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[Characteristics of the resistance of Pseudomonas aeruginosa plasmids]
Abstract:
A total of 503 clinical strains of Ps. aeruginosa isolated in hospitals of 4 towns in 1976 - 1978 were studied. It was shown that a significant number of the isolates were resistant to high concentrations of streptomycin (83.3 per cent), kanamycin (71 per cent), sulfanilamide (70.2 per cent) and mercuric chloride (61.6 per cent). Strains resistant to gentamicin (29.8 per cent) and carbenicillin (20.2 per cent) occurred comparatively rare. Resistance to polymyxin and rifampicin was recorded in 2 and 4 per cent f the isolates respectively. It was found that 77 per cent of the isolates could transfer on conjugation the resistance determinants to the polyauxotrophic strains of Ps. aeruginosa ML 4262 (PAO). 83 conjugative plasmids controlling resistance to streptomycin (85.5 per cent), tetracycline (20.5 per cent), chloramphenicol (30.1 per cent), gentamicin (18.0 per cent), kanamycin (7.2 per cent), carbenicillin (13.7 per cent), sulfanilamides (125.3 per cent), organic and inorganic mercury compounds, hydroxyanions of chromium, tellurium and boron and UV radiation were isolated. The frequency of the plasmid transfer ranged from 10(-1) to 10(-6) (per donor cell). 4 nonconjugative plasmids were isolated. 2 of them determined resistance to streptomycin and sulfanilamide and 2 resistance to streptomycin, sulfanilamide and carbenicillin. The molecular mass of the plasmids was within 5.5 to 280 Md. The majority of the conjugative plasmids were classified as belonging to the incompatibility group P-2, the others belonged to groups P-1, P-3, P-5 and P-7. The nonconjugatiplasmids belonged to the incompatibility group P-4.
Insights
High rates of antibiotic resistance in Pseudomonas aeruginosa strains were observed, with many strains transferring resistance genes via plasmids. This highlights the significant role of plasmids in spreading antimicrobial resistance.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen frequently isolated from hospital environments.
- Antimicrobial resistance in P. aeruginosa poses a significant threat to patient treatment.
- Understanding the mechanisms of resistance, particularly plasmid-mediated transfer, is crucial.
Purpose of the Study:
- To investigate the prevalence of antibiotic resistance in clinical P. aeruginosa isolates.
- To characterize the plasmids responsible for transferring resistance determinants.
- To determine the incompatibility groups of the isolated plasmids.
Main Methods:
- Isolation and characterization of 503 clinical P. aeruginosa strains.
- Antimicrobial susceptibility testing against various antibiotics and heavy metals.
- Conjugation experiments to assess the transfer of resistance determinants.
- Plasmid isolation, molecular mass determination, and incompatibility grouping.
Main Results:
- High resistance rates observed for streptomycin (83.3%), kanamycin (71%), sulfanilamide (70.2%), and mercuric chloride (61.6%).
- 77% of isolates transferred resistance determinants via conjugation.
- 83 conjugative plasmids conferring resistance to multiple agents (antibiotics, heavy metals, UV) were isolated, with molecular masses ranging from 5.5 to 280 Md.
- Majority of conjugative plasmids belonged to incompatibility group P-2.
Conclusions:
- Clinical P. aeruginosa strains exhibit widespread resistance to common antimicrobial agents.
- Conjugative plasmids play a significant role in the dissemination of antibiotic resistance in P. aeruginosa.
- Plasmid incompatibility grouping provides insights into their epidemiology and potential for co-selection.