Targeted phage aerosol for environmental control of CR-Kpn in the ICU: a prospective intervention study

This study aimed to evaluate the effect of targeted Carbapenem-resistant Klebsiella pneumoniae (CR-Kpn) phage aerosol combined with routine disinfection on the decontamination of CR-Kpn in the ICU environment, as well as its incidence rate, drug resistance rate, and antibiotic use.

A prospective two-phase study design was adopted. During the baseline phase (P1), routine terminal disinfection with chlorine-containing agents was performed. In the intervention phase (P2), targeted phage aerosol spray was added to the isolation rooms of CR-Kpn patients. Multivariable models were fitted to isolate the intervention effect, adjusting for patient-days, imipenem use intensity, and carbapenem-resistant Acinetobacter baumannii (CRAB) incidence density. Outcomes including environmental CR-Kpn detection rate, incidence density, carbapenem resistance rate of K. pneumoniae, and antibiotic use intensity were compared between the two phases.

Following the combined intervention, the overall detection rate of CR-Kpn in the ICU environment decreased from 17.28% (47/272) to 0.96% (1/104), with the detection rate in sink drains dropping from 85.29% (29/34) to 7.69% (1/13). Clinical data showed that the incidence density of CR-Kpn significantly decreased from 10.16 cases/1,000 patient-days to 4.71 cases/1,000 patient-days (p = 0.007), whereas the incidence density of carbapenem-resistant A. baumannii (CRAB) increased significantly, suggesting the species-specificity of the intervention. Concurrently, the carbapenem resistance rate of K. pneumoniae decreased from 62.50 to 53.80%, and the use intensity of key antibiotics (tigecycline, polymyxin B, meropenem) significantly declined (reductions of 52.6, 58.5, and 36.6%, respectively; p < 0.01 for all).

The combination of phage aerosol and routine disinfection showed potential in controlling CR-Kpn contamination in the ICU environment, reducing its incidence and carbapenem resistance rate, and decreasing the use of related antibiotics. This approach may provide a safe and effective biological disinfection strategy for controlling the spread of CR-Kpn.