Molecular Epidemiology of tet(A)-v1-Positive Carbapenem-Resistant Klebsiella pneumoniae in Pediatric Patients in a Chinese Hospital

<b>Background:</b> The emergence and spread of the tigecycline resistance gene <i>tet</i>(A)-v1 in carbapenem-resistant <i>Klebsiella pneumoniae</i> (CRKP) poses significant public health challenges. However, the prevalence of <i>tet</i>(A)-v1-positive CRKP, especially in pediatric patients, remains poorly understood. This study aims to address the gap by performing an in-depth analysis of isolates collected from a children's hospital in China. <b>Methods</b>: A 4-year retrospective study was conducted in the children's hospital in Suzhou, China. Non-duplicated specimens were obtained from pediatric patients, and antimicrobial susceptibility profiles were assessed. Whole-genome sequencing and bioinformatics analyses were conducted to characterize the genetic background, antimicrobial resistance determinants, hypervirulence-associated genes, diversity of <i>tet</i>(A)-v1-carrying plasmids, the genetic environment of <i>tet</i>(A)-v1, and the potential for clonal transmission. Conjugative transferability of <i>tet</i>(A)-v1-carrying plasmids was also evaluated via conjugation assays. <b>Results</b>: Of the 73 <i>tet</i>(A)-v1-positive CRKP isolates from pediatric patients, 10.96% were non-susceptible to tigecycline. These isolates exhibited high genetic diversity, spanning across 13 STs (sequence types), with ST17 being predominant. Three carbapenemases were identified, with IMP being the most common. Isolates from diverse backgrounds, such as ST17, ST20, ST323, ST792, and ST3157, demonstrated evidence of clonal transmission. The <i>tet</i>(A)-v1 gene was located on 14 distinct plasmids across seven replicon types, with IncFIA/IncHI1 and IncFII being most commonly detected. All <i>tet</i>(A)-v1-carrying plasmids were multidrug-resistant, and 68.49% were conjugatively transferable, indicating a high potential for horizontal transfer. Four genetic contexts bordering <i>tet</i>(A)-v1 were identified, which points to active clonal dissemination. <b>Conclusions</b>: Although limited to a single hospital, this study represents one of the first in-depth investigations of <i>tet</i>(A)-v1-positive CRKP in pediatric patients, providing valuable insights into the prevalence and spread of <i>tet</i>(A)-v1 in this vulnerable group. These findings emphasize the urgent need for enhanced surveillance and infection control measures to curb the spread of <i>tet</i>(A)-v1-positive CRKP in pediatric healthcare environments, offering critical insights to mitigate its public health impact.