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Pseudomonas aeruginosa clinical isolates: serotypes, resistance phenotypes and plasmid profiles
M Millesimo1, G de Intinis, M G Chirillo
1Department of Clinical and Biological Sciences, University of Turin, San Luigi Hospital, Orbassano, Italy.
Abstract:
78 Pseudomonas aeruginosa strains were isolated from the respiratory tract of 56 patients, 15 of which were affected by cystic fibrosis (CF). The epidemiological typing scheme was based on serotyping, antibiotic resistance pattern and plasmid DNA profile. All strains (except 2 mucoid strains) were typed using a rapid slide O-agglutination technique. Most common serotypes in both group were 0:1, 0:10 and 0:6. Moreover we observed a correlation among 0:12 serotype and CF patients. Plasmid DNA analysis showed that 45.2% (on average) of strains isolated from patients with and w/o CF harboured 1-3 plasmids ranging in size from 1 to 15 Md. Plasmid prevalence was higher in strains isolated from CF patients in specimens collected after antibiotic therapy. A correlation was found between 1 and 1.9 Md plasmids and resistance to aminoglycosides. Our results indicate that the analysis of antibiotic resistance phenotypes combined with plasmid analysis may be useful, in association to serotyping, to characterize the circulation of P. aeruginosa strains and the spread of resistance in these bacteria.
Insights
Pseudomonas aeruginosa strains from cystic fibrosis (CF) patients showed specific serotypes and plasmid DNA profiles. Antibiotic resistance patterns combined with serotyping and plasmid analysis can track the spread of P. aeruginosa and resistance.
Area of Science:
- Clinical Microbiology
- Bacterial Genetics
- Infectious Diseases
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen frequently isolated from respiratory tracts.
- Cystic fibrosis (CF) patients are particularly susceptible to P. aeruginosa infections.
- Understanding the epidemiology and resistance mechanisms of P. aeruginosa is crucial for patient management.
Purpose of the Study:
- To characterize Pseudomonas aeruginosa strains isolated from patients with and without cystic fibrosis.
- To investigate the correlation between serotypes, antibiotic resistance, and plasmid DNA profiles.
- To assess the utility of combined typing methods for epidemiological surveillance.
Main Methods:
- Isolation and characterization of 78 P. aeruginosa strains from patient respiratory tracts.
- Epidemiological typing using serotyping (O-agglutination), antibiotic resistance patterns, and plasmid DNA profiling.
- Correlation analysis between strain characteristics and patient groups (CF vs. non-CF).
Main Results:
- Common serotypes identified were O:1, O:10, and O:6; serotype O:12 showed a correlation with CF patients.
- 45.2% of strains harbored 1-3 plasmids (1-15 Md); plasmid prevalence was higher in CF patients post-antibiotic therapy.
- Plasmids of 1-1.9 Md correlated with aminoglycoside resistance.
Conclusions:
- Serotyping, antibiotic resistance, and plasmid analysis provide valuable tools for characterizing P. aeruginosa strains.
- These combined methods can help in understanding the circulation and spread of P. aeruginosa, especially in CF patients.
- The findings highlight the potential for tracking antimicrobial resistance dissemination through integrated epidemiological approaches.