Clinical and operational value of the extensively drug-resistant tuberculosis definition.
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Currently, no information is available on the effect of resistance/susceptibility to first-line drugs different from isoniazid and rifampicin in determining the outcome of extensively drug-resistant tuberculosis (XDR-TB) patients, and whether being XDR-TB is a more accurate indicator of poor clinical outcome than being resistant to all first-line anti-tuberculosis (TB) drugs. To investigate this issue, a large series of multidrug-resistant TB (MDR-TB) and XDR-TB cases diagnosed in Estonia, Germany, Italy and the Russian Federation during the period 1999-2006 were analysed. Drug-susceptibility testing for first- and second-line anti-TB drugs, quality assurance and treatment delivery was performed according to World Health Organization recommendations in all study sites. Out of 4,583 culture-positive TB cases analysed, 361 (7.9%) were MDR and 64 (1.4%) were XDR. XDR-TB cases had a relative risk (RR) of 1.58 to have an unfavourable outcome compared with MDR-TB cases resistant to all first-line drugs (isoniazid, rifampicin ethambutol, streptomycin and, when tested, pyrazinamide), and an RR of 2.61 compared with "other" MDR-TB cases (those susceptible to at least one first-line anti-TB drug among ethambutol, pyrazinamide and streptomycin, regardless of resistance to the second-line drugs not defining XDR-TB). The emergence of extensively drug-resistant tuberculosis confirms that problems in tuberculosis management are still present in Europe. While waiting for new tools which will facilitate management of extensively drug-resistant tuberculosis, accessibility to quality diagnostic and treatment services should be urgently ensured and adequate public health policies should be rapidly implemented to prevent further development of drug resistance. (+info)
Evolution of the extensively drug-resistant F15/LAM4/KZN strain of Mycobacterium tuberculosis in KwaZulu-Natal, South Africa.
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BACKGROUND: Although several hot spots of multidrug-resistant tuberculosis have been identified on the African continent, extensive drug resistance (XDR) has not been reported until recently, when a large number of XDR cases were identified in KwaZulu-Natal. The majority of the patients involved were infected with the same strain of Mycobacterium tuberculosis (F15/LAM4/KZN). We report this strain's development from multidrug resistance to XDR. METHODS: We searched databases for studies performed during the period 1994-2005 that involved the resistance patterns of isolates of M. tuberculosis with the F15/LAM4/KZN strain fingerprint. RESULTS: As early as 1994, the F15/LAM4/KZN strain was responsible for a number of cases of multidrug-resistant tuberculosis, indicating the ability of the strain to cause cases of primary resistant tuberculosis. Some of the isolates were also resistant to streptomycin. From 1994 onwards, multidrug-resistant isolates with resistance to additional drugs were found, and the first XDR isolate was discovered in 2001. CONCLUSIONS: Drug resistance to as many as 7 drugs developed in a local strain of M. tuberculosis in slightly more than a decade. This coincided with the introduction of the directly observed therapy-based and directly observed therapy-plus-based tuberculosis-control programs. It is postulated that the introduction of these programs in the absence of susceptibility testing or drug resistance surveillance has been instrumental in the development of XDR in this highly transmissible F15/LAM4/KZN strain. The expanding pool of human immunodeficiency virus-infected, tuberculosis-susceptible individuals has likely contributed to this development. (+info)
Colorimetric detection of multidrug-resistant or extensively drug-resistant tuberculosis by use of malachite green indicator dye.
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The malachite green microtube (MGMT) susceptibility assay was performed directly on sputum specimens (n = 80) and indirectly on Mycobacterium tuberculosis clinical isolates (n = 60). The technique is based on the malachite green dye, which changes color in response to M. tuberculosis growth. The MGMT assay is simple and rapid and does not require expensive instruments. (+info)
Extensively drug-resistant tuberculosis in South Korea: risk factors and treatment outcomes among patients at a tertiary referral hospital.
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Multidrug-resistant and extensively drug-resistant tuberculosis: implications for the HIV epidemic and antiretroviral therapy rollout in South Africa.
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Extensively drug-resistant (XDR) tuberculosis: an old and new threat.
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Tuberculosis (TB) remains a worldwide emergency (8 million new cases per year, 2 million deaths annually) mostly affecting poor countries. To this old, persistent threat, a new emergency is adding further challenge, i.e., the multidrug-resistant TB, which in its extreme and highly lethal form is called XDR TB (extensively drug-resistant TB). How to fight XDR TB is a high research and public health priority. (+info)
High frequency of resistance to the drugs isoniazid and rifampicin among tuberculosis cases in the city of Cabo de Santo Agostinho, an urban area in Northeastern Brazil.
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The objective of the present study was to investigate the frequency and risk factors for developing multidrug-resistant tuberculosis in Cabo de Santo Agostinho, PE. This was a prospective study conducted from 2000 to 2003, in which suspected cases were investigated using bacilloscopy and culturing. Out of 232 confirmed cases of tuberculosis, culturing and antibiotic susceptibility tests were performed on 174. Thirty-five of the 174 cultures showed resistance to all drugs. The frequencies of primary and acquired resistance to any drug were 14% and 50% respectively, while the frequencies of primary and acquired multidrug resistance were 8.3% and 40%. Previous tuberculosis treatment and abandonment of treatment were risk factors for drug resistance. The high levels of primary and acquired resistance to the combination of isoniazid and rifampicin contributed towards the difficulties in controlling tuberculosis transmission in the city. (+info)