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Journal of Clinical Microbiology, 03 1997, 663-666, Vol 35, No. 3
WH Haas, G Bretzel, B Amthor, K Schilke, G Krommes, S Rusch-Gerdes, V Sticht- Groh and HJ Bremer
Mycobacterium africanum is a pathogen found in tuberculosis patients in
certain parts of Africa and is a member of the Mycobacterium tuberculosis
complex. Biochemically, strains of M. africanum exhibit a high degree of
variability, with some tendency to cluster according to their geographical
origin. To investigate whether this phenotypic variability is reflected at
the genetic level, we performed DNA fingerprint analysis of strains
isolated from patients with pulmonary tuberculosis in Uganda and Sierra
Leone. IS6110 DNA fingerprinting was carried out by the mixed-linker PCR
method. A total of 138 strains of M. africanum were analyzed: 42 isolates
from Uganda and 96 isolates from Sierra Leone. With few exceptions, the
resulting DNA fingerprint patterns grouped together according to their
country of origin. A striking lack of variability of DNA fingerprints was
found for strains from Sierra Leone, where 70 of 96 isolates (61.5%) fell
into clusters. The two largest clusters accounted for 41.7% of all isolates
and differed by only one band, as confirmed by standard DNA fingerprinting.
In contrast, only two clusters (7.1%) with two and three isolates,
respectively, were found for M. africanum isolates collected in Uganda, and
three of the DNA fingerprints contained fewer than seven bands. Strains of
M. tuberculosis collected and processed during the same time period were
highly variable in both countries. Our results support the concept of
geographically defined subtypes of M. africanum. In addition, they
demonstrate that natural geographic differences in the variability of
IS6110 DNA fingerprints within the M. tuberculosis complex must be
considered if this technique is used for epidemiologic studies.
Copyright © 1997 by the American Society for Microbiology. All rights reserved.
Comparison of DNA fingerprint patterns of isolates of Mycobacterium africanum from east and west Africa
Department of General Pediatrics, Children's Hospital, Heidelberg University, Germany. ic1@aixterm1.urz.uni-heidelberg.de
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