Table 3

Criteria of interpretation of biofilm production

Biofilm production

average optical density (OD)

no biofilm producer

≤ ODc

weak biofilm producer

ODc < ~ ≤ 2 × ODc

moderate biofilm producer

2 × ODc < ~ ≤ 4 × ODc

strong biofilm producer

> 4 × ODc

Note: optical density cut-off value (ODc) = average OD of negative control + 3 × SD of negative control.

Zhao and Liu BMC Microbiology 2010 10:140   doi:10.1186/1471-2180-10-140