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Molecular distribution of ROB-1 beta-lactamase in Actinobacillus pleuropneumoniae
J M Juteau1, M Sirois, A A Medeiros
1Départment de Microbiologie, Faculté de Médecine, Université Laval, Québec, Canada.
Abstract:
The plasmid content and molecular distribution of the ROB-1 beta-lactamase was investigated in 31 swine isolates of Actinobacillus pleuropneumoniae. Three types of plasmid patterns were observed in ampicillin-resistant isolates: a predominant one consisting of 2.6-, 2.9-, and 5.0-kb plasmids and two other patterns consisting of 4.2- and 5.5-kb plasmids and of a 6.8-kb plasmid. Plasmid DNA preparations were hybridized with a blaROB-1 intragenic fragment from the Haemophilus influenzae Rrob plasmid. Positive hybridizations were observed with all ampicillin-resistant isolates. The blaROB-1 gene was found on 3 plasmids of 2.6, 5.5, and 6.8 kb. One swine isolate of Pasteurella multocida also had a 2.6-kb plasmid bearing blaROB-1. ROB-1 was confirmed in typical isolates by isoelectric focusing and blaROB-1 sequences were confirmed by polymerase chain reaction amplification with an intragenic set of primers. Plasmids bearing blaROB-1 were successfully electro-transformed in a susceptible A. pleuropneumoniae isolate. These results emphasize the importance of ROB-1 in A. pleuropneumoniae and identify a possible reservoir of beta-lactam resistance.
Insights
The ROB-1 beta-lactamase gene, conferring ampicillin resistance, was identified on plasmids in Actinobacillus pleuropneumoniae swine isolates. These findings highlight a potential reservoir for beta-lactam resistance in this species.
Area of Science:
- Veterinary Microbiology
- Molecular Biology
- Antimicrobial Resistance
Background:
- Actinobacillus pleuropneumoniae is a significant swine pathogen.
- Beta-lactamase enzymes, like ROB-1, are a major cause of antibiotic resistance.
- Understanding the genetic basis of resistance in animal pathogens is crucial for public health.
Purpose of the Study:
- To investigate the plasmid content and molecular distribution of the ROB-1 beta-lactamase in Actinobacillus pleuropneumoniae swine isolates.
- To determine the genetic location and characteristics of the blaROB-1 gene.
- To assess the potential for horizontal gene transfer of beta-lactam resistance.
Main Methods:
- Plasmid profiling of 31 Actinobacillus pleuropneumoniae swine isolates.
- Hybridization assays using a blaROB-1 intragenic fragment.
- Isoelectric focusing for ROB-1 confirmation.
- Polymerase chain reaction (PCR) amplification of blaROB-1 sequences.
- Electro-transformation of plasmids into susceptible isolates.
Main Results:
- Three plasmid patterns were observed in ampicillin-resistant isolates.
- The blaROB-1 gene was located on plasmids of 2.6, 5.5, and 6.8 kb.
- A 2.6-kb plasmid carrying blaROB-1 was also found in a Pasteurella multocida swine isolate.
- Transmissible plasmids carrying blaROB-1 were successfully introduced into susceptible A. pleuropneumoniae.
Conclusions:
- ROB-1 beta-lactamase is prevalent in Actinobacillus pleuropneumoniae swine isolates.
- Plasmids carrying the blaROB-1 gene are mobile and can be transferred between bacteria.
- These findings identify a potential reservoir and transmission route for beta-lactam resistance in swine.