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Transposon-mediated amikacin resistance in Klebsiella pneumoniae
M E Tolmasky1, R M Chamorro, J H Crosa
1Instituto de Investigaciones Bioquímicas Fundación Campomar, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina.
Abstract:
A multiresistant Klebsiella pneumoniae strain isolated from neonates in Mendoza, Argentina, harbored a 48-kilobase-pair (kbp) plasmid, pMET1, with genetic determinants for resistance to amikacin and also ampicillin, kanamycin, streptomycin, and tobramycin. This plasmid was compared with pJHCMW1, a previously isolated 11-kbp plasmid carrying transposon Tn1331, which encodes resistance to amikacin, as well as ampicillin, kanamycin, streptomycin, and tobramycin, and which was originally present in a K. pneumoniae strain that caused an outbreak in a hospital in Buenos Aires, Argentina. The comparison demonstrated that the replication regions of the two plasmids are unrelated. However, in pMET1 an 11-kbp transposition element, Tn1331.2, was identified; it was closely related to Tn1331, with the difference that a 3-kbp BamHI DNA fragment carrying the aminoglycoside resistance genes was duplicated in tandem.
Insights
A novel plasmid, pMET1, carrying multiple antibiotic resistance genes was identified in Klebsiella pneumoniae from neonates in Argentina. It contains a variant of transposon Tn1331 with duplicated aminoglycoside resistance genes.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Multiresistant Klebsiella pneumoniae poses a significant threat, particularly in neonatal intensive care units.
- Antibiotic resistance is often mediated by plasmids carrying mobile genetic elements like transposons.
- Previous outbreaks of K. pneumoniae in Argentina have been linked to specific resistance plasmids.
Purpose of the Study:
- To characterize the genetic elements responsible for multidrug resistance in a K. pneumoniae strain isolated from neonates in Mendoza, Argentina.
- To compare the novel plasmid with previously identified resistance plasmids from K. pneumoniae outbreaks in Argentina.
- To investigate the structure and origin of the resistance determinants within the novel plasmid.
Main Methods:
- Plasmid DNA isolation and characterization (e.g., size determination, restriction enzyme digestion).
- Comparison of plasmid sequences and genetic elements (e.g., transposons, resistance genes) using bioinformatics tools.
- Analysis of DNA fragments and gene organization using techniques like BamHI digestion.
Main Results:
- A 48-kbp plasmid, designated pMET1, was isolated from a multiresistant K. pneumoniae strain.
- pMET1 harbors genetic determinants for resistance to amikacin, ampicillin, kanamycin, streptomycin, and tobramycin.
- pMET1 contains an 11-kbp transposition element, Tn1331.2, closely related to Tn1331 but with a duplicated 3-kbp DNA fragment encoding aminoglycoside resistance genes.
- The replication regions of pMET1 and the previously studied pJHCMW1 plasmid are unrelated.
Conclusions:
- The emergence of pMET1 highlights the dynamic nature of plasmid evolution and the spread of antibiotic resistance in K. pneumoniae.
- The duplicated aminoglycoside resistance genes in Tn1331.2 may contribute to higher levels of resistance.
- Understanding the genetic makeup of such plasmids is crucial for developing effective strategies to control multidrug-resistant infections.