T uberculosis (TB) remains a major cause of illness and death worldwide, especially in Africa and Asia (1). In Cameroon, the incidence of all clinical forms of tuberculosis is about 25,000 new cases per year (National Tuberculosis Programme [NTP] report no. 16, May 2011).The understanding of tuberculosis transmission dynamics and epidemiology has been greatly enhanced by molecular epidemiologic studies using various DNA typing techniques in conjunction with classical epidemiological approaches (2). These techniques exploit various DNA elements as markers to assess the overall dissemination of strains. One such method is spoligotyping, which analyzes DNA polymorphism observed in the spacer sequences found in the direct repeat (DR) locus of the Mycobacterium tuberculosis complex (MTBC) genome. This technique is simple, rapid, and robust and has the advantage of enabling simultaneous distinction between MTBC isolates at subspecies level. It also measures overall diversity, thus providing information about major lineages. Furthermore, an international database has been established for the purpose of comparison of MTBC spoligotypes (3).An initial retrospective study on the characterization of M. tuberculosis genotype strains collected in the Western Region of Cameroon was carried out between July 1997 and June 1998. This area was chosen by the NTP as a model to assess the impact of various interventions. The application of spoligotyping showed the striking regression of Mycobacterium africanum as an etiologic agent of tuberculosis from 50% in the 1970s to 9% in the 1990s (4). This study also showed the predominance of a group of strains named "Cameroon family" strains, representing 43% of tuberculosis cases and designated LAM-10 CAM in SpolDB4. Further analysis confirmed that the lack of spacers 22, 23, and 24 was the specific signature of this family due to the removal of IS6110 in the DR region (5).To further investigate the genetic diversity evolution and the dynamics of the dissemination of strains in the Western Region of Cameroon, spoligotyping was used to perform a retrospective analysis on a new collection of strains obtained during a 1-year survey (February 2004 to March 2005 to evaluate the impact of tuberculosis control on resistance to antituberculosis drugs, 7 years after the first study.Bacterial strains and spoligotyping. Bacterial strains used in this study were isolated at the Mycobacteriology Reference Laboratory of the Centre Pasteur of Cameroon from pulmonary tuberculosis patients in the Western Region over a 1-year period (February 2004 to March 2005. All sputum smear-positive cases aged more than 15 years were included in the prospective survey. One sputum sample was collected from each patient in a transport medium solution (0.6% cetyl pyridinium bromide) and sent to the Mycobacteriology Reference Laboratory. Each sample was cultured on Löwenstein-Jensen (LJ) medium and LJ medium supplemented with 0.4% pyruvate. We isolated 622 MTBC strains identified by biochemical and phenotypical methods: 25...