Kaldhone Pravin R, Carlton Ashlyn, Aljahdali Nesreen, Khajanchi Bijay K, Sanad Yasser M, Han Jing, Deck Joanna, Ricke Steven C, Foley Steven L
Division of Microbiology, U.S. Food and Drug Administration, National Center for Toxicological Research, Jefferson, AR, United States.
Center for Food Safety and Food Science Department, University of Arkansas, Fayetteville, AR, United States.
Front Vet Sci. 2019 Sep 6;6:298. doi: 10.3389/fvets.2019.00298. eCollection 2019.
Mobile genetic elements, such as plasmids, can potentially increase the ability of bacteria to infect and persist in vertebrate host cells. IncI1 plasmids are widely distributed in from food animal sources and associated with clinically important strains. These plasmids often encode antimicrobial resistance; however, little is known about their impact on the virulence of strains. To assess the potential impact of the plasmids on virulence, 43 IncI1-positive isolates from human and animal sources were subjected to whole genome sequence (WGS) analyses and evaluated for their abilities to invade and persist for 48 h in Caco-2 human intestinal epithelial cells, form biofilms and encode bacteriocins. Draft WGS data were submitted to predict the presence of virulence and antimicrobial resistance genes, plasmid replicon types present, conduct plasmid multilocus sequence typing (pMLST), and core genome MLST (cgMLST) in the isolates. Caco-2 cells were infected with strains and incubated for both one and 48 h for the invasion and persistence assays, respectively. Additionally, isolates and IncI1 plasmid carrying transconjugants ( = 12) generated in were assessed for their ability to produce biofilms and bacteriocin inhibition of growth of other bacteria. All isolates infected Caco-2 cells and persisted in the cells at 48 hrs. Persistent cell counts were observed to be significantly higher than invasion assay cell counts in 26% of the isolates. Among the IncI1 plasmids, there were 18 pMLST types. Nearly 35% ( = 15) of isolates produced biofilms; however, none of the IncI1-positive transconjugants produced increased biofilms compared to the recipient. Approximately 65% ( = 28) of isolates and 67% ( = 8) of IncI1-positive transconjugants were able to inhibit growth of at least one strain; however, none inhibited the growth of strains from species other than . The study characterized IncI1 positive isolates and provided evidence about the potential contributions of IncI1 plasmids virulence phenotypes and areas where they do not. These findings should allow for more focused efforts to assess the impact of plasmids on bacterial pathophysiology and human health.
移动遗传元件，如质粒，可能会增强细菌感染脊椎动物宿主细胞并在其中持续存在的能力。IncI1质粒广泛分布于来自食用动物源的细菌中，并与具有临床重要性的菌株相关。这些质粒通常编码抗菌抗性；然而，关于它们对菌株毒力的影响知之甚少。为了评估质粒对毒力的潜在影响，对43株来自人和动物源的IncI1阳性大肠杆菌分离株进行了全基因组序列（WGS）分析，并评估了它们侵入Caco-2人肠上皮细胞并在其中持续48小时的能力、形成生物膜的能力以及编码细菌素的能力。提交了WGS草图数据以预测毒力和抗菌抗性基因的存在、所存在的质粒复制子类型、进行质粒多位点序列分型（pMLST）以及分离株中的核心基因组MLST（cgMLST）。用大肠杆菌分离株感染Caco-2细胞，并分别在1小时和48小时进行侵入和持续存在试验。此外，评估了大肠杆菌分离株和在大肠杆菌中产生的携带IncI1质粒的转接合子（n = 12）形成生物膜的能力以及细菌素对其他细菌生长的抑制作用。所有大肠杆菌分离株均感染了Caco-2细胞并在48小时时在细胞中持续存在。在26%的分离株中观察到持续存在的细胞计数显著高于侵入试验细胞计数。在IncI1质粒中，有18种pMLST类型。近35%（n = 15）的大肠杆菌分离株形成了生物膜；然而，与受体相比，IncI1阳性转接合子均未产生更多的生物膜。约65%（n = 28）的分离株和67%（n = 8）的IncI1阳性转接合子能够抑制至少一种大肠杆菌菌株的生长；然而，没有一种能抑制除大肠杆菌以外其他物种菌株的生长。该研究对IncI1阳性大肠杆菌分离株进行了表征，并提供了有关IncI1质粒对毒力表型潜在贡献以及它们没有贡献的领域的证据。这些发现应有助于更有针对性地评估质粒对细菌病理生理学和人类健康的影响。
