Biofilm production * Average OD Average OD results Number of isolates (%)
Non- biofilm producer ≤ ** ODc OD ≤ 0.163 3 (7.1)
Weakly- biofilm producer ODc < ~ ≤ 2× ODc 0.163 <  OD ≤ 0.326 9 (21.4)
Moderately- biofilm producer 2× ODc < ~ ≤ 4× ODc 0.326 <  OD ≤ 0.652 12 (28.6)
Strongly- biofilm producer > 4× ODc > 0.652 18 (42.9)
* Stepanovic et al. (2007) parameters [22]
** Optical density cut-off value (ODc) = average OD of negative control + 3SD of negative control.
Table 2: Classification of biofilm production of bacteria based on optical density measured at OD570 by ELISA reader.