Characteristics of airborne micro-organisms in a neurological intensive care unit: Results from China

Distribution and the trend of airborne particles and bio-aerosol concentration in pediatric intensive care units with different ventilation setting at two hospitals in Riyadh, Saudi Arabia

OBJECTIVE

To examine the distribution and the trend of airborne particles and bio-aerosol concentration in pediatric intensive care units (PICUs) in two tertiary care hospitals with different ventilation setting.

METHODS

Hospitals A but not B is provided with a central HEPA filter. PICUs in both hospitals were categorized into protective environment (PE) with room HEPA filter, semi-protective environment (SPE) with portable air-purifier, and non-protective environment (NPE) with neither system. Fine particles (≤ 2.5 µm) and coarse particles (≤ 10.0 µm) were obtained using optical particle counter (Lighthouse Handheld 3016) and total bacterial (TBC) and fungal (TFC) counts were obtained using Andersen air sampler.

RESULTS

Hospital B had significantly higher levels of fine and coarse particles (in all room), TBC (in PE), but not TFC compared with matched rooms in hospital A. In hospital B, the levels of fine particles, coarse particles, and TBC were lowest in SPE (p < 0.001, p = 0.004, and p = 0.006, respectively) while TFC was lowest in NPE (p = 0.014). Airborne particles, TBC, and TFC had variable trends with some of the indoor peaks follow outdoor peaks. Gram-positive bacteria (69 %) were the predominant bacteria in hospital A while bacterial flora (70 %) were the predominant bacteria in hospital B (p < 0.001 for each).

CONCLUSIONS

The levels of airborne contaminants and microbial counts in PICUs are significantly affected by the ventilation system and to less extent by outdoor levels. The results indicated that advanced filtration system and central HEPA filters play a significant role in the reduction of indoor fine particulates and TBC.

Fungi in the indoor air of critical hospital areas: a review

Invasive fungal infection is an important cause of mortality and morbidity in neonates, especially in low-birthweight neonates. The contribution of fungi in the indoor air to the incidence of mucocutaneous colonization and to the risk of invasive fungal infection in this population is uncertain. This review aimed to identify and to summarize the best available evidence on the fungal contamination in the indoor air of critical hospital areas with an emphasis on pediatric/neonatal ICUs. Publications from 2005 to 2019 were searched in the databases Scientific Electronic Library Online (SciELO), US National Library of Medicine National Institutes of Health Search (PubMed), and Latin American Caribbean Health Sciences (LILACS). Descriptors in Health Sciences (DeCS) were used. Research papers published in Portuguese, English, and Spanish were included. Twenty-nine papers on all continents except Australia were selected. The results showed that the air mycobiota contained several fungal species, notably Aspergillus, Penicillium, Cladosporium, Fusarium, and yeast (Candida) species. The selected papers point out the risks that fungi pose to neonates, who have immature immune system, and describe simultaneous external factors (air humidity, seasonality, air and people flow, use of particulate filters, and health professionals' hand hygiene) that contribute to indoor air contamination with fungi. Improving communication among health professionals is a great concern because this can prevent major health complications in neonates, especially in low-birthweight neonates. The results reinforced the need to monitor environmental fungi more frequently and efficiently in hospitals, especially in neonatal ICUs.

Investigating the effect of several factors on concentrations of bioaerosols in a well-ventilated hospital environment

This study characterized and quantified the bacterial and fungal bioaerosols in nine wards of the Razavi Hospital (Mashhad, Iran) that is equipped with an advanced heating, ventilating, and air conditioning (HVAC) system including HEPA filters for air cleaning. In this study, 432 samples were taken from the indoor air of multiple hospital wards during the morning and afternoon shifts during summer and autumn. The particle number concentrations with sizes of > 0.3, > 0.5, > 1, > 2, > 5, and > 10 μm were measured using a 6-channel handheld particle counter. A greater diversity of bioaerosol types were observed during the morning shifts and during summer. The microbial load was not affected significantly by the temperature, relative humidity, working shift, season, and number of visitors, indicating the effectiveness of a well-designed ventilation system to eliminate site-specific variations. For microbial number concentrations, a significant correlation was only observed between the number of particles with a diameter of > 10 μm and the airborne microbial loading. Thus, passive sampling may not properly reflect the actual concentrations of smaller bioaerosols. In conclusion, HEPA filters in the HVAC system successfully decreased the bioaerosol concentrations in the hospital environment. Additionally, we recommend that active sampling be used in cases where a well-functioning HVAC system exists.

Study on the relationship between the concentration and type of fungal bio-aerosols at indoor and outdoor air in the Children's Medical Center, Tehran, Iran

Fungal bio-aerosols are of concern due to their adverse health effects, especially in indoor environments. The aim of this study was to evaluate the relationship between the concentration and type of fungal bio-aerosols in the indoor and outdoor of Children's Medical Center in Tehran, Iran. In the present descriptive-analytical study, the fungal bio-aerosols' concentrations in both indoor and outdoor of the hospital air were measured. The measurements were carried out by the Anderson method using a Quick Take 30 pump at 28.3 L min^-1 and 2.5 min sampling that was placed on a Sabouraud dextrose agar with chloramphenicol. The average concentrations of total fungal bio-aerosols in the hospital indoor and outdoor air were 40.48 and 119.6 CFU/m³, respectively. Onco-hematology and bone marrow transplantation wards were the most and least contaminated units, respectively (11.09 CFU/m³ vs 1.47 CFU/m³). The most common fungi isolated from the indoor environment were Penicillium spp. (45.86%) which was followed by Cladosporium spp. (31.92%), Aspergillus section Nigri (6.26%), sterilized mycelia (5.05%), and Aspergillus section Flavi (2.83%). Cladosporium spp. (61.10 CFU/m³) and Penicillium spp. (18.56 CFU/m³) had the highest mean concentrations in outdoor and indoor air, respectively. The indoor-to-outdoor ratio of fungal aerosols was < 1 at most sampling sites, indicating that the indoor fungal bio-aerosols may have originated from the outdoor environment.

Airborne Infectious Microorganisms ☆

Inhalation exposes the upper and lower respiratory tracts of humans to a variety of airborne particles and vapors. Airborne transmission of pathogenic microorganisms to humans from the environment, animals, or other humans can result in disease. Inhalation is an important route of exposure as the lung is more susceptible to infection than the gastrointestinal tract. Ingested microorganisms must pass through the acidic environment of the stomach before they can colonize tissue while inhaled microorganisms are deposited directly on the moist surfaces of the respiratory tract. Inhalation of microbial aerosols can elicit adverse human health effects including infection, allergic reaction, inflammation, and respiratory disease. Following inhalation, infectious viruses, bacteria, and fungi can establish in host cells of the respiratory tract. Some are translocated and infect the gastrointestinal tract and other tissues. This article discusses human viral, bacterial, and fungal diseases transmitted via aerosols. Viral diseases presented are influenza, severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), enteric viruses related infections, hantavirus disease, measles, and varicella. Bacterial diseases are Legionnaires’ disease, tuberculosis, and nontubercule mycobacterial disease. Exposure to some Gram-negative and Gram-positive bacteria, endotoxin, and actinomycetes when dispersed through the air can result in disease following inhalation. Fungal diseases included are histoplasmosis, coccidiomycosis, blastomycosis, cryptococcosis, and aspergillosis. The threat of bioterrorism with airborne infectious agents is also briefly presented.