Extensively Drug-Resistant Tuberculosis in the United States, 1993-2007 [JAMA]

[Giuseppe]

Extensively Drug-Resistant Tuberculosis in the United States, 1993-2007 [JAMA]

Extensively Drug-Resistant Tuberculosis in the United States, 1993-2007

N. Sarita Shah, MD, MPH; Robert Pratt, BS; Lori Armstrong, PhD; Valerie Robison, DDS, MPH, PhD; Kenneth G. Castro, MD; J. Peter Cegielski, MD, MPHJAMA. 2008;300(18):2153-2160.

Context
Worldwide emergence of extensively drug-resistant tuberculosis (XDR-TB) has raised global public health concern, given the limited therapy options and high mortality.

Objectives
To describe the epidemiology of XDR-TB in the United States and to identify unique characteristics of XDR-TB cases compared with multidrug-resistant TB (MDR-TB) and drug-susceptible TB cases.

Design, Setting, and Patients
Descriptive analysis of US TB cases reported from 1993 to 2007. Extensively drug-resistant TB was defined as resistance to isoniazid, a rifamycin, a fluoroquinolone, and at least 1 of amikacin, kanamycin, or capreomycin based on drug susceptibility test results from initial and follow-up specimens.

Main Outcome Measures
Extensively drug-resistant TB case counts and trends, risk factors for XDR-TB, and overall survival.

Results
A total of 83 cases of XDR-TB were reported in the United States from 1993 to 2007. The number of XDR-TB cases declined from 18 (0.07% of 25 107 TB cases) in 1993 to 2 (0.02% of 13 293 TB cases) in 2007, reported to date. Among those with known human immunodeficiency virus (HIV) test results, 31 (53%) were HIV-positive. Compared with MDR-TB cases, XDR-TB cases were more likely to have disseminated TB disease (prevalence ratio [PR], 2.06; 95% confidence interval [CI], 1.19-3.58), less likely to convert to a negative sputum culture (PR, 0.55; 95% CI, 0.33-0.94), and had a prolonged infectious period (median time to culture conversion, 183 days vs 93 days for MDR-TB; P < .001). Twenty-six XDR-TB cases (35%) died during treatment, of whom 21 (81%) were known to be HIV-infected. Mortality was higher among XDR-TB cases than among MDR-TB cases (PR, 1.82; 95% CI, 1.10-3.02) and drug-susceptible TB cases (PR, 6.10; 95% CI, 3.65-10.20).

Conclusion
Although the number of US XDR-TB cases has declined since 1993, coinciding with improved TB and HIV/AIDS control, cases continue to be reported each year.

Author Affiliations:
Division of Tuberculosis Elimination, Centers for Disease Control and Prevention, Atlanta, Georgia. Dr Shah is now with the Department of Medicine, Albert Einstein College of Medicine, Bronx, New York.
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<cite cite="http://jama.ama-assn.org/cgi/content/abstract/300/18/2153?etoc">JAMA -- Abstract: Extensively Drug-Resistant Tuberculosis in the United States, 1993-2007, November 12, 2008, Shah et al. 300 (18): 2153</cite>

[mixin]

XDR-TB: Deadlier And More Mysterious Than Ever

Patients with XDR-TB are four times as likely to fail treatment and three times more likely to die than patients with other forms of multi-drug-resistant TB (MDR-TB), according to a recent study that directly compared patients with XDR-TB to individuals with other types of MDR-TB to determine the differences in treatment outcomes and long-term survival rates. Researchers also found that MDR-TB was "a major threat to public health," representing 2.7 percent of new TB cases in South Korea in 2004, up from 1.6 percent in 1994.

The results were published in the second issue for November of the American Journal of Respiratory and Critical Care Medicine, a journal of the American Thoracic Society.

The study reviewed the medical records of more than 1,400 patients in South Korea with MDR-TB (which includes XDR-TB) from all national hospitals, Korean National TB Association chest clinics and select university hospitals. In addition to the patients' demographic information, their history of TB and previous treatments were noted with regard to outcome. In this study, XDR-TB was defined as MDR-TB resistant to both ofloxacin and at least one second-line injectable drug.

Full story: http://www.sciencedaily.com/releases...1106064354.htm