Virulence of drug-resistant Mycobacterium tuberculosis and activity of drug combinations against drug-resistant and drug-susceptible isolates in ex-vivo and in vitro models

• Autores: Emma Rey Jurado
• Directores de la Tesis: Griselda Tudó Vilanova (dir. tes.), Julià González Martín (dir. tes.)
• Lectura: En la Universitat de Barcelona ( España ) en 2013
• Idioma: inglés
• Tribunal Calificador de la Tesis: Miguel Santín Cerezales (presid.), Pere Joan Cardona Iglesias (secret.), Leonard Amaral (voc.)
• Materias:
  • Ciencias de la vida
    • Microbiología
      • Antibióticos
  • Ciencias médicas
    • Ciencias clínicas
      • Microbiología clínica
    • Medicina interna
      • Enfermedades infecciosas
    • Farmacología
• Enlaces
  • Tesis en acceso abierto en:  TDX  Dipòsit Digital de la UB 
• Resumen

  • Tuberculosis (TB) remains a global threat worldwide with nearly nine million incident cases of TB. The emergence of M. tuberculosis resistance to antituberculous drugs has led to the need for careful TB surveillance and control. Further knowledge of drug-resistant M. tuberculosis plays an important role in avoiding TB transmission as well as designing more efficient schedules of treatment. The objectives were: 1) to analyse of clinical isolates of Mycobacterium tuberculosis resistant to antituberculous drugs to penetrate and grow within murine macrophages compared with drug-susceptible isolates; 2) to determine the in vitro synergistic activity of the following combinations against clinical isolates of M. tuberculosis resistant to isoniazid (INH) compared with drug-susceptible isolates: a) INH-rifampicin (RIF)-ethambutol (EMB), b) ofloxacin (OFL)-RIF-EMB; 3) to determine the in vitro synergistic activity of the following combinations against clinical isolates of multi-drug resistant M. tuberculosis compared with drug-susceptible isolates: a) levofloxacin (LEV)-linezolid(LNZ)-amikacin(AMK), b) LEV-LNZ-EMB, c) LEV-AMK-EMB; 4) to determine the antimicrobial and the synergistic activity of drug combinations of objective 3 against multidrug-resistant (MDR) and drug-susceptible clinical isolates of M. tuberculosis in a cell culture model of human macrophages from the THP-1 cell line. In the study of murine macrophages, we found that INH-resistant and MDR isolates with mutations in the katG gene showed decreased multiplication inside murine macrophages, suggesting a lower fitness of M. tuberculosis with these resistance patterns. With the results of this thesis, the reliability of the method of the three-drug chequerboard assay has been showed. The combination including INH, RIF and EMB could be efficient to treat TB cases with low level INH resistance (MICs ? 0.8µg/ml) due to the synergistic effect of the combination showed. The combination including OFL, RIF and EMB shows better efficacy than that of INH, RIF and EMB, being of potential use in drug-susceptible and in INH-resistant isolates. The combinations including second-choice drugs (LEV-AMK-EMB; LEV-AMK-LNZ; LEV-EMB-LNZ) are equally effective to the combination of INH, RIF and EMB with the checkerboard assay. On the other hand, these drug combinations including second-choice drugs tested against M. tuberculosis-infected macrophages show antimicrobial activity, with the combinations including LNZ and LEV displaying an antagonistic effect.