Aminoglycoside resistance of <i>Trueperella pyogenes</i> isolated from pigs in China

Abstract

We aimed to determine the resistance mechanisms of 27 T. pyogenes isolates from swine in the Jilin province of China. Drug sensitivity analysis indicated that most of the isolated strains were resistant to aminoglycosides. We investigated the genes involved in target alteration, drug inactivation, and increased efflux as potential resistance mechanisms. Two known aminoglycoside resistance genes (aphA1 and strB) were not found in the genomic DNA of any isolate. A 3-bp (CCC) deletion in one 16S rRNA operon was detected in all isolates, and efflux pumps were not active in the resistant group. Ultimately, genes encoding aminoglycoside-modifying enzymes carried by class 1 integrons were identified as the main cause of resistance to aminoglycosides in T. pyogenes.

New Determinants of Aminoglycoside Resistance and Their Association with the Class 1 Integron Gene Cassettes in Trueperella pyogenes

“…Other studies also showed a higher level of resistance to gentamicin in T. pyogenes bovine isolates [ 33 , 34 , 35 ]. Interestingly, a significantly high percentage of strains resistant to aminoglycosides, such as gentamicin (77.8%), kanamycin (77.8%), amikacin (74.1%), streptomycin (77.8%), and spectinomycin (63%), was reported in case of T. pyogenes isolated from pigs in China [ 15 , 36 ]. The similar observation was reported by Galán-Relaño et al for T. pyogenes swine isolates in Spain, characterized by high MICs of neomycin and streptomycin but low MICs of gentamicin and apramycin [ 37 ].…”

“…In this study, MIC breakpoints approved for Corynebacterium spp. and coryneforms [ 40 ] as well as the criteria previously used by Dong et al [ 15 ] were applied to interpret susceptibility testing results for gentamicin, streptomycin, and kanamycin, respectively. Our study provided new important data on MIC value ranges of gentamicin, streptomycin, and kanamycin determined for T. pyogenes isolates from livestock and wild animals.…”

“…Importantly, in most cases the integron-positive isolates were from small ruminant and swine origin. Similarly, a high prevalence (approximately 60%) of the class 1 integron was noted in strains isolated from pigs [ 15 ] and forest musk deer [ 7 ] in China. In contrast, Liu et al [ 5 ] reported a higher prevalence (50%) of the class 1 integrons among T. pyogenes bovine isolates also in China.…”

“…Two genes associated with the macrolide resistance, ermB and ermX , are carried by variable genetic elements in T. pyogenes , such as plasmids or transposons [ 13 , 14 ]. Additionally, it was found that in the T. pyogenes resistance to trimethoprim, chloramphenicol, aminoglycosides, and β-lactam antibiotics, integrons may also play an essential role [ 5 , 7 , 15 ].…”

“…[ 25 ], Streptococcus spp. [ 26 ], and T. pyogenes [ 5 , 7 , 15 ]. However, issues concerning transfer and dissemination of integrons between T. pyogenes and other bacteria, Gram-positive and Gram-negative, are still unclear and require further investigation.…”