information

Tuberculosis occurs in 4% of patients who have AIDS and in fact Mycobacterium tuberculosis located in any site in immunocompromised persons whose CD4 cells per microliter of blood are less than 200 is considered an AIDS-defining disease. Tuberculosis is on the rise in the U.S. and persons with HIV are at a much higher risk of developing it than persons who are not immunocompromised. Additionally TB tends to present itself when the CD4 count drops to 400 or 300 cells per mm, which is earlier than most opportunistic infections occur. TB is an infectious disease and can be transmitted by microscopic particles released in the air by the cough or sneeze of someone with active TB, though usually infection is the result of prolonged exposure to someone with TB. Coughed up blood by an infected person is also contagious. In the general population those most at risk reside, visit or work in:

  • prisons
  • hospitals
  • homeless shelters
  • soup kitchens
  • nursing homes
  • medical clinics

A dramatic increase in TB cases in this country has occurred since 1986 -- the incidence of cases in New York City since 1986 has increased by nearly 70%. Those persons at highest risk include:

  • immunocompromised persons
  • African Americans
  • Latinos
  • Alaskan natives
  • IV drug users
  • alcoholics
  • substance abusers
  • the elderly
  • the homeless
  • those foreign-born persons from countries where TB rates are high including Africa and the Caribbean

The bacterium Mycobacterium tuberculosis causes TB and like HIV itself tends to become resistant to drugs. It can be latent in the body or it can present as active TB, the most common site of active TB infection being the lungs. This is called pulmonary TB. When the CD4 cell count is between 300 and 400, TB is usually located in the lungs but when the CD4 cell count drops it may present as an extrapulmonary disease affecting any organ -- it can spread to different areas of the body via the blood and lymphatic systems.

Extrapulmonary TB has increased at more than six times the rate of pulmonary TB -- 25% of extrapulmonary TB is HIV related while over 50% of active TB cases in patients with AIDS is extrapulmonary. However, pulmonary and extrapulmonary disease may occur at the same time.

HIV infected patients are predisposed to:

  • acquire a new infection
  • have a reactivation of latent TB
  • develop active TB (which can progress rapidly) -- it is estimated that fully 10% of HIV infected persons will develop active TB sometime during their lifetime

Early detection and treatment of TB is extremely important in patients who are HIV positive. Following diagnosis of HIV, a TB test should be given and prophylactic treatment or treatment for active TB begun without delay. One of the reasons for this is because in those HIV positive patients who develop active TB, levels of HIV in their bloodstream increase dramatically, from 5 to 160 times over. The raising of HIV levels in the blood due to active TB increases the risk of AIDS and mortality because of the increased replication of HIV.

Symptoms

In cases of pulmonary TB symptoms include:

  • cough lasting longer than three weeks
  • blood in the sputum

In both pulmonary and extrapulmonary cases, symptoms can include:

  • fever
  • rapid weight loss
  • night sweats
  • malaise

Diagnosis/Treatment

The PPD (Purified Protein Derivative) skin test is the standard screening test for TB -- within 48 to 72 hours the skin will have developed a hard red bump or an induration if the test is positive for TB. This does not indicate whether the TB is latent or active and causing disease. Sputum should be cultured to help diagnose active disease and to evaluate if a patient has a drug-resistant form of TB. A clinical exam and chest X-ray will also help determine if active disease is present. It takes several weeks for the results of the cultured sputum but your health care provider will most likely initiate drug therapy based on best guesswork given from other indicators rather than delay treatment initiation.

When CD4 cells drop below 200, the PPD skin test may not be result in an induration large enough to satisfy diagnosis of TB -- but that dos not mean TB is not present. An anergy or skin test may also be indicated to help with diagnosis.

If during diagnosis, active TB is discovered, treatment should not be delayed.

Treatment begins with 4 to 6 drugs. The CDC recommends drug therapy consisting of 4 drugs:

  • isoniazid
  • rifampin
  • pyrazinamide
  • ethambutol/streptomycin

TB is considered multidrug-resistant if it does not respond to two or more of the standard drugs listed above used to treat TB. Unfortunately most cases of multidrug-resistance has occurred because of treatment interruption or noncompliance -- resistant strains of TB have already arisen and new resistant strains may arise due to stopping drugs too soon. Medication must be taken exactly as prescribed. Help prevent new strains from occurring because of noncompliance.

It is beneficial for you to be treated by an experienced health care provider in the field of HIV. For those patients taking protease inhibitors certain problems may arise when taking several of the TB medications simultaneously. Since TB speeds up HIV replication, the use of protease inhibitors is important but because of certain adverse effects associated with the mixing of the inhibitors with drugs for TB, your health care provider may recommend postponing use of protease inhibitors while TB drug therapy is completed, according to guidelines issued by the CDC.

If you are diagnosed with TB by a positive PPD but the TB is not active, you should begin prophylactic treatment immediately. Also if you test negative but have been exposed to someone with active TB, prophylactic treatment is indicated. HIV positive patients exposed to multidrug-resistant forms of TB should also have prophylactic treatment for at least one year.

Prognosis is generally considered good even in seriously immunocompromised patients with proper medication taken as directed and supportive treatment afterwards is generally not needed. We at Always Your Choice have had experience in treating many cases of HIV-related tuberculosis. If you have symptoms of active tuberculosis or would like to be tested for tuberculosis we would be glad to make an appointment with you.