First Molecular Epidemiology Study of Mycobacterium tuberculosis in Kiribati

Tuberculosis incidence rates in Kiribati are among the highest in the Western Pacific Region, however the genetic diversity of circulating Mycobacterium tuberculosis complex strains (MTBC) and transmission dynamics are unknown. Here, we analysed MTBC strains isolated from culture positive pulmonary tuberculosis (TB) cases from the main TB referral centre between November 2007 and October 2009. Strain genotyping (IS6110 typing, spoligotyping, 24-loci MIRU-VNTR and SNP typing) was performed and demographic information collected. Among 73 MTBC strains analysed, we identified seven phylogenetic lineages, dominated by Beijing strains (49%). Beijing strains were further differentiated in two main branches, Beijing-A (n = 8) and -B (n = 28), that show distinct genotyping patterns and are characterized by specific deletion profiles (Beijing A: only RD105, RD207 deleted; Beijing B: RD150 and RD181 additionally deleted). Many Kiribati strains (59% based on IS6110 typing of all strains) occurred in clusters, suggesting ongoing local transmission. Beijing-B strains and over-crowded living conditions were associated with strain clustering (likely recent transmission), however little evidence of anti-tuberculous drug resistance was observed. We suggest enhanced case finding amongst close contacts and continued supervised treatment of all identified cases using standard first-line drugs to reduce TB burden in Kiribati. Beijing strains can be subdivided in different principle branches that might be associated with differential spreading patterns in the population.     

Epidemiology of Clinical Isolates of Mycobacterium tuberculosis at Ibadan, Nigeria

Despite the huge burden of tuberculosis (TB) in Nigeria, case detection rate of infectious cases still remain low, thus constituting obstacle to eradication of the disease in the community. We carried out a 15 month (1st January 2008 to 30th March 2009) retrospective review of epidemiology of clinical isolates of M. tuberculosis isolated at TB regional reference laboratory at the department of Medical Microbiology and Parasitology, University College Hospital, Ibadan, Nigeria. Fifty isolates were recovered from 720 specimens during the period of study with a recovery rate of 6.9%. Sixty- two (8.6%) of the specimens were contaminated. Thirty eight (76.0%) isolates were from the specimens of male subjects and 12 (24.0%) from female subjects giving a male to female ratio of 3.2: 1.0 Majority (62.0%) of the isolates were from subjects aged 20 years and above with an isolation rate of 7.3% while only two clinical isolates (4.0%) were recovered from specimens from children. A high yield of 20.8% was recovered from specimen collected from Hausa ethnic group who predominantly domiciled in a particular part of the metropolis. In terms of socio-economic status, clinical isolates recovered from specimens from unskilled workers (76.0%) was more than thrice from that obtained from the professionals (24.0%). Seven (14.0%) of the total isolates were recovered from extra-pulmonary lesions while the majority 43 (86.0%) were for pulmonary TB. The isolation rate from children and extra-pulmonary sites are low. This suggests a need to pay more attention to diagnosis of childhood and extra-pulmonary TB in Ibadan, Nigeria.Keywords: M. tuberculosis, Isolates, Epidemiology, Ibadan.