Hu Jiangang, Che Chuanyan, Jiang Wei, Chen Zhaoguo, Tu Jian, Han Xiangan, Qi Kezong
Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, Anhui Agricultural University, Hefei 230036, China.
Shanghai Veterinary Research Institute, The Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai 200241, China.
Vet Sci. 2022 Feb 23;9(3):98. doi: 10.3390/vetsci9030098.
Avian pathogenic Escherichia coli (APEC) is a causative agent of colibacillosis, one of the principal causes of morbidity and mortality in poultry worldwide. Nowadays, antibiotics are mainly used to prevent and control poultry colibacillosis, but the situation of drug resistance is serious. 5′-methylthioadenosine/S-adenosylhomocysteine nucleosidase (Pfs) is involved in methylation reactions, polyamine synthesis, vitamin synthesis, and quorum sensing (QS) pathways. In this study, compared with the APEC wild-type strain DE17, the pfs deletion strain DE17Δpfs was more susceptible to β-lactam antibiotics (amoxicillin, ceftazidime, cefuroxime) by drug sensitivity test and minimum inhibitory concentration (MIC), and the MIC of the DE17Δpfs was half that of the DE17. Quorum sensing signal molecule AI-2 is involved in antibiotic resistance. In the case of pfs inactivation, the DE17Δpfs cannot synthesize AI-2, so it is necessary to add AI-2 to study whether it affects APEC resistance. When the exogenous AI-2 was added, the MIC of all APEC did not change. Transcriptome sequencing indicated that the transcription levels of a lot of outer membrane protein genes and metabolic genes had changed due to the deletion of pfs. Moreover, the transcription levels of the efflux pump gene tolC and penicillin binding protein (fstI and mrcA) were significantly reduced (p < 0.05), while the transcription levels of the porin protein genes (ompF, ompC, and ompD) were significantly increased (p < 0.05). In addition, it was also found that the outer membrane permeability of the DE17Δpfs was significantly increased (p < 0.05). The results indicated that pfs does not affect APEC strain DE17 resistance to β-lactam antibiotics through AI-2, but pfs affects the sensitivity of APEC to β-lactam antibiotics by affecting antibiotic-related genes. This study can provide a reference for screening new drug targets.
禽致病性大肠杆菌（APEC）是禽大肠杆菌病的病原体，是全球家禽发病和死亡的主要原因之一。目前，抗生素主要用于预防和控制家禽大肠杆菌病，但耐药情况严重。5'-甲硫腺苷/S-腺苷同型半胱氨酸核苷酶（Pfs）参与甲基化反应、多胺合成、维生素合成和群体感应（QS）途径。在本研究中，通过药敏试验和最低抑菌浓度（MIC）测定，与APEC野生型菌株DE17相比，pfs缺失菌株DE17Δpfs对β-内酰胺类抗生素（阿莫西林、头孢他啶、头孢呋辛）更敏感，且DE17Δpfs的MIC是DE17的一半。群体感应信号分子AI-2参与抗生素耐药性。在pfs失活的情况下，DE17Δpfs无法合成AI-2，因此有必要添加AI-2来研究其是否影响APEC的耐药性。当添加外源性AI-2时，所有APEC的MIC均未改变。转录组测序表明，由于pfs缺失，许多外膜蛋白基因和代谢基因的转录水平发生了变化。此外，外排泵基因tolC和青霉素结合蛋白（fstI和mrcA）的转录水平显著降低（p<0.05），而孔蛋白基因（ompF、ompC和ompD）的转录水平显著升高（p<0.05）。此外，还发现DE17Δpfs的外膜通透性显著增加（p<0.05）。结果表明，pfs不通过AI-2影响APEC菌株DE17对β-内酰胺类抗生素的耐药性，但pfs通过影响抗生素相关基因来影响APEC对β-内酰胺类抗生素的敏感性。本研究可为筛选新的药物靶点提供参考。
