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DNA fingerprinting of Mycobacterium tuberculosis has been shown to be a powerful epidemiologic tool. We propose a standardized technique which exploits variability in both the number and genomic position of IS6110 to generate strain-specific patterns. General use of this technique will permit comparison of results between different laboratories. Such comparisons will facilitate investigations into the international transmission of tuberculosis and may identify specific strains with unique properties such as high infectivity, virulence, or drug resistance.

These guidelines are not intended to impose a standard of care. They provide the basis for rational decisions in the diagnosis of tuberculosis in the context of the existing evidence. No guidelines can take into account all of the often compelling unique individual clinical circumstances.

Background Individuals infected with Mycobacterium tuberculosis (Mtb) may develop symptoms and signs of disease (tuberculosis disease) or may have no clinical evidence of disease (latent tuberculosis infection [LTBI]). Tuberculosis disease is a leading cause of infectious disease morbidity and mortality worldwide, yet many questions related to its diagnosis remain. Methods A task force supported by the American Thoracic Society, Centers for Disease Control and Prevention, and Infectious Diseases Society of America searched, selected, and synthesized relevant evidence. The evidence was then used as the basis for recommendations about the diagnosis of tuberculosis disease and LTBI in adults and children. The recommendations were formulated, written, and graded using the Grading, Recommendations, Assessment, Development and Evaluation (GRADE) approach. Results Twenty-three evidence-based recommendations about diagnostic testing for latent tuberculosis infection, pulmonary tuberculosis, and extrapulmonary tuberculosis are provided. Six of the recommendations are strong, whereas the remaining 17 are conditional. Conclusions These guidelines are not intended to impose a standard of care. They provide the basis for rational decisions in the diagnosis of tuberculosis in the context of the existing evidence. No guidelines can take into account all of the often compelling unique individual clinical circumstances.

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The emergence of multidrug-resistant (MDR) tuberculosis (TB) highlights the urgent need to understand the mechanisms of resistance to the drugs used to treat this disease. The aminoglycosides kanamycin and amikacin are important bactericidal drugs used to treat MDR TB, and resistance to one or both of these drugs is a defining characteristic of extensively drug-resistant TB. We identified mutations in the ؊10 and ؊35 promoter region of the eis gene, which encodes a previously uncharacterized aminoglycoside acetyltransferase. These mutations led to a 20 -180-fold increase in the amount of eis leaderless mRNA transcript, with a corresponding increase in protein expression. Importantly, these promoter mutations conferred resistance to kanamycin [5 g/mL < minimum inhibitory concentration (MIC) <40 g/mL] but not to amikacin (MIC <4 g/mL). Additionally, 80% of clinical isolates examined in this study that exhibited low-level kanamycin resistance harbored eis promoter mutations. These results have important clinical implications in that clinical isolates determined to be resistant to kanamycin may not be cross-resistant to amikacin, as is often assumed. Molecular detection of eis mutations should distinguish strains resistant to kanamycin and those resistant to kanamycin and amikacin. This may help avoid excluding a potentially effective drug from a treatment regimen for drug-resistant TB.T he World Health Organization estimates that 9.2 million new cases of tuberculosis (TB) occur each year (1). Despite intensive efforts to ensure proper drug dosages and patient compliance with drug regimens, multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains of Mycobacterium tuberculosis have emerged (2). These strains cause extensive mortality in immunocompromised individuals (3) and hinder the control and prevention of the disease. XDR and MDR TB infections cannot be adequately treated with the first-line anti-TB drugs and require expensive, prolonged treatment with second-line anti-TB drugs. The rapid determination of the resistance profile of an isolate can facilitate selection of an appropriate drug regimen and preclude development of additional drug resistances. Rapid detection of resistances is best achieved with molecular diagnostic approaches, particularly in developing countries where access to culture facilities is limited. Such strategies require a detailed understanding of the molecular basis for drug resistance. Although the mechanisms of resistance to first-line drugs such as isoniazid and rifampin are well characterized, much less is known about such mechanisms for the second-line drugs (4).An important second-line anti-TB drug is the aminoglycoside kanamycin (KAN), which binds to the 16S rRNA in the 30S ribosomal subunit and inhibits protein synthesis (5). In other bacteria, characterized mechanisms of KAN resistance include altered efflux or influx of the drug, inactivation of the drug by enzymatic modification, and mutation or methylation of rRNA, which disrupts binding of the drug to the riboso...

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The immune response of the host to the antigens of Mycobacterium tuberculosis plays the key role in determining immunity from infection with as well as the pathogenicity of this organism. A 65-kilodalton (kDa) protein has been identified as one of the medically important antigens of M. tuberculosis. The gene encoding this antigen was isolated from a Agtll-M. tuberculosis recombinant DNA library using monoclonal antibodies directed against the 65-kDa antigen as the specific probes. The nucleotide sequence of this gene was determined, and a 540-amino-acid sequence was deduced. This sequence was shown to correspond to that of the 65-kDa antigen by constructing a plasmid in which this open reading frame was fused to the lacZ gene. The resulting fusion protein reacted specifically with the anti-65-kDa protein antibodies. A second long open reading frame was found downstream of the 65-kDa antigen gene which could encode a protein of 517 amino acids. This putative protein contained 29 tandemly arranged partial or complete matches to a pentapeptide sequence.