1. Front Med (Lausanne). 2020 Sep 17;7:527. doi: 10.3389/fmed.2020.00527. 
eCollection 2020.

Synergistic Effects of Pulsed Lavage and Antimicrobial Therapy Against 
Staphylococcus aureus Biofilms in an in-vitro Model.

Poilvache H(1)(2)(3), Ruiz-Sorribas A(2), Sakoulas G(4), Rodriguez-Villalobos 
H(5), Cornu O(1)(3), Van Bambeke F(2).

Author information:
(1)Laboratoire de Neuro-Musculo-Squelettique, Institut de Recherche 
Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium.
(2)Laboratoire de Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research 
Institute, Université Catholique de Louvain, Brussels, Belgium.
(3)Orthopaedic Surgery Department, Cliniques Universitaires Saint-Luc, Brussels, 
Belgium.
(4)School of Medicine, University of California, San Diego, San Diego, CA, 
United States.
(5)Clinical Microbiology Department, Cliniques Universitaires Saint-Luc, 
Brussels, Belgium.

Background: Prosthetic joint infections (PJI) are difficult to treat 
complications of joint arthroplasty. Debridement with implant retention is a 
common treatment strategy and frequently involves the use of pulsed lavage (PL). 
However, PL effects on biofilms and antibiotic activity have been scarcely 
studied in-vitro. We report the effects of PL, vancomycin or flucloxacillin used 
independently or in combination against Staphylococcus aureus biofilms. Methods: 
Biofilms of 3 methicillin-susceptible (MSSA) and of 3 methicillin-resistant 
(MRSA) S. aureus were grown on Ti6Al4V coupons in TGN (TSB + 1%glucose + 
2%NaCl). After 24 h, PL was applied to half of the samples (50 mL saline from 5 
cm). Samples were either reincubated for 24 h in TGN or TGN + flucloxacillin or 
vancomycin. Analyses included CFUs counts, biomass assays or fluorescence 
microscopy. Results: PL transiently reduced bacterial counts by 3-4 Log10 
CFU/coupon, but bacterial regrowth to baseline levels was seen after 24 h. At 20 
mg/L, flucloxacillin reduced both the CFU counts (3 Log10 CFU/coupon) and 
biomass (-70%) in one MSSA only, while vancomycin had no effects against MRSA. 
PL combined with a 24 h reincubation with vancomycin or flucloxacillin at 20 
mg/L was synergistic (-5 to 6.5 Log10 CFU/coupon; 81-100% biomass reduction). 
Fluorescence microscopy confirmed that PL removed most of the biofilm and that 
subsequent antibiotic treatment partially killed bacteria. Conclusions: While PL 
only transiently reduces the bacterial load and antibiotics at clinically 
relevant concentrations show no or limited activity on biofilms, their 
combination is synergistic against MRSA and MSSA biofilms. These results 
highlight the need for thorough PL before antibiotic administration in PJI.

Copyright © 2020 Poilvache, Ruiz-Sorribas, Sakoulas, Rodriguez-Villalobos, Cornu 
and Van Bambeke.

DOI: 10.3389/fmed.2020.00527
PMCID: PMC7527469
PMID: 33043028