Mycobacterium bovis is the causative agent of bovine tuberculosis. The diagnostic laboratory confirmation is made through bacterial isolation. The aim of interlaboratory tests is to assess the performance of each participant in comparison with other of similar capacities. The test objective was to determine the efficiency of isolation of M. bovis. Four laboratories were part of the test and processed 25 blind tissue samples from granulomatous lesions and with previous M. bovis isolation. The laboratory that had the highest proportion of isolates was A (68%), followed by C (60%) and then B and D (both with 52%). The greatest concordance was observed between B-D and B-C laboratories (68%). The differences could be due to specific factors in each laboratory procedures. This type of interlaboratory tests highlights errors in the bacteriology and identifies critical points in the process to detect M. bovis accurately.

Mycobacterium bovis es el agente etiológico de la tuberculosis bovina. La confirmación diagnóstica en el laboratorio se realiza a través del aislamiento bacteriológico. Los ensayos interlaboratorio permiten evaluar el desempeño de cada laboratorio participante comparándolo con otros de capacidades similares. El objetivo del presente estudio fue determinar la eficiencia en el aislamiento de M. bovis. Este estudio contó con la participación de 4 laboratorios, los cuales procesaron a ciego 25 muestras de tejidos con lesiones, seleccionadas previamente por aislamiento. El laboratorio A obtuvo la mayor proporción de aislamientos (68%), seguido del C (60%) y luego del B y D (ambos con el 52%). Las mayores concordancias se observaron entre los pares de laboratorios B-C y B-D (68%). Las diferencias pudieron deberse a factores propios de los procedimientos en cada laboratorio. Este tipo de análisis interlaboratorio permite evidenciar posibles errores en los procedimientos bacteriológicos e identificar puntos críticos del proceso para detectar M. bovis de manera eficiente.

Mycobacterium bovis is the causative agent of bovine tuberculosis (TB), a disease that affects approximately 5% of Argentinean cattle. Among the molecular methods for genotyping, the most convenient are spoligotyping and variable number of tandem repeats (VNTR). A total of 378 samples from bovines with visible lesions consistent with TB were collected at slaughterhouses in three provinces, yielding 265 M. bovis spoligotyped isolates, which were distributed into 35 spoligotypes. In addition, 197 isolates were also typed by the VNTR method and 54 combined VNTR types were detected. There were 24 clusters and 27 orphan types. When both typing methods were combined, 98 spoligotypes and VNTR types were observed with 27 clusters and 71 orphan types. By performing a meta-analysis with previous spoligotyping results, we identified regional and temporal trends in the population structure of M. bovis. For SB0140, the most predominant spoligotype in Argentina, the prevalence percentage remained high during different periods, varying from 25.5-57.8% (1994-2011). By contrast, the second and third most prevalent spoligotypes exhibited important fluctuations. This study shows that there has been an expansion in ancestral lineages as demonstrated by spoligotyping. However, exact tandem repeat typing suggests dynamic changes in the clonal population of this microorganism.