Staphylococcal Persistence Due to Biofilm Formation in Synovial Fluid Containing Prophylactic Cefazolin

Abstract

Antibiotic prophylaxis is standard for patients undergoing surgical procedures, yet despite the wide use of antibiotics, breakthrough infections still occur. In the setting of total joint arthroplasty, such infections can be devastating. Recent findings have shown that synovial fluid causes marked staphylococcal aggregation, which can confer antibiotic insensitivity. We therefore asked in this study whether clinical samples of synovial fluid that contain preoperative prophylactic antibiotics can successfully eradicate a bacterial challenge by pertinent bacterial species. This study demonstrates that preoperative prophylaxis with cefazolin results in high antibiotic levels. Furthermore, we show that even with antibiotic concentrations that far exceed the expected bactericidal levels, Staphylococcus aureus bacteria added to the synovial fluid samples are not eradicated and are able to colonize model implant surfaces, i.e., titanium pins. Based on these studies, we suggest that current prophylactic antibiotic choices, despite high penetration into the synovial fluid, may need to be reexamined.I nfection remains a major concern with orthopedic procedures, although infection rates are generally Ͻ1% (1). Because of the high prophylactic antibiotic levels within synovial fluid, the use of minimally invasive techniques, and short surgical times, infection rates remain low. However, with increasing numbers of total knee arthroplasties, infections are projected to exceed 60,000 to 70,000 cases in the United States by 2020 (2, 3). When hardware, such as a prosthesis, is present, infection is recalcitrant to antibiotic treatment. Once established, infection can cause prolonged disability, multiple operations, and increased health care costs (3, 4). According to the WHO, patients with a surgical site infection have twice the mortality rate, are twice as likely to spend time in an intensive care unit, and are five times more likely to be readmitted to the hospital than uninfected patients (5).To avoid the establishment of infection, antibiotic prophylaxis has become the standard of care (6, 7). For orthopedic procedures, cefazolin (CFZ), which is bactericidal for staphylococci, streptococci, and Escherichia coli (8, 9), is commonly used in the absence of a penicillin allergy (10). Alternative prophylactic antibiotics include fusidic acid, cloxacillin (11), cefixime (12), vancomycin, and gentamicin (13). Interestingly, synovial fluid has been suggested to possess antibacterial properties (14-16) that are attributed to hyaluronic acid within the synovial fluid (17), the induction of bactericidal/permeability-increasing protein (15), or unknown compounds, including antimicrobial peptides, within the synovial fluid (14). We recently reported that this ostensible decrease in bacterial numbers, which is perceived to be an "antibacterial" effect, is actually due to the clumping of bacteria within synovial fluid, which masks the true microbial load levels (18).The recognition of this behavior also helps to elucidate the difficulties ...

Role of Phenol-Soluble Modulins in Formation of Staphylococcus aureus Biofilms in Synovial Fluid

“…Even when SF was isolated from patients who had received high doses of prophylactic antibiotic, which leads to high concentrations of antibiotic in SF (28), biofilms formed on titanium disks over the course of 48 h (Fig. 1A), underscoring the notion that S. aureus PJIs are recalcitrant to antibiotic treatment due to the formation of biofilms (4,28). Notably, extensive biofilm-like aggregates formed within minutes after incubation of the bacteria in SF and were characterized by the attachment of fibrous material (Fig.…”

“…In the present study, we asked which factors are responsible for the excessively strong degree of aggregate and biofilm formation in SF, which is the basis for the notorious recalcitrance of such infections to antibiotic treatment (28). We identified the low activity of Agr and consequentially low production of PSMs as major factors contributing to that phenotype.…”

Bacteriophage Lysin CF-301, a Potent Antistaphylococcal Biofilm Agent

“…Here, the synergy between CF-301 Ex vivo analysis of biofilms formed in HSF. Human synovial fluid (HSF) is known to support the formation of strong antibiotic-resistant biofilms composed of host factors (including fibrin) and bacterial proteins (including fibronectin-and fibrinogenbinding proteins) (50). We showed that biofilms formed by MRSA strain BAA-42 in HSF Antimicrobial Agents and Chemotherapy were susceptible to removal and killing by CF-301 between 4 and 24 h (Fig.…”

“…Aggressive antibiotic therapies can reduce biofilms and control dispersed planktonic bacteria; however, eradication is difficult because of the high antibiotic concentrations that must be sustained (50,(52)(53)(54). To avoid the limitations of antibiotics, a promising new strategy was proposed based on the emerging understanding of bacteriophage lysins as antibiofilm agents (32,43).…”

Tissue Plasminogen Activator Coating on Implant Surfaces Reduces Staphylococcus aureus Biofilm Formation

“…Unfortunately, fibrin-rich S. aureus biofilms appear rapidly, which might decrease the efficacy of antibiotic prophylaxis (30) and blunt phagocytosis (9,11,31,32). Importantly, tPA coating prevents the first step of biofilm formation, the adhesion of S. aureus to the implant surface, thereby expanding the window of opportunity and allowing more efficient pathogen clearance.…”