Assessment of Staphylococcal Clinical Isolates from Periprosthetic Joint Infections for Potential Bacteriophage Therapy

Bacteriophage ISP eliminates Staphylococcus aureus in planktonic phase, but not in the various stages of the biofilm cycle

Metal-implant associated bacterial infections are a major clinical problem due to antibiotic treatment failure. As an alternative, we determined the effects of bacteriophage ISP on clinical isolates of Staphylococcus aureus in various stages of its life cycle in relation to biofilm formation and maturation. ISP effectively eliminated all planktonic phase bacteria, whereas its efficacy was reduced against bacteria attached to the metal implant and bacteria embedded within biofilms. The biofilm architecture hampered the bactericidal effects of ISP, as mechanical disruption of biofilms improved the efficacy of ISP against the bacteria. Phages penetrated the biofilm and interacted with the bacteria throughout the biofilm. However, most of the biofilm-embedded bacteria were phage-tolerant. In agreement, bacteria dispersed from mature biofilms of all clinical isolates, except for LUH15394, tolerated the lytic activity of ISP. Lastly, persisters within mature biofilms tolerated ISP and proliferated in its presence. Based on these findings, we conclude that ISP eliminates planktonic phase Staphylococcus aureus while its efficacy is limited against bacteria attached to the metal implant, embedded within (persister-enriched) biofilms, and dispersed from biofilms.

Feasibility of using bacteriophage therapy to treat Staphylococcal aureus fracture-related infections

OBJECTIVE

Staphylococcus aureus fracture-related infections (FRIs) are associated with significant morbidity in part because conventional antibiotic therapies have limited ability to eradicate S. aureus in sessile states. Therefore, the objective of this study was to assess the feasibility of using Staphylococcal bacteriophages for FRI by testing the activity of a library of Staphylococcal bacteriophage therapeutics against historically preserved S. aureus FRI clinical isolates.

METHODS

Current Procedural Terminology codes were used to identify patients with FRI from January 1, 2021 to December 31, 2021. Preserved S. aureus FRI isolates from the cases were then tested against a library of 51 Staphylococcal bacteriophages from an American company. This was conducted by assessing the ability of bacteriophages to reduce bacterial growth over time. Growth inhibition greater than 16 h was considered adequate for this study.

RESULTS

All of the S. aureus preserved clinical isolates had at least one bacteriophage with robust lytic activity and six bacteriophages (11.8 %) had robust lytic activity to seven or more of the clinical isolates. However, 41 of the bacteriophages (80.4 %) had activity to less than three of the clinical isolates and no bacteriophage had activity to all the clinical isolates.

CONCLUSION

Our findings show that Staphylococcal bacteriophage therapeutics are readily available for S. aureus FRI clinical isolates. However, when correlated with the current barriers to using bacteriophages to treat FRI, designated Staphylococcal bacteriophage cocktails with broad spectrum activity should be created.

Bacteriophage therapy and current delivery strategies for orthopedic infections: A SCOPING review

OBJECTIVES

Interest in phages as adjunctive therapy to treat difficult infections has grown in the last decade. However, phage dosing and delivery for orthopedic infections have not been systematically summarized.

METHODS

Following PRISMA-ScR guidelines, we conducted a SCOPING review through September 1st, 2023, of MEDLINE, Embase, Web of Science Core Collection, and Cochrane Central.

RESULTS

In total, 77 studies were included, of which 19 (24.7%) were in vitro studies, 17 (22.1%) were animal studies, and 41 (53.2%) were studies in humans. A total of 137 contemporary patients receiving phage therapy are described.

CONCLUSIONS

Direct phage delivery remains the most studied form of phage therapy, notably in prosthetic joint infections, osteomyelitis, and diabetic foot ulcers. Available evidence describing phage therapy in humans suggests favorable outcomes for orthopedic infections, though this evidence is composed largely of low-level descriptive studies. Several phage delivery devices have been described, though a lack of comparative and in-human evidence limits their therapeutic application. Limitations to the use of phage therapy for orthopedic infections that need to be overcome include a lack of understanding related to optimal dosing and phage pharmacokinetics, bacterial heterogeneity in an infection episode, and phage therapy toxicity.

The stability of Staphylococcal bacteriophages with commonly used prosthetic joint infection lavage solutions

The aim of this study was to assess the viability of four Staphylococcal bacteriophages when exposed to different concentrations of commonly used lavage solutions in the surgical treatment of prosthetic joint infections (PJI). Four tailed Staphylococcal bacteriophages and six different lavage solutions (chlorhexidine 4%, hydrogen peroxide 3%, acetic acid 3%, povidone iodine 10%, sodium hypochlorite 0.5%, and Vashe solution) at 100%, 1%, and 0.01% concentrations were used in this experiment. In addition, the temporal impact of exposing bacteriophages to these lavage solutions was also evaluated at 5-min exposures and 24-h exposures. The results show that the titers of the four bacteriophages were statistically significantly decreased for all lavage solutions (100% and 1%) at 5-min exposures and 24-h exposures. However, with 0.01% concentrations of the lavage solutions, only acetic acid caused a statistically significant decrease in bacteriophage titers compared to normal saline control. Our findings suggest that tailed Staphylococcal bacteriophages do not remain stable in high concentrations of the most commonly used lavage solutions. However, at very dilute concentrations the bacteriophages do remain viable. This has important clinical ramifications in that it shows when using bacteriophage therapy for PJI it is critical to thoroughly wash out any lavage solutions before the introduction of therapeutic bacteriophages especially when acetic acid is used.

The stability of Staphylococcal bacteriophage in presence of local vancomycin concentrations used in clinical practice

PURPOSE

To evaluate the stability of a clinically used Staphylococcal bacteriophage with doses of vancomycin that are encountered with local administration of vancomycin for musculoskeletal infections.

METHODS

A Staphylococcal bacteriophage was evaluated for stability in different pH ranges. Then that same bacteriophage was evaluated for stability with different concentrations of vancomycin and with vancomycin biodegradable antibiotic beads.

RESULTS

The bacteriophage had stability within a pH range of 4-10. There was a statistically significant (P < 0.05) decrease in the amount of bacteriophage over 24 h for vancomycin concentrations of 10 mg/mL and 100 mg/mL compared to lower vancomycin concentrations (1 mg/mL, 0.1 mg/mL and normal saline). However, no statistically significant decrease in the amount of bacteriophage was seen with biodegradable vancomycin beads over 24 h.

CONCLUSION

These findings have important clinical ramifications in that they show local administration of bacteriophages with concomitant local vancomycin powder therapy should be avoided. Moreover, these findings should spearhead further research into bacteriophage stability in in vivo environments.

Feasibility of Using Bacteriophage Therapy to Reduce Morbidity and Mortality Associated with Spinal Epidural Abscesses

BACKGROUND

The aim of this study was to determine the feasibility of using bacteriophage therapeutics in spinal epidural abscess (SEA) by reviewing the causes and outcomes of SEA at a single institution and testing a bacteriophage for activity against preserved SEA clinical isolates.

MATERIALS AND METHODS

Medical records were reviewed of patients that received incision and drainage for SEA at a single medical center. Causative organisms, incidence of coinciding bacteremia and outcomes were recorded. A subset of SEA patients (N = 11), that had preserved clinical isolates, were assessed to evaluate if a bacteriophage therapeutic had ample activity to those isolates as seen with spot tests and growth inhibition assays.

RESULTS

Staphylococcus aureus was the predominate bacterial cause (71%) and bacteremia was associated with 96% of S. aureus SEA. Over 50% of the patients either died within three months, had recurrence of their infection, required repeat debridement, or had long term sequalae. A single bacteriophage had positive spot tests for all the S. aureus clinical isolates and inhibited bacterial growth for more than 24 hours for 9 of the 11 (82%) clinical isolates.

CONCLUSION

SEA is associated with significant mortality and morbidity making this a potential indication for adjuvant bacteriophage therapeutics. Since S. aureus is the predominate cause of SEA and most cases are associated bacteremia this creates a potential screening and treatment platform for Staphylococcal bacteriophages therapeutics, allowing for potential pilot studies to be devised.

Experience Using Adjuvant Bacteriophage Therapy for the Treatment of 10 Recalcitrant Periprosthetic Joint Infections: A Case Series

Periprosthetic joint infections are a devastating complication of joint replacement surgery. One novel therapeutic that has potential to change the current treatment paradigm is bacteriophage therapy. Herein, we discuss our experiences with bacteriophage therapy for 10 recalcitrant periprosthetic joint infections and review the treatment protocols utilized to achieve successful outcomes.

Bacteriophage therapy in infection after fracture fixation (IAFF) in orthopaedic surgery

Infection after fracture fixation (IAFF) in orthopaedic surgery is a significant complication that can lead to disability due to chronic infection and/or relapsing disease, non-union necessitating revision surgery. Management of IAFF is a major challenge facing orthopaedic surgeons across the world due to two key pathogenic mechanisms of Biofilm formation and antimicrobial resistance (AMR) against traditional antibiotics. Advanced prophylactic and treatment strategies to help eradicate established infections and prevent the development of such infections are necessary. Bacteriophage therapy represents an innovative modality to treat IAFF due to multi-drug resistant organisms. We assess the current role and potential therapeutic applications of the novel bacteriophage therapy in the management of these recalcitrant infections to achieve a successful outcome.

Bacteriophage therapy for periprosthetic joint infections: Current limitations and research needed to advance this therapeutic

Bacteriophage therapy is a promising treatment for periprosthetic joint infections (PJIs), particularly given these agents have innate abilities to degrade the biofilm matrix and lyse bacteria within. However, many aspects of this therapy are poorly understood causing treatments to lack uniform effectiveness and reproducibility, which is in part a consequence of several inherent limitations to using bacteriophages to treat PJI. Herein, these limitations are discussed as are additional translational research that needs to be conducted to advance this therapeutic. These include determining if bacteria causing PJIs are polyclonal, consequences of bacteriophage attachment receptor phenotypic variations and ramifications of bacteriophage activity when bacteria interact with in vivo macromolecules. Only with the realization of the current limitations and subsequent knowledge gained from translational research will the potential of bacteriophages to reduce the morbidity and mortality in PJI be fully elucidated.

Impact of Bacterial Phenotypic Variation with Bacteriophage therapy: A Pilot Study with Prosthetic Joint Infection Isolates

BACKGROUND

Given the specificity of bacteriophage attachment receptors, a single bacterial isolate is currently utilized to match to a bacteriophage therapeutic thereby extrapolating activity to all bacteria in vivo. Obstinately, the main bacteriophage attachment receptor for Staphylococcus aureus is teichoic acid and it is known that this receptor has phenotypic variations in different in vivo environments. Consequently, the aim of this study was to determine if bacteriophage activity is similar across all in vivo prosthetic joint infection environments.

METHODS

Three patients with prosthetic joint infections who had S. aureus grow from arthrocentesis cultures and at least three deep tissue cultures were analyzed for growth inhibition with a library of 56 bacteriophages RESULTS: Discordant bacteriophage activity was seen across the different in vivo environments. As well bacteriophages with the most robust lytic potential to the arthrocentesis isolates usually did not have activity to all the deep tissues clinical isolates.

CONCLUSION

Variations of bacteriophage activity can occur between the different in vivo clinical environments which is likely secondary to different glycosylation patterns of teichoic acid. Consequently, if discordant activity is present then retreating with bacteriophages that have activity is likely needed for effective, reproducible outcomes.