Multidrug-resistant Klebsiella pneumoniae in a pediatric ICU: Emergence of newly identified ST7120 and the first report of ST792 in Taiwan

Multidrug-resistant (MDR) Klebsiella pneumoniae outbreaks in pediatric intensive care units (PICUs) pose serious risks to vulnerable patients. We report a one-year clustering of MDR K. pneumoniae in a PICU, along with the genetic relatedness, antimicrobial resistance profiles, and resistance mechanisms of the isolates. We investigated a one-year clustering of MDR K. pneumoniae in a 14-bed PICU from September 2021 to August 2022. Selected clinical isolates underwent pulsed-field gel electrophoresis, multilocus sequence typing, and resistance gene detection. Patient location and transfer records were reviewed to infer possible transmission pathways. Twenty K. pneumoniae isolates from 12 patients, including 10 preterm infants, were obtained and classified into six sequence types. Two predominant sequence types (STs) were identified: ST792 (CTX-M-14, SHV-12), not previously reported in Taiwan, and the newly identified ST7120 (CTX-M-15, SHV-11, TEM-1). The cluster exhibited two temporal peaks, driven by different STs. During the second peak, up to three STs circulated simultaneously. One patient carried both ST792 and ST7120, suggesting coinfection or sequential acquisition. Three invasive infections occurred, two with carbapenem-resistant ST7120 (including one fatal case) and one with extended-spectrum β-lactamase-producing ST792, which had severe neurologic sequelae. This MDR K. pneumoniae cluster involved a newly identified ST , ST7120, and the first reported case of ST792 in Taiwan, both were associated with prolonged colonization and invasive disease . Molecular typing revealed complex transmission routes not detectable through phenotypic methods alone. Integrating molecular epidemiology into routine MDRO surveillance could improve early outbreak detection and containment. • One-year MDR K. pneumoniae cluster in a pediatric ICU. • First report of ST792 in Taiwan and a newly assigned ST7120. • Molecular typing revealed complex transmission routes not detected phenotypically. • ST792 and ST7120 were repeatedly detected; invasive infections occurred. • Findings support integrating molecular epidemiology into routine MDRO surveillance.