Adalbert Laszlo

Global Surveillance for Antituberculosis-Drug Resistance, 1994–1997

BACKGROUND Drug-resistant tuberculosis threatens efforts to control the disease. This report describes the prevalence of resistance to four first-line drugs in 35 countries participating in the World Health Organization-International Union against Tuberculosis and Lung Disease Global Project on Anti-Tuberculosis Drug Resistance Surveillance between 1994 and 1997. METHODS The data are from cross-sectional surveys and surveillance reports. Participating countries followed guidelines to ensure the use of representative samples, accurate histories of treatment, standardized laboratory methods, and common definitions. A network of reference laboratories provided quality assurance. The median number of patients studied in each country or region was 555 (range, 59 to 14,344). RESULTS Among patients with no prior treatment, a median of 9.9 percent of Mycobacterium tuberculosis strains were resistant to at least one drug (range, 2 to 41 percent); resistance to isoniazid (7.3 percent) or streptomycin (6.5 percent) was more common than resistance to rifampin (1.8 percent) or ethambutol (1.0 percent). The prevalence of primary multidrug resistance was 1.4 percent (range, 0 to 14.4 percent). Among patients with histories of treatment for one month or more [corrected], the prevalence of resistance to any of the four drugs was 36.0 percent (range, 5.3 to 100 percent), and the prevalence of multidrug resistance was 13 percent (range, 0 to 54 percent). The overall prevalences were 12.6 percent for resistance to any of the four drugs [corrected] (range, 2.3 to 42.4 percent) and 2.2 percent for multidrug resistance (range, 0 to 22.1 percent). Particularly high prevalences of multidrug resistance were found in the former Soviet Union, Asia, the Dominican Republic, and Argentina. CONCLUSIONS Resistance to antituberculosis drugs was found in all 35 countries and regions surveyed, suggesting that it is a global problem.

Global trends in resistance to antituberculosis drugs.

Background Data on global trends in resistance to antituberculosis drugs are lacking. Methods We expanded the survey conducted by the World Health Organization and the International Union against Tuberculosis and Lung Disease to assess trends in resistance to antituberculosis drugs in countries on six continents. We obtained data using standard protocols from ongoing surveillance or from surveys of representative samples of all patients with tuberculosis. The standard sampling techniques distinguished between new and previously treated patients, and laboratory performance was checked by means of an international program of quality assurance. Results Between 1996 and 1999, patients in 58 geographic sites were surveyed; 28 sites provided data for at least two years. For patients with newly diagnosed tuberculosis, the frequency of resistance to at least one antituberculosis drug ranged from 1.7 percent in Uruguay to 36.9 percent in Estonia (median, 10.7 percent). The prevalence increased in Estonia, from 28....

Epidemiology of antituberculosis drug resistance (the Global Project on Anti-tuberculosis Drug Resistance Surveillance): an updated analysis.

BACKGROUND The burden of tuberculosis is compounded by drug-resistant forms of the disease. This study aimed to analyse data on antituberculosis drug resistance gathered by the WHO and International Union Against Tuberculosis and Lung Disease Global Project on Anti-tuberculosis Drug Resistance Surveillance. METHODS Data on drug susceptibility testing for four antituberculosis drugs--isoniazid, rifampicin, ethambutol, and streptomycin--were gathered in the third round of the Global Project (1999-2002) from surveys or ongoing surveillance in 79 countries or geographical settings. These data were combined with those from the first two rounds of the project and analyses were done. Countries that participated followed a standardised set of guidelines to ensure comparability both between and within countries. FINDINGS The median prevalence of resistance to any of the four antituberculosis drugs in new cases of tuberculosis identified in 76 countries or geographical settings was 10.2% (range 0.0-57.1). The median prevalence of multidrug resistance in new cases was 1.0% (range 0.0-14.2). Kazakhstan, Tomsk Oblast (Russia), Karakalpakstan (Uzbekistan), Estonia, Israel, the Chinese provinces Liaoning and Henan, Lithuania, and Latvia reported prevalence of multidrug resistance above 6.5%. Trend analysis showed a significant increase in the prevalence of multidrug resistance in new cases in Tomsk Oblast (p<0.0001). Hong Kong (p=0.01) and the USA (p=0.0002) reported significant decreasing trends in multidrug resistance in new cases of tuberculosis. INTERPRETATION Multidrug resistance represents a serious challenge for tuberculosis control in countries of the former Soviet Union and in some provinces of China. Gaps in coverage of the Global Project are substantial, and baseline information is urgently required from several countries with high tuberculosis burden to develop appropriate control interventions.

Drug-resistant tuberculosis: laboratory issues: World Health Organization recommendations

There is a suggestion that drug resistance rates decreased in developing countries over the period 1962-85, while recent data suggest that resistance may be increasing. The initial decrease in resistance appears to be associated with well-functioning National Tuberculosis Control Programmes (NTP), while the recently observed increase may be due either to understaffed, resource-poor programmes or to the effect of the HIV epidemic, or to both. It is possible that the HIV epidemic may overwhelm the NTP, resulting in decreased programme efficiency and ultimately increased drug resistance. Resistance surveillance appears to be a good measure of programme efficiency. For research purposes, primary drug resistance surveys should be done on a sample of relevant patients which includes and distinguishes between HIV-positive and HIV-negative patients. At this time, there is not enough information to warrant a recommendation regarding HIV testing of TB patients for surveillance purposes. In order for resistance surveys to be relevant from the public health perspective, one must know the proportion of patients presenting for treatment having previously received treatment. The meaningful denominator for drug resistance surveys from the programme evaluation perspective should be the number of patients presenting for treatment. For initial drug resistance surveys the measurement should be the number of people never having received prior TB treatment with resistant bacilli, divided by the number of new patients presenting for treatment. For acquired resistance, one should look at all patients who begin treatment with susceptible bacilli who become resistant 6 months later.

Occupational Transmission of Mycobacterium tuberculosis to Health Care Workers in a University Hospital in Lima, Peru

From November 1996 through March 1997, presumptive active pulmonary tuberculosis (TB) was detected in 44 health care workers (HCWs) at a university hospital in Lima, Peru. To further assess the magnitude of the outbreak and determine risk factors for occupational Mycobacterium tuberculosis transmission, we identified HCWs in whom active pulmonary TB was diagnosed from January 1994 through January 1998, calculated rates by year and hospital work area, and conducted a tuberculin skin test (TST) survey. Thirty-six HCWs had confirmed active pulmonary TB. The rate of TB was significantly higher among the 171 HCWs employed in the laboratory than among HCWs employed in all other areas. In multivariate analysis, the only independent risk factor for HCW M. tuberculosis infection in HWCs employed in the laboratory was the use of common staff areas. Very high rates of active pulmonary TB were detected among HCWs at this hospital, and occupational acquisition in the laboratory was associated with HCW-to-HCW transmission.

Twenty Years of Global Surveillance of Antituberculosis-Drug Resistance

The emergence and dissemination of drug-resistant Mycobacterium tuberculosis is a global threat to health. In this report, surveillance of drug-resistant tuberculosis during the past 20 years is described.

Tuberculosis Laboratory Procedures for Developing Countries

Two of the main requirements for a successful National Tuberculosis Program (NTP) in developing countries have been clearly defined (1): 1. Government commitment to a tuberculosis (TB) program aiming at nationwide coverage, conceived as a permanent health system activity, integrated into the existing health structure with effective technical leadership from a central unit 2. Case detection and treatment follow-up based on bacteriological examinations Tuberculosis bacteriology—a fundamental element of the NTP—must interrelate closely with the administrative, epidemiological, and clinical components of the program. Bacteriological diagnostic services must be developed concurrently with the other activities of the NTP and should be integrated in the general health services of the country to attain maximum coverage (2).