Rapid test for identification of a highly transmissible Mycobacterium tuberculosis Beijing strain of sub-Saharan origin

Abstract

The development of a rapid test to identify Mycobacterium tuberculosis Beijing isolates and specifically strain GC1237, coming from a sub-Saharan country, is needed due to its alarming wide spread on Gran Canaria Island (Spain). A rapid test that detects IS6110 present between dnaA and dnaN in the Beijing strains and in a specific site for GC1237 (Rv2180c) has been developed. This test would be a useful tool in the surveillance of subsequent cases.

Fig 1

(A) Results of multiplex PCR visualized with agarose gel electrophoresis. Lane 1, molecular size markers (100-bp DNA ladder); lane 2, Beijing GC1237 genotype (1,626 bp and 550 bp); lane 3, a Beijing genotype different from strain GC1237 (550 bp and 261 bp); lane 4, strain H37Rv (261 bp); lane 5, negative PCR control; lanes 6, 7, and 8, different clinical isolates of M. tuberculosis. (B and C) Schematic representations of the positions and orientations of the two IS6110 insertions used for the diagnostic test, the dnaA-dnaN region in the Beijing strains (B) and the Rv2180c region in strain GC1237 (C). The IS6110 element is represented by the white arrow, with the arrowhead indicating the direction of transcription of the putative transposase. The primers are represented by the small black arrows above the schematic representations.

Fig 2

Dendrogram showing the IS6110 RFLP fingerprints patterns of M. tuberculosis Beijing isolates used to verify the multiplex PCR technique. Isolates 1 to 8 shows high similarity to strain GC1237, and isolate 9 had a different pattern.