Prevalence of antimicrobial-resistant microorganisms in the NICU environments: Implications for neonatal health

The presence of antimicrobial-resistant microorganisms (AMRMs), particularly those exhibiting simultaneous resistance to disinfectants and antimicrobial drugs poses a significant challenge in neonatal intensive care units (NICUs). AMRMs compromise treatment efficacy, hinder infection prevention strategies and affect neonatal health outcomes. This work was performed to study the prevalence of AMRMs with co-selection mechanisms in NICU environments and their characteristics and to assess their potential implications for infant safety within the framework of the One Health approach.

A total of 32 samples from air, surfaces, and drinking water distribution system (DWDS) biofilms were collected from the NICUs of two major hospitals in Isfahan, Iran, and tested for bacterial and fungal presence and their resistance to antimicrobial drugs and disinfectants. Identification of AMRMs was then performed using Sanger sequencing.

Antibiotic-resistant bacteria (ARB) were detected in 44% of samples, with the highest occurrence in DWDS biofilms. Among the ARB isolates recovered from media containing a selective antibiotic, the highest resistance rate was observed against β-lactam antibiotics. All ARB from air and surface samples were resistant to at least four disinfectants and 50% of the DWDS isolates tolerated chlorine at 0.5 ppm for 30 min. Bacillus spp., Staphylococcus spp. and Brevundimonas spp. were the most frequently detected resistant bacteria. Opportunistic fungi were absent in air samples but frequently detected on exhaust vent surfaces (100%) and in DWDS biofilms (42%), showing high resistance to disinfectants despite low antifungal drug resistance.

The findings underscore the critical risk posed by AMRMs in NICUs and highlight the urgent need for comprehensive surveillance of antimicrobial resistance in these high-risk settings. Moreover, the results show the need for evidence-based selection and application of disinfectants to effectively eliminate resistant pathogens in clinical settings.