Evidence Map and Systematic Review of Disinfection Efficacy on Environmental Surfaces in Healthcare Facilities

Efficacy of Antimicrobial Dry Fog in Improving the Environmental Microbial Burden in an Inpatient Ward

Background/Objectives: In healthcare environments with high microbial loads, effective infection control measures are critical for reducing airborne and surface contamination. One of the novel modalities in the achievement of these goals is the use of antimicrobial mists, such as droplets, in the form of dry fog. Although the usage of dry fog in the disinfection of contained healthcare microenvironments is well known, the effect of such a system in terms of a meaningful reduction in the microbial burden in an open inpatient ward is unclear. Our objective was to assess the impact of scheduled dry fogging on microbial reduction in such settings. Methods: We collected air and surface samples from rooms receiving daily, biweekly, or no fogging (controls) over six months, establishing the baseline contamination and evaluating the reduction trends in treated rooms. The "reduction effect" was measured by tracking microbial isolation trends before and after treatment, while the "degree of reduction" assessed differences across rooms with varied disinfection schedules. Results: The results indicate that scheduled dry fogging significantly reduced microbial loads in treated rooms, especially with daily disinfection (SE = 64.484, p = 0.002). The airborne contamination in treated rooms showed a strong downward trend over time (SE = 19.192, p < 0.001). Surface contamination remained challenging due to frequent recontamination; however, treated rooms exhibited a consistent reduction in microbial presence (SE = 2.002, p = 0.010), confirming dry fogging's role as a valuable adjunct to routine cleaning. Conclusions: In conclusion, this study highlights that dry fogging effectively reduces microbial loads in open, high-traffic healthcare environments, supporting its use as part of a multimodal infection control strategy.

Critically ill patients will benefit from single isolated laminar-air-flow wards by improving the environmental microbial composition

BACKGROUND

Hospital-associated infection (HAI) is an important issue in intensive care units (ICUs). We still lack direct evidence on whether the ICU patients and/or the medical system can benefit from single isolated laminar-air-flow (LAF) wards.

METHODS

High-touched-surface (HTS) swabs from 5 sites in two kinds of wards with different ventilation systems were longitudinally collected for 16 S rRNA sequencing and Type IIB restriction site-associated DNA sequencing for Microbiome (2bRAD-M). Samples were collected for 3 months. The clinical data of patients admitted to different wards during the sampling time and the whole year were collected and compared.

RESULTS

The α-diversity of single wards with isolated LAF was significantly higher than open regions without LAF (p<0.01). β-diversity analysis showed differences between different wards and similarities among the same region. We also identified 3 genera attributed to the most difference between the two kinds of wards. 2bRAD-M analysis further revealed community divergence among different HTS sites. There was an overlap between HTS microbiome profiling and the clinically cultivated pathogens of patients with HAI. People in single wards had a better outcome than those in open regions (p<0.05), indicating that single wards had a protective effect for critically ill patients.

CONCLUSION

Overall, there was a prominent difference in the microbiome community between single wards and open regions. Single wards had more balanced communities which may lead to better outcomes for patients. For critically ill patients, single ward is recommended when arranging and constructing.

[Multi-resistant pathogens - are they also resistant to disinfectants?]

Epidemiological studies show that the care of patients in rooms with a previous stay by a person with evidence of multi-resistant pathogens (MRP) is associated with an increased risk of these pathogens occurring. The question therefore regularly arises as to whether MRP also exhibit resistance to the disinfectants used. To date, there are no standardised definitions for "resistance" to disinfectants. However, disinfectants authorised on the market are also effective against multi-resistant pathogens and the failure of efficient disinfection is mainly caused by application errors (insufficient cleaning, incomplete wetting, incorrect application concentration or exposure time etc.). The effectiveness of disinfectants depends on a variety of environmental factors (especially accompanying contamination). A reduced sensitivity to disinfectants can occur in individual isolates due to selection under sub-inhibitory concentrations of disinfectants. Resistance mechanisms to antibiotics do not mediate cross-resistance to disinfectants, but a change in the permeability of bacterial cells can influence sensitivity to disinfectants and antibiotics. In general, the success of routine disinfection can be improved by suitable process controls and contribute to reducing the transmission of MRP.

Water disinfection using hydrogen peroxide with fixed bed hematite catalyst - kinetic and activity studies

A lab-scale reactor with a fixed-bed hematite catalyst for the effective decomposition of H2O2 and bacteria inactivation was designed. The bactericidal effect is the largest at a low initial bacterial count of 2·103 CFU/L, which is typical for natural surface waters. When using a 5 mM H2O2 solution and a residence time of 104 min, the reduction in the number of E. coli bacteria is about 3.5-log. At a higher initial bacterial count of 1-2·104 CFU/L, a 5 mM H2O2 solution reduces the bacteria number by about 4-log. The H2O2 decomposition follows the log-linear kinetics of a first-order reaction while the bacterial inactivation does not. The kinetics of bacterial inactivation was described using the Weibull model in the modified form: log10(N0/N) = b · tn. The values of the non-linearity parameter n were found to be lower than 1, indicating that bacterial inactivation slows down over time. With increasing initial H2O2 concentration, the rate parameter b increases while the non-linearity parameter n decreases. With increasing temperature, both parameters increase. The stability of the catalyst has been proved by XRD, FTIR, SEM, and ICP-OES. The concentration of iron leaching into water during disinfection is much lower than the limit declared by WHO for iron in drinking water. The results show that technical-grade hematite is a promising Fenton-like catalyst for water disinfection. The fixed-bed reactor can be the basis of the mobile installations for water purification in emergencies.

Superiority of manual disinfection using pre-soaked wipes over automatic UV-C radiation without prior cleaning

BACKGROUND

The efficacy of ultraviolet C (UV-C) radiation against a broad spectrum of micro-organisms has been demonstrated in several studies, but differences in the specific doses and the extent of microbial reduction were found. Furthermore, the conditions of laboratory tests differ greatly from reality, such that efficacy achieved in tests may not necessarily be assumed in reality. Consequently, it is important to investigate the effectiveness of UV-C in representative field trials. The aim was therefore to develop and establish a field test to evaluate automatic UV-C in comparison to manual disinfection.

METHODS

Before and after disinfection, samples were repeatedly collected from naturally highly contaminated surfaces using the swab technique to obtain representative data sets for disinfected and non-disinfected surfaces. Subsequently, the log reduction values (LRV) and the disinfection success were evaluated for UV-C radiation and full compliant manual disinfection using alcohol-based wipes.

RESULTS

Surfaces that are naturally contaminated with bacteria on a regular and nearly uniform basis have been identified as particularly suitable for field testing. Mean contamination was reduced from 23.3 to 1.98 cfu/cm2 (LRV 0.9) and 29.7 to 0.26 cfu/cm2 (LRV 1.2) for UV-C and manual disinfection, respectively. UV-C disinfection achieved 75.5% successful disinfected surfaces, whereas manual disinfection showed 98.1%.

CONCLUSIONS

Full compliant manual disinfection showed slightly higher LRVs and disinfection success than automatic UV-C disinfection. Successful, operator-independent UV-C disinfection still has the potential to improve disinfection performance in addition to manual disinfection.

Phenotypic Variation in Clinical S. aureus Isolates Did Not Affect Disinfection Efficacy Using Short-Term UV-C Radiation

Pigmentation, catalase activity and biofilm formation are virulence factors that cause resistance of Staphylococcus aureus to environmental stress factors including disinfectants. In recent years, automatic UV-C room disinfection gained greater importance in enhanced disinfection procedures to improve disinfection success in hospitals. In this study, we evaluated the effect of naturally occurring variations in the expression of virulence factors in clinical S. aureus isolates on tolerance against UV-C radiation. Quantification of staphyloxanthin expression, catalase activity and biofilm formation for nine genetically different clinical S. aureus isolates as well as reference strain S. aureus ATCC 6538 were performed using methanol extraction, a visual approach assay and a biofilm assay, respectively. Log10 reduction values (LRV) were determined after irradiation of artificially contaminated ceramic tiles with 50 and 22 mJ/cm2 UV-C using a commercial UV-C disinfection robot. A wide variety of virulence factor expression was observed, indicating differential regulation of global regulatory networks. However, no direct correlation with the strength of expression with UV-C tolerance was observed for either staphyloxanthin expression, catalase activity or biofilm formation. All isolates were effectively reduced with LRVs of 4.75 to 5.94. UV-C disinfection seems therefore effective against a wide spectrum of S. aureus strains independent of occurring variations in the expression of the investigated virulence factors. Due to only minor differences, the results of frequently used reference strains seem to be representative also for clinical isolates in S. aureus.

Direct and indirect healthcare and carbon savings with ACTIVE Particle ControlTM air-purification

Controlling airborne transmitted disease remains a challenge to clinicians, healthcare administrators, and engineers. Engineering measures are critical to any infection control program but can require extensive installation procedures, may be expensive to maintain, and may not always demonstrate clinical or financial benefit. We determined the financial and carbon benefits of an engineering solution to combat air pollutants and to control airborne transmitted disease. We determined the costs of healthcare associated infections (HAIs), and the costs of installation, maintenance, energy demands, and carbon impacts of an ACTIVE Particle ControlTM (APC) air-purification system. In a 20 month study with over 65,000 patient days the significant reductions in HAIs resulted in significant financial, energy, maintenance, and carbon savings from this engineering solution. Positive clinical and financial outcomes are possible with novel air-purification solutions such as APC.