Most healthcare-associated infections (HCAIs) develop due to the colonisation of patients and healthcare workers by multidrug-resistant organisms (MDRO). Here, we investigated whether the particulate matter from the ventilation systems (Vent-PM) of health facilities can harbour MDRO and other microbes, thereby acting as a potential reservoir of HCAIs. Dust samples collected in the ventilation grilles and adjacent air ducts underwent a detailed analysis of physicochemical properties and biodiversity. All Vent-PM samples included ultrafine PM capable of reaching the alveoli. Strikingly, >70% of Vent-PM samples were contaminated, mostly by viruses (>15%) or multidrug-resistant and biofilm-producing bacterial strains (60% and 48% of all bacteria-contaminated specimens, respectively). Total viable count at 1 m from the ventilation grilles was significantly increased after opening doors and windows, indicating an association between air flow and bacterial contamination. Both chemical and microbial compositions of Vent-PM considerably differed across surgical vs. non-surgical and intensive vs. elective care units and between health facilities located in coal and chemical districts. Reduced diversity among MDRO and increased prevalence ratio in multidrug-resistant to the total Enterococcus spp. in Vent-PM testified to the evolving antibiotic resistance. In conclusion, we suggest Vent-PM as a previously underestimated reservoir of HCAI-causing pathogens in the hospital environment.
Background. Most healthcare-associated infections (HAI) develop due to a colonization of patients and healthcare workers by hospital strains of pathogens. The aim to study was to assess whether the dust within the health facilities can harbor microorganisms acting as a reservoir of HAIs.Materials and methods. Dust samples collected in the air ducts and ventilation grilles of health facilities underwent a detailed physicochemical analysis by means of scanning electron microscopy, dynamic light scattering, energy-dispersive X-ray spectroscopy, and high-temperature catalytic oxidation. Bacterial and viral diversity was investigated using an automated biochemical analyzer and polymerase chain reaction, respectively. Investigation of the microenvironment included detection of biofilms using a catalase indicator and quantification of viable microorganisms per 1 m3 air.Results. Dust from the hospital ventilation grilles and air ducts was contaminated with microorganisms in 71.13% of cases. Strikingly, multidrug-resistant and biofilm-forming strains have been found in 69.4% and 48.0% of samples, respectively. The total viable count before and after opening doors and windows was 276 and 462 colony-forming units/m3 respectively (p = 0.046). Biodiversity was represented by 21 genera of microorganisms which were consistently detected upon 6 months of follow-up. All samples contained a nanosized particulate matter. Chemical elements comprising dust were carbon (16.26–50.69%), oxygen (20.02–37.50%), nitrogen (1.59–25.03%), hydrogen (2.03–6.67%), sulfur (0.15–2.38%), calcium (0.19–7.49%), silicon (0.21–4.64%), chlorine (0.05–2.83%), sodium (0.07–1.86%), aluminum (0.36–1.78%), iron (0.08–1.61%), magnesium (0.11–1.40%), potassium (0.04–0.85%), and phosphorus (0.04–0.81%).Discussion. A wide range of multidrug-resistant strains of bacteria, detected in a hospital particulate matter with a diverse chemical composition, indicates the persistence of HAI-causing pathogens in the hospital environment.Conclusion. Dust from the ventilation grilles and adjacent air ducts should be considered as an additional reservoir of multidrug-resistant strains of bacteria in the healthcare settings.
The novel coronavirus SARS-CoV-2 has caused a global health threat. This review summarizes comprehensive research findings about the SARS-CoV-2 persistence in inanimate surfaces and opportunities for applying biocides to limit spread of COVID-19. SARS-CoV2 is highly stable at 4°C but sensitive to heat and extremely stable in a wide range of pH values at room temperature. Coronaviruses also well survive in suspension. Desiccation has a more severe effect. SARS-CoV-2 can survive in the air for hours and on surfaces for days. Hospitals are significant epicenters for the human-to-human transmission of the SARS-CoV-2 for healthcare workers. The most contaminated SARS-CoV-2 zones and objects in isolation wards, in intensive care unit specialized for novel coronavirus pneumonia, are under discussion. SARS-CoV2 is sensitive to standard disinfection methods. Studies revealed that 62-71% ethanol, 0.5% hydrogen peroxide or 0.1% sodium hypochlorite inactivated SARS-CoV2 in 1 minute exposition; while 0.05-0.2% benzalkonium chloride or 0.02% chlorhexidine digluconate were less effective. Both ethanol and isopropanol were able to reduce viral titers after 30-seconds exposure. It was found for reusing personal protective equipment vaporized hydrogen peroxide treatment exhibits the best combination of rapid inactivation of SARS-CoV-2 and preservation of N95 respirator integrity under the experimental conditions. Overall, SARS-CoV-2 can be highly stable in a favourable environment, but it is also susceptible to standard disinfection methods. Environmental infection control of the air and especially for surfaces is considered as a mandatory step in addition to limiting person-to-person contact.
For decades, there have been a number of controversial issues regarding the airborne transmission of hospital pathogens. Here we decided to perform a critical review on this topic in light of the current COVID-19 pandemic. We summarise the existing knowledge on biological aerosols including techniques of their generation, propagation of bioaerosol particles in a hospital environment, particle size-, shape- and composition-dependent airborne transmission, and microorganisms inhabitating such particles. It is still unclear which of the particles transfer the pathogens, which of the pathogens are capable of adhering to the particulate matter, and whether such adhesion affects pathogen virulence. Intriguingly, viruses, bacteria and fungi seemingly have distinct patterns of interactions with the bioaerosols. Moreover, particle formation and their colonization may be separated in time, further complicating the puzzle. Apparently, pathogen interactions with the particulate matter are of paramount importance to better understand the role of bioaerosol particles as a potential pathogen reservoir in the hospital environment and to properly assess the influence of environmental pollutants, novel biomedical materials and treatment technologies on airborne transmission of hospital pathogens.
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