Fungal infections after haematology unit renovation: evidence of clinical, environmental and economical impact

Environmental monitoring for filamentous fungal pathogens in hematopoietic cell transplant units

The incidence of invasive fungal disease (IFD) is on the rise due to increasing numbers of highly immunocompromized patients. Nosocomial IFD remains common despite our better understanding of its risk factors and pathophysiology. High-efficiency particulate air filtration with or without laminar air flow, frequent air exchanges, a positive pressure care environment, and environmental hygiene, amongst other measures, have been shown to reduce the mould burden in the patient environment. Environmental monitoring for moulds in areas where high-risk patients are cared for, such as hematopoietic cell transplant units, has been considered an adjunct to other routine environmental precautions. As a collaborative effort between authors affiliated to the Infection Prevention and Control Working Group and the Fungal Infection Working Group of the International Society of Antimicrobial Chemotherapy (ISAC), we reviewed the English language literature and international guidance to describe the evidence behind the need for environmental monitoring for filamentous fungi as a quality assurance approach with an emphasis on required additional precautions during periods of construction. Many different clinical sampling approaches have been described for air, water, and surface sampling with significant variation in laboratory methodologies between reports. Importantly, there are no agreed-upon thresholds that correlate with an increase in the clinical risk of mould infections. We highlight important areas for future research to assure a safe environment for highly immunocompromized patients.

COVID-19 Outbreak and Hospital Air Quality: A Systematic Review of Evidence on Air Filtration and Recirculation

The outbreak of SARS-CoV-2 has made us all think critically about hospital indoor air quality and the approaches to remove, dilute, and disinfect pathogenic organisms from the hospital environment. While specific aspects of the coronavirus infectivity, spread, and routes of transmission are still under rigorous investigation, it seems that a recollection of knowledge from the literature can provide useful lessons to cope with this new situation. As a result, a systematic literature review was conducted on the safety of air filtration and air recirculation in healthcare premises. This review targeted a wide range of evidence from codes and regulations, to peer-reviewed publications, and best practice standards. The literature search resulted in 394 publications, of which 109 documents were included in the final review. Overall, even though solid evidence to support current practice is very scarce, proper filtration remains one important approach to maintain the cleanliness of indoor air in hospitals. Given the rather large physical footprint of the filtration system, a range of short-term and long-term solutions from the literature are collected. Nonetheless, there is a need for a rigorous and feasible line of research in the area of air filtration and recirculation in healthcare facilities. Such efforts can enhance the performance of healthcare facilities under normal conditions or during a pandemic. Past innovations can be adopted for the new outbreak at low-to-minimal cost.

Effects of indoor environmental parameters related to building heating, ventilation, and air conditioning systems on patients' medical outcomes: A review of scientific research on hospital buildings

The indoor environment of a mechanically ventilated hospital building controls infection rates as well as influences patients' healing processes and overall medical outcomes. This review covers the scientific research that has assessed patients' medical outcomes concerning at least one indoor environmental parameter related to building heating, ventilation, and air conditioning (HVAC) systems, such as indoor air temperature, relative humidity, and indoor air ventilation parameters. Research related to the naturally ventilated hospital buildings was outside the scope of this review article. After 1998, a total of 899 papers were identified that fit the inclusion criteria of this study. Of these, 176 papers have been included in this review to understand the relationship between the health outcomes of a patient and the indoor environment of a mechanically ventilated hospital building. The purpose of this literature review was to summarize how indoor environmental parameters related to mechanical ventilation systems of a hospital building are impacting patients. This review suggests that there is a need for future interdisciplinary collaborative research to quantify the optimum range for HVAC parameters considering airborne exposures and patients' positive medical outcomes.

Outcome of non-mold effective anti-fungal prophylaxis in patients at high-risk for invasive fungal infections after allogenic stem cell transplantation

Patients who develop severe graft-versus-host disease (GvHD) after allogeneic stem cell transplantation (alloSCT) have a higher risk for invasive fungal infection (IFI). At our center, fluconazole prophylaxis is standard and upfront mold-effective prophylaxis performed only in patients with specific risk constellations. A total of 290 patients undergoing alloSCT between May 2002 and August 2011 were analyzed. Patients were regarded as high-risk if they suffered from acute GvHD II-IV° or extensive chronic GvHD. The 2-year incidence of an IFI after alloSCT was 8.97% (26/290) in the entire cohort and 7.78% (7/90) in the high-risk group. Mortality due to IFI was 3.85% (1/26) without including a high-risk patient. In the multivariate analysis a pre-transplant fungal infection was the only significant risk factor for developing an IFI after alloSCT (HR = 5.298; p = .001). A fluconazole prophylaxis in patients with GvHD after alloSCT is feasible in facilities with HEPA filtration and high awareness of clinical signs for IFI.

Profiles of Environmental Mold: Indoor and Outdoor Air Sampling in a Hematology Hospital in Seoul, South Korea

Inhalation of fungal spores can cause various spectrums of fungal diseases in immunocompromised hosts. The aim of this study was to evaluate the concentrations and profiles of fungal species in air collected at different locations in hematology wards and outside of the hospital in Seoul St. Mary's Hospital over the course of a year. Air sampling was performed at four locations-outside the hospital (O), in the general ward (GW), in the lounge in the cleanroom (CR_L), and in the patients' room in the cleanroom (CR_R)-by using Andersen single-stage air sampler at every two weeks between May 2017 and May 2018. The results showed higher mean fungal density in summer, and the concentrations of fungi decreased as follows: O (954.8 colony-forming units, CFU/m³) > GW (4.2 CFU/m³) > CR_L (0.7 CFU/m³) > CR_R (0 CFU/m³). Aspergillus was most prevalent both inside (47%) and outside (62%) of the hospital. However, the outdoor fungal profile was more diverse than the indoor profile. Within the hospital, Penicillium was the second most dominant species. In conclusion, the outdoor fungal profile is diverse even in Seoul, a highly urbanized area in Korea. The distribution of indoor air fungi is significantly different from outdoor due to air quality systems. Heating, ventilation, and air conditioning (HVAC), as well as high-efficiency particulate air (HEPA)-filtered systems should be established to effectively reduce levels of indoor fungi.

Fungal Genomes and Genotyping

The availability of complete fungal genomes is expanding rapidly and is offering an extensive and accurate view of this "kingdom." The scientific milestone of free access to more than 1000 fungal genomes of different species was reached, and new and stimulating projects have meanwhile been released. The "1000 Fungal Genomes Project" represents one of the largest sequencing initiative regarding fungal organisms trying to fill some gaps on fungal genomics. Presently, there are 329 fungal families with at least one representative genome sequenced, but there is still a large number of fungal families without a single sequenced genome. In addition, additional sequencing projects helped to understand the genetic diversity within some fungal species. The availability of multiple genomes per species allows to support taxonomic organization, brings new insights for fungal evolution in short-time scales, clarifies geographical and dispersion patterns, elucidates outbreaks and transmission routes, among other objectives. Genotyping methodologies analyze only a small fraction of an individual's genome but facilitate the comparison of hundreds or thousands of isolates in a small fraction of the time and at low cost. The integration of whole genome strategies and improved genotyping panels targeting specific and relevant SNPs and/or repeated regions can represent fast and practical strategies for studying local, regional, and global epidemiology of fungi.

Cost-effectiveness analysis of interventions for prevention of invasive aspergillosis among leukemia patients during hospital construction activities

OBJECTIVES

Invasive Aspergillosis (IA) is a serious problem among hematological patients and it is associated with high mortality. This situation can worsen at times of hospital construction, however there are several preventive measures available. This work aims to define the cost-effectiveness of some of these interventions.

PATIENTS AND METHODS

A decision tree model was used, it was divided into four arms according to each 1 of the interventions performed. A cost-effectiveness incremental analysis comparing environmental control measures, high efficiency particulate absorption (HEPA) filter installation and prophylaxis with posaconazole was done. Probabilistic and deterministic sensitivity analyses were also carried out.

RESULTS

Among 86 patients with 175 hospitalization episodes, the incidence of IA with environmental protection measures, antifungal prophylaxis and hospitalization in rooms with HEPA filters was 14.4%, 6.3% and 0%, respectively. An Incremental Cost Effectiveness Ratio analysis was performed and it was found that HEPA filtered rooms and environmental protection measures are cost saving interventions when compared with posaconazole prophylaxis (-$2665 vs -$4073 vs $42 531 US dollars, respectively) for IA episode prevented.

CONCLUSION

The isolation of inpatients with acute leukemia during hospital construction periods in HEPA filtered rooms could reduce the incidence of IA and might be a cost-effective prevention strategy.

Effectiveness of environmental control measures to decrease the risk of invasive aspergillosis in acute leukaemia patients during hospital building work

BACKGROUND

Invasive aspergillosis (IA) is a significant problem in acute leukaemia patients. Construction work near hospital wards caring for immunocompromised patients is one of the main risk factors for developing invasive pulmonary aspergillosis (IPA).

AIM

To assess the impact of environmental control measures used during hospital construction for the prevention of IA in acute leukaemia patients.

METHODS

A retrospective cohort study was developed to evaluate the IA incidence in acute leukaemia patients with different environmental control measures employed during hospital construction. We used European Organisation for the Research and Treatment of Cancer (EORTC) criterial diagnosis parameters for definition of IA.

FINDINGS

A total of 175 episodes of inpatient care were evaluated, 62 of which did not have any environmental control measures (when an outbreak occurred), and 113 that were subject to environmental control measures directed to preventing IA. The study showed an IA incidence of 25.8% for the group without environmental control measures vs 12.4% for those who did receive environmental control measures (P=0.024). The relative risk for IA was 0.595 (95% confidence interval: 0.394-0.897) for the group with environmental control measures.

CONCLUSION

The current study suggests that the implementation of environmental control measures during a hospital construction has a positive impact for prevention of IA in patients hospitalized with acute leukaemia.

Recombination detection in Aspergillus fumigatus through single nucleotide polymorphisms typing

The first evidence of sexual reproduction in Aspergillus fumigatus was reported in 2009. Nevertheless, it remains difficult to understand how A. fumigatus is able to reproduce through this mode in its natural environment and how frequently this occurs. The aim of this study was to analyse single nucleotide polymorphisms (SNPs) in a set of environmental and clinical isolates of A. fumigatus to detect signatures of recombination. A group of closely related Portuguese A. fumigatus isolates was characterized by mating type and the genetic diversity of the intergenic regions, microsatellites and multilocus sequence typing (MLST) genes. A group of 19 SNPs, organized in nine association groups and inherited in blocks, was identified and compared. Several variations on the association panel were detected on reference isolates of A. fumigatus AF293 and A1163, the sequence types available at MLST database and six clinical and environmental Portuguese isolates. About one to four haplotype disruptions were observed per isolate. Considering clinical and environmental isolates, sexual reproduction seems to occur more frequently than previously admitted in A. fumigatus. In this study, a practical SNP approach is proposed for detection of recombination events in larger collections of A. fumigatus.

Testing an innovative device against airborne Aspergillus contamination

Aspergillus fumigatus is a major airborne nosocomial pathogen that is responsible for severe mycosis in immunocompromised patients. We studied the efficacy of an innovative mobile air-treatment device in eliminating A. fumigatus from the air following experimental massive contamination in a high-security room. Viable mycological particles were isolated from sequential air samples in order to evaluate the device's effectiveness in removing the fungus. The concentration of airborne conidia was reduced by 95% in 18 min. Contamination was reduced below the detection threshold in 29 min, even when the machine was at the lowest airflow setting. In contrast, during spontaneous settling with no air treatment, conidia remained airborne for more than 1 h. This indoor air contamination model provided consistent and reproducible results. Because the air purifier proved to be effective at eliminating a major contaminant, it may prove useful in preventing air-transmitted disease agents. In an experimental space mimicking a hospital room, the AirLyse air purifier, which uses a combination of germicidal ultraviolet C irradiation and titanium photocatalysis, effectively eliminated Aspergillus conidia. Such a mobile device may be useful in routine practice for lowering microbiological air contamination in the rooms of patients at risk.

Assessment of microbiological air quality in hemato-oncology units and its relationship with the occurrence of invasive fungal infections: an integrative review

Worldwide aging of the human population has promoted an increase in the incidence of neoplasia, including hematological cancers, which render patients particularly vulnerable to invasive fungal infections. For this reason, air filtration in hematooncology units has been recommended. However, scarce literature has assessed the impact of microbiological air quality on the occurrence of fungal infections in this population. We performed an integrative review of studies in the MEDLINE database that were published between January 1980 and October 2012, using the following combinations of keywords: air × quality × HEPA, air × quality × hematology, and airborne fungal infections. The search yielded only 13 articles, suggesting that high-efficiency filtering of the ambient air in hemato-oncology units can prevent the incidence of invasive fungal infections. However, no randomized clinical trial was found to confirm this suggestion. Currently, there is no consensus about the maximum allowable count of fungi in the air, which complicates filtration monitoring, including filter maintenance and replacement, and needs to be addressed in future studies.

Effectiveness of a Protective Environment implementation for cancer patients with chemotherapy-induced neutropenia on fever and mortality incidence

In a quasiexperimental study conducted to evaluate the impact of a Protective Environment implementation, febrile neutropenia (P = .009), overall mortality (P = .001), and 30-day adjusted mortality (P = .02) were reduced in cancer patients with chemotherapy-induced neutropenia. Our study highlights the potential success of a set of prevention measures mainly designed to reduce invasive environmental fungal infections in allogeneic hematopoietic stem cell transplant patients, in reducing fever and mortality among neutropenic cancer patients.

Immunological aspects of Candida and Aspergillus systemic fungal infections

Patients with allogeneic stem cell transplantation (SCT) have a high risk of invasive fungal infections (IFIs) even after neutrophil regeneration. Immunological aspects might play a very important role in the IFI development in these patients. Some data are available supporting the identification of high-risk patients with IFI for example patients receiving stem cells from TLR4 haplotype S4 positive donors. Key defense mechanisms against IFI include the activation of neutrophils, the phagocytosis of germinating conidia by dendritic cells, and the fight of the cells of the innate immunity such as monocytes and natural killer cells against germlings and hyphae. Furthermore, immunosuppressive drugs interact with immune effector cells influencing the specific fungal immune defense and antimycotic drugs might interact with immune response. Based on the current knowledge on immunological mechanism in Aspergillus fumigatus, the first approaches of an immunotherapy using human T cells are in development. This might be an option for the future of aspergillosis patients having a poor prognosis with conventional treatment.

[Quantitative assessment of fungal risk in the case of construction works in healthcare establishments: Proposed indicators for the determination of the impact of management precautions on the risk of fungal infection]

Construction works in healthcare establishments produce airborne fungal spores and considerably increase the risk of exposure of immunosuppressed patients. It is necessary to reinforce protective measures, or even to implement specific precautions, during this critical phase. The aim of these precautions is to protect both those areas, which are susceptible to dust, and patients at risk of a fungal infection particularly invasive aspergillosis. When construction works are planned in healthcare establishments, the first step consists in the characterisation of the environmental fungal risk and the second one in proposing risk management methods. It is then essential to establish impact indicators in order to evaluate the risk management precautions applied. The working group promoted by the French societies of medical mycology and hospital hygiene (SFMM & SF2H) details here both environmental and epidemiological impact indicators that can be used.

Fungal aero-decontamination efficacy of mobile air-treatment systems

Immunosuppressed patients are at high risk of acquiring airborne fungal infections, mainly caused by Aspergillus species. Although HEPA filters are recommended to prevent environmental exposure, mobile air-treatment units can be an alternative. However, many different models of mobile units are available but there are few data on their fungal aero-decontamination efficacy and usefulness in the prevention of Aspergillus infections. Thus, we developed a challenge test, based on the aerosolization of 10(6) Aspergillus niger conidia, in order to compare the particle and fungal decontamination efficacy of the following four mobile air-treatment systems; Plasmair T2006, Mobil'Air 1200 (MA1200), Mobil'Air 600 (MA600) combined with Compact AirPur Mobile C250 (C250), and the prototype unit Compact AirPur Mobile 1800 (C1800). The use of all these air-treatment systems was able to significantly decrease the concentration of particles or fungal viable conidia. ISO7 was the maximum particle class reached within 20 min with the Plasmair T2006 and MA1200, 1 h by the combined MA600/C250, and 1 h and 30 min with the C1800. After 2 h, fungal counts were significantly lower with Plasmair T2006, MA1200 and the combined MA600/C250 (2.2 ± 1.9 to 5.0 ± 3.7 CFU/m(3)) than achieved with the C1800 (23.8 ± 12.8 CFU/m(3); P ≤ 6.0E-3). All the air-treatment systems were able to decrease aerial particle and fungal counts, but their efficacy was variable, depending on the units' air-treatment modalities and rates of air volume that was processed. This comparative study could be helpful in making an informed choice of mobile units, and in improving the prevention of air-transmitted fungal infections in non-protected areas.

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.

Cytotoxicity of Aspergillus strains isolated from the neonatal intensive care unit environment

PURPOSE

It is essential in the medical care for immunocompromised patients that the environment should create minimal infection risk. Particularly, it concerns fungal infections. Fungi belonging to the Aspergillus genus are second frequent group of nosocomial pathogens producing opportunistic infections.

MATERIAL AND METHODS

The objective of the study was evaluation of prevalence and cytotoxicity of selected Aspergillus strains isolated from the neonatal intensive care unit environment. During 5 consecutive days, 30 samples of indoor air and 120 imprints from the ward environment were collected. Cytotoxicity of 17 strains was evaluated using a MTT (3-(4,5-dimethylthiazol-2-yl) 2,5 diphenyltetrazolium bromide) test.

RESULTS

Mean numbers of fungi in the indoor air varied from 50 to 2370 c.f.u.xm-3 while in the imprints from 0.04 to 8.83 c.f.u.xcm-2. Moulds were isolated from most of the materials. All of the 17 strains subject to MTT test were cytotoxic.

CONCLUSION

All of the Aspergillus strains isolated from the neonatal intensive care unit were cytotoxic. Cytotoxic Aspergillus strains present in the environment of immunocompromised patients may be potentially dangerous to them.

Simple and highly discriminatory microsatellite-based multiplex PCR for Aspergillus fumigatus strain typing

The answers to important questions concerning Aspergillus fumigatus pathogenicity, transmissions routes and efficacy of treatments require highly discriminating and reproducible genotyping methods. The present study was aimed at improving microsatellite methodology for A. fumigatus typing by reducing the task of strain identification to a single multiplex reaction and by selecting highly accurate short tandem repeat polymorphisms. A set of eight primer pairs was used for the genotype determination of 116 clinical isolates of A. fumigatus obtained from three healthcare centres. A new, automated and highly discriminatory typing method is described for A. fumigatus strains. The optimized multiplex PCR was successfully performed with all tested clinical strains and showed a discriminatory power of 0.9997 among presumably unrelated isolates. The comparison of groups of strains from different health centres showed that 99.6% of the genotypic variation was present within groups. Strains with the same genotype were isolated from the same patient, sometimes recovered more than 1 year later. A few cases of patients at the same clinic unit carrying strains of identical genotype strongly suggested colonization by A. fumigatus during their hospitalization. Specific measures must therefore be taken in order to prevent and restrict such incidents.