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In vitro pyocin activity of Pseudomonas aeruginosa strains pretreated with antibiotics
Abstract:
Fifty-six selected strains of Pseudomonas aeruginosa belonging to 8 different pyocin types (H, I, 15, 6, PTI-1, PTI-2, PTI-3, PTI-4) were treated with subinhibitory concentrations (MIC/2) of either gentamicin or carbenicillin. Both treatments induced changes in pyocin patterns for all types but at different levels. The percentage of strains that retained their pyocin pattern were more or less equal in both treatments. In treated and untreated producers, the growth inhibition ability for 5 different strains of Enterobacteriaceae (Escherichia coli K12, E. coli EB, Proteus vulgaris, Salmonella typhi, Shigella flexneri) was also investigated. In all pyocin patterns the number of producers that inhibit the growth of these strains was lower after treatment with gentamicin or with carbenicillin, a smaller decrease was detected in the latter treatment. It appeared that the subinhibitory concentrations of these antibiotics are capable of protecting the Enterobacteriaceae strains from the action of the pyocins.
Insights
Subinhibitory antibiotic concentrations alter Pseudomonas aeruginosa pyocin patterns and reduce their ability to inhibit Enterobacteriaceae growth. Gentamicin and carbenicillin treatments protect Enterobacteriaceae from pyocin activity.
Area of Science:
- Microbiology
- Bacteriology
- Antimicrobial Resistance
Background:
- Pseudomonas aeruginosa produces pyocins, bacteriocins that target other bacteria.
- Antibiotic treatments can influence bacterial characteristics, including pyocin production and activity.
- Understanding these interactions is crucial for managing infections and antibiotic resistance.
Purpose of the Study:
- To investigate the effect of subinhibitory antibiotic concentrations on Pseudomonas aeruginosa pyocin types.
- To assess the impact of these treatments on the growth inhibition ability of pyocins against Enterobacteriaceae.
- To determine if antibiotics can confer protection to Enterobacteriaceae against pyocin action.
Main Methods:
- Fifty-six Pseudomonas aeruginosa strains of 8 pyocin types were treated with subinhibitory concentrations (MIC/2) of gentamicin or carbenicillin.
- Changes in pyocin patterns were analyzed post-treatment.
- The growth inhibition of 5 Enterobacteriaceae strains by treated and untreated P. aeruginosa producers was evaluated.
Main Results:
- Both gentamicin and carbenicillin treatments induced changes in pyocin patterns across all tested types.
- The percentage of strains retaining their original pyocin pattern was similar for both antibiotics.
- Treated P. aeruginosa strains showed reduced ability to inhibit the growth of Enterobacteriaceae compared to untreated strains, with a smaller decrease observed for carbenicillin.
Conclusions:
- Subinhibitory concentrations of gentamicin and carbenicillin can alter Pseudomonas aeruginosa pyocin expression and patterns.
- These antibiotic treatments reduce the efficacy of pyocins in inhibiting the growth of susceptible Enterobacteriaceae.
- Antibiotics at subinhibitory levels may offer a protective effect to Enterobacteriaceae against pyocin-mediated killing.