Deciphering an Outbreak of Drug-Resistant
            <i>Mycobacterium tuberculosis</i>

Dahle, Ulf R.; Sandven, Per; Heldal, Einar; Mannsaaker, Turid; Caugant, Dominique A.

doi:10.1128/jcm.41.1.67-72.2003

Cited by 35 publications

(32 citation statements)

References 22 publications

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“…The major outbreak identified by IS6110 RFLP in Norway during the study period was due to a drug-resistant and multidrug-resistant strain of M. tuberculosis. This strain was mainly isolated from Somali refugees in Oslo and is believed to influence the present results [18]. Seven of 10 multidrug-resistant cases of tuberculosis were found in this group.…”

Section: Discussionmentioning

confidence: 99%

“…Most of the African-born patients had recently arrived to Norway as refugees from Somalia. The incidence of tuberculosis in Somalia is among the highest in the world with a high transmission of tuberculosis [15,16,18]. Such disease may possibly have been exacerbated by prolonged periods in transit centres and refugee camps.…”

Section: Discussionmentioning

confidence: 99%

“…Many may, therefore, have been infected with the same strain prior to arrival to Norway. However, by assessing epidemiological links in Norway, it was clear that some of these were infected after arrival to Norway [18]. The proportion of patients with clustered isolates may remain high even after several years in a new country, such as observed in Denmark [20].…”

Section: Discussionmentioning

confidence: 99%

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Risk factors for recent transmission ofMycobacterium tuberculosis

Heldal¹,

Dahle²,

Sandven³

et al. 2003

Eur Respir J

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In recent decades, the decline of tuberculosis has stopped in Western Europe, mainly due to increased immigration from high-prevalence countries. The objective of the current study was to identify risk factors for developing tuberculosis following recent infection, in order to better target interventions.Strains from 861 culture-positive cases, diagnosed in Norway in 1994-1999, were analysed by use of restriction fragment length polymorphism (RFLP). A cluster was defined as two or more isolates with identical RFLP patterns. Risk factors for being part of a cluster were identified by univariate and multivariate analysis.A total of 134 patients were part of a cluster. These constituted 5% Asian-born, 18% Norwegian-born, 24% European-born and 29% African-born patients. Four independent risk factors for being part of a cluster were identified: being born in Norway, being of young age, being infected with an isoniazid-resistant strain and being infected with a multidrug-resistant strain.Transmission of tuberculosis may be further reduced by improving case management, contact tracing, preventive treatment, screening of immigrants and access to health services for the foreign-born population. Eur Respir J 2003; 22: 637-642.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Risk factors for recent transmission ofMycobacterium tuberculosis

Heldal¹,

Dahle²,

Sandven³

et al. 2003

Eur Respir J

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“…31 Many outbreaks of drug-resistant strains in community settings have been described using IS6110-RFLP analysis, the standardized and most widely applied molecular typing method for M. tuberculosis. 8 Our aim was to prospectively analyze the prevalence of molecular genetic mechanisms for M. tuberculosis INH and RIF resistance in the urban area of Barcelona. We also compared the genotypic analysis with phenotypic properties such as catalase-peroxidase activity or minimum inhibitory concentration (MIC) of INH.…”

Section: Introductionmentioning

confidence: 99%

Molecular Analysis of Isoniazid and Rifampin Resistance inMycobacterium tuberculosisIsolates Recovered from Barcelona

Coll

Aragón²,

Alcaide³

et al. 2005

Microbial Drug Resistance

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We studied the presence of mutations in the whole katG gene and specific regions of the oxyR-ahpC and mabAinhA regulatory region in 61 Mycobacterium tuberculosis isoniazid-resistant isolates. An 81-bp region of the rpoB gene was also sequenced in 17 rifampin-resistant strains. Alterations in the katG gene were detected in 55% of the isolates. Mutation in codon 315 was the most prevalent (32%). Strains showed a high level of resistance, and most maintained a substantial catalase-peroxidase activity. Three strains with an isoniazid MIC of Ն32 g/ml lacked catalase-peroxidase activity. Two of them had deletions in the catalytic domain of the KatG protein. One strain with deletion and three strains with mutations in the C-terminal domain showed low-level resistance and conserved the catalase-peroxidase activity. Mutations in the mabA-inhA regulatory region were identified in 32% of the isolates. All had low-level resistance, and the vast majority conserved catalase-peroxidase activity. Seventeen percent of the isoniazid-resistant isolates had no detectable alterations at the studied loci. Resistance to rifampin was associated with mutations in the 81-bp of the rpoB gene in all cases. IS6110 analysis indicated that recent transmission contributed substantially to the emergence of isoniazid-resistant tuberculosis in Barcelona through short transmission chains. A rapid genotypic assay, including the 315-katG codon and the ؊15 nucleotide of the mabA-inhA regulatory region, may cover 62% of isoniazid-resistant strains in Barcelona. In contrast, the targeting of the 81-bp region of rpoB would detect all our rifampin-resistant isolates. 107

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“…La Tb multidrogo resistente es reconocida como una infección con Mycobacterium tuberculosis resistente a las drogas isoniazida (INH) y rifampicina (RIF) de manera simultánea, que son agentes antituber- culosos de primera línea y la columna vertebral del actual tratamiento antituberculosis 2,3 . En 2008, los casos nuevos de Tb-MDR se estimaron en 440.000 casos y los casos prevalentes son estimados en sobre un millón 1,4 .…”

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