Brilhante M, Perreten V, Donà V
Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland; Graduate School of Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland.
Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
Vet J. 2019 Feb;244:60-68. doi: 10.1016/j.tvjl.2018.12.015. Epub 2018 Dec 12.
Enterovirulent Escherichia coli infections cause significant losses in the pig industry. However, information about the structures of the virulence and multidrug resistance (MDR) plasmids harboured by these strains is sparse. In this study, we used whole-genome sequencing with PacBio and Illumina platforms to analyse the molecular features of the multidrug-resistant enterotoxigenic E. coli (ETEC) strain 14OD0056 and the multidrug-resistant hybrid Shiga toxin-producing/enterotoxigenic E. coli (STEC/ETEC) strain 15OD0495 isolated from diarrheic pigs in Switzerland. Strain 14OD0056 possessed three virulence plasmids similar to others previously found in ETEC strains, while 15OD0495 harboured a 119-kb multivirulence IncFII/IncX1 hybrid STEC/ETEC plasmid (p15ODTXV) that co-carried virulence genes of both ETEC and STEC pathotypes, confirming the key role of plasmids in the emergence of hybrid pathotypes. All resistance genes of 14OD0056 that conferred resistance to ampicillin (bla), gentamicin (aac(3)-IIa), kanamycin (aph(3')-Ia), sulfonamide (sul1 and sul2), streptomycin (aph(3″)-Ib, aph(6)-Id), tetracycline (tet(B)) and trimethoprim (dfrA1) were identified on a single 207-kb conjugative MDR plasmid of incompatibility group (Inc) IncHI1/IncFIA (p14ODMR). Strain 15OD0495 carried two antimicrobial resistance plasmids (p15ODAR and p15ODMR). The 99-kb IncI1 plasmid p15ODAR harboured only aminoglycoside resistance genes (aac(3)-IIa, aph(3″)-Ib, aph(6)-Id, aph(4)-Ia), whilst the 49-kb IncN MDR plasmid p15ODMR carried genes conferring resistance to ampicillin (bla), sulfonamide (sul2), streptomycin (aph(6)-Id), tetracycline (tet(A)) and trimethoprim (dfrA14). Filter mating assays showed that p14ODMR, p15ODMR and p15ODAR were conjugative at room temperature and 37°C. The co-localization of multiple resistance genes on MDR conjugative plasmids such as p14ODMR and p15ODMR poses the risk of simultaneous selection of several resistance traits during empirical treatment. Thus, preventive strategies and targeted therapy following antibiotic susceptibility testing should be encouraged to avoid further dissemination of such plasmids.
肠毒性大肠杆菌感染给养猪业造成了重大损失。然而，关于这些菌株所携带的毒力和多重耐药性（MDR）质粒结构的信息却很少。在本研究中，我们使用PacBio和Illumina平台进行全基因组测序，以分析从瑞士腹泻猪中分离出的多重耐药性产肠毒素大肠杆菌（ETEC）菌株14OD0056和多重耐药性产志贺毒素/产肠毒素大肠杆菌（STEC/ETEC）杂交菌株15OD0495的分子特征。菌株14OD0056拥有三个与先前在ETEC菌株中发现的其他质粒相似的毒力质粒，而15OD0495携带一个119 kb的多毒力IncFII/IncX1杂交STEC/ETEC质粒（p15ODTXV），该质粒同时携带ETEC和STEC两种致病型的毒力基因，证实了质粒在杂交致病型出现中的关键作用。14OD0056中所有赋予对氨苄青霉素（bla）、庆大霉素（aac(3)-IIa）、卡那霉素（aph(3')-Ia）、磺胺类药物（sul1和sul2）、链霉素（aph(3″)-Ib、aph(6)-Id）、四环素（tet(B)）和甲氧苄啶（dfrA1）耐药性的耐药基因都在一个单一的207 kb不相容群（Inc）IncHI1/IncFIA接合型MDR质粒（p14ODMR）上被鉴定出来。菌株15OD0495携带两个抗微生物耐药质粒（p15ODAR和p15ODMR）。99 kb的IncI1质粒p15ODAR仅携带氨基糖苷类耐药基因（aac(3)-IIa、aph(3″)-Ib、aph(6)-Id、aph(4)-Ia），而49 kb的IncN MDR质粒p15ODMR携带赋予对氨苄青霉素（bla）、磺胺类药物（sul2）、链霉素（aph(6)-Id）、四环素（tet(A)）和甲氧苄啶（dfrA14）耐药性的基因。滤膜交配试验表明，p14ODMR、p15ODMR和p15ODAR在室温及37°C下均可接合。诸如p14ODMR和p15ODMR等MDR接合型质粒上多个耐药基因的共定位，在经验性治疗期间存在同时选择多种耐药性状的风险。因此，应鼓励采取预防策略以及在抗生素敏感性试验后进行靶向治疗，以避免此类质粒的进一步传播。
