Antibiotic intervention redisposes bacterial interspecific interacting dynamics in competitive environments

Area of Science:

• Microbiology
• Infectious Diseases
• Bacterial Pathogenesis

Background:

• Bacterial interspecific interactions are crucial for polymicrobial community development.
• The impact of antibiotic therapy on pathogenic bacterial dynamics remains poorly understood.

Purpose of the Study:

• To investigate how antibiotics influence the interaction between Pseudomonas aeruginosa and Staphylococcus aureus.
• To elucidate the mechanisms behind antibiotic-mediated shifts in bacterial pathogen dynamics.

Main Methods:

• Utilized Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus (MRSA) as model organisms.
• Assessed bacterial interactions under varying antibiotic concentrations, focusing on subinhibitory streptomycin.
• Analyzed gene expression related to quorum sensing (QS) in P. aeruginosa.
• Evaluated MRSA iron-uptake systems and pathogenicity.

Main Results:

• P. aeruginosa typically inhibits S. aureus via QS-controlled molecules.
• Subinhibitory streptomycin treatment reversed this interaction, inhibiting P. aeruginosa.
• Streptomycin reduced QS gene expression in P. aeruginosa, alleviating MRSA stress.
• Extracellular products from streptomycin-treated P. aeruginosa enhanced MRSA's iron uptake and pathogenicity.

Conclusions:

• Antibiotics can establish antibiotic-determined mutual invasion relationships between bacterial pathogens.
• This study explains species substitution and persistent coexistence in chronic polymicrobial infections under repeated antibiotic therapies.
• Findings contribute to understanding the pathogenesis of complex infections involving multiple bacterial species.