Multidrug resistance genes are associated with a 42-kb island TGI1 carrying a complex class 1 integron in Trueperella pyogenes

Abstract Objectives This research was conducted to ascertain the context and location of the antibiotic resistance determinants in multiple antibiotic-resistant Trueperella pyogenes(T. pyogenes) isolate TP1. Methods The genome was sequenced using PacBio RS II and the filtered data were assembled using Canu. Sequences were annotated on the basis of ones in GenBank and the genomic island(GI) of the TP1 was predicted by IslandPath-DIMOB. Results TP1 as a multiple antibiotic-resistant isolate was recovered at Jilin province (China) in 2017 from dairy cow with pneumonia. TP1 exhibited resistance to aminoglycosides (gentamicin and amikacin), macrolides (erythromycin), lincosamides (clindamycin), sulfonamides (sulfamonomethoxine), tetracyclines (tetracycline and doxycycline) and chloramphenicols (chloramphenicol and florfenicol). An antibiotic-resistance gene clustered together with the aadB, aadA1, cmlA5 and cmlA6 resistance genes located on a 7-kilobase (kb) multidrug-resistance (MDR) region, constituting a complex class 1 integron. MDR region was located at the one end of 42-kb GI, and IS6100Δ1 mediated genetic rearrangement with the complex class 1 integron like SGI1 and formed a composite transposon. Furthermore, the tetW gene was located outside the 4 GIs consistent with tetracycline and doxycycline resistance. The ermD gene positioned in front-end of 42-kb GI played an important role in mediating acquired erythromycin and clindamycin resistance. Conclusions Multiple resistance genes are located in a complex class 1 integron within a 42-kb T. pyogenes genomic island (TGI1), leading TP1 multiple drug resistance. In comparison with SG1 families, TGI1 possesses versatile gene distribution and specific gene context for its upstream and downstream, and it represents a new lineage of genomic resistance islands.