Tuberculosis Today

written by By Lorie A. Madsen, RNC, BSN

Despite a well-established battery of effective drugs, TB is on the rise again. Here's the latest intelligence for nurses who are on the front lines against the ravaging disease.

Louis Sullivan, the Secretary of Health and Human Services, is calling for a concerted effort to eliminate tuberculosis from the United States by the year 2010. His timetable will surprise people who thought the disease was already a problem of the past. In fact, a long sustained decline in tuberculosis reversed in 1985, and in 1988 alone, this nation's doctors saw some 22,000 cases.

Nurses have a pivotal role to play in making tuberculosis truly a disease of yesterday. You'll need to have up-to-date answers to many questions: Who's at risk of infection? How do you confirm a suspected diagnosis of TB? What are the nursing implications of treatment? How long does the patient remain contagious after starting treatment? What public health measures are most likely to slow down the spread of tuberculosis?

The patients most likely to be Infected

Antibiotics have been available since the 1940s to cure tuberculosis and prevent infection from spreading to patients' contacts. As a result, a person's risk is highest if he has lived in geographic areas where medical care is scarce, and the disease is, accordingly, more prevalent.

Nurses must be alert to the possibility of tuberculosis whenever a patient presents with respiratory symptoms, but especially if the patient has spent any amount of time in a less developed nation or has had restricted access to medical care in this country. Hispanics, American Indians, blacks, and Asians may be at greater risk, for example. In fact, these groups account for approximately two-thirds of tuberculosis cases in the United States. Homeless people are also at high risk.

Next to likelihood of exposure, a person's general health is the most important determinant, of tuberculosis risk. The bacillus meets less opposition when HIV Infection, debilitation associated with advanced age, malnutrition, cancer chemotherapy, or steroid medication in excess of 15 mg/day has reduced a person's immunity. Also at risk are those patients who have insulin-dependent diabetes, chronic renal failure, and lungs scarred by silicosis.

Using the PPD test to screen for infection

When William Wagner went to his doctor for a routine physical, tuberculosis was the last thing anybody expected to find. The 43-year-old professional felt fine. Since he didn't mention his service in Vietnam 20 years before, there was no obvious reason to think he might have been exposed to the bacillus. A chest X-ray, however, revealed a lesion of the right upper lobe.

Carl Carver was more obviously at risk. The 54-year-old malnourished alcoholic revealed that an X-ray taken 15 years earlier had shown a "spot" or his lungs. Recently, he had lost 25 pounds and developed fever, cough, and night sweats.

Wagner and Carver, like all patients who have X-ray evidence or symptoms suggesting pulmonary tuberculosis, immediately received a tuberculin skin test with purified protein derivative of tuberculin (PPD Four out of five infected individuals mount a significant immune response to PPD, which is made up of noninfectious proteins derived from tuberculosis bacilli.

To give this test, inject PPD intradermally on the smooth side of the forearm using a 27-gauge needle. Two to three days later, examine the boundaries of induration-the raised hard area-at the injection site. Use a ruler that has millimeter markings to measure its widest diameter. If the induration is difficult to see, you can mark its boundaries by drawing a line from a few centimeters away toward the site, stopping when you bump against the edge, and repeating the process on the opposite side.

Mr. Wagner formed an induration wider than 10 mm, indicating infection. Mr. Carver's response was in the borderline range at 8 mm, but his caregivers interpreted this as probably one of the test's 20% false negatives.

The PPD test needs special interpretation when patients have suppressed immunity from HIV or another cause. It can also produce a false negative when tuberculosis infection is so longstanding that the immune system has stopped reacting to it. That's why doctors order two consecutive tuberculin skin tests for some patients. Even though the results of the first test are negative, the PPD dose may serve as a "booster" to waken the body's dormant antibody response. A repeat test a week or two later may be positive.

Completing the diagnosis requires a sputum culture

Mr. Wagner's positive X-ray and PPD, and Mr. Carver's positive X-ray and symptoms, strongly suggested pulmonaly tuberculosis. The next step was to take sputum specimens for culturing, the only test that diagnoses pulmonary tuberculosis with certainty. The same specimen can be used to identify the drugs to which the patient's organism is vulnerable, and those it resists.

To obtain a useful sputum sample, instruct the patient to be sure to give you a specimen he's coughed up from his lungs- not spittle. If the patient has trouble producing sputum, have him inhale nebulized normal saline. Postural drainage and clapping; procedures may also help. As a last resort, nurses sometimes pass a nasogastric tube before breakfast and aspirate stomach contents, which contain sputum the patient has swallowed while asleep.

The physician will generally order three sputum samples taken at different time to enhance the chances of discovering any infection.

Sputum cultures give results in three to eight weeks. For a quick preliminary screen, meanwhile, a smear from the specimen is immediately examined under the microscope on a slide that's stained to show acid-fast bacilli. Identification of acid-fast staining mycobacterial organisms strengthens suspicion of tuberculosis, although they may represent a non-tubercular species such as Mycobacterium avium intracellulare. Failure to identify mycobacterial organisms does not rule out the possibility of tuberculosis.

Wagner and Carver both produced positive sputum smears.

Multidrug treatment is the rule

Physicians didn't wait for results from sputum cultures to start treating Wagner and Carver. Three weeks is too long to delay when there is a suspicious history or symptomatology backed up by a positive X-ray, PPD, or sputum smear.

Doctors started both patients on isoniazid (INH), the most effective anti-tuberculosis drug. Mr. Carver's physician supplemented isoniazid with rifampin (Rifadin, Rimactane) and pyrazinamide. Experts advise giving three or more drugs pending the results of sputum cultures, to make sure that resistant organisms are covered.

Mr. Wagner's physician prescribed only rifampinand isoniazid. This proved to be a mistake, because Mr. Wagner's organisms were resistant to both of them. The patient's history of probable exposure in Vietnam might have tipped off the doctors to this possibility, bacause isoniazid can be obtained without prescription in many foreign countries. Easy availability encourages haphilzald use, which leads to the development of resistant organisms in those geographical areas.

For nursing considerations if giving isoniazid and other major anti-tuberculosis drugs, see the opposite page.

Care and infection control in the hospital

A patient with tuberculosis is assigned to a private room with closed door. Air from the room should ideally be vented to the outside of the hospital rather than recirculated, because the patient launches live bacilli into the air when he coughs and talks. Once outside, bacilli have little chance of surviving and infecting other people, because they are killed by the ultraviolet component of sunlight. An ultraviolet light in the patient's room helps reduce risk of contagion.

Caregivers and visitors need to wear masks in the patient's room. Instruct the patient to cover nose and mouth with tissue when he coughs, and give cough suppressants if the problem interferes with sleep or daily living. Tubercular fevers can go very high and tend to peak in the afternoon. Aspirin and other antipyretics help control them.

Tuberculosis can cause wasting, so patients require high-calorie diet. Many have poor appetite. To encourage food in take, offer frequent small meals rather than a few big ones. Have the patient rinse his mouth with water before eating to cut the bad taste left by medicines and purulent sputum. Another helpful trick is to uncover the meal tray outsdie the room and allow strong odors to disperse before serving the patient.

Listen to the patient's worries about his condition. some patients find themselves isolated from family and friends, who fear catching the disease. In many cases, education can resolve such estrangement.

From discharge to cure is a very long road

Mr. Wagner's disease escalated while he was on ineffective drug therapy. He developed symptoms, and his X-ray showed progressively more extensive necrotic tissue in the right upper lobe. Finally the doctors decided to resect the lobe to lessen the load of tuberculosis bacilli in the patient's body. Although such extreme measures are seldom necessary, the case illustrates the harm that tuberculosis-and drug resistance-can do.

The operation and a new drug regimen eventually brought Mr. Wagner's disease under control. Most patients can leave the hospital and resume their normal activities a week after the start of effective drug therapy.

The signals for discharge are a declining number of mycobacterial organisms on repeat sputum smears and a reduction in clinical manifestations, especially sputum production. When these milestones occur, the period of greatest infectiousness is past. If the patient's family, friends, and colleagues didn't become infected when the disease was at its most contagious, they're unlikely to do so now.

Regardless, the patient needs to be taught not to take risks-for example, by visiting people who have compromised immunity. He should continue to cover his nose and mouth with tissues when coughing, and dispose of the tissue in a closed paper bag.

Patients need to understand the discharge does not mean they are cured. It's vitally important to follow through with the entire drug therapy regimen-which usually lasts from six months to a year. In Mr. Wagner's case, it took two years of treatment to eliminate his resistant organisms.

Screening contacts helps intercept TB's spread

Mr. Carver's hospital stay went much more smoothly than Mr. Wagner's, and he was released after only three weeks. Before long, however, he was back.

The Denver health department insists that all tuberculosis patients receive every dose of medication under a health worker's supervision. They believe this is neccessary to help prevent partially compliant patients from developing and introducing drug-resistant strains into the community. When Mr. Carver failed to keep three consecutive clinic appointments, the health department placed him in the hospital under statutory quarantine.

Besides supervising compliance, public health officials conduct epidemiological investigations to find everyone who may have become infected from each known case. Standard procedure is to first administer PPD tests to those who share the most air with the patients, usually the patient's household. When Mr. Wagner's wife's test proved positive, epidemiologist widened the circle of investigation to include the people with whom he has the next closest contacts, his co-workers. All were free of infection, so the search stopped there. Had a colleague been infected, epidemiologist would have tested his friends.

Testing Mrs. Wagner's contacts wasn't necessary since her sputum contained no organisms.

Why eliminating TB will take time

Mr. Wagner was released from the hospital after eight weeks and continued multidrug therapy for two years. Mrs. Wagner underwent a year of therapy with isonizaid only, as is standard when a person is PPD postive but has no clinical evidence of active disease. After several false start, Mr. Carver got the message about compliance and completed his therapy.

Both men's experience were more complicated than those of most TB patients. They illustrate possibilities, however, that the nurse must keep in mind.

Their cases also show some of the reasons TB has been difficult to eliminate. As in Mr. Wagner's case, historical facts that would suggest possible exposure are often buried. As in both cases, person can have asymptomatic infection for years.

Another fairly common scenario is for a patient newly admitted to a nursing home to have longstanding tuberculous infection that is not contagious as long as it's held in check by the immune system. When increasing debility damage immunity however, the infection can progress and can become active and communicable. That's why some nursing homes administer dual skin tests to all new residents.

Anti-tuberculosis drugs can cure almost every known case of tuberculosis. But because of foreign-born persons entering the country, persons dually infected with HIV and tuberculosis, and unsuspected cases, it will be some time before we can realize Secretary Sullivan's hope of total elimination of TB. The situation can be comparedc to a garden where weeds are pulled up as soon as they appear. Complete clearance takes more than one season because seeds keep flying in on the wind, and some are germinating underground.