Table 4.

Methodological index for in vitro studies and the respective mean of all studies.

Criterion	Mean
1. A clearly stated aim: The hypothesis/aim of the study is explicitly stated and testable by statistical means.	1.93
2. Detection of bias: Data were collected according to an established protocol. At least 3 independent experiments were performed for each assay.	1.64
3. An adequate control group: There is a control group corresponding to untreated biofilms.	1.93
4. Appropriate methodology: Description and explanation of the methods in accordance with the desired outcomes. The used methods are the same for control and exposure treatment.	1.84
5. Pathogens description: The pathogens species and quantity used for inoculation are described.    0: not reported    1: organism species OR organism quantity    2: organism species AND organism quantity	1.64
6. Antibiofilm substances: Description of substances used to control/prevent biofilm formation, including identity/origin and concentration.    0: not reported    1: description of origin OR concentration    2: description of origin AND concentration	1.87
7. Culture conditions: Description of how assays were performed in sufficient detail to repeat (or detailed methodology is referenced), including culture medium, hydrodynamic conditions and temperature.    0: not described    1: sufficient detail to repeat OR a description of culture medium OR hydrodynamic conditions OR temperature    2: sufficient detail to repeat AND a description of culture medium AND hydrodynamic conditions AND temperature	1.27
8. Biofilm formation period: Because some microorganisms may grow/act slower, longer incubation periods may be needed to ensure successful biofilm inhibition.    0: duration of exposure not reported    1: culture of < 6 h    2: culture of ≥ 6 h	1.76
9. Surface: Description of substratum for biofilm formation.    0: not described    1: description of surface OR biofilm platform    2: description of surface AND biofilm platform	1.84
10. Predictive value: In vitro studies may use inoculum concentrations exceeding those encountered in a clinical scenario.    0: not described    1: inoculation with flora at the same concentration as that found in clinical scenario (<105 CFU/mL)    2: inoculation with a concentration of bacteria that exceeds that found in clinical scenario (>105 CFU/mL)	1.07
11. Results clarity: The results of the study are presented in a clear and organized way.    0: results are not clear    1: results are clear    2: results are clear and easy to understand AND cell concentrations or optical density values either for control or treatment experiments were reported	1.58
12. Adequate statistical analyses: Description and implementation of statistical tests appropriate to the dataset, with the calculation of confidence intervals and p values.	1.31

CFU, Colony-Forming Units.