Mycobacterium mucogenicum and other non-tuberculous mycobacteria in potable water of a trauma hospital: a potential source for human infection.

This study examined the frequency of occurrence of non-tuberculous mycobacteria (NTM) in potable water samples from a main trauma hospital in Mexico City. Sixty-nine potable water samples were collected, 23 from each source: cistern, kitchen tap and bathroom showers. Of the 69 samples, 36 harboured NTM species. Twenty-nine of the 36 isolates were Mycobacterium mucogenicum, two Mycobacterium rhodesiae, one Mycobacterium peregrinum, one Mycobacterium fortuitum and three were Mycobacterium spp. Hospital potable water harbouring NTM represents a potential source for nosocomial infections, therefore we suggest that hospital potable water microbiological guidelines should include testing for NTM species.

A novel multiplex-PCR for the rapid identification of Mycobacterium bovis in clinical isolates of both veterinary and human origin.

Bovine tuberculosis is a zoonotic disease that not only causes huge economic losses but also poses an important risk for human infection. The definitive identification of a clinical isolate relies on time-consuming, highly specialized and laborious biochemical tests. We have developed a method for the rapid and reliable identification of Mycobacterium bovis and for its simultaneous differentiation from other members of the M. tuberculosis complex. Furthermore, the technique also allowed us to distinguish M. tuberculosis complex members from other Mycobacterial species. The method comprises both a single PCR and a multiplex-PCR and can be confidently applied to samples of both veterinary and human origin.

Characterization of an rRNA operon (rrnB) of Mycobacterium fortuitum and other mycobacterial species: implications for the classification of mycobacteria.

Mycobacteria are thought to have either one or two rRNA operons per genome. All mycobacteria investigated to date have an operon, designated rrnA, located downstream from the murA gene. We report that Mycobacteriun fortuitum has a second rrn operon, designated rrnB, which is located downstream from the tyrS gene; tyrS is very close to the 3' end of a gene (3-mag) coding for 3-methylpurine-DNA-glycosylase. The second rrn operon of Mycobacterium smegmatis was shown to have a similar organization, namely, 5' 3-mag-tyrS-rrnB 3'. The rrnB operon of M. fortuitum was found to have a single dedicated promoter. During exponential growth in a rich medium, the rrnB and rrnA operons were the major and minor contributors, respectively, to pre-rRNA synthesis. Genomic DNA was isolated from eight other fast-growing mycobacterial species. Samples were investigated by Southern blot analysis using probes for murA, tyrS, and 16S rRNA sequences. The results revealed that both rrnA and rrnB operons were present in each species. The results form the basis for a proposed new scheme for the classification of mycobacteria. The approach, which is phylogenetic in concept, is based on particular properties of the rrn operons of a cell, namely, the number per genome and a feature of 16S rRNA gene sequences.