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Mycobacterium avium was isolated from hot and cold water samples and from sediment (biofilm) collected from the showerhead in the home of a woman with M. avium pulmonary disease lacking known M. avium risk factors. IS1245/IS1311 DNA fingerprinting demonstrated that M. avium isolates from the hot and cold water and showerhead sediment demonstrated a clonal relationship with the patient's M. avium isolate. The data provide evidence that showers may serve as sources of infection by waterborne M. avium.

Mycobacterium kansasii consists of 5 genetically distinct groups, of which 2 are associated with human disease. Determinants of the differences in virulence are unknown. Potential genes of interest are esat-6 and cfp-10, which are associated with virulence of Mycobacterium tuberculosis and Mycobacterium bovis but are lacking in bacille Calmette-Guérin and in most environmental mycobacteria (M. kansasii is an exception). We investigated esat-6 and cfp-10 genes in 22 clinical and 14 environmental isolates of M. kansasii. Both were present in all isolates; each genetic group had its own characteristic Southern-blot pattern corresponding to a highly conserved fingerprint pattern. Nucleotide sequences of the genes differed 12.6% and 10.1%, respectively, from the M. tuberculosis homologues, but the deduced amino acid sequences were ≤5% different. In vitro, clinical and environmental genotypes of M. kansasii expressed CFP-10 and ESAT-6. Thus, virulence of M. kansasii is not directly related to esat-6 and cfp-10 genes or gene expression. [ABSTRACT FROM AUTHOR]

To determine whether the Beijing genotype of Mycobacterium tuberculosis is emerging in the Netherlands, we collected data on 6,829 patients during 1993 to 2000. Six percent had the Beijing genotype. This genotype was associated with diagnosis in recent years, young age, nationality, and multidrug resistance. [ABSTRACT FROM AUTHOR]

This study estimated to what extent tuberculosis transmission in the Netherlands depends on the age and sex of source cases. DNA fingerprints of Mycobacterium tuberculosis isolates were matched to patient information in the Netherlands Tuberculosis Register for 1993-1998. Clusters were defined as groups of patients with pulmonary tuberculosis whose isolates had identical DNA fingerprints. Source cases were assigned by using two models. The first-case model assumed that the first diagnosed case was the source case. The incidence rate model estimated source case probabilities from the incidence rates of potential source cases and the time of diagnosis. DNA fingerprints of 6,102 isolates were matched to patient information on 5,080 (83%) cases, 3,479 of whom had pulmonary disease. According to both models, the number of infectious cases generated per source case was lower for female than for male source cases and decreased with increasing age of the source case. The authors concluded that transmission of tuberculosis is associated with the age and sex of source cases as well as the age of secondary cases. Increased transmission among immigrant groups in the Netherlands is largely attributable to the relatively young age of immigrant source cases. Am J Epidemiol 2001;154:934-43. [ABSTRACT FROM AUTHOR]