Liu Gang, Bogaj Karolina, Bortolaia Valeria, Olsen John Elmerdahl, Thomsen Line Elnif
Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
National Food Institute, Technical University of Denmark, Lyngby, Denmark.
Front Microbiol. 2019 Sep 10;10:2119. doi: 10.3389/fmicb.2019.02119. eCollection 2019.
Previously, we showed that cefotaxime (CTX) exposure increases conjugative transfer of a encoding IncI1 plasmid (IncI1/pST49/CTX-M-1) in in a SOS-independent manner. This study aimed at investigating whether the observation was unique for that plasmid/strain/antibiotic combination or whether antibiotic-induced plasmid transfer (PT) is a more general phenomenon among plasmids in . Whole genome sequences of 25 strains were analyzed to identify different extended spectrum beta-lactamases (ESBL) plasmids enabling selection of a diverse collection of plasmids. Experiments were performed following exposure of these strains to 1/2 minimal inhibitory concentration (MIC) of CTX, ampicillin (AMP), or ciprofloxacin (CIP) before conjugation experiments. The frequency of PT was measured and compared to that of donors not exposed to antibiotics. Reverse-transcribed-quantitative real time polymerase chain reaction (RT-qPCR) was used to measure mRNA levels of five PT genes and two SOS response genes in donors exposed to antibiotics. The PT of eight strains (30.8% of strains tested) with IncI1/pST7/CTX-M-1, IncI1/pST49/CTX-M-1, IncI1/pST3/CTX-M-1, IncI1/pST293/CTX-M-1, IncI1/pST295/CTX-M-1, IncI1/pST16/CTX-M-55, and IncFII/CTX-M-14 ( = 2) plasmids was significantly increased following antibiotic exposure. CTX increased PT in all of these eight strain/plasmid combinations, AMP and CIP increased the PT in six and three strains, respectively. RT-qPCR showed that PT genes were up-regulated in the presence of the three antibiotics, whereas SOS-response genes were up-regulated only following CIP exposure. Our findings reveal that antibiotics can increase PT in strains with various ESBL plasmids. Thus, antibiotic-induced conjugative transfer of ESBL plasmids appears to be a common phenomenon in , having important implications for assessing the risks of antibiotic use.
此前，我们发现头孢噻肟（CTX）暴露以不依赖SOS的方式增加了携带编码IncI1质粒（IncI1/pST49/CTX-M-1）的接合转移。本研究旨在调查这一观察结果是否仅针对该质粒/菌株/抗生素组合，或者抗生素诱导的质粒转移（PT）在大肠杆菌中的质粒中是否是一种更普遍的现象。分析了25株大肠杆菌的全基因组序列，以鉴定不同的超广谱β-内酰胺酶（ESBL）质粒，从而能够选择多种质粒。在进行接合实验之前，将这些菌株暴露于CTX、氨苄青霉素（AMP）或环丙沙星（CIP）的1/2最低抑菌浓度（MIC）下进行实验。测量PT频率并与未暴露于抗生素的供体进行比较。使用逆转录定量实时聚合酶链反应（RT-qPCR）测量暴露于抗生素的供体中五个PT基因和两个SOS反应基因的mRNA水平。携带IncI1/pST7/CTX-M-1、IncI1/pST49/CTX-M-1、IncI1/pST3/CTX-M-1、IncI1/pST293/CTX-M-1、IncI1/pST295/CTX-M-1、IncI1/pST16/CTX-M-55和IncFII/CTX-M-14（n = 2）质粒的8株菌株（占测试菌株的30.8%）在抗生素暴露后PT显著增加。CTX在所有这8种菌株/质粒组合中均增加了PT，AMP和CIP分别在6株和3株菌株中增加了PT。RT-qPCR表明，在三种抗生素存在下PT基因上调，而SOS反应基因仅在CIP暴露后上调。我们的研究结果表明，抗生素可增加携带各种ESBL质粒的大肠杆菌菌株中的PT。因此，抗生素诱导的ESBL质粒接合转移似乎在大肠杆菌中是一种常见现象，对评估抗生素使用风险具有重要意义。
