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Plasmid profiles compared with serotyping and pyocin typing for epidemiological surveillance of Pseudomonas
1Department of Microbiology, Faculty of Medicine, National University of Singapore.
Abstract:
The plasmid profiles of 112 clinical isolates of Pseudomonas aeruginosa were determined by two reproducible, rapid, plasmid screening methods. Plasmid DNA was present in 15% of isolates examined. Plasmids varied in size from 1.2 X 10(6) to 60.2 X 10(6) mol. wt. The dominant serotypes encountered were O:11 and O:4, which comprised 38% and 12% of strains, respectively. Four pyocin types (1, 10, 3 and 5) dominated (respective frequencies: 56, 15, 12 and 6%). Reproducibility of pyocin typing was distinctly inferior to both plasmid profiling and serotyping. Strains of identical serotypes could be further differentiated by dissimilar plasmid profiles. Serologically untypable or polyagglutinable strains were successfully characterised by plasmid profile patterns. Thus, plasmid profiling was shown to be a useful adjunct to serotyping for the epidemiological typing of P. aeruginosa.
Insights
Plasmid profiling effectively differentiates Pseudomonas aeruginosa strains, complementing traditional serotyping methods for improved epidemiological analysis. This technique aids in characterizing strains that are difficult to classify using serological methods alone.
Area of Science:
- Microbiology
- Epidemiology
- Molecular Biology
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen.
- Accurate epidemiological typing is crucial for controlling its spread.
- Traditional methods like serotyping have limitations.
Purpose of the Study:
- To evaluate plasmid profiling as an adjunct to serotyping for Pseudomonas aeruginosa.
- To assess the reproducibility and utility of plasmid profiling and pyocin typing.
Main Methods:
- Plasmid DNA screening of 112 clinical isolates.
- Serotyping and pyocin typing for comparison.
- Analysis of plasmid size variation and frequency.
Main Results:
- Plasmid DNA was detected in 15% of isolates.
- Plasmid profiling differentiated strains with identical serotypes.
- Plasmid profiles characterized serologically untypable strains.
- Pyocin typing showed inferior reproducibility compared to plasmid profiling and serotyping.
Conclusions:
- Plasmid profiling is a valuable tool for P. aeruginosa epidemiological typing.
- It enhances traditional serotyping, especially for difficult-to-type strains.
- This method offers a reproducible and rapid adjunct for strain characterization.