Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada.
PLoS One. 2023 Aug 10;18(8):e0289703. doi: 10.1371/journal.pone.0289703. eCollection 2023.
Proteus mirabilis is an opportunistic pathogen associated with a variety of human infections, including urinary tract infections. The prevalence of P. mirabilis in foods of animal origin and in the manure by-products created in animal production is not well documented. Further, the prevalence and persistence of extended-spectrum cephalosporin (ESC) resistant P. mirabilis is largely unknown. In this study, we characterized ESC-resistant P. mirabilis recovered from various stages of dairy manure anaerobic digestion. Isolates were screened by PCR for blaCTX-M, blaCMY and blaSHV, and antimicrobial susceptibility testing was performed. Fifty-six P. mirabilis carrying CTX-M were sequenced with short and long read sequencing technologies, and the assembled chromosomes and plasmids were compared. ESC-resistant Proteus was found in four of the six manure digesters, an indication that not all digesters were colonized with resistant strains. Both CTX-M-1 and CTX-M-15 plasmids were found in P. mirabilis isolates. Transfer of plasmid DNA by conjugation was also explored, with ESC-resistance plasmids able to transfer to Escherichia coli at high frequency. We concluded that P. mirabilis can harbour and transfer ESC-resistance genes and plasmids, and may be an overlooked reservoir of antimicrobial resistance.
奇异变形杆菌是一种机会致病菌，与多种人类感染有关，包括尿路感染。奇异变形杆菌在动物源性食品和动物生产中产生的粪便副产品中的流行情况尚未得到很好的记录。此外，广泛耐药的头孢菌素（ESC）的奇异变形杆菌的流行和持续存在很大程度上是未知的。在这项研究中，我们从奶牛粪便厌氧消化的各个阶段中分离出了对 ESC 具有耐药性的奇异变形杆菌，并对其进行了鉴定。通过 PCR 对 blaCTX-M、blaCMY 和 blaSHV 进行了筛选，并进行了药敏试验。使用短读和长读测序技术对 56 株携带 CTX-M 的奇异变形杆菌进行了测序，并对组装的染色体和质粒进行了比较。在六个粪肥消化器中的四个中发现了耐 ESC 的变形杆菌，这表明并非所有消化器都被耐药菌株定植。在奇异变形杆菌分离物中发现了 CTX-M-1 和 CTX-M-15 两种质粒。通过接合转移质粒 DNA 的能力也得到了探索，发现 ESC 耐药质粒能够以高频率转移到大肠杆菌中。我们得出结论，奇异变形杆菌可以携带和转移 ESC 耐药基因和质粒，可能是一种被忽视的抗生素耐药性库。
