Case: Mr. Fraeger, age 46 years, has had a persistent unproductive cough for several months that did not respond to cough medications. Recently, he has developed a productive cough accompanied by fatigue, anorexia, and night sweats. Examination indicated abnormal chest sounds and weight loss. A chest radiograph showed a small cavity and infiltrate, the tuberculin test was positive, and the sputum sample contained a small amount of blood and numerous acid-fast bacilli, confirming the diagnosis of active tuberculosis.
Question 1: Discuss the pathologic changes occurring during the development of active tuberculosis.
Mycobacterium tuberculosis is the usual cause of tuberculosis and primarily affects the lungs but it might invade other organs as well. Mycobacterium is an acid-fast, aerobic, slowing-growing bacillus that is somewhat resistant to drying and many disinfectants. It can survive in dried sputum for weeks and are destroyed by UV light, heat, alcohol, glutaraldehyde, and formaldehyde. The cell wall appears to protect the organism from destruction by normal body defenses. Primary infection of tuberculosis occurs when the microorganisms enter the lungs first, are then engulfed by macrophages which then causes a local inflammatory response. Some bacilli migrate to the lymph nodes which activate a type y or cell-mediated hypersensitivity response. A granuloma is formed at the site of inflammation which contain the bacilli forming a tubercle. Caseation necrosis develops in the center of the tubercle, forming a core of cheese-like material consisting of dead macrophages and necrotic tissue. Typically, a healthy person can resist this invasion and will be walled off by fibrous tissue and eventually calcify in a dormant state. Secondary or reinfection is the stage of active infection that often arises years after the primary infection, when the bacilli; hidden in the tubercles as discussed earlier are reactivated because of decreased host resistance; may be due to a new invasion of microbes. As the organism multiplies, tissue destruction occurs which forms a large area of necrosis. Cavitation occurs with formation of a large open area in the lung and erosion into the bronchi and blood vessels. Spread of the organisms into other parts of the lung is promoted due to cavitation and bacilli are present in the sputum where they may be passed on to others. Infection may also spread into the pleural cavity which causes pleuritis and adhesions.
Question 2: Discuss the transmission of TB and the conditions predisposing to the development of TB.
TB is transmitted by oral droplets that are released from a person with active infection that are inhaled into the lungs. Persons living in crowded conditions or those whose resistance is lowered because of immunodeficiency, malnutrition, alcoholism, conditions of war, or chronic disease are more frequently susceptible to TB. Children are also more likely to be infected than adults. More frequent travel has been shown to increase risk of TB contraction, increased homeless population who are malnourished and frequently have other diseases also have been shown to have a higher prevalence for TB as well as patients with AIDS.
Question 3: Discuss the treatment of tuberculosis and the precautions involved for health care personnel coming into contact with the patient.
Active TB is typically treated in either a hospital or at the person’s home now. Long-term treatment in combo with drugs is often recommended to eradicate the infecting microbes and reduce the risk of resistant bacteria. 6 months to a year or longer is the typical time frame of treating active TB, just depends on the severity and such. Drugs of choice include isoniazid (INH), rifampin, ethambutol, pyrazinamide, and streptomycin. Patient compliance with the drug regimen for the entire time is essential to totally eradicate the infection and prevent the development of drug-resistant microbes.
Precautions both patients and healthcare personnel can take include covering the mouth when coughing, wearing a mask when in contact with others, and avoidance of sustained close contact with others. Routine testing of health care providers is common practice and prophylactic medication may be required if the person shows a new positive tuberculin test in the absence of any other signs or symptoms of infection. Detailed protocols vary with the licensing bodies responsible for professional practice and the public health statutes. It is recommended that contacts of the patient be given prophylactic isoniazid for 1 year and receive TB resting as well.
Question 4: Suggest how family members or co-workers can protect themselves.
The best way for family members to protect themselves from being infected with TB is by observing high standards of hygiene. They should wash their hands regularly and take note not to share utensils, if shared, they should be cleansed appropriately before use. They can also prevent themselves by wearing masks to avoid coming into contact with any droplets from the infected individuals. Moreover, they can avoid regular contact with the infected person.
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