Lavage with at least 2.5 mL/cm sterile saline reduces bacterial load in a subcutaneous tissue model

To quantify the volume of lavage required to decrease the bacterial load below a standard of 105 CFUs/mL on a subcutaneous tissue model.

This was a benchtop experimental study conducted between May 1, 2023, through July 31, 2023 that included 20 sterile silicone skin models with a 10-cm incision. The silicone skin model was inoculated with a 1,000-fold dilution of approximately 1.5 X 108 CFUs/mL of isolated Staphylococcus pseudintermedius or Escherichia coli. Bacterial quantification samples were taken preinoculation, 20 minutes postinoculation, and after incremental saline lavage to total a volume of 2.5, 5, and 10 mL/cm incisional length bacterial quantification.

For S pseudintermedius and E coli, a reduction of bacterial colonies below 105 CFUs/mL was noted in all lavage volumes, with an initial 3-log decrease from postinoculation to the 2.5 mL/cm lavage for both S pseudintermedius and E coli. Microbial growth demonstrated a 1-log reduction with increased lavage volumes from 2.5 mL/cm to 10 mL/cm for S pseudintermedius. For E coli, microbial growth demonstrated a 1-log reduction with the second lavage (total of 5 mL/cm) and a half-log reduction with the third lavage (total of 10 mL/cm).

Surgeons should consider a minimum of 2.5 mL/cm lavage when aiming to decontaminate SC tissues in linear surgical wounds. Further work in clinical cases is required to evaluate differences in live tissue compared to this model.

This work provides surgeons with a reference point for deciding what volume of lavage to use for purposes of decontaminating an SC space.