Abstract
Trueperella pyogenes is an important opportunistic animal pathogen. Different antimicrobials, including aminoglycosides, are used to treat T. pyogenes infections. The aim of the present study was to evaluate aminoglycoside susceptibility and to detect aminoglycoside resistance determinants in 86 T. pyogenes isolates of different origin. Minimum inhibitory concentration of gentamicin, streptomycin, and kanamycin was determined using a standard broth microdilution method. Genetic elements associated with aminoglycoside resistance were investigated by PCR and DNA sequencing. All studied isolates were susceptible to gentamicin, but 32.6% and 11.6% of them were classified as resistant to streptomycin and kanamycin, respectively. A total of 30 (34.9%) isolates contained class 1 integrons. Class 1 integron gene cassettes carrying aminoglycoside resistance genes, aadA11 and aadA9, were found in seven and two isolates, respectively. Additionally, the aadA9 gene found in six isolates was not associated with mobile genetic elements. Moreover, other, not carried by gene cassettes, aminoglycoside resistance genes, strA-strB and aph(3’)-IIIa, were also detected. Most importantly, this is the first description of all reported genes in T. pyogenes. Nevertheless, the relevance of the resistance phenotype to genotype was not perfectly matched in 14 isolates. Therefore, further investigations are needed to fully explain aminoglycoside resistance mechanisms in T. pyogenes.
Highlights
Trueperella pyogenes is a Gram-positive, nonmotile, nonspore-forming, irregular rod
minimum inhibitory concentration (MIC) of tested aminoglycosides for all T. pyogenes isolates are presented in Table S1 of Supplementary Materials
Two T. pyogenes isolates from European bison were resistant to kanamycin, while the majority of them were susceptible to all tested aminoglycosides
Summary
Trueperella pyogenes (formerly Arcanobacterium pyogenes) is a Gram-positive, nonmotile, nonspore-forming, irregular rod. T. pyogenes can be pathogenic for both domestic and wild animals and causes different diseases, including mastitis, metritis, balanoposthitis, pneumonia, and abscesses in various organs and tissues [1,3,4,5]. Those infections are especially important in swine, cattle, and small ruminants, since they lead to serious economic losses [4,5,6,7,8]. Aminoglycosides, β-lactam antibiotics, tetracyclines, macrolides, and fluoroquinolones are antimicrobials commonly used to treat infections caused by different Actinomycetales, including T. pyogenes. It was found that in the T. pyogenes resistance to trimethoprim, chloramphenicol, aminoglycosides, and β-lactam antibiotics, integrons may play an essential role [5,7,15]
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