Objectives

Our primary objective was to determine the effectiveness of an enhanced disinfection strategy, a disinfection cabinet using Ultraviolet C (UV-C) and 6% nebulized hydrogen peroxide by volume, on frequently used and difficult-to-dinfect PT equipment. Our secondary objective was to describe and characterize the contamination of frequently used PT equipment after undergoing standard disinfection.

Patient consent statement

This study was reviewed by the Duke University Health System Institutional Review Board and received an “exempt” status.

Study setting

We completed a microbiological analysis of and randomized controlled trial involving equipment used in adult or pediatric PT at Duke University Health System, Durham, NC.

Study protocol

Our study involved two phases. First, we evaluated baseline contamination present on used physical therapy equipment following standard disinfection. Second, we performed a randomized controlled trial to compare residual contamination of equipment for a novel disinfection strategy compared to standard disinfection. Standard disinfection was defined as the use of a disinfectant wipe on fomites following PT patient treatment: Oxivir Tb wipes (Diversey, Fort Mill, NC, USA) for patients on contact precautions and the Sani-Cloth for all others (PDI, Woodcliff Lake, NJ, USA). For both phases, physical therapy equipment, hereafter “study fomites,” was obtained from PT staff returning from patient treatment in an inpatient unit and split into two symmetric halves, left and right, for sampling. Clinical data was collected from the corresponding patient for fomites that were used on a single patient since the fomites last disinfection. Clinical data was not collected on some fomites as they were used unit-wide since the fomites last disinfection, such as walkers, since they were not linked to a specific patient.

During the trial, study fomite sides were randomized 1:1 to intervention and control. Standard disinfection was not completed before sampling. For each piece of equipment, the control fomite side was sampled before intervention exposure. The fomite then underwent the intervention and was disinfected using the standard disinfection cycle of the PURitALL 3030L disinfection cabinet. The PURitALL 3030L utilizes UV-C in combination with 6% nebulized hydrogen peroxide by volume inside a stainless-steel casing for disinfection over the course of an estimated 15-to-20-minute runtime. The intervention fomite side was then sampled after the intervention exposure. The above approach allowed us to evaluate three sets of data: prior to any disinfection (Phase 2 control), following standard disinfection (Phase 1 “baseline”), and following the intervention (Phase 2 intervention) (Figure 1).

Figure 1. Study workflow and comparisons.

Microbiological methods

Samples were taken with premoistened cellulose sponges and processed using the stomacher technique. ¹¹ Sponges were placed in stomacher bags with 45 mL phosphate-buffered saline with 1% Tween 20 and homogenized for 60 seconds at 260 revolutions per minute (RPM). Homogenates were then centrifuged at 3200 RPM for 15 minutes, and all but approximately 5 mL of the resulting supernatant was discarded. Then, each sample’s volume was measured to control for variability and rehomogenized via vortex. A total of 200 μL of the final homogenate was plated onto study media and incubated at 37°C for 24 hours. ^{Reference Warren, Barrett, Graves, King, Turner and Anderson5} Homogenates were plated on Trypticase soy agar with 5% sheep’s blood for general bioburden, Bile-esculin agar for Enterococcus spp., Mannitol salt for S. aureus, and MacConkey agar for Gram-negative species. Gram-negative isolates were speciated with 16S rRNA gene sequencing and were assessed for carbapenemase gene presence via polyemerase chain reaction (PCR) with primers designed for Klebsiella Pneumoniae Carbapenemase (KPC), New Delhi metallo-beta-lactamase 1 (NDM-1), OXA-48, IMP, and VIM. ^{Reference Solanki, Vanjari, Subramanian, Aparna, Nagapriyanka and Lakshmi12–Reference Srinivasan, Karaoz and Volegova14}

We defined clinically important pathogens (CIPs) as S. aureus (methicillin-resistant S. aureus [MRSA] or methicillin-sensitive S. aureus), Enterococci spp. (vancomycin-resistant Enterococcus [VRE] or vancomycin-sensitive Enterococcus), Acinetobacter spp., Pseudomonas spp., and Enterobacterales of interest such as Escherichia coli and Klebsiella spp. We defined antimicrobial-resistant clinically important pathogens (AMR CIP) as MRSA, VRE, and Multidrug resistant (MDR)-Gram-negatives and non-AMR CIP as methicillin-sensitive staphylococcus aureus (MSSA), Vancomycin sensitive Enterococcus (VSE), and Gram-negative species. Study fomites were grouped as 1) walking aids (walkers or canes), 2) pediatric toys, 3) balls (medicine, dodge, etc.), and 4) other (Foam roller, sliding board, etc.).

Outcomes

The primary outcome is the amount of bioburden, measured in colony-forming units (CFUs), on intervention sides of fomites in phase 2. Our secondary outcomes were the bioburden on fomites following standard disinfection and the proportion of samples positive for CIPs. Outcomes were compared between left and right fomite sides for standard disinfection measurements and control and intervention sides for intervention measurements.

Data analysis

The Wilcoxon ranked sum test was used to compare CFU measurements and the Z score proportionality test was used to compare proportions of samples with CIPs. P < .05 was considered significant, all statistical tests were 2-tailed, and all testing was completed using R software (R Foundation for Statistical Computing, Vienna, Austria).