Figure 3: TRS-induced Mtb biofilm formation requires nucleic acids and protein synthesis.

(a) Mtb cultures at an OD₆₀₀ of 1.0 were exposed to DTT for 3 h, followed by independent treatment with the first-line TB drugs INH, RIF and ETB at MIC 1 × and 10 × for 29 h, at which time the CV assay was performed. The numerals and the abbreviated drug names indicate the fold MIC (1 × or 10 × ) used in the experiment. (b) CV assay of Mtb after treatment with INH, RIF or ETB at 100 × MIC. All the antibiotics were added after 3 h of induction with DTT. (c) As with the above experiment, a CV assay was performed after treatment with the DNA gyrase inhibitors levofloxacin (L-flox) and ofloxacin (O-flox), and the protein synthesis inhibitor tetracycline (Tet) at 1 × MIC each. The data in c are expressed as the mean (±s.e.m.). Statistical significance was determined using Student’s t-test. *P<0.05. These figures (a–c) are representative of at least three independent biological experiments performed in triplicate. Insets are the pictures of CV staining.