STEP PERSPECTIVE, Volume 7, No. 2 -Summer/1995; A Publication of the Seattle Treatment Exchange Project e-mail: step@eskimo.com
Norma Rolfsen, RN

Tuberculosis is caused by Mycobacterium tuberculosis complex (M.tb), an airborne bacterial infection. It is spread when a person has close prolonged contact with someone who has active symptomatic infectious disease. TB is spread in the air only by coughing, and is not spread by blood, sexual, or other contact. It is important to understand the difference between TB infection and TB disease. The immune system responds to TB infection within two to ten weeks after exposure to someone with contagious disease. For the majority of those with TB infection, the disease becomes dormant once the immune system responds. This is the latent infection stage. In this latent stage, a person is not contagious nor symptomatic. The immunocompetent person with TB infection in the U.S. has a 10% lifetime risk of developing active disease. In those who are HIV-positive, there is an 8-10% yearly risk of developing TB disease. Those with HIV often bypass the dormant stage, directly developing active disease.

It is only during active disease that one is both symptomatic and contagious and symptoms of TB include a persistent cough, night sweats, fever, chills, weight loss, fatigue, sometimes chest pain and coughing of blood. Those with HIV are at greater risk of developing TB outside of the lungs, called extrapulmonary TB. Extrapulmonary TB occurs in one-to two-thirds of TB cases involving HIV. People with extrapulmonary TB are usually not infectious unless there is a draining abscess containing M.tb.

It is vital that clinicians consider TB when diagnosing and treating people with HIV infection. Testing methods include a skin test with PPD (purified protein derivative), chest X-rays, and sputum smears and cultures. The Mantoux test is used to screen for TB infection. A small amount (0.1 milliliters) of PPD is injected just beneath the skin on the forearm. The reaction to the test is read by an experienced health care professional 48-72 hours later. People with HIV, the CDC recommends that the test be considered positive when induration below the skin measures 5mm or greater. Redness or surface swelling does not indicate a positive test. In HIV individuals at high risk for TB infection, 10mm of induration is considered a positive test. This test is of limited usefulness for people with HIV infection because people who are immunocompromised become less able to develop a response to the test. Decreased CD4 counts correlate to decreased response to the PPD and a false negative may result. For this reason, testing with controls, also known as anergy panels, is recommended for people who are HIV positive. Two of three control solutions (candida, mumps, or tetanus toxoid) are injected and read, in the same way as the PPD, in order to determine the body's ability to mount a reaction. These solutions are used in the United States as most people have been exposed to these diseases either by infection or vaccination. People with a positive PPD, regardless of response to the controls, are considered to have TB infection. It is concluded that those with positive controls and negative PPD do not have TB infection. In those with negative controls, and negative PPD, the results may be inaccurate and cannot be used for diagnosis.

Anergy is the term used when the body is unable to mount an immune response. Other factors besides HIV infection may also cause anergy, including acute TB disease, febrile or viral illnesses, oral steroid use, cancer, insulin dependent diabetes, bone marrow disease, use of immunosuppressive drugs, or other conditions. Anergy testing, while recommended by the CDC, remains controversial. TB Monitor (November 1994) quotes David Rose, M.D., Associate Professor of Medicine, and Director of the AIDS Program at Mount Sinai School of Medicine in New York, "It does give us some information. The problem with the test is that it gives us imperfect information and we have to make clinical decisions on the basis of imperfect information." In people with HIV, who have been exposed to TB, or who have developed symptoms, further testing is indicated regardless of PPD status. A chest X-ray and sputum specimens should be obtained. Clinicians should be aware that X-ray changes in those with low CD4 counts do not follow typical patterns. If a sputum smear is positive for mycobacterium (+AFB), the person is potentially infectious, and treatment for TB should begin. Cultures from the sputum specimen may take up to 8 weeks to differentiate M.tb from other organisms. Drug susceptibility tests will also be performed to determine drug efficacy in treating TB. These tests also take several weeks.

Preventive therapy for those who have TB infection, but not active disease, is indicated. Daily Isoniazid (INH) is normally used alone unless INH resistance is known. In HIV-positive persons the daily dose is 300mg for 12 months. Twice weekly dosing for some may be effective. People receiving mycobutin 300mg daily, for MAI prophylaxis, do not need to take INH while on this therapy. However, mycobutin is not used to treat active disease in place of INH.

In HIV-positive persons with active TB disease, 3 to 4 drug therapy is recommended until susceptibility is determined. These drugs are INH, rifampin, pyrazinamide, and/or ethambutol. If the organism is culture sensitive to INH and rifampin, the person will continue only on these two medications. Multiple drug therapy has become standard practice since the emergence of multi-drug resistant TB (MDR TB). MDR TB is an organism resistant to INH and rifampin. MDR TB cases have increased dramatically, particularly in New York City, although few cases have been documented in Seattle-King County.

It is important that clinicians provide education about, and monitoring for, adverse reactions of anti-TB drugs. These include allergic reaction, liver problems; including hepatitis, peripheral neuropathy, and decreased platelet count. In severely immunocompromized people with TB, drug treatment may be less effective due to HIV-related malabsorption. Alcohol use also increases risk for decreased liver function. Anti-TB drugs also interact with numerous other drugs. Rifampin may accelerate metabolism of numerous other drugs including anti-convulsants, digitalis, fluconazole, ketoconazole, oral diabetes agents, and methadone. Peoples receiving methadone may need to have their dose increased by as much as 50%. Rifampin may also cause oral contraceptives and contraceptive implants (e.g., Norplant) to be ineffective. INH interacts with Dilantin and Antabuse.

Drug therapy will continue for a total of 9 to 12 months, or 18 plus months for MDR TB. Sputum cultures should be collected at least monthly until the cultures convert to negative. Other factors to consider when measuring effectiveness of therapy include X-ray improvement and clinical improvement. When there is poor response to treatment due to a failing drug regimen, two new drugs should always be added simultaneously. Adding only one drug may further increase drug resistance.

Many people receiving treatment for TB disease find it difficult to complete the recommended regimen and a full 25% do not do so. Inadequate treatment can lead to disease relapse, ongoing transmission, and development of drug resistance. It is essential that public health departments, and other health care workers take all possible measures to assist people in adherence to drug regimens. This is vital both in treating individuals and controlling the spread of TB. Numerous studies have documented the effectiveness of directly observed therapy (DOT). This means that a health care worker watches the person swallow each dose of medication. DOT should be considered for all people, as clinicians may be inaccurate in predicting adherence. DOT can yield decreased rates of relapse and drug resistance, and is useful in determining treatment failure vs. non-adherence.

To be most effective, clinicians must negotiate treatment plans with the individual and their family or support person(s). The development of a therapeutic rapport between a clinician or outreach worker, and the person may increase the person's ability to understand and choose treatment goals and self-care interventions. Whenever possible, people should work with outreach staff of similar cultural and linguistic backgrounds. Incentives may be used to increase adherence. These may include providing food, transportation, and even housing. Urine tests, to check for the presence of drug metabolites, and/or pill counts may be done. These should also be negotiated with the person. Adherence may also be increased with the use of fixed dose combination drugs, thereby decreasing the number of pills the person must take. Within impoverished communities, at least one study has shown greatly increased adherence when food was given along with the medication regimen. This intervention was shown to be cost effective due to the reduction in transmission of TB in the community.

Suspect TB cases must be reported to the public health department. They should also be consulted when it is noted that a person with TB is unable or unwilling to adhere to treatment. They are able to increase services to enable the person to complete therapy. If this is ineffective, the health department will seek appropriate action even to the detention of an infectious person at risk of spreading TB to the community. Infection control measures must be implemented in all settings where people with TB, or at risk for TB, are seen. Engineering controls should be used to decrease the spread and reduce concentration of airborne TB particles. Isolation rooms, with ventilation systems to maintain negative pressure and exhaust air properly, should be available and maintained appropriately. Filters in ventilation systems and ultra-violet lighting may be effective in conjunction with other infection control practices. Special masks (personal respirators) should be used by people who must leave an isolation setting and by health care workers in areas where there is an increased risk of exposure. Visitors should also wear these masks while the person is considered infectious. All health care workers should be educated about TB transmission, infection, and infection control. Protocols should be developed for PPD screening for workers and volunteers of agencies which serve TB clients, or those at risk.

The first priority in TB control must be identifying and treating those with TB disease. It is essential that those persons who have been in contact with TB are also evaluated. To impact the current trends in TB infection, it is critical that community risk/needs assessments be done to identify each community's high risk groups. Primary care providers must be educated to facilitate early diagnosis and treatment. Public health nurses and outreach workers must be aware of the persons's individual needs, including racial, cultural, language, and economic factors. Community leaders may become involved to assist persons at risk to access the health care system, and assist public health officials to reach those who are at risk.

Norma Rolfsen, RN is the Nursing Coordinator of the Bailey-Boushay House and Seattle/Puget Sound chapter President of Association of Nurses in AIDS Care (ANAC)

These articles were provided by the Seattle Treatment Education Project - Copyright (c) 1997 - Seattle Treatment Education Project. Noncommercial reproduction encouraged. Distributed by AEGIS - http://www.aegis.com
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Copyright © 1995 - Seattle Treatment Education Project (STEP) - All rights reserved. Noncommercial reproduction is encouraged. STEP is published four times a year by the Seattle Treatment Education Project, 127 Broadway East, 3rd Floor, Seattle, WA 98102.    Email: step100@aol.com  STEP web page