Fungal surveillance of an open haematology ward

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.

Cluster of Fusarium verticillioides bloodstream infections among immunocompetent patients in an internal medicine department after reconstruction works in Larissa, Central Greece

BACKGROUND

Fusarium spp. can cause disseminated infections, particularly in immunocompromised patients. Fusarium verticillioides is a human pathogen, and sporadic cases of fusariosis have been reported.

AIM

To report a nosocomial cluster of F. verticillioides bloodstream infections among seven immunocompetent inpatients following reconstruction works.

METHODS

Identification was performed using macroscopic and microscopic morphology, and molecular assays (sequencing the nuclear ribosomal internal transcribed spacer region and translation elongation factor-1α gene). Susceptibility testing was performed in accordance with the guidelines of the Clinical and Laboratory Standards Institute. Environmental surveillance specimens were taken and cultured on Sabouraud dextrose agar plates.

FINDINGS

In total, 16 blood cultures obtained from the seven patients were positive for F. verticillioides. All surveillance cultures were negative.

CONCLUSIONS

In order to prevent fungaemia, it is important to implement effective infection control measures, before, during and after demolition and construction activities in healthcare settings.

Fungal pollution of indoor environments and its management

Indoor environments play important roles in human health. The health hazards posed by polluted indoor environments include allergy, infections and toxicity. Life style changes have resulted in a shift from open air environments to air tight, energy efficient, environments, in which people spend a substantial portion of their time. Most indoor air pollution comes from the hazardous non biological agents and biological agents. Fungi are ubiquitous in distribution and are a serious threat to public health in indoor environments. In this communication, we have reviewed the current status on biotic indoor air pollution, role of fungi as biological contaminants and their impact on human health.

Fungal pollution of indoor environments and its management

Indoor environments play important roles in human health. The health hazards posed by polluted indoor environments include allergy, infections and toxicity. Life style changes have resulted in a shift from open air environments to air tight, energy efficient, environments, in which people spend a substantial portion of their time. Most indoor air pollution comes from the hazardous non biological agents and biological agents. Fungi are ubiquitous in distribution and are a serious threat to public health in indoor environments. In this communication, we have reviewed the current status on biotic indoor air pollution, role of fungi as biological contaminants and their impact on human health.

Dynamics of fungal colonization in a new medical mycology laboratory

OBJECTIVE OF THE STUDY

Study of the spatio-temporal fungal colonization in a new medical mycology laboratory.

METHODS

A 17-month survey of airborne fungal contamination was conducted in a new medical mycology laboratory at a tertiary care university hospital. This survey was implemented at three different periods: before the new premises were occupied (period A), during the move into the new laboratory (period B) and after resumption of the mycological activities in these new premises (period C).

RESULTS

During period A, the airborne fungal load ranged from 2.3 to 6 cfu/m(3). The most frequently recovered airborne fungi were Penicillium spp. (75 to 100%). During period B, a dramatic increase in Penicillium chrysogenum conidia was observed in the air of the new laboratory (40 to 160 cfu/m(3)). During period C, the fungal load ranged from 4.5 to 8.4 cfu/m(3). Penicillium was the most common genus identified in rooms of the laboratory where no filamentous fungi were handled, while Aspergillus was clearly the predominant genus (78%) in the room dedicated to the culture of filamentous fungi.

CONCLUSIONS

We suggest that the specific fungal ecology in air of the room dedicated to the culture of filamentous fungi is due to the handling of a large number of medical strains of A. fumigatus.

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.

Influence of internal and outdoor factors on filamentous fungal flora in hematology wards

BACKGROUND

Nosocomial invasive filamentous fungi infections could result from inhalation of filamentous fungi conidia present in hospital environment.

METHODS

The environmental fungal flora in 3 different hospital wards with similar air conditioning was prospectively studied during 30 months and compared to internal (presence of agranulocytosis patient, behavioral practices, activity, cleaning work) and outdoor factors (meteorologic data, outdoor fungi). The general preventive measures differed from one unit to another.

RESULTS

The hematology wards with filamentous fungi preventive measures were significantly less contaminated than a conventional ward without specific measures. Internal and outdoor factors influenced the level of fungal flora. However, the influence of internal factors was greater in the conventional ward than in hematology wards. The variation of flora in the hospital environment was seasonal, and the level of this contamination in each ward was influenced by the meteorology. However, outdoor factors more readily explain the variations of fungal load in hematology than in the conventional ward.

CONCLUSION

This study highlights that specific preventive measures participate significantly in the control of the filamentous fungal flora intensity due to internal factors but not those due to outdoor factors, stressing the importance of high-efficiency particulate air filtration in high-risk units.

Invasive Aspergillus infections in allo-SCT recipients: environmental sampling, nasal and oral colonization and galactomannan testing

A study was performed to investigate the air quality of a haematopoietic SCT ward, colonization of the upper airways with Aspergillus spp. and the role of galactomannan (GM) ELISA testing in serum in the diagnosis of invasive aspergillosis (IA). In 102 allo-SCT recipients, two cases of IA (one proven and one probable) were seen. Of 2071 serum samples, 12 were positive, two in a patient with proven IA and 10 in patients without IA. Of the 2059 negative samples, 22 were taken from the patient with probable IA. Of the 245 environmental samples, 20 (8.2%) were positive for filamentous fungi. Aspergillus fumigatus was seen in 14 samples. A total of 657 oral and nasal swabs were taken. Seven nasal samples and one oral sample were positive for Aspergillus species (A. fumigatus 4, A. niger 4) in four patients, one of whom had probable IA. In summary, most environmental samples were negative, colonization of the oral and nasal cavities was rare and IA was diagnosed in only 2% of patients. The GM ELISA test remained negative in one of two patients with IA and does not seem useful in a population of patients with a low incidence of IA.

Genomic islands in the pathogenic filamentous fungus Aspergillus fumigatus

We present the genome sequences of a new clinical isolate of the important human pathogen, Aspergillus fumigatus, A1163, and two closely related but rarely pathogenic species, Neosartorya fischeri NRRL181 and Aspergillus clavatus NRRL1. Comparative genomic analysis of A1163 with the recently sequenced A. fumigatus isolate Af293 has identified core, variable and up to 2% unique genes in each genome. While the core genes are 99.8% identical at the nucleotide level, identity for variable genes can be as low 40%. The most divergent loci appear to contain heterokaryon incompatibility (het) genes associated with fungal programmed cell death such as developmental regulator rosA. Cross-species comparison has revealed that 8.5%, 13.5% and 12.6%, respectively, of A. fumigatus, N. fischeri and A. clavatus genes are species-specific. These genes are significantly smaller in size than core genes, contain fewer exons and exhibit a subtelomeric bias. Most of them cluster together in 13 chromosomal islands, which are enriched for pseudogenes, transposons and other repetitive elements. At least 20% of A. fumigatus-specific genes appear to be functional and involved in carbohydrate and chitin catabolism, transport, detoxification, secondary metabolism and other functions that may facilitate the adaptation to heterogeneous environments such as soil or a mammalian host. Contrary to what was suggested previously, their origin cannot be attributed to horizontal gene transfer (HGT), but instead is likely to involve duplication, diversification and differential gene loss (DDL). The role of duplication in the origin of lineage-specific genes is further underlined by the discovery of genomic islands that seem to function as designated “gene dumps” and, perhaps, simultaneously, as “gene factories”.

Aspergillus is an extremely diverse genus of filamentous ascomycetous fungi (molds) found ubiquitously in soil and decomposing vegetation. Being supreme opportunists, aspergilli have adapted to overcome various chemical, physical, and biological stresses found in heterogeneous environments. While most species in the genus are saprophytes, a surprising number are able to infect wounded plants and animals. Remarkably, the allergic human host also responds abnormally to the aspergilli with lung and sinus disease. The advent of immunosuppressive agents and other medical advances have created a large worldwide pool of human hosts susceptible to some Aspergillus species, including the world's most harmful mold and the causative agent of invasive aspergillosis, Aspergillus fumigatus. In this study, we have used the power of comparative genomics to gain insight into genetic mechanisms that may contribute to the metabolic versatility and pathogenicity of this important human pathogen. Comparison of the genomes of two A. fumigatus clinical isolates and two closely related, but rarely pathogenic species showed that their genomes contain several large isolate- and species-specific chromosomal islands. The metabolic capabilities encoded by these highly labile regions are likely to contribute to their rapid adaptation to heterogeneous environments such as soil or a living host.

Ten-year air sample analysis of Aspergillus prevalence in a university hospital

Airborne fungal samples were collected on a monthly basis for 10 years, from 1995 to 2005, at a tertiary university hospital. Paired samples were cultured at 25 and 37 degrees C. Data were interpreted according to the air filtration systems serving each location. Samples cultured at 37 degrees C from the patient care areas had a mean recovery of 18% of the mean recovery from outdoor air (22 versus 122cfu/m(3)). Recovery of Aspergillus spp. at 37 degrees C in the high-efficiency particulate air (HEPA)-filtered locations was positive for Aspergillus spp. approximately one-third of the time; the rest of the patient care areas were positive half of the time and the outdoor samples were positive 95% of the time. We found 48 sporadic bursts at 37 degrees C which produced counts >3 SD above the mean. Hospital-acquired infection was related to high recovery of Aspergillus fumigatus on at least one occasion. We have found it impossible, without implementing impractical measures, to provide an environment completely devoid of Aspergillus spp. We conclude that routine air sampling is not an effective means of predicting hospital-acquired infections. However, a transient spike, or burst, may be useful in identifying an in-house source of contamination and may be used to consider additional interventional treatments for patients at risk. Emphasis should be placed on maintaining high-efficiency filtration of the outside air and on ensuring that other environmental control methods are used to prevent dissemination of environmental opportunistic fungal spores.

The utility of intensified environmental surveillance for pathogenic moulds in a stem cell transplantation ward during construction work to monitor the efficacy of HEPA filtration

A 12-week environmental study was performed to ensure that the patient rooms of an SCT ward with high-efficiency particulate air (HEPA) filtration remained uncontaminated by moulds during close-by construction work. The sampling included measuring the ventilation channel pressure, particle count measurements, air sampling, settled dust analysis and fungal cultures from the oral and nasal cavities of the patients. No changes in the air pressure occurred. Median particle counts in patient rooms were 63-420 particles/l. The mean particle count of the outside air was 173,659 particles/l. Patient room air samples were negative for aspergilli in 32 of 33 cases. All samples of the outside air were positive for moulds. Aspergillus fumigatus was isolated at the beginning of excavation works at the construction area and in two of 33 dust samples from patient rooms. All 70 nasal samples were negative. Of 35 mouth samples, one sample was positive for A. niger in a patient with a previously diagnosed aspergillus infection. During a median follow-up of 214 days, no invasive aspergillus infections were diagnosed in the 55 patients treated during the construction period. In conclusion, the HEPA filters seemed to have performed well in preventing an aspergillosis outbreak.

Catheter-related bloodstream infections in hematology

Central venous catheters are essential in the management of many malignant disorders, but catheter-related bloodstream infections (CR-BSIs) are significant complications in terms of morbidity, mortality, and healthcare expenditure. These outcome measures are useful for monitoring of infection control practice and the effect of preventive strategies. Unlike intensive care unit (ICU) populations, surveillance for CR-BSIs in the hematology population is not standardized, despite the potential value of detecting changes in rate, etiology, and changes in risk for infective complications in association with increasingly intensive chemotherapeutic regimens in this immunocompromised population. Essential components of a successful surveillance strategy include selection of a health outcome of significance, definition of goals of the surveillance system, involvement of key stakeholders in planning and development, application of valid case definitions, allocation of resources and trained personnel, risk stratification, and use of appropriate statistical methods for analysis. These are discussed with reference to patients with hematologic malignancy, together with review of previous surveillance strategies in this population. Only when these issues are addressed can a surveillance strategy reliably assess trends and compare data, leading to improved patient outcomes and a reduction in healthcare expenditure for patients with hematologic malignancy.

Levels of total fungus and Aspergillus on a pediatric hematopoietic stem cell transplant unit

The purpose of this descriptive study was to determine the levels of total fungus (TF) and Aspergillus in a pediatric hematopoietic stem cell transplant (HSCT) unit. One hundred twenty air samples and 120 floor samples were collected from the same locations in 10 patient rooms and bathrooms for 4 consecutive days. The count in colony-forming units of TF and Aspergillus from each of the samples was measured by the institution's mycology laboratory. Means, standard deviations, minimum values, and maximum values were determined for levels of TF and Aspergillus from different locations and on different days in the air and on the floor. Determination of a mean value of TF and Aspergillus for each room allowed for analysis of mean values of TF and Aspergillus for sample category, room side, room type, and room status. After visual examination of the mean values for the air samples collected, it was determined that the TF and Aspergillus in the air were less than the institution's acceptable air baseline standard. t tests and analysis of variance were used to verify the findings.

Impact of portable air filtration units on exposure of haematology-oncology patients to airborne Aspergillus fumigatus spores under field conditions

We undertook a one-year study to investigate the impact of the NSA model 7100A/B portable air filtration unit on exposure of haematology-oncology patients to airborne Aspergillus fumigatus spores under field conditions. Weekly measurements for airborne A. fumigatus were conducted in indoor and outdoor air, and surveillance for invasive aspergillosis was based on a combination of ward liaison, targeted chart review and consultation with the medical staff. The mean indoor A. fumigatus counts (8.1 cfu/m3; range, <0.8 to 42 cfu/m3) reflected the fungal load of outdoor air (9.4 cfu/m3; range, <0.8 to 50 cfu/m3), and were reduced by only about one third in rooms with portable air filtration units (5.3 cfu/m3; range, <0.8 to 41 cfu/m3). During the study period, a total of five cases (incidence density, 0.8 per 1000 patient-days) of invasive aspergillosis (one proven case, four suspected cases; case fatality rate 40%) were recorded. None of these five patients was allocated to a room with portable air filtration unit, however, the difference between incidence densities in rooms with and without portable air filtration units was non-significant (Fisher's exact test, P=0.33). Due to the noise level and thermal discomfort, patient compliance with the air filtration units was poor. We conclude that under field conditions this air filtration unit cannot be recommended for prevention of invasive aspergillosis in neutropenic haematology-oncology patients.

Environmental surveillance of filamentous fungi in three tertiary care hospitals in Greece

The environmental fungal load (FL) of three hospitals was studied in representative regions in Greece (Thessalonika, Northern Greece, Athens, Central Greece and Heraklion, Southern Greece). Air, surfaces and tap water from high-risk departments were sampled monthly during one year. Air FL was [median (range)] 10.6 (1.2-37), 5.5 (3-28.8) and 7.7 (3.1-12.1) cfu/m(3) at Thessalonika, Athens and Heraklion, respectively. Air FL was lower in winter and higher in summer and autumn but seldom above acceptable levels. Aspergillus spp. constituted 70.5% of the filamentous fungi isolated. Aspergillus niger was the most prevalent species in the air of all the hospitals followed by Aspergillus flavus and Aspergillus fumigatus. The least contaminated departments were the intensive care units, whilst most contaminated were the solid organ transplantation in Athens and haematology departments in Thessalonika. No correlation between fungal species, season, hospital or departments was observed. Sixty per cent of all surfaces examined yielded filamentous fungi and/or blastomycetes. While no fungi were recovered from water in Thessalonika and Athens, one-third of the samples in Heraklion (apart from those of ICU) yielded multiple fungal species. The higher air FL in Thessalonika and Athens was recorded in departments located close to renovation works. These findings suggest that the air and surface FL fluctuates over the year, is due to varying fungal species, but does not differ greatly among hospitals. The variation among hospitals, as well as the role of hospital water fungal contamination and appropriate measures to eliminate it, need further study.

Environmental surveillance and other control measures in the prevention of nosocomial fungal infections

The steady world-wide increase in the number of severely immunocompromised patients in most hospitals has made the control and prevention of nosocomial systemic fungal infections a critical quality-of-care standard. Early diagnosis and antifungal prophylaxis of these infections are complicated, so avoiding the acquisition of the pathogen in the case of Aspergillus and minimizing the predisposing risk factors in the case of Candida are more effective approaches. The maintenance of good air quality in critical areas in hospitals is mandatory to reduce the incidence of invasive aspergillosis. We review the currently available Center for Disease Control recommendations and report our own experiences in the field. The indications and problems of fungal environmental and patient surveillance are also discussed.

Relationship between environmental fungal contamination and the incidence of invasive aspergillosis in haematology patients

Invasive aspergillosis (IA) is a major opportunistic infection in haematology patients. Spore inhalation is the usual route of Aspergillus infection, suggesting a determining role of environmental contamination by spores in the epidemiology of IA. We prospectively examined the relationship between environmental contamination by Aspergillus and other fungal species and the incidence of invasive nosocomial aspergillosis (INA) in a bone marrow transplantation unit and two haematology wards. During a four-year period, levels of air and surface fungal contamination were determined bi-monthly in patients' rooms (some equipped with HEPA filters and LAF systems), and various common sites in each ward (corridors, nursing stations, etc.). Results were compared to the incidence of INA. A total of 3100 air and 9800 surface samples were collected, and 79 cases of IA were diagnosed, of which 64 were probably or possibly INA. Patterns of fungal contamination were comparable in the three wards, with a gradient ranging from high levels in common sites to a virtual absence in rooms equipped with HEPA filters and LAF systems. Using a regression model, a significant relationship was found between the incidence of INA and the degree of fungal contamination of air and surfaces in conventional patient rooms (not equipped with HEPA) and common sites. This study shows that in a non-epidemic setting, there is a significant relationship between environmental fungal contamination in haematology wards and the incidence of INA. Our findings underline the importance of environmental surveillance and strict application of preventive measures.