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In vitro virulence activity of Pseudomonas aeruginosa, enhanced by either Acinetobacter baumannii or Enterococcus
Ghazale Laliany1, Saeid Amel Jamehdar2, Ali Makhdoumi3
1Department of Biology, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran.
Abstract:
Microbes within an infection impact neighbors' pathogenicity. This study aimed to address in vitro virulence activity of Pseudomonas aeruginosa under the binary interaction with Acinetobacter baumannii or Enterococcus faecium, co-isolated from two chronic wound infections. The biofilm formation of Pseudomonas was enhanced 1.5- and 1.4-fold when it was simultaneously cultured with Acinetobacter and Enterococcus, respectively. Pseudomonas motility was increased by 1.9- and 1.5-fold (swimming), 3.6- and 1.9-fold (swarming), and 1.5- and 1.5-fold (twitching) in the dual cultures with Acinetobacter and Enterococcus, respectively. The synergistic hemolysis activity of Pseudomonas was observed with the heat-killed Acinetobacter and Enterococcus cells. The minimum inhibitory concentration of ciprofloxacin against Pseudomonas was increased from (μg mL-1) 25 to 400 in the individual and mixed cultures, respectively. The pyocyanin production by Pseudomonas in the single and mixed cultures with Acinetobacter and Enterococcus was (μg/mL) 1.8, 2.3, and 2.9, respectively. The expression of lasI, rhlI, and pqsR genes was up-regulated by 1.0-, 1.9-, and 16.3-fold, and 4.9-, 1.0-, and 9.3-fold when Pseudomonas was incubated with Acinetobacter and Enterococcus, respectively. Considering the entire community instead of a single pathogen may lead to a more effective therapeutic design for persistent infections caused by Pseudomonas.
Insights
Interactions between Pseudomonas aeruginosa and other microbes like Acinetobacter baumannii enhance its virulence. This suggests treating wound infections requires considering the microbial community, not just single pathogens.
Area of Science:
- Microbiology
- Infectious Diseases
- Bacterial Pathogenesis
Background:
- Microbial interactions significantly influence infection dynamics.
- Chronic wound infections often involve polymicrobial communities.
- Understanding interspecies interactions is crucial for effective treatment strategies.
Purpose of the Study:
- To investigate the in vitro virulence of Pseudomonas aeruginosa in binary interactions with Acinetobacter baumannii and Enterococcus faecium.
- To assess the impact of these interactions on biofilm formation, motility, hemolysis, antibiotic resistance, and virulence factor production.
- To analyze the gene expression changes in P. aeruginosa during co-culture.
Main Methods:
- Co-culture experiments of P. aeruginosa with A. baumannii or E. faecium isolated from chronic wounds.
- Quantification of biofilm formation, bacterial motility (swimming, swarming, twitching), and pyocyanin production.
- Assessment of synergistic hemolysis activity.
- Determination of minimum inhibitory concentration (MIC) of ciprofloxacin.
- Gene expression analysis (lasI, rhlI, pqsR) using quantitative PCR.
Main Results:
- Co-culturing P. aeruginosa with A. baumannii and E. faecium significantly enhanced its biofilm formation, motility, and pyocyanin production.
- Synergistic hemolytic activity was observed with heat-killed A. baumannii and E. faecium.
- The MIC of ciprofloxacin against P. aeruginosa increased dramatically in mixed cultures.
- Gene expression analysis revealed significant up-regulation of key virulence genes (lasI, rhlI, pqsR) in P. aeruginosa during co-culture.
- P. aeruginosa virulence was notably amplified in the presence of A. baumannii and E. faecium.
Conclusions:
- Pseudomonas aeruginosa exhibits enhanced virulence in vitro when interacting with Acinetobacter baumannii and Enterococcus faecium.
- These polymicrobial interactions contribute to increased antibiotic resistance and virulence factor production.
- Therapeutic strategies for chronic wound infections should consider the entire microbial community for improved efficacy.
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