Molecular typing with IS6110 was applied to Mycobacterium tuberculosis isolates from all parts of Malaysia. The degree of clustering increased with patient age, suggesting that reactivation may contribute to clustering. Identical banding patterns were also obtained for isolates from widely separate regions. Therefore, the use of clustering as a measure of recent transmission must be treated with caution. Strains related to the Beijing family were common in Peninsular Malaysia but were less common in Sabah and Sarawak, while a distinct group of strains comprised nearly 40% of isolates from East Malaysia but such strains were rare in Peninsular Malaysia. Single-copy strains, common in South and Southeastern Asia, constituted nearly 20% of isolates from the peninsula but were virtually absent in East Malaysia. The marked geographical difference in the prevailing strains indicates not only a restricted dissemination of M. tuberculosis but also a considerable degree of stability in the banding patterns.
DNA fingerprinting with the insertion sequence IS6110 (also known as IS986) has become established as a major tool for investigating the spread of tuberculosis. Most strains of Mycobacterium tuberculosis have multiple copies of IS6110, but a small minority carry a single copy only. We have examined selected strains from Malaysia, Tanzania and Oman, in comparison with M. bovis isolates and BCG strains carrying one or two copies of IS6110. The insertion sequence appears to be present in the same position in all these strains, which suggests that in these organisms the element is defective in transposition and that the loss of transposability may have occurred at an early stage in the evolution of the M. tuberculosis complex.
Melioidosis is caused by Burkholderia pseudomallei, a Gram-negative bacillus, primarily found in soils in Southeast Asia and northern Australia. A recent case of melioidosis in non-endemic Arizona was determined to be the result of locally acquired infection, as the patient had no travel history to endemic regions and no previous history of disease. Diagnosis of the case was confirmed through multiple microbiologic and molecular techniques. To enhance the epidemiological analysis, we conducted several molecular genotyping procedures, including multi-locus sequence typing, SNP-profiling, and whole genome sequence typing. Each technique has different molecular epidemiologic advantages, all of which provided evidence that the infecting strain was most similar to those found in Southeast Asia, possibly originating in, or around, Malaysia. Advancements in new typing technologies provide genotyping resolution not previously available to public health investigators, allowing for more accurate source identification.