Mycobacterium tuberculosis

CASE 1

• A 32 year old man has been having fatigue, cough, and mild chills for the past 3 months. The cough has become increasingly productive, and the patient decided to seek medical attention when he noticed blood in his sputum. He is not aware of weight loss but has noticed that his clothes fit more lossely than usual. He is a tro-tro driver who does not use alcohol or tobacco.

• On physical examination, the patient had a temperature of 37.8 degrees. The other vital signs were normal. Examination of his chest revealed dullness to percussion in the right upper lung fields and crackles in the same area. A chest xray was ordered (see below) and showed a right upper lobe (apical) infiltrate with some evidence of cavity formation.

• Becuase of the suspicion of tuberculosis, an acid-fast stain of the sputum was performed and showed the following:

Questions:

    1. Does this patient have active pulmonary tuberculosis?
    2. Is he infectious to other people?
    3. Can you speculate about when he might have acquired this infection initially?
    4. If you wished to isolate this organism in the laboratory, how would this be accomplished? What special precautions are required?
    5. When would you expect his culture to turn positive?
    6. What other laboratory techniques can also be used to diagnose this infection?
    7. What additional laboratory tests are needed before initiating treatment for this patient?
    8. The patient will be treated initially with four antimicrobial drugs. Why?
    9. What would be the outcome of this case if the patient is lost to follow-up and never treated?

 

CASE 2

• A 28 year old man has fever, cough, and left-sided chest pain for the past week. The pain is sharp and stabbing and occurs when the patient coughs or breathes deeply. The cough is productive of large amounts of yellow-white sputum. During the year prior to the onset of this illness, the patient had been gradually losing weight and feeling increasingly weak.

• On examination, the patient had a temperature of 38.6. The mouth was remarkable for the presence of oral thrush on the hard palate and buccal mucosa. The left chest was dull to percussion with decreased breath sounds. There were bilateral crackles heard in the lower lung fields.

• A chest xray is shown. An acid fast stain of the sputum was similar to the one shown in Case #1 above. An HIV test was positive

Questions:

    1. How is the presentation of this case with HIV-positivity difference from Case #1?
    2. Could this illness be due to a mycobacterium other than M. tuberculosis? How can you be certain which mycobacterium is causing the lung disease?
    3. What will be the likely outcome if this patient is not treated for his tuberculosis?
    4. What can you expect as an outcome if the patient is treated with the same regimen as the patient in Case #1? Will this patient need treatment for the rest of his life?

 

CASE 3

• A 25 year old Internal Medicine resident developed increasing pain in the mid-lumbar spine iver a period of 3 weeks. The pain is localized and midline; there is no radiation. However, there is tenderness to percussion over L2. He denied any fever, chills, cough, or weight loss in the preceding year. Once a week, the resident attends the TB Clinic at his hospital.

• An xray of the lumbar spine was taken and showed a decrease in the L1-L2 disc space with destruction of the superior border of L2 (compare the affected disc space with the L2-L3 space below).

• A needle biopsy of the affected disc space was performed. The pathology was non-specific, and the acid-fast stain was negative. However, the patient was treated with anti-tuberculous therapy and expereinced a gradual reduction of pain over the next 2 weeks. By 6 weeks, all discomfort was essentially gone.

Questions:

    1. Can this clinical scenario be explained by tuberculosis?
    2. In this case, how did the organism likely enter this resident's body? Where was the primary infection?
    3. What abnormalities -- if any at all -- would you expect to find in a chest xray?
    4. Is this patient contagious to others?
    5. How does the treatment of this form of tuberculosis differ from that of Case #1?