The distribution of 20 variable regions resulting from insertiondeletion events in the genomes of the tubercle bacilli has been evaluated in a total of 100 strains of Mycobacterium tuberculosis, Mycobacterium africanum, Mycobacterium canettii, Mycobacterium microti, and Mycobacterium bovis. This approach showed that the majority of these polymorphisms did not occur independently in the different strains of the M. tuberculosis complex but, rather, resulted from ancient, irreversible genetic events in common progenitor strains. Based on the presence or absence of an M. tuberculosis specific deletion (TbD1), M. tuberculosis strains can be divided into ancestral and ''modern'' strains, the latter comprising representatives of major epidemics like the Beijing, Haarlem, and African M. tuberculosis clusters. Furthermore, successive loss of DNA, reflected by region of difference 9 and other subsequent deletions, was identified for an evolutionary lineage represented by M. africanum, M. microti, and M. bovis that diverged from the progenitor of the present M. tuberculosis strains before TbD1 occurred. These findings contradict the often-presented hypothesis that M. tuberculosis, the etiological agent of human tuberculosis evolved from M. bovis, the agent of bovine disease. M. canettii and ancestral M. tuberculosis strains lack none of these deleted regions, and, therefore, seem to be direct descendants of tubercle bacilli that existed before the M. africanum3 M. bovis lineage separated from the M. tuberculosis lineage. This observation suggests that the common ancestor of the tubercle bacilli resembled M. tuberculosis or M. canettii and could well have been a human pathogen already.evolution ͉ diagnostic ͉ identification T he mycobacteria grouped in the Mycobacterium tuberculosis complex are characterized by 99.9% similarity at the nucleotide level and identical 16S rRNA sequences (1, 2) but differ widely in terms of their host tropisms, phenotypes, and pathogenicity. Assuming that they all are derived from a common ancestor, it is intriguing that some are exclusively human (M. tuberculosis, Mycobacterium africanum, Mycobacterium canettii) or rodent pathogens (Mycobacterium microti), whereas others have a wide host spectrum (Mycobacterium bovis). What was the genetic organization of the last common ancestor of the tubercle bacilli, and in which host did it live? Which genetic events may have contributed to the fact that the host spectrum is so different and often specific? Where and when did M. tuberculosis evolve? Answers to these questions are important for a better understanding of the pathogenicity and the global epidemiology of tuberculosis and may help to anticipate future trends in the spread of the disease.Because of the unusually high degree of conservation in their housekeeping genes, it has been suggested that the members of the M. tuberculosis complex underwent an evolutionary bottleneck at the time of speciation, estimated to have occurred roughly 15,000-20,000 years ago (2). Also, it has been speculated tha...

Objective: To assess the relative risk of major congenital malformation (MCM) from in utero exposure to antiepileptic drug (AEDs). Methods: Prospective data collected by the UK Epilepsy and Pregnancy Register were analysed. The presence of MCMs recorded within the first three months of life was the main outcome measure. Results: Full outcome data were collected on 3607 cases. The overall MCM rate for all AED exposed cases was 4.2% (95% confidence interval (CI), 3.6% to 5.0%). The MCM rate was higher for polytherapy (6.0%) (n = 770) than for monotherapy (3.7%) (n = 2598) (crude odds ratio (OR) = 1.63 (p = 0.010), adjusted OR = 1.83 (p = 0.002)). The MCM rate for women with epilepsy who had not taken AEDs during pregnancy (n = 239) was 3.5% (1.8% to 6.8%). The MCM rate was greater for pregnancies exposed only to valproate (6.2% (95% CI, 4.6% to 8.2%) than only to carbamazepine (2.2% (1.4% to 3.4%) (OR = 2.78 (p,0.001); adjusted OR = 2.97 (p,0.001)). There were fewer MCMs for pregnancies exposed only to lamotrigine than only to valproate. A positive dose response for MCMs was found for lamotrigine (p = 0.006). Polytherapy combinations containing valproate carried a higher risk of MCM than combinations not containing valproate (OR = 2.49 (1.31 to 4.70)). Conclusions: Only 4.2% of live births to women with epilepsy had an MCM. The MCM rate for polytherapy exposure was greater than for monotherapy exposure. Polytherapy regimens containing valproate had significantly more MCMs than those not containing valproate. For monotherapy exposures, carbamazepine was associated with the lowest risk of MCM.

SUMMARY With an estimated 9.4 million new cases globally, tuberculosis (TB) continues to be a major public health concern. Eighty percent of all cases worldwide occur in 22 high-burden, mainly resource-poor settings. This devastating impact of tuberculosis on vulnerable populations is also driven by its deadly synergy with HIV. Therefore, building capacity and enhancing universal access to rapid and accurate laboratory diagnostics are necessary to control TB and HIV-TB coinfections in resource-limited countries. The present review describes several new and established methods as well as the issues and challenges associated with implementing quality tuberculosis laboratory services in such countries. Recently, the WHO has endorsed some of these novel methods, and they have been made available at discounted prices for procurement by the public health sector of high-burden countries. In addition, international and national laboratory partners and donors are currently evaluating other new diagnostics that will allow further and more rapid testing in point-of-care settings. While some techniques are simple, others have complex requirements, and therefore, it is important to carefully determine how to link these new tests and incorporate them within a country's national diagnostic algorithm. Finally, the successful implementation of these methods is dependent on key partnerships in the international laboratory community and ensuring that adequate quality assurance programs are inherent in each country's laboratory network.

A moxifloxacin dose of 800 mg/day is likely to achieve excellent M. tuberculosis microbial kill and to suppress drug resistance. However, tolerability of this higher dose is still unknown.

Rifampin is a cornerstone of modern antituberculosis therapy. However, rifampin's half-life of 3 h is believed to limit its utility for intermittent therapy, so new congeners with long half-lives are being developed. Using an in vitro pharmacokinetic-pharmacodynamic model of tuberculosis, we examined the relationships between rifampin exposure, microbial killing of log-phase-growth Mycobacterium tuberculosis, and suppression of resistance. Rifampin's microbial killing was linked to the area under the concentration-time curve-to-MIC ratio. The suppression of resistance was associated with the free peak concentration (C max )-to-MIC ratio and not the duration that the rifampin concentration was above MIC. Rifampin prevented resistance to itself at a free C max /MIC ratio of >175. The postantibiotic effect duration was >5.2 days and was most closely related to the C max /MIC ratio (r 2 ‫؍‬ 0.96). To explain rifampin's concentration-dependent effect, we examined the kinetics of rifampin entry into M. tuberculosis. Rifampin achieved concentration-dependent intracellular steady-state concentrations within 15 min. Our results suggest that doses of rifampin higher than those currently employed would optimize the effect of rifampin, if patients could tolerate them. Another major implication is that in the design of new rifampin congeners for intermittent therapy, the important properties may include (i) the efficient entry of the rifamycin into M. tuberculosis, (ii) the achievement of a free C max /MIC of >175 that can be tolerated by patients, and (iii) a long postantibiotic effect duration.Tuberculosis (TB) is arguably the most important infectious disease to have confronted humankind. Currently, Mycobacterium tuberculosis infects 2 billion of the 6 billion people worldwide (50). The discovery of rifampin 40 years ago (31) was revolutionary in allowing the creation of potent combination drug regimens against this ancient nemesis. Rifampin is the backbone of modern anti-TB chemotherapy by virtue of being active against M. tuberculosis in exponential growth phase as well as possessing activity against nonreplicating persistent bacilli. Major limitations to rifampin use are believed to include its short half-life (t 1/2 ), which allows cycles of M. tuberculosis regrowth and resistance emergence.It has been the belief for almost half a century that if a drug such as rifampin was given once a week in the initial phase of therapy, its short serum t 1/2 of 3 h would allow short periods of microbial killing followed by regrowth between doses (33, 37). The inference is that the length of time that rifampin is above a certain threshold concentration is the most important index associated with M. tuberculosis killing and the prevention of resistance. Thus, one of the strategic goals of the World Health Organization, the pharmaceutical industry, and research scientists has been to develop rifampin congeners with long t 1/2 s, such as rifapentine, which would make intermittent dosing more effective (3,9,24,26).It is widely believed...