A problem of hospital hygiene: the presence of aspergilli in hospital wards with different air-conditioning features

Evaluation of the Results of a Periodic Environmental Biosecurity Assessment Program on Air Quality in Controlled Environment Rooms of Hospitals

AIM

Determine the utility of the Periodic Environmental Biosecurity Assessment Program (PEBAP) in achieving clean air as measured by the number of colony-forming units (CFU) of fungi and bacteria in the air.

BACKGROUND

There is no international consensus on the sampling frequency, the recommended limits for microorganisms in the air nor on the usefulness of routine microbiological air monitoring of hospitals.

METHODS

During the PEBAP, data were recollected between 2010 and 2017 in eight hospitals in southeast Spain. Air samples were collected in very high risk rooms (VHRRs) and high risk rooms (HRRs), unoccupied, using active sampling methods. Temperature, relative humidity, air changes per hour (ACH), and differential pressure were measured. When limits of CFU of opportunistic fungi and bacteria established in the PEBAP were exceeded, corrective measures were adopted.

RESULTS

We found a reduction (p < .01) of percentage of air samples with fungi growth throughout the years of PEBAP in all rooms. Aspergillus was the most frequent opportunistic fungus. We found a high compliance of the standards of CFU of bacteria in HRR, and the percentage of compliance in VHRR was lower than in HRR in all years. Differences in environmental and design parameters were statistically significant (p < .05) between rooms, except for ACH.

CONCLUSIONS

PEBAP resulted in a useful tool to maintain and improve air quality in hospitals. The control of environmental biosecurity requires a multidisciplinary approach from preventive medicine, engineering, and cleaning services. Aspergillus is the most frequent opportunistic fungus in southeast Spain.

A systematic review and meta-analysis of indoor bioaerosols in hospitals: The influence of heating, ventilation, and air conditioning

OBJECTIVES

To evaluate (1) the relationship between heating, ventilation, and air conditioning (HVAC) systems and bioaerosol concentrations in hospital rooms, and (2) the effectiveness of laminar air flow (LAF) and high efficiency particulate air (HEPA) according to the indoor bioaerosol concentrations.

METHODS

Databases of Embase, PubMed, Cochrane Library, MEDLINE, and Web of Science were searched from 1st January 2000 to 31st December 2020. Two reviewers independently extracted data and assessed the quality of the studies. The samples obtained from different areas of hospitals were grouped and described statistically. Furthermore, the meta-analysis of LAF and HEPA were performed using random-effects models. The methodological quality of the studies included in the meta-analysis was assessed using the checklist recommended by the Agency for Healthcare Research and Quality.

RESULTS

The mean CFU/m3 of the conventional HVAC rooms and enhanced HVAC rooms was lower than that of rooms without HVAC systems. Furthermore, the use of the HEPA filter reduced bacteria by 113.13 (95% CI: -197.89, -28.38) CFU/m3 and fungi by 6.53 (95% CI: -10.50, -2.55) CFU/m3. Meanwhile, the indoor bacterial concentration of LAF systems decreased by 40.05 (95% CI: -55.52, -24.58) CFU/m3 compared to that of conventional HVAC systems.

CONCLUSIONS

The HVAC systems in hospitals can effectively remove bioaerosols. Further, the use of HEPA filters is an effective option for areas that are under-ventilated and require additional protection. However, other components of the LAF system other than the HEPA filter are not conducive to removing airborne bacteria and fungi.

LIMITATION OF STUDY

Although our study analysed the overall trend of indoor bioaerosols, the conclusions cannot be extrapolated to rare, hard-to-culture, and highly pathogenic species, as well as species complexes. These species require specific culture conditions or different sampling requirements. Investigating the effects of HVAC systems on these species via conventional culture counting methods is challenging and further analysis that includes combining molecular identification methods is necessary.

STRENGTH OF THE STUDY

Our study was the first meta-analysis to evaluate the effect of HVAC systems on indoor bioaerosols through microbial incubation count. Our study demonstrated that HVAC systems could effectively reduce overall bioaerosol concentrations to maintain better indoor air quality. Moreover, our study provided further evidence that other components of the LAF system other than the HEPA filter are not conducive to removing airborne bacteria and fungi.

PRACTICAL IMPLICATION

Our research showed that HEPA filters are more effective at removing bioaerosols in HVAC systems than the current LAF system. Therefore, instead of opting for the more costly LAF system, a filter with a higher filtration rate would be a better choice for indoor environments that require higher air quality; this is valuable for operating room construction and maintenance budget allocation.

Effects of air-conditioning systems in the public areas of hospitals: A scoping review

Almost all hospitals are equipped with air-conditioning systems to provide a comfortable environment for patients and staff. However, the accumulation of dust and moisture within these systems increases the risk of transmission of microbes and have on occasion been associated with outbreaks of infection. Nevertheless, the impact of air-conditioning on the transmission of microorganisms leading to infection remains largely uncertain. We conducted a scoping review to screen systematically the evidence for such an association in the face of the coronavirus disease 2019 epidemic. PubMed, Embase and Web of Science databases were explored for relevant studies addressing microbial contamination of the air, their transmission and association with infectious diseases. The review process yielded 21 publications, 17 of which were cross-sectional studies, three were cohort studies and one case−control study. Our analysis showed that, compared with naturally ventilated areas, microbial loads were significantly lower in air-conditioned areas, but the incidence of infections increased if not properly managed. The use of high-efficiency particulate air (HEPA) filtration not only decreased transmission of airborne bioaerosols and various microorganisms, but also reduced the risk of infections. By contrast, contaminated air-conditioning systems in hospital rooms were associated with a higher risk of patient infection. Cleaning and maintenance of such systems to recommended standards should be performed regularly and where appropriate, the installation of HEPA filters can effectively mitigate microbial contamination in the public areas of hospitals.

Indoor hospital air and the impact of ventilation on bioaerosols: a systematic review

Healthcare-acquired infections (HAIs) continue to persist in hospitals, despite the use of increasingly strict infection-control precautions. Opportunistic airborne transmission of potentially pathogenic bioaerosols may be one possible reason for this persistence. Therefore, this study aimed to systematically review the concentrations and compositions of indoor bioaerosols in different areas within hospitals and the effects of different ventilation systems. Electronic databases (Medline and Web of Science) were searched to identify articles of interest. The search was restricted to articles published from 2000 to 2017 in English. Aggregate data was used to examine the differences in mean colony forming units per cubic metre (cfu/m³) between different hospital areas and ventilation types. A total of 36 journal articles met the eligibility criteria. The mean total bioaerosol concentrations in the different areas of the hospitals were highest in the inpatient facilities (77 cfu/m³, 95% confidence interval (CI): 55-108) compared with the restricted (13cfu/m³, 95% CI: 10-15) and public areas (14 cfu/m³, 95% CI: 10-19). Hospital areas with natural ventilation had the highest total bioaerosol concentrations (201 cfu/m³, 95% CI: 135-300) compared with areas using conventional mechanical ventilation systems (20 cfu/m³, 95% CI: 16-24). Hospital areas using sophisticated mechanical ventilation systems (such as increased air changes per hour, directional flow and filtration systems) had the lowest total bioaerosol concentrations (9 cfu/m³, 95% CI: 7-13). Operating sophisticated mechanical ventilation systems in hospitals contributes to improved indoor air quality within hospitals, which assists in reducing the risk of airborne transmission of HAIs.

Does the air condition system in busses spread allergic fungi into driver space?

The aim of this study was to establish whether the air-conditioning system in buses constitutes an additional source of indoor air contamination with fungi, and whether or not the fungi concentration depends on the period from the last disinfection of the system, combined with replacement of the cabin dust particle filter. The air samples to fungi analysis using impact method were taken in 30 buses (20 with an air-conditioning system, ACS; 10 with a ventilation system, VS) in two series: 1 and 22 weeks after cabin filter replacement and disinfection of the air-conditioning system. During one test in each bus were taken two samples: before the air-conditioning or ventilation system switched on and 6 min after operating of these systems. The atmospheric air was the external background (EB). After 1 week of use of the system, the fungi concentrations before starting of the ACS and VS system were 527.8 and 1053.0 cfu/m3, respectively, and after 22 weeks the concentrations were 351.9 and 1069.6 cfu/m3, respectively. While in the sample after 6 min of ACS and VS system operating, the fungi concentration after 1 week of use was 127.6 and 233.7 cfu/m3, respectively, and after 22 weeks it was 113.3 and 324.9 cfu/m3, respectively. Results do not provide strong evidence that air-conditioning system is an additional source of indoor air contamination with fungi. A longer operation of the system promoted increase of fungi concentration in air-conditioned buses only.

Detection of Common Respiratory Viruses and Mycoplasma pneumoniae in Patient-Occupied Rooms in Pediatric Wards

Few studies have assessed viral contamination in the rooms of hospital wards. This cross-sectional study evaluated the air and objects in patient-occupied rooms in pediatric wards for the presence of common respiratory viruses and Mycoplasma pneumoniae.Air samplers were placed at a short (60-80 cm) and long (320 cm) distance from the head of the beds of 58 pediatric patients, who were subsequently confirmed to be infected with enterovirus (n = 17), respiratory syncytial virus (RSV) (n = 13), influenza A virus (n = 13), adenovirus (n = 9), or M pneumoniae (n = 6). Swab samples were collected from the surfaces of 5 different types of objects in the patients' rooms. All air and swab samples were analyzed via real-time quantitative polymerase chain reaction assay for the presence of the above pathogens.All pathogens except enterovirus were detected in the air, on the objects, or in both locations in the patients' rooms. The detection rates of influenza A virus, adenovirus, and M pneumoniae for the long distance air sampling were 15%, 67%, and 17%, respectively. Both adenovirus and M pneumoniae were detected at very high rates, with high concentrations, on all sampled objects.The respiratory pathogens RSV, influenza A virus, adenovirus, and M pneumoniae were detected in the air and/or on the objects in the pediatric ward rooms. Appropriate infection control measures should be strictly implemented when caring for such patients.

Microorganisms associated particulate matter: a preliminary study

This study aims to determine the microbiological quality of particulate matter (PM) in an urban area in Jeddah, Saudi Arabia, during December 2012 to April 2013. This was achieved by the determination of airborne bacteria, fungi, and actinobacteria associated PM10 and PM2.5, as well as their relationships with gaseous pollutants, O3, SO2 and NO2, and meteorological factors (T°C, RH% and Ws). High volume samplers with PM10 and PM2.5 selective sizes, and glass fiber filters were used to collect PM10 and PM2.5, respectively. The filters were suspended in buffer phosphate and aliquots were spread plated onto the surfaces of trypticase soy agar, malt extract agar, and starch casein agar media for counting of bacteria, fungi and actinobacteria-associated PM, respectively. PM10 and PM2.5 concentrations averaged 159.9 μg/m(3) and 60 μg/m(3), respectively, with the ratio of PM2.5/PM10 averaged ~0.4. The concentrations of O3, SO2 and NO2 averaged 35.73 μg/m(3), 38.1μg/m(3) and 52.5 μg/m(3), respectively. Fungi and actinobacteria associated PM were found in lower concentrations than bacteria. The sum of microbial loads was higher in PM10 than PM2.5, however a significant correlation (r=0.57, P ≤ 0.05) was found between the sum of microbial loads associated PM10 and PM2.5. Aspergillus fumigatus and Aspergillus niger were the common fungal types associated PM. Temperature significantly correlated with both PM10 (r=0.44), and PM2.5 (r=0.5). Significant negative correlations were found between O3 and PM2.5 (r=-0.47), and between SO2 with PM10 (r=-0.48). Wind speed positively correlated with airborne microorganisms associated PM. The regression model showed that the inverse PM2.5 concentration (1/PM2.5) was a significant determinant of fungal count associated PM. Chemical processes and environmental factors could affect properties of PM and in turn its biological quality.

Monitoring environmental Aspergillus spp. contamination and meteorological factors in a haematological unit

The opportunistic pathogens belonging to the Aspergillus genus are present in almost all seasons of the year, and their concentration is related to meteorological conditions. The high density of Aspergillus spp. conidia in a haematological hospital ward may be a significant risk factor for developing invasive fungal diseases in immunocompromised patients. Aim of the present study was to evaluate the variability of airborne Aspergillus spp. conidia contamination in a Haematological Unit (HU) within a period of 16 months in relation with some meteorological parameters. An environmental Aspergillus surveillance was conducted in the HU in four rooms and their bathrooms, in the corridor and in three external sites using an agar impact sampler. During each sampling, temperature and relative humidity at each site were recorded and current wind speed and rainfall events were taken from the official weather service. Aspergillus spp. conidia concentration differed significantly across the sampling sites. Internal Aspergillus spp. loads were significantly dependent on temperature, internal relative humidity and rain. External conidia concentrations were significantly influenced by outdoor temperature and relative humidity. A suitable indicator was introduced to evaluate the seasonal distribution of Aspergillus spp. conidia in the sampling sites, and a significant dependence on this indicator was observed inside the HU. Seventeen different fungal species belonging to the Aspergillus genus were detected during the sampling period. Aspergillus fumigatus was the most frequently isolated species and its distribution depended significantly on the seasonal indicator both inside and outside the hospital ward.

Fungal microbiota in air-conditioning installed in both adult and neonatal intensive treatment units and their impact in two university hospitals of the central western region, Mato Grosso, Brazil

To evaluate fungal microbiota in air-conditioning units installed in intensive care units in two university hospitals in Cuiaba city, Mato Grosso, central western region of Brazil, 525 solid environmental samples were collected, 285 from Hospital A and 240 from Hospital B. Collections were performed using sterile swabs on air-conditioning unit components: cooling coils, ventilators, and filters. Mycelial fungi identification was achieved by observation of the macroscopic and micromorphological characteristics in different culture mediums (maize meal, oatmeal and potato dextrose agars and malt extract) using the Ridell technique. Eleven genera and 27 distinct species belonging to the hyphomycetes and ascomycetes classes were isolated and identified. The most frequently detected genera in both hospitals were Aspergillus spp, Penicillium spp, and Cladosporium spp. Values for colony-forming units per gram were 64 and 75%, well above the limits recommended by Health Ministry resolution 176/00 at the locations selected for analysis in Hospitals A and B, respectively. In conclusion, evaluation of fungal microbiota in the air-conditioning units indirectly determined that the air quality was compromised in both university hospitals analyzed, which constitutes a risk factor for the acquisition of infection in the intensive care units.

The impact of portable high-efficiency particulate air filters on the incidence of invasive aspergillosis in a large acute tertiary-care hospital

BACKGROUND

Worldwide, the frequency of invasive fungal infections has been increasing, with a corresponding increase in the numbers of high-risk patients. Exposure reduction through the use of high-efficiency particulate air (HEPA) filters has been the preferred primary preventive strategy for these high-risk patients. Although the efficiency and benefits of fixed HEPA filters is well proven, the benefits of portable HEPA filters are still inconclusive.

METHODS

This was a retrospective study to assess the impact of 48 portable HEPA filter units deployed in selected wards in Singapore General Hospital, an acute tertiary-care hospital in Singapore. Data were extracted between December 2005 and June 2008 on the diagnoses at discharge and microbiological and histological laboratory findings. All patients with possible, probable, or proven invasive aspergillosis (IA) were included.

RESULTS

In wards with portable HEPA filters, the incidence rate of IA of 34.61/100,000 patient-days in the pre-installation period was reduced to 17.51/100,000 patient-days in the post-installation period (P = .01), for an incidence rate ratio of 1.98 (95% confidence interval [CI], 1.10-2.97). In wards with no HEPA filters, there was no significant change in the incidence rate during the study period. Portable HEPA filters were associated with an adjusted odds ratio of 0.49 (95% CI, 0.28-0.85; P = .01), adjusted for diagnosis and length of hospital stay.

CONCLUSIONS

Portable HEPA filters are effective in the prevention of IA. The cost of widespread portable HEPA filtration in hospitals will be more than offset by the decreases in nosocomial infections in general and in IA in particular.

Potential for preventing spread of fungi in air-conditioning systems constructed using copper instead of aluminium

AIMS

As copper has been previously suggested as an antimicrobial surface, we tested the effectiveness of copper as an antifungal surface which could be used in air-conditioning systems as an alternative to aluminium.

METHODS AND RESULTS

Coupons of copper (C11000) and aluminium were inoculated with fungal isolates (Aspergillus spp., Fusarium spp., Penicillium chrysogenum and Candida albicans) for various time periods. Culture on potato dextrose agar and an in situ viability assay using the fluorochrome FUN-1 were used to determine whether spores had survived. The results showed increased die off of fungal isolates tested compared to aluminium. In addition, copper also prevented the germination of spores present, thereby reducing the risk of the release of spores.

CONCLUSIONS

Copper offered an antifungal surface and prevented subsequent germination of spores present. FUN-1 demonstrated that fungal spores entered into a viable but not culturable (VBNC) state on copper indicating the importance of using such methods when assessing the effect of an antifungal as culture alone may give false results.

SIGNIFICANCE AND IMPACT OF STUDY

Copper offers a valuable alternative to aluminium which could be used in air-conditioning systems in buildings, particularly in hospital environments where patients are more susceptible to fungal infections.

Adverse health effects of particulate air pollution: modification by air conditioning

BACKGROUND

The short-term effects of particulate matter (PM) on mortality and morbidity differ by geographic location and season. Several hypotheses have been proposed for this variation, including different exposures with air conditioning (AC) versus open windows.

METHODS

Bayesian hierarchical modeling was used to explore whether AC prevalence modified day-to-day associations between PM10 and mortality, and between PM2.5 and cardiovascular or respiratory hospitalizations, for those 65 years and older. We considered yearly, summer-only, and winter-only effect estimates and 2 types of AC (central and window units).

RESULTS

Communities with higher AC prevalence had lower PM effects. Associations were observed for cardiovascular hospitalizations and central AC. Each additional 20% of households with central AC was associated with a 43% decrease in PM2.5 effects on cardiovascular hospitalization. Central AC prevalence explained 17% of between-community variability in PM2.5 effect estimates for cardiovascular hospitalizations.

CONCLUSIONS

Higher AC prevalence was associated with lower health effect estimates for PM.

Immune reconstitution following hematopoietic stem-cell transplantation

Hematopoietic stem-cell transplantation is associated with a profound immune deficiency manifested as an increased propensity to develop infections and probably also malignancies. Innate immunity, including epithelial barriers and phagocytes, typically recovers within weeks after grafting, and B-cell counts and CD8 T-cell counts recover within months. CD4 T-cell counts are low for years, and their recovery is particularly slow in older patients with poor thymic function. Therapies to improve immune function include vaccinations, immunoglobulins for recurrent infections, cytokines, and antigen-specific donor lymphocyte infusions.