Genotyping and screening of phenotypic and genetic resistance to rifampicin and isoniazid in Mycobacterium bovis strains isolated from bovine lymph nodes from slaughterhouse in midwestern region of Sao Paulo State

Author(s)

Marília Masello Junqueira Franco

• Document type: Doctoral Thesis
• Press: Botucatu. 2016-08-22.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Medicina Veterinária e Zootecnia. Botucatu
• Defense date: 2016-08-12
• Advisor: Antonio Carlos Paes

Abstract

Tuberculosis caused by Mycobacterium bovis (bTB) is a zoonosis of worldwide distribution with broad host range. In countries where bTB is prevalent, 10-20% of the human cases of tuberculosis are caused by M. bovis. All over the world there are few studies investigating the resistance to isoniazid (INH) and rifampicin (RMP) in M. bovis strains from cattle, wild reservoirs, and human cases of tuberculosis. The genotypic diversity of 67 M. bovis strains obtained out of 100 lymph nodes with caseous lesions from slaughtered animals was investigated by Spoligotyping and MIRU-VNTR techniques, as well as the assessment of their phenotypic profile of resistance to INH and RMP by REMA method and the search of possible genetic basis for antimicrobial resistance. Among the obtained isolates, 11 (16%) were classified as MDR-TB, 8 (12%) INH-resistant and 2 (3%) RMP-resistant. The use of GenoType MTBDRplus ver. 2.0 did not pointed the presence of genetic mutations in any of the phenotypically resistant isolates. Sixteen different spoligotype patterns were identified. The BOV_1 subfamily predominated with 52 (77.6%) isolates, with SITs 481, 482, 594, 665, 691, 698, 1021, 1667, 1852, 2141 and two isolates without a given SIT. BOV_2 was identified in 8 (11.9%) isolates, within SIT 683. The SITs 982, 1851 and 1853 were grouped in BOV family. Two isolates were not classified in family or subfamily. The MIRU-VNTR analysis using the 12 classical MIRUs, identified a cluster of 31 isolates belonging to the MIT 49, one on MIT 5 and 35 “orphans” isolates. The combination of Spoligotyping and MIRU-VNTR analysis allowed the grouping of the isolates in 12 clusters (containing, in total, 46 isolates) and 21 isolates with unique profiles. The study highlights the high frequency of M. bovis among the sampled lymph nodes, emphasizing the impact of the pathogen as the causal agent of lymphadenitis and tuberculosis in cattle herds in the study area. In addition, points up the multidrug-resistance of M. bovis lineages to first-line drugs used in the human treatment of tuberculosis, a fact that raises public health concerns. Further studies are required to elucidate the basis of drug resistance and the occurrence of genotypic diversity in M. bovis strains. (AU)

• FAPESP's process: 14/04929-7 - Genotyping and screening of phenotypic and genetic resistance to rifampicin and isoniazid in Mycobacterium bovis strains isolated from bovine lymph nodes from slaughterhouse in Midwestern region of São Paulo State
• Grantee: Marília Masello Junqueira Franco
• Support Opportunities: Scholarships in Brazil - Doctorate