Air dispersal of multi-drug-resistant organisms including meticillin-resistant Staphylococcus aureus, carbapenem-resistant Acinetobacter baumannii and carbapenemase-producing Enterobacterales in general wards: surveillance culture of air grilles

BACKGROUND

The environmental surveillance of air grilles in clinical areas has not been systematically analysed.

METHODS

Samples were collected from frequently touched items (N = 529), air supply (N = 295) and exhaust (N = 184) grilles in six medical and 11 surgical wards for the cultures of multi-drug-resistant organisms (MDROs): meticillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Acinetobacter baumannii (CRAB) and carbapenemase-producing Enterobacterales (CPE), and isolates were selected for whole-genome sequencing (WGS). The contamination rates were correlated with the colonization pressures of the respective MDROs.

RESULTS

From 3rd October to 21st November 2023, 9.8% (99/1008) of the samples tested positive, with MRSA (24.2%, 24/99), CRAB (59.6%, 59/99) and CPE (2.0%, 2/99), being the only detected MDROs. The contamination rate in air exhaust grilles (26.6%, 49/184) was significantly higher than in air supply grilles (5.8%, 17/295; P<0.001). The contamination rate of air exhaust grilles with any MDRO in acute medical wards (73.7%, 14/19) was significantly higher than in surgical wards (12.5%, 4/32; P<0.001). However, there was no difference in the contamination rate of air exhaust grilles between those located inside and outside the cohort cubicles for MDROs (27.1%, 13/48 vs 28.8%, 30/104; P=0.823). Nevertheless, the weekly CRAB colonization pressure showed a significant correlation with the overall environmental contamination rate (r = 0.878; 95% confidence interval (CI): 0.136-0.986; P=0.004), as well as with the contamination rate in air supply grilles (r = 0.960; 95% CI: 0.375-0.999; P<0.001) and air exhaust grilles (r = 0.850; 95% CI: 0.401-0.980; P=0.008). WGS demonstrated clonal relatedness of isolates collected from patients and air exhaust grilles.

CONCLUSIONS

Air grilles may serve as MDRO reservoirs. Cohort nursing in open cubicles may not completely prevent MDRO transmission through air dispersal, prompting the consideration of future hospital design.

The role of hospital environment in transmissions of multidrug-resistant gram-negative organisms

Infections by multidrug-resistant (MDR) Gram-negative organisms (GN) are associated with a high mortality rate and present an increasing challenge to the healthcare system worldwide. In recent years, increasing evidence supports the association between the healthcare environment and transmission of MDRGN to patients and healthcare workers. To better understand the role of the environment in transmission and acquisition of MDRGN, we conducted a utilitarian review based on literature published from 2014 until 2019.

Strict Isolation

Strict isolation: suspected highly infectious and transmissible virulent and pathogenic microbes, highly resistant bacterial strains and agents that are not accepted in any form of distribution in the society or in the environment. Examples are completely resistant Mycobacterium tuberculosis, viral haemorrhagic fevers like Ebola and Lassa, pandemic severe influenza and coronavirus like SARS, MERS, etc. In most countries, strict isolation is a rarely used isolation regime but should be a part of the national preparedness plan. For instance, in Norway, strict isolation has not been used for the last 50–60 years, except for one case of imported Ebola infection in 2014. Patients in need of strict isolation should be placed in a separate isolation ward or building.

Infection spread by contact, droplet and airborne infection, aerosols, re-aerosols, airborne microbe-carrying particles, skin cells, dust, droplets and droplet nuclei. At the same time, it is always contact transmission (contaminated environment, equipment, textiles and waste).

The source of infection is usually a patient but may also be a symptomless carrier or a zoonotic disease.

Background Information: Isolation Routines

The isolation of patients with suspected or documented infections—to not spread to others—has been discussed for hundreds of years. Guidelines are many, methods are different, attitudes show vide variations, routines and procedures are still changing, regulations by law may be absent, and some healthcare professionals may be afraid of adverse outcomes of isolation [1–44]. Microbes that are spread in the environment, on the hands and equipment are invisible. The invisible agent does not call on attention before the infection; clinical disease, hospital infection or nosocomial infection is a factum that can be registered [23, 28, 29, 35–37]. How to stop the transmission is often “to believe and not believe” in infection control.

Protection of Upper Respiratory Tract, Mouth and Eyes

Pathogenic bacteria and viruses may invade via upper and lower respiratory tract and via eye mucosa. When an infected person coughs or sneezes heavily, small, invisible droplets with the infective agent may reach a good distance from the source. By using the right form of protection at the right time, infection and disease are prevented. The present chapter is focused on the protection against airborne infections.

Impact of pulsed xenon ultraviolet light on hospital-acquired infection rates in a community hospital

BACKGROUND

The role of contaminated environments in the spread of hospital-associated infections has been well documented. This study reports the impact of a pulsed xenon ultraviolet no-touch disinfection system on infection rates in a community care facility.

METHODS

This study was conducted in a community hospital in Southern Florida. Beginning November 2012, a pulsed xenon ultraviolet disinfection system was implemented as an adjunct to traditional cleaning methods on discharge of select rooms. The technology uses a xenon flashlamp to generate germicidal light that damages the DNA of organisms in the hospital environment. The device was implemented in the intensive care unit (ICU), with a goal of using the pulsed xenon ultraviolet system for disinfecting all discharges and transfers after standard cleaning and prior to occupation of the room by the next patient. For all non-ICU discharges and transfers, the pulsed xenon ultraviolet system was only used for Clostridium difficile rooms. Infection data were collected for methicillin-resistant Staphylococcus aureus, C difficile, and vancomycin-resistant Enterococci (VRE). The intervention period was compared with baseline using a 2-sample Wilcoxon rank-sum test.

RESULTS

In non-ICU areas, a significant reduction was found for C difficile. There was a nonsignificant decrease in VRE and a significant increase in methicillin-resistant S aureus. In the ICU, all infections were reduced, but only VRE was significant. This may be because of the increased role that environment plays in the transmission of this pathogen. Overall, there were 36 fewer infections in the whole facility and 16 fewer infections in the ICU during the intervention period than would have been expected based on baseline data.

CONCLUSION

Implementation of pulsed xenon ultraviolet disinfection is associated with significant decreases in facility-wide and ICU infection rates. These outcomes suggest that enhanced environmental disinfection plays a role in the risk mitigation of hospital-acquired infections.

Roles of sunlight and natural ventilation for controlling infection: historical and current perspectives

Background

Infections caught in buildings are a major global cause of sickness and mortality. Understanding how infections spread is pivotal to public health yet current knowledge of indoor transmission remains poor.

Aim

To review the roles of natural ventilation and sunlight for controlling infection within healthcare environments.

Methods

Comprehensive literature search was performed, using electronic and library databases to retrieve English language papers combining infection; risk; pathogen; and mention of ventilation; fresh air; and sunlight. Foreign language articles with English translation were included, with no limit imposed on publication date.

Findings

In the past, hospitals were designed with south-facing glazing, cross-ventilation and high ceilings because fresh air and sunlight were thought to reduce infection risk. Historical and recent studies suggest that natural ventilation offers protection from transmission of airborne pathogens. Particle size, dispersal characteristics and transmission risk require more work to justify infection control practices concerning airborne pathogens. Sunlight boosts resistance to infection, with older studies suggesting potential roles for surface decontamination.

Conclusions

Current knowledge of indoor transmission of pathogens is inadequate, partly due to lack of agreed definitions for particle types and mechanisms of spread. There is recent evidence to support historical data on the effects of natural ventilation but virtually none for sunlight. Modern practice of designing healthcare buildings for comfort favours pathogen persistence. As the number of effective antimicrobial agents declines, further work is required to clarify absolute risks from airborne pathogens along with any potential benefits from additional fresh air and sunlight.