<b>Tight linkage between the SOS response and horizontal transfer of </b><b><i>bla</i></b>_{<strong>NDM</strong>}<b>-carrying IncX3 plasmid in Carbapenem-resistant </b><b><i>Enterobacteriaceae</i></b>

<p dir="ltr">The rapid dissemination of the <i>bla</i>_NDM gene among<i> Enterobacteriaceae</i> in children has become a prominent public health concern in the pediatric population. <i>bla</i>_NDM is mainly located on IncX3 and can be horizontally transferred across different bacterial species via conjugation. The SOS response can promote plasmid conjugation, thereby facilitating the plasmid-mediated transfer of antimicrobial resistance genes. However, it remains unclear whether, and if so, how the SOS response participates in the spread of <i>bla</i>_NDM mediated by IncX3 plasmids (<i>bla</i>_NDM-IncX3).</p><p dir="ltr">Herein, we collected a total of 250 clinical CRE strains from Children’s Hospital of Fudan University, and retrieved 4210 carbapenemase gene-carrying plasmids and 1780 publicly available IncX3 plasmids from public databases. After confirmation the close linkage between <i>bla</i>_NDM and IncX3 plasmids, we found<i> bla</i>_NDM-IncX3 plasmids specifically express the SOS-promoting<i> </i>factors including <i>stpA</i>,<i> rfaH</i>, <i>pir</i>, <i>bin3</i>, <i>virD4</i>,<i> </i>and<i> virB1-11</i>, while lacked the anti-SOS genes such as <i>psiB</i>, <i>ssb,</i> and<i> spo0C</i>. These findings reveal a compelling genetic basis: <i>bla</i>_NDM-IncX3 plasmids are enriched in SOS-promoting factors but deficient in SOS inhibitors, indicating that an enhanced SOS response may contribute to their successful dissemination.</p>