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Published on: May 4, 2018
A Potential High-Risk Clone of Pseudomonas aeruginosa ST463
Yanyan Hu1, Wenjing Peng2, Yifan Wu2
1Clinical Microbiology Laboratory, The Second Affiliated Hospital of Zhejiang University, School of Medicine, Zhejiang University, Hangzhou, China.
Abstract:
Pseudomonas aeruginosa is one of the most common opportunistic pathogens, which causes severe nosocomial infections because of its well-known multidrug-resistance and hypervirulence. It is critical to curate routinely the epidemic P. aeruginosa clones encountered in the clinic. The aim of the present study was to investigate the connection between virulence factors and antimicrobial resistance profiles in epidemic clones. Herein, we found that ST463 (O4), ST1212 (O11), and ST244 (O5) were prevalent in 30 isolates derived from non-cystic fibrosis patients, based on multilocus sequence type (MLST) and serotype analysis. All isolates were multidrug-resistant (MDR) and each was resistance to at least three classes of antibiotics in antimicrobial susceptibility tests, which was consistent with the presence of the abundant resistance genes, such as bla OXA-50, bla PAO, aph(3'), catB7, fosA, crpP, and bla KPC-2. Notably, all bla KPC-2 genes were located between ISKpn6-like and ISKpn8-like mobile genetic elements. In addition, classical exotoxins encoded by exoU, exoS, and pldA were present in 43.44% (13/40), 83.33% (25/30), and 70% (21/30) of the isolates, respectively. The expression of phz operons encoding the typical toxin, pyocyanin, was observed in 60% of isolates (18/30) and was quantified using triple quadrupole liquid chromatograph mass (LC/MS) assays. Interestingly, compared with other MLST types, all ST463 isolates harbored exoU, exoS and pldA, and produced pyocyanin ranging from 0.2 to 3.2 μg/mL. Finally, we evaluated the potential toxicity of these isolates using hemolysis tests and Galleria mellonella larvae infection models. The results showed that ST463 isolates were more virulent than other isolates. In conclusion, pyocyanin-producing ST463 P. aeruginosa, carrying diverse virulence genes, is a potential high-risk clone.
Insights
Multidrug-resistant Pseudomonas aeruginosa clones ST463, ST1212, and ST244 were identified in non-cystic fibrosis patients. ST463 isolates showed higher virulence due to pyocyanin production and diverse virulence genes, posing a significant clinical risk.
Area of Science:
- Clinical Microbiology
- Infectious Diseases
- Genomics and Molecular Epidemiology
Background:
- Pseudomonas aeruginosa is a frequent cause of nosocomial infections, characterized by multidrug resistance and hypervirulence.
- Routine surveillance of epidemic P. aeruginosa clones is crucial for effective clinical management.
- Understanding the interplay between antimicrobial resistance and virulence factors in prevalent clones is essential.
Purpose of the Study:
- To investigate the relationship between virulence factors and antimicrobial resistance profiles in epidemic P. aeruginosa clones.
- To identify prevalent sequence types (STs) and serotypes in P. aeruginosa isolates from non-cystic fibrosis patients.
- To assess the virulence potential of identified clones using in vitro and in vivo models.
Main Methods:
- Multilocus sequence typing (MLST) and serotyping were performed on 30 P. aeruginosa isolates.
- Antimicrobial susceptibility testing and detection of resistance genes (e.g., blaKPC-2) were conducted.
- Virulence gene profiling (exoU, exoS, pldA), pyocyanin quantification (LC/MS), hemolysis assays, and Galleria mellonella infection models were employed.
Main Results:
- ST463 (O4), ST1212 (O11), and ST244 (O5) were identified as prevalent clones, all exhibiting multidrug resistance (MDR).
- Resistance genes, including blaKPC-2 located within mobile genetic elements, were abundant.
- ST463 isolates uniquely harbored exoU, exoS, and pldA, produced significant pyocyanin (0.2–3.2 μg/mL), and demonstrated higher virulence in hemolysis and G. mellonella models compared to other STs.
Conclusions:
- Pyocyanin-producing ST463 P. aeruginosa, possessing a combination of virulence genes and MDR, represents a high-risk clone.
- The study highlights the importance of molecular surveillance for identifying and characterizing virulent, drug-resistant clones in clinical settings.
- Targeting specific virulence factors and resistance mechanisms in ST463 may offer novel therapeutic strategies.
