Introduction
Environmental services (EVS) and infection prevention personnel consider factors such as efficacy, wet-contact and kill times, safety, ease of use, and cost when selecting cleaning and disinfection products. Reference Donskey1,Reference Rutala and Weber2 Many products are distributed as a concentrate that is diluted to in-use concentrations. The use of dilutable products may reduce costs and can be beneficial for disinfectants that are more stable as a concentrate than at in-use concentrations. Reference Deshpande and Mana3,Reference Cadnum, Jencson, O’Donnell, Flannery, Nerandzic and Donskey4
Dilutable disinfectants are often dispensed from automated wall-mounted systems that mix concentrated disinfectant and water. Reference Boyce5 However, monitoring is required to ensure that the dispensers are working correctly. Boyce et al. Reference Boyce, Sullivan, Booker and Baker6 found variations in the concentration of a dilutable quaternary ammonium disinfectant delivered by an automated dispenser; the issues were resolved after installation of water-pressure regulators and modifications of the flow-control devices in concentrate containers. It was recommended that hospitals utilizing dispensing stations conduct periodic testing to verify that appropriate concentrations are being dispensed. Reference Boyce, Sullivan, Booker and Baker6 Others have demonstrated that automated systems sometimes deliver lower-than-predicted disinfectant concentrations. Reference O’Neill, Ramage, Wyatt and Ballantyne7 In a culture survey, we found high rates of surface contamination after completion of post-discharge cleaning and disinfection in some hospitals using automated dispensers. Therefore, we conducted an evaluation of automated dispensing systems in several hospitals.
Methods
The study protocol was approved by the Cleveland VA Medical Center’s Research and Development Committee. We conducted a point-prevalence evaluation of automated disinfectant dispensing systems in a convenience sample of 10 hospitals from 4 healthcare systems in 5 states. For a minimum of 5 medical-surgical wards and/or intensive care units, we collected 10 mL disinfectant samples from dispensers and buckets of in-use disinfectant. The disinfectants included quaternary ammonium disinfectant cleaners (Virex Plus, Diversey, Fort Mill, SC; 3M HB Quat Disinfectant Cleaner Concentrate, 3M, St. Paul, MN), and a peracetic acid/hydrogen peroxide product (OxyCide Daily Disinfectant Cleaner, Ecolab, St. Paul, MN).
For the peracetic acid product, pH was measured with Micro Essential Lab Single-Roll Hydrion pH Test Paper (Fisher Scientific). Peracetic acid concentrations were also measured using a dropper-bottle method (Peracetic Acid Test Kit, LaMotte, Chestertown, MD) with a lower limit-of-detection of 300 ppm. The expected in-use concentration of peracetic acid is ∼1300 ppm (0.13%) with pH ∼3; 8 samples with >1,800 ppm were considered to have higher-than-expected concentrations. For the peracetic acid product, the manufacturer recommends quarterly calibration of the systems and provides posters with user instructions (Supplementary material). The instructions include guidance to check a Green/Red low product indicator for when the concentrate bottle should be changed (i.e., change when indicator window shows three-fourths red) and an optional intermittent pH check. For the quaternary ammonium disinfectants, quaternary ammonium concentrations were measured using Micro Essential Lab Hydrion Quaternary Test Paper Kits (Fisher Scientific, Hampton, NH); the expected in-use concentrations of the products are ∼700–800 parts per million (ppm) with pH 8–9. Reference Boyce, Sullivan, Booker and Baker6
To assess the efficacy of samples with lower-than-expected disinfectant levels, the American Society for Testing and Materials (ASTM) standard quantitative carrier disk test method was used with 5% fetal calf serum as soil load. 9 The test organisms included a clinical methicillin-resistant Staphylococcus aureus (MRSA) strain for the quaternary ammonium product and Clostridioides difficile American Type Culture Collection strain 43598 for the peracetic acid product. The exposure times were 5 and 10 minutes for the peracetic acid and quaternary ammonium disinfectants, respectively.
For one hospital using the quaternary ammonium product, additional point-prevalence evaluations were conducted after EVS implemented interventions that included increased monitoring of quaternary ammonium concentrations of dispensed product. The supplementary material provides details on the intervention.
Results
None of the hospitals reported conducting routine monitoring of disinfectant dispensers. Nine of 10 (90%) hospitals had 1 or more systems dispensing lower-than-expected disinfectant concentrations, and 8 (80%) had dispensers that delivered product with no detectable disinfectant (Table 1). Overall, 29 of 107 (27.1%) systems dispensed product with lower-than-expected concentrations, including 15 (14.0%) with no detectable disinfectant.
Table 1. Concentrations of disinfectant measured in samples obtained from automated dispensers and from in-use buckets on environmental services carts in 6 hospitals
QA, quaternary ammonium disinfectant; PA, peracetic acid-based disinfectant; ND, no data.
a Expected concentrations, ∼1,300 parts per million (PPM) for PA and ∼800 PPM for QA; higher-than-expected concentration of peracetic acid, >1,800 ppm.
b Lower than expected concentration, 300–900 PPM for PA and 200–400 PPM for QA.
c No disinfectant detected, limit of detection (∼300 PPM for PA and ∼150 PPM for QA).
d Wrong product, the in-use product that was supposed to be PA or QA was a detergent used for floors.
e For the one facility (hospital 5) that had only expected concentrations of disinfectant, the dispenser was a 3M Flow Control Chemical Management System (3M, St. Paul, MN); the dispensers used by the other hospitals were either J fill Quattro Select Dispensing Systems (Diversey, Fort Mill, SC) OxyCide Dilution Management Systems (Ecolab, St. Paul, MN).
Of 45 samples of peracetic acid product, 26 (57.8%) had higher-than-expected peracetic acid concentrations (≥1800 ppm; peak 2,100 ppm), 9 (20.0) had expected concentrations (1,200–1,500 ppm), 4 (8.9%) had lower-than-expected concentrations (300–900 ppm), and 6 (13.3%) had undetectable concentrations. pH measurements distinguished dispensers with expected or higher-than-expected peracetic acid disinfectant concentrations (pH ∼3) versus those with lower-than-expected concentrations (pH 3.5–5.0) versus no detectable disinfectant (pH ∼6.0).
Table 2 shows reasons for malfunction of the 15 systems that dispensed undetectable levels of disinfectant. The identified reasons included concentrate container not being connected correctly (n = 7), concentrate container top being damaged (n = 3), low product indicator not functioning correctly resulting in use of an empty concentrate container (n = 1), and personnel not changing the container when the low product indicator indicated that a change was due (n = 1). In 3 cases, the reason for the malfunction was not clear.
Table 2. Evaluation of potential reasons for malfunction of 15 automated dispensing systems that dispensed product with undetectable levels of disinfectant
QA, quaternary ammonium; PA, peracetic acid-based.
a Green/Red low product indicator indicates that a new container should be placed when the color window shows ≥75% red and ≤25% green.
b For all instances of damage to the container top, it was suspected that environmental services personnel had purposely manipulated the container in the belief that it would dispense a higher concentration of disinfectant and have greater efficacy.
Of 80 in-use disinfectant samples obtained from EVS carts, 27 (33.8%) had lower-than-expected disinfectant concentrations, including 14 (17.5%) with no detectable disinfectant. One sample with no detectable disinfectant was from a functioning dispenser but the environmental services worker acknowledged not obtaining fresh product for days. Of 9 employees using product with no detectable disinfectant who were interviewed, 3 had not noticed that the product was incorrect, whereas 6 noticed that the product did not smell or appear right but had not notified their supervisor. In 4 instances, in-use products that EVS personnel identified as disinfectants were dilutable detergents intended for floors.
ASTM testing demonstrated that samples with ≤900 ppm of peracetic acid and ≤400 ppm of quaternary ammonium disinfectant resulted in <3 log10 colony-forming unit reductions in C. difficile spores and MRSA, respectively.
For the hospital using the quaternary ammonium product that conducted an intervention, initial testing after the intervention demonstrated that 1 of 12 dispensers delivered no detectable disinfectant. However, in 2 subsequent assessments, product from all dispensers had the expected disinfectant concentrations.
Discussion
Regular monitoring is essential to ensure that automated disinfectant dispensing systems are functioning and being used correctly. Reference Boyce, Sullivan, Booker and Baker6,Reference O’Neill, Ramage, Wyatt and Ballantyne7 In the current study, 9 of 10 study hospitals had at least one dispenser delivering lower-than-expected disinfectant concentrations, and 14% of the dispensed product had no detectable disinfectant. Failure to dispense any disinfectant was usually attributable to human error (i.e., container not connected correctly or damaged, container not changed when indicated). However, in one instance the low product indicator did not function correctly resulting in dispensing product with no disinfectant and in three instances the reason for failure was unclear.
Our findings suggest that there is an urgent need for improved monitoring of automated disinfectant dispensers. Regular monitoring of pH or disinfectant concentrations might be helpful to ensure that dispensers are functioning and being used correctly. At a minimum, we recommend testing when a new container of concentrate is placed in the dispenser and if the dispensed product does not smell or appear appropriate.
For the peracetic acid product, 58% of systems dispensed higher-than-expected peracetic acid concentrations (≥1800 ppm). Others have reported that automated systems sometimes dispense higher-than-expected peracetic acid concentrations. Reference Hawley, Casey, Cummings, Edwards, Johnson and Cox-Ganser10 Additional evaluations are needed to assess whether the higher-than-expected concentrations pose a risk to EVS personnel. Reference Hawley, Casey, Cummings, Edwards, Johnson and Cox-Ganser10
Our study has some limitations. Only 10 hospitals were included and not all dispensers were tested. The effect of an intervention that included monitoring was only assessed in 1 facility. Additional studies are needed to identify effective approaches to ensure that dispensers function correctly and are monitored regularly.
Supplementary material
The supplementary material for this article can be found at https://doi.org/10.1017/ice.2024.148.
Acknowledgments
We thank the Environmental Management Services team at the Louis Stokes Cleveland VA Medical Center for helpful discussions and for assistance with the intervention.
Financial support
Supported by the Department of Veterans Affairs.
Competing interests
C.J.D has received research grants from Clorox and Pfizer. All other authors report no conflicts of interest relevant to this article.
