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Characterizing interactions of Staphylococcus aureus and Escherichia coli in dual-species implant-associated biofilms
Amita Sekar1,2, Fawaz Ben Malick1, Shweta Uma Deepak1
1Harris Orthopaedics Laboratory, Massachusetts General Hospital, Boston, MA, USA.
Abstract:
While Staphylococcus aureus is the predominant pathogen in periprosthetic joint infections (PJI), polymicrobial infections involving Gram-negative organisms, such as Escherichia coli, complicate clinical outcomes. Little is known regarding implant-associated polymicrobial interactions; consequently, current PJI treatments are not optimized for their treatment. This study explored the dynamics of S. aureus-E. coli dual-species biofilms, focusing on biofilm properties, antibiotic susceptibility, and molecular interactions. Co-culture experiments revealed that E. coli significantly suppressed S. aureus biofilm viability, observed for methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA). Microscopic analyses demonstrated enhanced E. coli attachment facilitated by S. aureus matrix proteins; however, over time, E. coli dominated the biofilm composition. In the presence of E. coli, MSSA biofilm exhibited improved gentamicin susceptibility while MRSA showed limited change, underscoring strain-specific interactions. Notably, E. coli biofilms exhibited enhanced resistance to gentamicin in dual-species settings. Gene expression profiling revealed molecular adaptation in S. aureus and E. coli, triggered by the differential regulation of stress, adhesion, virulence, and biofilm-associated genes within a dual-species implant-associated biofilm. The suppression of S. aureus by E. coli presents potential therapeutic avenues, and in vivo studies and mechanistic investigations are crucial for optimizing treatment strategies targeting polymicrobial PJIs.
Insights
Escherichia coli significantly reduces Staphylococcus aureus viability in dual-species biofilms, impacting antibiotic susceptibility. Understanding these interactions is key for optimizing treatments for polymicrobial periprosthetic joint infections.
Area of Science:
- Microbiology
- Biomedical Engineering
- Infectious Diseases
Background:
- Periprosthetic joint infections (PJI) are often caused by Staphylococcus aureus.
- Polymicrobial infections involving Gram-negative bacteria like Escherichia coli complicate PJI treatment outcomes.
- Limited knowledge exists on implant-associated polymicrobial interactions, hindering optimized PJI therapies.
Purpose of the Study:
- To investigate the dynamics of Staphylococcus aureus-Escherichia coli dual-species biofilms.
- To analyze biofilm properties, antibiotic susceptibility, and molecular interactions in vitro.
- To identify potential therapeutic strategies for polymicrobial PJI.
Main Methods:
- Co-culture experiments were performed to study dual-species biofilms.
- Biofilm viability, composition, and microscopic structure were analyzed.
- Antibiotic susceptibility (gentamicin) and gene expression profiling were conducted.
Main Results:
- Escherichia coli significantly suppressed Staphylococcus aureus viability in dual-species biofilms (both MSSA and MRSA).
- E. coli attachment was enhanced by S. aureus matrix proteins, but E. coli eventually dominated biofilm composition.
- Strain-specific antibiotic susceptibility changes were observed; E. coli biofilms showed increased gentamicin resistance.
Conclusions:
- Escherichia coli's suppression of Staphylococcus aureus in biofilms presents potential therapeutic targets.
- Understanding these polymicrobial dynamics and molecular adaptations is crucial for developing effective PJI treatments.
- Further in vivo studies are necessary to validate findings and optimize therapeutic strategies for polymicrobial PJI.
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