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In vitro activity of phages against periprosthetic joint infection-associated staphylococcal biofilms
Krupa Parmar1, Waqas Chaudhry2, Joseph R Fackler2
1Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
Abstract:
Lytic phages are potential therapeutic options, based on their ability to lyse bacteria in vitro. Although many infection-types for which phage therapy is being considered involve biofilms, in vitro anti-biofilm activity of phage is poorly defined, in part due to a lack of standardized methods for assessment. Here, phages SaMD07phi1 and SaRBI05030phi5 were evaluated against Staphylococcus aureus SaMD07 and SaRBI05030, respectively, in biofilms formed in 96-well plates and on glass beads, and planktonically, in TSB and PBS, with endpoints including by CFUs and Biolog Omnilog hold times. The bead biofilm assay in TSB using the Omnilog (BBTO) was employed to test eight staphylococcal phages against S. aureus, Staphylococcus epidermidis, and Staphylococcus lugdunensis from periprosthetic joint infection. Biofilms on beads in TSB showed better eradication than in microtiter wells, with no significant changes with PBS in either format. CFU counts and Omnilog units correlated linearly through 8 h of testing. In the bead assay, CFU counts showed that phage SaMD07phi1 eliminated growth at 4 h, while SaRBI05030phi5 achieved a ~ 3-log reduction at 8 h; with Omnilog hold times of 37 and 28 h, respectively. Diverse activity and good reproducibility of the BBTO was observed among 8 phages, with SaMD07phi1 showing the highest activity. In conclusion the BBTO is a promising potential method for biofilm susceptibility testing.
Insights
Lytic phage therapy shows promise for treating bacterial biofilms. A novel bead biofilm assay in TSB using the Omnilog (BBTO) demonstrated effective phage activity against Staphylococcus biofilms.
Area of Science:
- Microbiology
- Bacteriology
- Phage Therapy
Background:
- Lytic phages offer potential for bacterial infection treatment.
- Assessing phage efficacy against biofilms requires standardized methods.
- Current methods for evaluating in vitro anti-biofilm activity are limited.
Purpose of the Study:
- To evaluate the in vitro anti-biofilm activity of specific lytic phages against Staphylococcus species.
- To assess the efficacy of a novel bead biofilm assay in TSB using the Omnilog (BBTO) for phage susceptibility testing.
- To compare biofilm eradication in different formats (96-well plates vs. glass beads) and media (TSB vs. PBS).
Main Methods:
- Phages SaMD07phi1 and SaRBI05030phi5 were tested against Staphylococcus aureus biofilms.
- Biofilms were formed in 96-well plates and on glass beads.
- The bead biofilm assay in TSB using the Omnilog (BBTO) was used to test eight staphylococcal phages against S. aureus, S. epidermidis, and S. lugdunensis.
Main Results:
- Biofilms on beads in TSB showed better eradication than in microtiter wells.
- Phage SaMD07phi1 eliminated growth at 4 hours, and SaRBI05030phi5 achieved a ~3-log reduction at 8 hours in the bead assay.
- The BBTO assay demonstrated diverse activity and good reproducibility among eight tested phages.
Conclusions:
- The bead biofilm assay in TSB using the Omnilog (BBTO) is a promising method for assessing phage activity against bacterial biofilms.
- Standardized methods like BBTO are crucial for advancing phage therapy for biofilm-related infections.
- Phage therapy holds potential for combating challenging Staphylococcus biofilm infections.
