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Diversity of resistance phenotypes and plasmid analysis in multi-resistant 0:12 Pseudomonas aeruginosa
A Tsakris1, A C Vatopoulos, L S Tzouvelekis
1Department of Microbiology, University of Athens, Greece.
Abstract:
Antibiotic resistance phenotypes, plasmid content and ability of conjugal transfer of antibiotic resistance genes of 35 multi-resistant Pseudomonas aeruginosa strains were examined. The strains were isolated in 12 Greek hospitals and the majority of them (80%) belonged to serotype 0:12. The isolates were distributed to a variety of different antibiotic resistance phenotypes. Plasmid analysis showed that 10 isolates harboured plasmids ranging in size from 20 to 100 Mda. Among these strains, four carried plasmids of 100 Mda, two strains had 60 Mda plasmid each while in three strains the plasmids detected were 65, 25 and 20 Mda, respectively. One strain harboured two plasmids of 100 and 60 Mda. All strains containing plasmids belonged to 0:12 serotype, except the one harbouring the 25 Mda plasmid, which belonged to serotype 0:6. Using a P. aeruginosa recipient resistant to rifampicin and ciprofloxacin, conjugal transfer was achieved in two occasions. These plasmids, 100 Mda in size, encoded high-level resistance to both gentamicin and tobramycin whereas resistance to other drugs was not transferable. Interestingly, all 100 Mda plasmids, including the self-transferable ones, were found to share a certain degree of homology as judged by restriction analysis. It is suggested that both resistance phenotypes and analysis of plasmid content might be useful in subdividing 0:12 multi-resistant P. aeruginosa.
Insights
Multi-resistant Pseudomonas aeruginosa strains, primarily serotype 0:12, were analyzed for antibiotic resistance and plasmid content. Large plasmids (100 Mda) conferred high-level gentamicin and tobramycin resistance, suggesting plasmid analysis aids in classifying these resistant bacteria.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Antibiotic resistance in Pseudomonas aeruginosa is a significant global health concern.
- Multi-resistant strains pose challenges in clinical settings, necessitating detailed characterization.
- Serotype 0:12 strains are frequently implicated in hospital-acquired infections.
Purpose of the Study:
- To investigate the antibiotic resistance phenotypes, plasmid profiles, and conjugal transfer capabilities of multi-resistant Pseudomonas aeruginosa.
- To determine the role of plasmids in the dissemination of antibiotic resistance genes within P. aeruginosa populations.
- To explore the potential of plasmid analysis for classifying specific P. aeruginosa serotypes.
Main Methods:
- Phenotypic characterization of antibiotic resistance patterns for 35 multi-resistant P. aeruginosa isolates.
- Plasmid DNA extraction and analysis using gel electrophoresis to determine size and quantity.
- Conjugal transfer experiments using a rifampicin and ciprofloxacin-resistant P. aeruginosa recipient strain.
- Restriction analysis to assess homology between plasmids.
Main Results:
- The majority (80%) of isolates belonged to serotype 0:12 and exhibited diverse resistance phenotypes.
- Ten isolates contained plasmids ranging from 20 to 100 Mda; 100 Mda plasmids were most common.
- Conjugal transfer of high-level gentamicin and tobramycin resistance was achieved via 100 Mda plasmids, which showed homology.
- The 25 Mda plasmid was associated with serotype 0:6, while other plasmids were found in serotype 0:12 strains.
Conclusions:
- Plasmid content analysis, particularly of large plasmids, is valuable for understanding antibiotic resistance mechanisms in P. aeruginosa.
- Specific plasmid profiles, especially those of 100 Mda, are linked to high-level resistance to gentamicin and tobramycin.
- Resistance phenotypes and plasmid profiles can aid in the subtyping and epidemiological tracking of multi-resistant P. aeruginosa, particularly serotype 0:12.