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Published on: September 5, 2013
The novel macrolide resistance genes mef(F) and msr(G) are located on a plasmid in Macrococcus canis and a transposon
Javier Eduardo Fernandez1, Vincent Perreten1, Sybille Schwendener1
1Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
Objectives:
To analyse macrolide resistance in a Macrococcus canis strain isolated from a dog with an ear infection, and determine whether the resistance mechanism is also present in other bacteria, and associated with mobile genetic elements.
Methods:
The whole genome of M. canis Epi0082 was sequenced using PacBio and Illumina technologies. Novel macrolide resistance determinants were identified through bioinformatic analysis, and functionality was demonstrated by expression in Staphylococcus aureus. Mobile genetic elements containing the novel genes were analysed in silico for strain Epi0082 as well as in other bacterial strains deposited in GenBank.
Results:
M. canis Epi0082 contained a 3212 bp operon with the novel macrolide resistance genes mef(F) and msr(G) encoding a efflux protein and an ABC-F ribosomal protection protein, respectively. Cloning in S. aureus confirmed that both genes individually confer resistance to the 14- and 15-membered ring macrolides erythromycin and azithromycin, but not the 16-membered ring macrolide tylosin. A reduced susceptibility to the streptogramin B pristinamycin IA was additionally observed when msr(G) was expressed in S. aureus under erythromycin induction. Epi0082 carried the mef(F)-msr(G) operon together with the chloramphenicol resistance gene fexB in a novel 39 302 bp plasmid pMiCAN82a. The mef(F)-msr(G) operon was also found in macrolide-resistant Macrococcus caseolyticus strains in the GenBank database, but was situated in the chromosome as part of a novel 13 820 bp or 13 894 bp transposon Tn6776.
Conclusions:
The identification of mef(F) and msr(G) on different mobile genetic elements in Macrococcus species indicates that these genes hold potential for further dissemination of resistance to the clinically important macrolides in the bacterial population.
Insights
Novel macrolide resistance genes mef(F) and msr(G) were identified in a dog
Area of Science:
- Veterinary Microbiology
- Molecular Biology
- Antimicrobial Resistance
Background:
- Macrolide antibiotics are crucial for treating bacterial infections.
- Emerging resistance mechanisms in bacteria pose a significant threat to public health.
- Understanding resistance in companion animals is vital for One Health approaches.
Purpose of the Study:
- To investigate macrolide resistance in a Macrococcus canis strain from a canine ear infection.
- To identify novel resistance genes and their association with mobile genetic elements.
- To assess the potential for dissemination of these resistance mechanisms.
Main Methods:
- Whole genome sequencing of Macrococcus canis Epi0082 using PacBio and Illumina.
- Bioinformatic analysis to identify novel macrolide resistance determinants.
- Functional validation of resistance genes through expression in Staphylococcus aureus.
- In silico analysis of mobile genetic elements in M. canis and other bacterial strains.
Main Results:
- A novel operon containing mef(F) and msr(G) genes conferring resistance to erythromycin and azithromycin was identified in M. canis Epi0082.
- Both genes individually conferred macrolide resistance when expressed in S. aureus.
- The mef(F)-msr(G) operon was located on a plasmid (pMiCAN82a) along with a chloramphenicol resistance gene (fexB).
- The mef(F)-msr(G) operon was also found on transposons (Tn6776) in macrolide-resistant Macrococcus caseolyticus strains.
Conclusions:
- The novel macrolide resistance genes mef(F) and msr(G) have been identified in Macrococcus species.
- These genes are associated with mobile genetic elements (plasmids and transposons).
- The presence of these genes on mobile elements suggests a potential for widespread dissemination of macrolide resistance in bacterial populations.
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