Spoligotypes of Mycobacterium tuberculosis complex isolates from patients residents of 11 states of Brazil.

One of the high tuberculosis (TB) incidence countries in the world, Brazil is characterized by considerable differences in TB incidence on regional and state level. In the present study, we describe Brazilian spoligotypes of 1991 Mycobacterium tuberculosis complex (MTC) clinical isolates from patients residents of 11 states from different regions of the country, diagnosed between 1996 and 2005. By performing spoligotyping on a large number of M. tuberculosis clinical isolates, one of the main objectives of this study was to determine the major genotype families causing TB in Brazil and to verify the region-associated genotype distribution. We observed a total of 577 distinct spoligopatterns, 12.6% of these corresponded to orphan patterns while 87.4% belonged to 326 shared-types (SITs). Among the latter, 86 SITs (isolated from 178 patients) had been observed for the first time in this study, the most frequent being SIT2517 which belonged to the T3-ETH lineage and was exclusively found among patients residents of Belém, the capital of the state of Pará (n=8 isolates). Irrespective of shared-type labeling, a total of 19.5% strains were unique (unclustered) in our study as opposed to 80.5% clustered isolates (189 clusters, size range from 2 to 205 isolates). The three largest clusters were SIT42 of the Latin-America & Mediterranean (LAM) 9 clade (10.3%), SIT53 of the T clade (7.6%), and SIT50 of the Haarlem clade (5.4%). The predominant MTC lineages in Brazil in decreasing order belonged to the LAM (46%); the ill-defined T (18.6%); the Haarlem (12.2%), the X (4.7%), the S (1.9%), and the East African Indian (EAI) (0.85%) families. The rest of clades grouped together as Mycobacterium africanum, Mycobacterium bovis, Beijing, Central Asian (CAS), and the Manu types, represented less than 1% of the strains. Finally, about 15% of the isolates showed spoligotype signatures that were not yet classified among well-defined lineages. In conclusion, we provide hereby a first insight into the population structure of MTC isolates in Brazil, showing the predominance of both LAM and T family and the existence of region-associated genotypes.

Genotyping did not evidence any contribution of Mycobacterium bovis to human tuberculosis in Brazil.

The contribution of Mycobacterium bovis to the global burden of tuberculosis (TB) in man is likely to be underestimated due to its dysgonic growth characteristics and because of the absence of pyruvate in most used media is disadvantageous for its primary isolation. In Brazil Mycobacterium culture, identification and susceptibility tests are performed only in TB reference centers, usually for selected cases. Moreover, solid, egg-based, glycerol-containing (without pyruvate supplementation) Löwenstein-Jensen (L-J) or Ogawa media are routinely used, unfavouring M. bovis isolation. To determine the importance of M. bovis as a public health threat in Brazil we investigated 3046 suspected TB patients inoculating their clinical samples onto routine L-J and L-J pyruvate enriched media. A total of 1796 specimens were culture positive for Mycobacterium spp. and 702 TB cases were confirmed. Surprisingly we did not detect one single case of M. bovis in the resulting collection of 1674 isolates recovered from M. bovis favourable medium analyzed by conventional and molecular speciation methods. Also, bacillary DNA present on 454 sputum smears from 223 TB patients were OxyR genotyped and none was recognized as M. bovis. Our data indicate that M. bovis importance on the burden of human TB in Brazil is marginal.

Antimicrobial susceptibility determined by the E test, Löwenstein-Jensen proportion, and DNA sequencing methods among Mycobacterium tuberculosis isolates discrepancies, preliminary results.

Mycobacterium tuberculosis strains resistant to streptomycin (SM), isoniazid (INH), and/or rifampin (RIF) as determined by the conventional Löwenstein-Jensen proportion method (LJPM) were compared with the E test, a minimum inhibitory concentration susceptibility method. Discrepant isolates were further evaluated by BACTEC and by DNA sequence analyses for mutations in genes most often associated with resistance to these drugs (rpsL, katG, inhA, and rpoB). Preliminary discordant E test results were seen in 75% of isolates resistant to SM and in 11% to INH. Discordance improved for these two drugs (63%) for SM and none for INH when isolates were re-tested but worsened for RIF (30%). Despite good agreement between phenotypic results and sequencing analyses, wild type profiles were detected on resistant strains mainly for SM and INH. It should be aware that susceptible isolates according to molecular methods might contain other mechanisms of resistance. Although reproducibility of the LJPM susceptibility method has been established, variable E test results for some M. tuberculosis isolates poses questions regarding its reproducibility particularly the impact of E test performance which may vary among laboratories despite adherence to recommended protocols. Further studies must be done to enlarge the evaluated samples and looked possible mutations outside of the hot spot sequenced gene among discrepant strains.

Antimicrobial susceptibility determined by the E test, Lõwenstein-Jensen proportion, and DNA sequencing methods among Mycobacterium tuberculosis isolates discrepancies, preliminary results

Mycobacterium tuberculosis strains resistant to streptomycin (SM), isoniazid (INH), and/or rifampin (RIF) as determined by the conventional Lõwenstein-Jensen proportion method (LJPM) were compared with the E test, a minimum inhibitory concentration susceptibility method. Discrepant isolates were further evaluated by BACTEC and by DNA sequence analyses for mutations in genes most often associated with resistance to these drugs (rpsL, katG, inhA, and rpoB). Preliminary discordant E test results were seen in 75 percent of isolates resistant to SM and in 11 percent to INH. Discordance improved for these two drugs (63 percent) for SM and none for INH when isolates were re-tested but worsened for RIF (30 percent). Despite good agreement between phenotypic results and sequencing analyses, wild type profiles were detected on resistant strains mainly for SM and INH. It should be aware that susceptible isolates according to molecular methods might contain other mechanisms of resistance. Although reproducibility of the LJPM susceptibility method has been established, variable E test results for some M. tuberculosis isolates poses questions regarding its reproducibility particularly the impact of E test performance which may vary among laboratories despite adherence to recommended protocols. Further studies must be done to enlarge the evaluated samples and looked possible mutations outside of the hot spot sequenced gene among discrepant strains.