Investigating the changing taxonomy and antimicrobial resistance of bacteria isolated from door handles in a new infectious disease ward pre- and post-patient admittance

Healthcare-associated infections (HAIs) are a significant burden to health systems, with antimicrobial resistance (AMR) further compounding the issue. The hospital environment plays a significant role in the development of HAIs, with microbial surveillance providing the foundation for interventions. We sampled 40 door handles at a newly built hospital prior to patients being admitted and then 6 and 12 months after this date. We utilized 16S rDNA sequencing to identify unique colonies, disc diffusion assays to assess the antibiotic resistance of Staphylococcus spp., and whole-genome sequenced (WGS) multidrug-resistant (MDR) isolates. Before patient admission, 43% of sites harbored Staphylococcus spp., increasing to 55% and 65% at six and 12 months, respectively, while Bacillus spp. saw a large increase from 3% to 68% and 85%, respectively. No ESKAPE pathogens were identified. Staphylococcus spp. showed relatively low resistance to all antibiotics except cefoxitin (56%) before patient admittance. Resistance was highest after 6 months of ward use, with an increase in isolates susceptible to all antibiotics after 12 months (11% and 54% susceptibility, respectively). However, MDR remained high. WGS revealed blaZ (25/26), and mecA (22/26) and aac6-aph2 (20/26) were the most abundant resistance genes. Two Staphylococcus hominis isolates identified at the first two time points, respectively, and three Staphylococcus epidermidis isolates identified at all three time points, respectively, were believed to be clonal. This study highlighted the prevalence of a resistant reservoir of bacteria recoverable on high-touch surfaces and the long-term persistence of Staphylococcus spp. first introduced prior to patient admission.