We recently detected the spoligotype patterns of strains of Mycobacterium pinnipedii, a species of the Mycobacterium tuberculosis complex, in sputum samples from nine cases with pulmonary tuberculosis residing in Porto Alegre, South Brazil. Because this species is rarely encountered in humans, we further characterized these nine isolates by additional genotyping techniques, including 24-locus mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) typing, verification of the loci TbD1, RD9, pks15/1, RD Rio , and fbpC, the insertion of IS6110 at a site specific to the M. tuberculosis Latin American Mediterranean (LAM) lineage, and whole-genome sequencing. The combined analysis of these markers revealed that the isolates are in fact M. tuberculosis and more specifically belong to the LAM genotype. Most of these isolates (n ‫؍‬ 8) were shown to be multidrug resistant (MDR), which prompted us to perform partial sequencing of the rpoA, rpoB, rpoC, katG, and inhA genes. Seven isolates (77.8%) carried the S315T mutation in katG, and one of these (11%) also presented the C(؊17)T single-nucleotide polymorphism (SNP) in inhA. Interestingly, six of the MDR isolates also presented an undescribed insertion of 12 nucleotides (CCA GAA CAA CCC) in codon 516 of rpoB. No putative compensatory mutation was found in either rpoA or rpoC. This is the first report of an M. tuberculosis LAM family strain with a convergent M. pinnipedii spoligotype. These spoligotypes are observed in genotype databases at a modest frequency, highlighting that care must be taken when identifying isolates in the M. tuberculosis complex on the basis of single genetic markers. M. tuberculosis is the predominant cause of human TB worldwide, but M. africanum and M. bovis remain important agents of human disease in certain geographical regions (9). The MTBC species share identical 16S rRNA sequences, and recent studies have improved our knowledge on the genetic diversity, host range, epidemiological aspects, and differences in pathogenicity and virulence among the species of the complex (10, 11). Based on the various genotyping techniques, like spoligotyping (12), restriction fragment length polymorphism (RFLP) (13), mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) typing (14), and whole-genome sequencing (15), M. tuberculosis strains have been subdivided into lineages and families. The most geographically widespread family worldwide (spoligotyping) is the Latin American Mediterranean (LAM) lineage, which is part of the heterogeneous Euro-American lineage, one of seven M. tuberculosis lineages (16). The LAM family strains are widespread across all five continents, with a marked incidence in