Physiology and antibiotic susceptibility of mycobacterial biofilms

Treatment of tuberculosis requires months of antimycobacterial therapy. This tolerance to antibiotics displayed by Mycobacterium tuberculosis could be attributed to biofilm formation. Biofilms are the cause of many chronic infections. The aim of this thesis was to apply laboratory methods for the culture of Mycobacterium smegmatis and M. tuberculosis H37Rv biofilms and to further characterise these bacterial phenotypes in terms of their physiology, gene expression and drug susceptibility The Modified Robbins Device (MRD) and the Constant Depth Film Fermenter (CDFF) laboratory models were applied alongside the previously established well-plate pellicle model. Antibiotic efficacy studies of M. tuberculosis pellicles identified drug-tolerant bacteria. These pellicle biofilms exhibited tolerance to rifampicin and isoniazid many times above the planktonic minimum inhibitory concentration (MIC). CDFF biofilms were tolerant to a planktonic MIC of isoniazid. CDFF and pellicle biofilms of M. tuberculosis and pellicle biofilms of M. smegmatis were investigated in terms of their gene expression using microarrays to determine the underpinning molecular mechanisms behind biofilm formation Biofilms of both mycobacterial ... (continues)