The modern era of effective tuberculosis chemotherapy began in 1952. Since then, strains of Mycobacterium tuberculosis have acquired resistance to various drugs. The rising prevalence of multidrug-resistant strains (resistant to isoniazid and rifampicin, with or without resistance to other drugs) is most ominous and has resulted in many cases of marginally treatable, often fatal, disease. The World Health Organization (WHO) noted in 1997 that not only is tuberculosis a global emergency, but that several “hot spots” exist where multidrug-resistant tuberculosis (MDRTB) prevalence is so high that control programs are threatened [1]. These “hot spots”, in conjunction with rising HIV prevalence, pose a serious threat to tuberculosis control programs. Many still consider MDRTB a focal problem that need not be addressed on a global scale. The contrary view, eloquently stated by Farmer et al, is that “... in choosing to ignore MDRTB as a global priority, we are setting our sights too low. Unambitious goals will insure millions of deaths and the persistence, in the human population, of resistant M. tuberculosis ” [2]. In this chapter we will focus on the care of patients with MDRTB as well as examine the origins, biologic mechanisms, and epidemiology of drug resistance, its impact on the outcome of therapy, and the implications of MDR-TB for standard initial therapeutic regimens.

Treatment of multidrug-resistant tuberculosis

In the last decade, DNA fingerprint techniques have become available to study the interperson transmission of tuberculosis and other mycobacterial infections. These methods have facilitated epidemiological studies at a population level. In addition, the species identification of rarely encountered mycobacteria has improved significantly. This article describes the state of the art of the main molecular typing methods for Mycobacterium tuberculosis complex and non-M. tuberculosis complex (atypical) mycobacteria. Important new insights that have been gained through molecular techniques into epidemiological aspects and diagnosis of mycobacterial diseases are highlighted.

https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-2796.2001.00772.x

Molecular epidemiology of tuberculosis and other mycobacterial infections: main methodologies and achievements.

There are many questions related to the contagiousness of tuberculosis, and unfortunately they are not simply answered. In this review, Dr. Kent Sepkowitz analyzes the literature on factors associated with contagiousness of this condition. He reminds us of the many elegant laboratory and epidemiologic studies conducted all over the world that have helped answer some of these questions. In addition, he highlights the urgent need for future studies to address the many remaining perplexing questions. The availability of molecular techniques holds promise for a clearer understanding of how contagious tuberculosis is.

How Contagious Is Tuberculosis

This review summarizes the epidemiological evidence for occupationally acquired tuberculosis and considers the implications for the prevention of tuberculosis The relevant epidemiological studies wer

Review of epidemiological studies on the occupational risk of tuberculosis in low-incidence areas.

Transbronchial biopsy in the diagnosis of pulmonary infiltrates in immunocompromised patients.

Objective:A retrospective investigation was made to compare the occupational risk of tuberculosis in personnel assisting human immunodeficiency virus (HIV)-infected and uninfected subjects with active tuberculosis.Design:We retrospectively reviewed 6 years of hospital activity in 3 units where HIV-infected patients with tuberculosis are hospitalized and in 2 units where non-HIV-infected tuberculosis patients are hospitalized. The risk of occupational tuberculosis in healthcare workers who assisted HIV-infected and non-HIV-infected patients with tuberculosis was investigated.Participants:The risk of occupational tuberculosis in healthcare workers was studied by considering the numbers of potential source cases (hospitalized patients with tuberculosis) in the two conditions investigated (HIV-positive and HIV-negative). Both potential source cases and cases of tuberculosis in healthcare workers had to be microbiologically proven in order to be considered..Results:Seven cases of tuberculosis occurred in persons who cared for 85 HIV-infected subjects with tuberculosis, while only 2 cases occurred in staff members who took care of 1,079 HIV-negative tuberculosis patients over the same period (relative risk=44.4; 95% confidence interval = 8.5-438).Conclusions:Tuberculosis seems no longer to be a neglectable risk in healthcare workers assisting patients with HIV infection. Further study is urgently needed to see whether such unexpectedly high dissemination of tuberculosis also is demonstrable in the community.

Sergio Bassetti

Papers

Transmission of HIV-associated tuberculosis to healthcare workers.

Transmission of HIV-associated tuberculosis to health-care workers