Assessing Biofilm Biomass in a High Throughput Testing Format

Background: Bacteria can form biofilms on the surfaces of medical equipment. Many of these surfaces are plastic, such as intravenous tubes and catheters.

Purpose: The main purpose of this research project was to study growth rate and biofilm formation of various clinical wound pathogens. The second objective was to categorize each strain as a strong, moderate, weak or non-adherent biofilm producer. The third objective was to determine if there is a correlation between bacterial growth rate and biofilm development. The bacterial genera tested were Staphylococcus, Acinetobacter, Enterobacter, and Pseudomonas. These organisms are four of the most common bacterial wound pathogens.

Methods: The organisms were grown in Tryptic Soy Broth for 24-hour and stained with crystal violet and safranin. 77 Staphylococcus, 43 Acinetobacter, 13 Enterobacter and 23 Pseudomonas strains were tested for biofilm production (a total of 156 strains).

Results: Our testing results demonstrated 33 Staphylococcus, 1 Acinetobacter, 2 Pseudomonas, and 6 Enterobacter strains were weak biofilm producers. 27 Staphylococcus, 14 Acinetobacter, 8 Pseudomonas, and 3 Enterobacter strains were moderate biofilm producers. 17 Staphylococcus, 28 Acinetobacter, 12 Pseudomonas, and 4 Enterobacter strains were strong biofilm producers. One Pseudomonas strain did not produce any biofilm. Our 96-well microtiter plate testing format can accurately measure the biofilm development of wound pathogens.

Conclusion: This testing approach allows simultaneous testing of multiple strains of the wound pathogens.