Tuberculosis and Non-Tubercular Mycobacterial Diseases
- Tuberculosis is still a prevalent disease in developing countries, and the incidence of non-tuberculous mycobacterium (NTM) is rising worldwide
- Treatment of drug-sensitive tuberculosis is largely medical, with high cure rates, if adequate therapy is delivered.
- As an adjunct to medical therapy, surgery has a role in increasing cure rates in select groups of patients, particularly with drug-resistant tuberculosis
- For NTM, failure of medical treatment and symptom relief are the most common indications for surgery
- In most cases of NTM or TB, the goal of surgery is to remove focal, persistent lung damage (bronchiectasis, cavitation, consolidation or destroyed lung) amenable to anatomic resection
- Anatomic resection poses increased technical complexity as compared to surgery for cancer, due to pleural symphysis, adhesions, bronchial circulation hypertrophy, and chronic hilar fibrosis associated with lymphadenopathy
- Multidrug-resistant (MDR) and extensive resistant (XDR) strains of TB have emerged which complicate treatment, and resistant strains of NTM have emerged as well. These resistant bacteria may require more aggressive use of surgery as an adjuvant to complement medical treatment
Tuberculosis is caused by infection with Mycobacterium tuberculosis, but species of non-tuberculous Mycobacteria, such as Mycobacterium Avium and other subspecies can produce similar pathologic changes. These infections most commonly involve the lungs, where cell-mediated immunity results in the formation of caseating granulomas; however, they can affect extra-pulmonary sites as well. In 2018, the World Health Organization reported that there were an estimated 10 million new (incident) TB cases worldwide, of which 5.7 million were men, 3.2 million were women and 1.1 million were children. Globally, the TB mortality rate fell by 42% between 2000 and 2018. The severity of national epidemics varies widely among countries, and Figure 1 shows the worldwide TB incidence rates. Globally in 2018, 484 000 people developed TB that was rifampicin-resistant (RR-TB), the most effective first-line drug, and of these, 78% had multidrug-resistant TB (MDR-TB). Drug resistance in TB can take the form of rifampin-resistance (RR-TB), rifampin and isoniazid resistance (MDR-TB), or resistance to these agents as well as second-line agents, called extensively drug-resistant tuberculosis (XDR-TB)., This newer strain broke out in South Africa and 34 other countries, including 17 cases from 2002 to 2005 in the United States., Among cases of MDR-TB in 2018, 6.2% were estimated to have extensively drug resistant TB (XDR-TB). XDR is resistant to at least isoniazid and rifampin (MDR) plus resistance to fluoroquinolones and one of the second-line injectable drugs (amikacin, kanamycin, or capreomycin). It has a high morbidity and mortality, especially when co-infected with human immunodeficiency virus (HIV). HIV incidence closely parallels the incidence of new and relapsed TB cases globally (Figure 2). In the developed world, organ transplantation is also a significant comorbidity that, via immunosuppression, can predispose patients to either TB or NTM infections.
The study of pulmonary mycobacterial infection is a fascinating travel through the history of medicine and surgery that starts from the dawn of civilization. At the beginning of the 20th century, tuberculosis was the foremost single cause of death among adults, and at that time, a system of sanatoriums that emphasized bed rest and nutrition was created to help fight the disease. It was in those institutions that the closure of tuberculous cavities by means of surgical modalities, such as phrenic nerve crush, thoracoplasty, and plombage, was found to be of value in controlling the infection. In North America as well as throughout Europe, these developments paralleled very closely those of thoracic surgery as a surgical specialty.
This chapter, however, reviews the pertinent aspects of the surgical treatment of mycobacterial diseases as they apply to the practice of thoracic surgery in the 21st century.
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