Abstract：
The genetic basis for the spread of vancomycin resistance in Enterococcus faecium is largely unexplored in India. The present study aimed to investigate the plasmid diversity and variation of Tn1546 associated with vanA harbouring VREfm isolates.
A total of 122 VREfm isolates collected from blood cultures were included in this study. MLST analysis was performed on all isolates, and they were also screened for the presence of vanA and vanB genes. Whole genome sequencing was performed for a subset of fifteen VREfm isolates belonging to ST1643.
All of the 122 VREfm isolates carried the vanA gene. Twenty-four different sequence types were seen; of these, ST1643, ST80 and ST17 were predominant. Whole genome sequencing was performed on 15 VREfm isolates belonging to ST1643. For eight isolates the vanA gene was found on pRUM-like circular plasmids, and for the remaining seven isolates, the vanA gene was found on the linear plasmids. Novel Tn1546 variants carrying vanA were found on both circular and linear plasmids. Interestingly, co-presence of vanA and optrA were seen in the backbone of three linear plasmids.
Multiple vanA-carrying plasmids and Tn1546-like elements were involved in the dissemination of vancomycin resistance in VREfm. The co-occurrence of Tn1546 carrying vanA and Tn554 family transposon carrying optrA on the backbone of plasmids is worrisome. The dissemination of such plasmids may pose treatment and infection control challenges.
A total of 122 VREfm isolates collected from blood cultures were included in this study. MLST analysis was performed on all isolates, and they were also screened for the presence of vanA and vanB genes. Whole genome sequencing was performed for a subset of fifteen VREfm isolates belonging to ST1643.
All of the 122 VREfm isolates carried the vanA gene. Twenty-four different sequence types were seen; of these, ST1643, ST80 and ST17 were predominant. Whole genome sequencing was performed on 15 VREfm isolates belonging to ST1643. For eight isolates the vanA gene was found on pRUM-like circular plasmids, and for the remaining seven isolates, the vanA gene was found on the linear plasmids. Novel Tn1546 variants carrying vanA were found on both circular and linear plasmids. Interestingly, co-presence of vanA and optrA were seen in the backbone of three linear plasmids.
Multiple vanA-carrying plasmids and Tn1546-like elements were involved in the dissemination of vancomycin resistance in VREfm. The co-occurrence of Tn1546 carrying vanA and Tn554 family transposon carrying optrA on the backbone of plasmids is worrisome. The dissemination of such plasmids may pose treatment and infection control challenges.
摘要：
在印度，万古霉素耐药性在屎肠球菌中传播的遗传基础尚未得到探索。本研究旨在研究与VREfm分离株vanA相关的Tn1546的质粒多样性和变异。
本研究包括从血液培养物收集的总共122个VREfm分离株。对所有分离株进行MLST分析，他们还对vanA和vanB基因进行了筛选。对属于ST1643的15个VREfm分离株的子集进行全基因组测序。
所有122个VREfm分离株都携带vanA基因。发现了24种不同的序列类型；其中，以ST1643、ST80和ST17为主。对属于ST1643的15个VREfm分离株进行全基因组测序。对于八个分离株，在pRUM样环状质粒上发现了vanA基因，剩下的七个分离株，在线性质粒上发现了vanA基因。在圆形和线性质粒上都发现了携带vanA的新型Tn1546变体。有趣的是,在三个线性质粒的主链中观察到vanA和optrA共存。
多个携带vanA的质粒和Tn1546样元件参与了VREfm中万古霉素抗性的传播。在质粒骨架上携带vanA的Tn1546和携带optrA的Tn554家族转座子的同时出现令人担忧。此类质粒的传播可能带来治疗和感染控制挑战。
本研究包括从血液培养物收集的总共122个VREfm分离株。对所有分离株进行MLST分析，他们还对vanA和vanB基因进行了筛选。对属于ST1643的15个VREfm分离株的子集进行全基因组测序。
所有122个VREfm分离株都携带vanA基因。发现了24种不同的序列类型；其中，以ST1643、ST80和ST17为主。对属于ST1643的15个VREfm分离株进行全基因组测序。对于八个分离株，在pRUM样环状质粒上发现了vanA基因，剩下的七个分离株，在线性质粒上发现了vanA基因。在圆形和线性质粒上都发现了携带vanA的新型Tn1546变体。有趣的是,在三个线性质粒的主链中观察到vanA和optrA共存。
多个携带vanA的质粒和Tn1546样元件参与了VREfm中万古霉素抗性的传播。在质粒骨架上携带vanA的Tn1546和携带optrA的Tn554家族转座子的同时出现令人担忧。此类质粒的传播可能带来治疗和感染控制挑战。
