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Tuberculosis (TB), a multisystemic disease with myriad presentations and manifestations, infects more than one third of the world's population and remains the leading killer of those infected with HIV.[1] Despite ongoing strides toward halting and reversing the TB epidemic, the World Health Organization (WHO) estimates that in 2014, more than 9.6 million people fell ill with TB, and 1.5 million died of it. The chest radiograph in the slide shows bilateral pleural effusions (left greater than right) in a patient with progressive pulmonary TB.
Image courtesy of Radiopaedia.org | A.Prof Dr. Frank Gaillard.
The chest radiograph in the slide demonstrates innumerable tiny pulmonary nodules consistent with miliary TB. Primary infection with TB is typically asymptomatic, though a small number of patients may have symptomatic hematologic dissemination, resulting in miliary tuberculosis. Only 5% of patients go on to progressive primary TB. Most symptomatic patients have postprimary TB (also referred to as reactivation TB), the symptoms of which may include fever, malaise, night sweats, weight loss, and cough with or without hemoptysis.
Image courtesy of Radiopaedia.org | Dr Mark Holland.
The lungs are the most common site of primary infection by Mycobacterium tuberculosis. They are a major source of disease spread, as well as of individual morbidity and mortality. Radiographic features can include patchy or lobar consolidation, cavitation (typically in postprimary TB), hilar and mediastinal adenopathy, and pleural effusions. Postprimary TB typically develops in the posterior upper lobes or the superior lower lobes. Miliary TB, representing hematogenous dissemination, is uncommon but carries a poor prognosis. The axial computed tomography (CT) image in the slide shows patchy consolidation with cavitation in the left upper lobe in a patient with postprimary TB.
Image courtesy of Radiopaedia.org | Dr Natalie Yang.
The chest CT scan in the slide shows apical disease of the right upper lung, in addition to emphysema in both upper lungs.
Which of the following conditions most increases a patient's risk of acquiring TB?
Image courtesy of Klaus Lessnau, MD, FCCP, and Jonathan Caronia, MD.
Answer: D. HIV infection.
The chest radiograph in the slide shows postprimary pulmonary TB in an HIV-positive patient. HIV alters the pathogenesis of TB, thereby greatly increasing the risk of developing TB for HIV-positive individuals, causing more frequent extrapulmonary involvement, and resulting in atypical radiographic manifestations. Globally, TB is the most common opportunistic infection in HIV-seropositive individuals and remains the leading cause of death in patients with AIDS.[2]
Image courtesy of Radiopaedia.org | Roberto Schubert, MD.
Immunocompromised patients (eg HIV-positive patients) are at higher risk for extrapulmonary manifestations of TB. Extrapulmonary TB may infect a diverse group of organs and structures, including the heart, liver, spleen, eyes, gastrointestinal tract, cerebral tissue, and spine. Many patients with extrapulmonary TB may have a normal chest x-ray. Pott disease (osteomyelitis/diskitis of the spine secondary to hematogenous spread of TB) may lead to progressive vertebral collapse and kyphosis.[3] Pott disease is shown on the sagittal postcontrast T1-weighted image of the spine in the slide.
Image courtesy of Radiopaedia.org | Dr Hani Al Salam.
The chest radiograph in the slide demonstrates a cavitary lesion, most likely in the superior segment of the right lower lobe. Currently, 11 drugs are approved by the US Food and Drug Administration (FDA) for treating TB. First-line medications include rifampin, isoniazid, pyrazinamide, and ethambutol, which are highly effective for susceptible TB. Other FDA-approved agents include rifapentine, cycloserine, ethionamide, para-aminosalicylic acid, streptomycin, and capreomycin; bedaquiline is approved for treatment of multidrug-resistant (MDR)-TB as part of combination therapy when other agents are unavailable.[4] Regimens for treating TB have an initial phase of 2 months, followed by a continuation phase of either 4 or 7 months, for which several options are available. In patients who have cavitation on the initial chest film and positive sputum cultures after 2 months of treatment, the continuation phase should be extended to 28 weeks.[2]
Image courtesy of Radiopaedia.org | Dr Aditya Shetty.
Treatment of TB is becoming challenging as the prevalence of drug-resistant TB increases worldwide. MDR-TB is defined as TB that is resistant to isoniazid and rifampin, the two most effective first-line drugs for TB. Extensively drug-resistant (XDR)-TB is resistant to isoniazid, rifampin, any fluoroquinolone, and at least one injectable second-line drug (ie, amikacin, kanamycin, or capreomycin).[5] Treatment of drug-resistant TB requires a long course of therapy (up to 2 years) using medications that have more side effects and are significantly more costly.[5] The axial CT scan in the slide shows a calcified left pleural effusion from a chronic empyema secondary to TB.
Image courtesy of Radiopaedia.org | Dr Rupesh Namdev.
The coronal CT scan in the slide, from a patient with TB, demonstrates a large cavitary lesion in the right upper lobe with multiple smaller nodular and cavitary lesions.
After 2 months of treatment, which of the following conditions would suggest infection with MDR-TB?
Image courtesy of Radiopaedia.org | Dr David Cuete.
Answer: D. Continued weight loss.
With effective treatment of TB, the patient's weight should increase. MDR-TB also should be suspected with continued fever, worsening chest x-ray, increasing cough, and continued night sweats, as well as with sputum cultures that will not convert to negative. The radiograph in the slide reveals biapical pleuroparenchymal scarring secondary to chronic TB.
Image courtesy of Radiopaedia.org | Dr Aditya Shetty.
The chest radiograph in the slide shows patchy consolidation in the left upper lobe, subsequently diagnosed as TB.
If a patient subsequently develops MDR with five-drug resistance, which of the following did not contribute to this outcome?
Image courtesy of Klaus Lessnau, MD, FCCP, and Jonathan Caronia, MD.
Answer: D. At-home treatment with directly observed therapy.
The chest radiograph in the slide shows a left apical cavity in a patient with TB. Patients with TB can be treated at home, provided that they are observed during administration of treatment; they need not be admitted to a hospital as long as directly observed therapy is available.
Image courtesy of Klaus Lessnau, MD, FCCP, and Jonathan Caronia, MD.
This axial CT image on bone windows demonstrates consolidation in the posterior right upper lobe, as well as paraspinal soft-tissue thickening and destruction of the adjacent vertebral body, in a patient with pulmonary TB and Pott disease. Multiple factors contribute to the drug resistance of M tuberculosis, including incomplete and inadequate treatment or adherence to treatment, logistical issues, virulence of the organism, multidrug transporters, host genetic factors, and HIV coinfection.
Image courtesy of Radiopaedia.org | A.Prof Dr. Frank Gaillard.
The axial CT scan in the slide shows a large cavitary lesion with bilateral pulmonary nodules in the left upper lobe consistent with TB infection. The patient has resistance to rifampin, isoniazid, pyrazinamide, ethambutol, and streptomycin.
Which of the following drugs should not be used for MDR-TB treatment in this patient?
Image courtesy of Radiopaedia.org | Dr Mohammad Taghi Niknejad.
Answer: B. Rifabutin.
Rifabutin is not effective in most patients with rifampin resistance. Capreomycin is a powerful drug for treatment of MDR-TB. Three additional drugs are used to prevent acquired capreomycin resistance. The CT scan in the slide shows advanced bilateral pulmonary tuberculosis with bilateral pulmonary nodular and consolidative opacities.
Image courtesy of Klaus Lessnau, MD, FCCP, and Jonathan Caronia, MD.
The chest radiograph in the slide shows patchy consolidation with small cavitary lesions in the right upper lobe of a patient with TB. The patient needs treatment for XDR-TB.
Which of the following drugs should not be used in this patient?
Image courtesy of Radiopaedia.org | A.Prof Dr. Frank Gaillard.
Answer: B. Capreomycin.
Capreomycin is used for the treatment of MDR-TB. By definition, XDR-TB is resistant to capreomycin. Because XDR-TB is resistant to the most potent TB drugs, the remaining treatment options are less effective, have more side effects, and are more expensive. Treatment is successful for an estimated 30-50% of patients with XDR-TB. Outcomes depend greatly on the extent of drug resistance, the severity of disease, the status of the patient's immune system, and the degree to which the patient adheres to treatment. In the United States, the risk of acquiring XDR-TB remains low, with only 63 cases reported between 1993 and 2011.[6] The axial CT scan in the slide demonstrates innumerable bilateral tiny nodules in a patient with miliary TB.
Image courtesy of Radiopaedia.org | Radswiki.
The chest radiograph in the slide shows right apical lung disease. For adults with HIV infection, the minimum treatment duration should be 6 months, even in the case of culture-negative TB; prolonged continuation phases should be considered for HIV-infected patients who exhibit a delayed response to therapy. Patients with advanced HIV infection should be treated with daily or thrice-weekly therapy in both initial and continuation phases. Once-weekly isoniazid and rifapentine should not be used during the continuation phase in any patient with HIV. A major concern for patients with HIV infection is the interaction of rifampin with certain antiretroviral agents; rifabutin has fewer problematic drug interactions and may be used as an alternative.[7]
Image courtesy of Klaus Lessnau, MD, FCCP, and Jonathan Caronia, MD.
The chest radiograph in the slide is from another patient with miliary TB. It is critically important to prevent the transmission of TB to other individuals and thereby to avert the onset of MDR-TB. Sputum specimens for microscopic examination and culture should be obtained from patients with TB at least monthly until two consecutive specimens are negative on culture. Sputum specimens should be obtained at the end of the initial phase (2 months) to determine whether the continuation phase should be extended. Treatment failure can lead to more acquired resistance, be devastating for patients, increase the cost of treatment, and elevate the risk of transmission to contacts.
Image courtesy of Radiopaedia.org | A.Prof Dr. Frank Gaillard.
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