Outbreak investigation

During April 1–30, 2021, at Thammasat University Hospital (Prathum Thani, Thailand), the first case of aspergillosis was detected in a COVID-19 ICU patient, followed by 3 additional cases in the same COVID-19 ICU, accounting for 16% of the 25 patients in the ICU within a month. All 4 patients were diagnosed with probable invasive pulmonary aspergillosis by positive fungal cultures obtained by bronchoalveolar lavage and positive serum galactomannan based on consensus definitions of invasive fungal disease from the European Organization for Research and Treatment of Cancer and the Mycoses Study Group Education and Research Consortium. ^{Reference Donnelly, Chen and Kauffman7} The fungal culture of the first patient revealed Aspergillus flavus, and cultures from the other 3 patients yielded Aspergillus fumigatus. All of these patients died within 2 weeks after positive fungal cultures. After these patients were identified, an outbreak investigation was initiated based on a bundle of key methods for preventing filamentous fungal infection associated with renovation and construction activities. ^{Reference Kanamori, Rutala, Sickbert-Bennett and Weber4} The hospital epidemiologist performed an infection control risk assessment (ICRA) of renovation and construction activity near the ICU. Initial outbreak investigation steps included air sampling to measure airborne fungal bioburden at the front of ICU, the nursing station, the index patient anterooms, and rooms. Airborne fungal bioburdens from air sampling were 235–290 CFU/m³ at all sites. In this hospital, the baseline standard airborne fungal bioburden was <500 CFU/m³ for the general unit and <150 CFU/m³ for the ICU and operating room. ^{Reference Apisarnthanarak, Khawcharoenporn and Mundy8} Air pressures in the COVID-19 unit were checked at the front of ICU, the nursing station, the index patient anterooms, and the index patient rooms and measured 0, 0, −5, and −10 kPa, respectively. The hospital epidemiology team assessed the standard of construction sites using the ICRA for all renovation and construction activities and identified the demolition work including removing the floor covering, ceiling tiles, case work, and new wall construction on the same floor as the COVID-19 ICU. Based on the ICRA matrix, the patient population was classified as the “highest risk group,” and the construction project was classified as type C, leading to a designation of class IV renovation/construction. (The ICRA matrix is available at https://www.ashe.org/icra2.) After inspecting the construction site to identify possible solutions, we instituted appropriate preventive measures.

Following the outbreak investigation, focused preventive efforts to reduce airborne fungal spores using the following interventions: site containment, installation of critical barriers to seal construction areas from clinical areas, cleaning of construction areas, use negative air-pressure handling of the construction site using exhaust fans, and installing portable HEPA filters at the construction site. Pressure at the ICU was recalibrated to be +10 kPa at the nursing station, −10 kPa in all anterooms, and −20 kPa in all patient rooms. Additional interventions included continuous monitoring and serial air sampling for airborne fungal bioburden at the front of ICU, the nursing station, the index patient’s anterooms, and rooms. Our interventions revealed a substantial reduction in airborne fungal bioburden in the air; airborne fungal levels declined to 30–50 CFU/m³ at all sites. Continued surveillance for healthcare-associated filamentous fungal infections during renovation and construction was performed for an additional 6 months, and no additional cases of aspergillosis in the same unit occurred.

In conclusion, hospital construction and renovations activities are never ending, and they are the main cause of healthcare-associated fungal outbreaks, ^{Reference Vonberg and Gastmeier5} which pose a serious threat to immunocompromised hosts, including high-risk patients (eg, COVID-19 pneumonia patients). Following ICRA for renovation and construction decreases the risk of healthcare-associated fungal outbreaks. However, ICRAs are not typically performed in developing countries, which may lead to healthcare-associated fungal outbreaks in settings such as ICUs, hematologic wards, and renal transplant units. ^{Reference Repetto, Giacomazzi and Castelli6} Although uncommon, healthcare-associated fungal outbreaks must be suspected when 2 or more cases occur in a short period. ^{Reference Repetto, Giacomazzi and Castelli6} Early outbreak investigation and identification of the source are likely to play a key role in limiting the spread of healthcare-associated fungal outbreaks. Such strategies, together with a full compliance with recommendations from a multidisciplinary coordination team, will help limit the construction-related fungal infection in a COVID-19 ICU. National strategies are needed in developing countries to promote the use of ICRA for renovation and construction to limit healthcare-associated fungal outbreaks.