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Published on: December 3, 2017
Assessment of Staphylococcal Clinical Isolates from Periprosthetic Joint Infections for Potential Bacteriophage
Brian J DePalma1, Sumon Nandi1, Waqas Chaudhry2
1Department of Orthopaedic Surgery, University of Maryland School of Medicine, Baltimore, Maryland.
Background:
Bacteriophage therapy is a potential adjunctive treatment for periprosthetic joint infections (PJIs) given the capabilities of bacteriophages to degrade biofilms, self-replicate, and lyse bacteria. However, many aspects of this therapeutic are ill-defined, and the narrow spectrum of bacteriophage activity along with limited available bacteriophage strains curb potential use for specific bacteria such as Staphylococcus aureus at the present time. Therefore, the aim of this study was to determine the feasibility of using bacteriophages for PJI by (1) categorizing the causative organisms in hip and knee PJI at a tertiary academic center and (2) evaluating in vitro activity of a group of bacteriophages against clinical S. aureus PJI isolates.
Methods:
Patients with chronic hip or knee PJI after undergoing the first stage of a 2-stage revision protocol from 2017 to 2020 were identified retrospectively by a query of the hospital billing database. The causative pathogens in 129 cases were reviewed and categorized. From this cohort, preserved S. aureus isolates were tested against a library of 15 staphylococcal bacteriophages to evaluate for bacterial growth inhibition over 48 hours.
Results:
S. aureus was the most common pathogen causing PJI (26% [33] of 129 cases). Of 29 S. aureus samples that were analyzed for bacteriophage activity, 97% showed adequate growth inhibition of the predominant planktonic colonies by at least 1 bacteriophage strain. However, 24% of the 29 samples demonstrated additional smaller, slower-growing S. aureus colonies, none of which had adequate growth inhibition by any of the initial 14 bacteriophages. Of 5 secondary colonies that underwent subsequent testing with another bacteriophage with enhanced biofilm activity, 4 showed adequate growth inhibition.
Conclusions:
Effective bacteriophage therapeutics are potentially available for S. aureus PJI isolates. The differences in bacteriophage activity against the presumed small-colony variants compared with the planktonic isolates have important clinical implications. This finding suggests that bacteriophage attachment receptors differ between the different bacterial morphologic states, and supports future in vitro testing of bacteriophage therapeutics against both planktonic and stationary states of PJI clinical isolates to ensure activity.
Insights
Bacteriophage therapy shows promise for treating Staphylococcus aureus periprosthetic joint infections (PJIs). While effective against planktonic bacteria, further research is needed to address activity against small-colony variants in PJIs.
Area of Science:
- Microbiology
- Infectious Diseases
- Biotechnology
Background:
- Periprosthetic joint infections (PJIs) pose a significant clinical challenge.
- Bacteriophage therapy offers a potential adjunctive treatment due to its biofilm degradation and bacteria-lysing capabilities.
- Current limitations include narrow bacteriophage spectrum and limited strain availability for pathogens like Staphylococcus aureus.
Purpose of the Study:
- To categorize causative organisms in hip and knee PJIs.
- To evaluate the in vitro activity of bacteriophages against clinical Staphylococcus aureus PJI isolates.
- To determine the feasibility of bacteriophage therapy for PJI treatment.
Main Methods:
- Retrospective review of 129 hip and knee PJI cases from 2017-2020.
- Identification and categorization of causative pathogens.
- In vitro testing of 15 staphylococcal bacteriophages against clinical Staphylococcus aureus isolates.
Main Results:
- Staphylococcus aureus was the most common PJI pathogen (26%).
- 97% of S. aureus isolates showed growth inhibition by at least one bacteriophage against planktonic colonies.
- 24% of isolates exhibited small-colony variants resistant to initial bacteriophages, but some responded to biofilm-active phages.
Conclusions:
- Bacteriophage therapeutics show potential for S. aureus PJI treatment.
- Differences in bacteriophage activity against planktonic and small-colony variants highlight the need for tailored therapeutic strategies.
- Future studies should test bacteriophage activity against both planktonic and stationary bacterial states in PJI isolates.
