Clonal patient-to-patient spread is associated with multidrug-resistant Acinetobacter baumannii infections in a Chinese pediatric hospital: an integrated phenotype–genotype–PFGE surveillance study
Background Carbapenem-resistant Acinetobacter baumannii is a critical-priority pathogen in pediatric hospitals, but the relative roles of clonal transmission and environmental reservoirs remain unclear. Methods We analyzed 42 non-duplicate A. baumannii isolates collected between 2020 and 2023 from clinical specimens (n = 28), medical waste (n = 8), and hospital-setting samples (n = 6) at Wuhan Children’s Hospital. Antimicrobial susceptibility testing, PCR-based resistance gene detection, pulsed-field gel electrophoresis, and crystal-violet biofilm assays were performed. Results Clinical isolates showed high multidrug resistance (75.0%, 21/28), with 75.0% resistant to piperacillin–tazobactam, ceftazidime, imipenem, meropenem, and ciprofloxacin. All isolates remained susceptible to tigecycline. OXA-23 was detected in all carbapenem-resistant clinical isolates, and aac(6′)-Ib-cr was present in all fluoroquinolone-resistant isolates. One dominant clinical clone, T11, accounted for 57.1% of clinical isolates and included one OXA-23/NDM co-producing isolate. PFGE revealed no clonal overlap between clinical and non-clinical isolates; all medical-waste and hospital-setting isolates were fully susceptible. Biofilm formation was detected in 97.6% of isolates; among clinical isolates, biofilm intensity was inversely associated with multidrug resistance, with susceptible isolates forming stronger biofilm (Fisher’s exact p < 0.001). Conclusion Pediatric multidrug-resistant A. baumannii infections in this hospital were most consistent with patient-to-patient dissemination of a dominant resistant clone rather than with contamination from the hospital-setting or medical-waste reservoirs sampled here, although the small environmental sample cannot definitively exclude such reservoirs. Phenotype–genotype–PFGE surveillance provides actionable guidance for infection control in resource-limited pediatric settings.