American Thoracic Society journal news tips for November 2004 (second issue)

11/09/04

RISK FACTORS FOR EARLY RELAPSE OF TUBERCULOSIS

In a large study of tuberculosis patients, researchers found that disease relapse was associated with a thrice weekly versus a daily drug therapy regimen and with the presence of cavitation (cavities) on the individual's chest X-ray at diagnosis. Researchers studied 12,183 patients who completed antituberculosis treatment between January 1, 1998, and December 31, 2000. Of this group, more than 105 cases relapsed within 30 months after commencement of treatment. The mean time to relapse was almost 15 months. A group of 166 controls completed 30 months of follow-up at clinics. Of those who took the standard 6-month therapy of isoniazid and rifampin supplemented by pyrazinamid for the first 2 months, 61 cases and 140 controls were given daily treatment throughout. A total of 44 cases and 56 control subjects received thrice-weekly treatment. According to the researchers, the definition for relapse refers to situations in which a patient becomes and remains culture negative while receiving antituberculosis drugs, but develops active tuberculosis after completion of treatment. The investigators pointed out that a better therapeutic efficacy for daily therapy was not surprising because risk factors for relapse are ultimately based on the bacterial load of the lesions. Since M. tuberculosis replicates approximately once daily when it is actively dividing, faster sterilization is expected when actively dividing bacteria are killed daily. They note that thrice-weekly medications can still be a cost-effective approach when no cavitation is shown on the initial chest X-ray. When cavities appear, they advise daily, prolonged therapy. The study appears in the second issue for November 2004 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.

EFFECTS OF OZONE ON MORTALITY IN 23 EUROPEAN CITIES

In their analysis of the effects of ozone on mortality in 23 European cities, investigators found that death due to respiratory disease was more strongly associated with ozone exposure than was either the total or cardiovascular rate. The researchers found that ozone's effects on mortality took place almost exclusively during the warm months. (Ozone is toxic gas that irritates tissue. Found commonly in the stratosphere, photochemical reactions occur under certain conditions at the earth's surface that produce concentrations which irritate the eyes, mucus membranes, and lung tissue. The compound is considered one of the most toxic components of the photochemical air pollution mixture.) For this study, data on mortality, including natural, cardiovascular, and respiratory death rates, was obtained from 23 European cities covering at least a three-year time period. According to the authors, in 19 of 23 cities, ozone was found to be associated with an increase in mortality during the warmer months. The investigators noted that the seasonal pattern of ozone was in direct contrast to the annual cycle of daily mortality which usually peaks during the winter months. They said that Turin, Prague, Budapest, and Athens had the highest median ozone concentrations, while Tel-Aviv, London, and Paris had the lowest. They said that the major part of the excess mortality linked to ozone levels is classified as cardiovascular or respiratory deaths, which probably occur in cardiopulmonary-compromised individuals. The study appears in the second issue for November 2004 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.

A SHORTER, STABLE CURE FOR MURINE TUBERCULOSIS

In a study employing a mouse model of tuberculosis (TB), researchers used a combination of rifampin, moxiflocacin, and pyrazinamide to shorten the time to negative cultures in the rodents by 2 months. Their improved results with moxifloxacin at 4 months were in direct contrast to the standard regimen of rifampin, isoniazid, and pyrazinamide which took 6 months to accomplish the same goal. They said that their results suggest the use of the three drugs, including moxifloxacin, could substantially shorten the duration of therapy needed to cure human TB. They noted that the development of an efficacious ultra-short course of 4 months for the treatment of TB in humans could be expected to promote treatment completion rates and facilitate the worldwide implementation of directly-observed treatment programs. The mice involved in the study were 7-week-old females. After they were infected with TB, they were placed randomly into 4 treatment groups. The control group received the standard 6-month therapy. The three experimental groups received a regimen of rifampin, pyrazinamide, and moxifloxacin, which varied in length of time and drug use. According to the investigators, up to now, moxifloxacin has been used as a second-line drug for the treatment of patients with multidrug-resistant TB or with patients who were intolerant of first-line agents. The study appears in the second issue for November 2004 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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