Environmental contamination in the isolation rooms of COVID-19 patients with severe pneumonia requiring mechanical ventilation or high-flow oxygen therapy

Abstract

Background: Identifying the extent of environmental contamination of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is essential for infection control and prevention. The extent of environmental contamination has not been fully investigated in the context of severe coronavirus disease (COVID-19) patients.

Aim: To investigate environmental SARS-CoV-2 contamination in the isolation rooms of severe COVID-19 patients requiring mechanical ventilation or high-flow oxygen therapy.

Methods: Environmental swab samples and air samples were collected from the isolation rooms of three COVID-19 patients with severe pneumonia. Patients 1 and 2 received mechanical ventilation with a closed suction system, while patient 3 received high-flow oxygen therapy and non-invasive ventilation. Real-time reverse transcription-polymerase chain reaction (rRT-PCR) was used to detect SARS-CoV-2; viral cultures were performed for samples not negative on rRT-PCR.

Findings: Of the 48 swab samples collected in the rooms of patients 1 and 2, only samples from the outside surfaces of the endotracheal tubes tested positive for SARS-CoV-2 by rRT-PCR. However, in patient 3's room, 13 of the 28 environmental samples (fomites, fixed structures, and ventilation exit on the ceiling) showed positive results. Air samples were negative for SARS-CoV-2. Viable viruses were identified on the surface of the endotracheal tube of patient 1 and seven sites in patient 3's room.

Conclusion: Environmental contamination of SARS-CoV-2 may be a route of viral transmission. However, it might be minimized when patients receive mechanical ventilation with a closed suction system. These findings can provide evidence for guidelines for the safe use of personal protective equipment.

Keywords: COVID-19; Environmental contamination; SARS-CoV-2; Severe pneumonia.

Figure 1

Results of, and locations from which, the environmental samples were collected in the room of patient 3. Twenty-eight environmental swab samples were obtained from patient 3's room. Nasal prongs of high-flow oxygen generator, door knob, and telephone are not shown. Swabs from the following tested negative on polymerase chain reaction (PCR): air inlet fan, intravenous pole, computer, medication cart, blind curtain, wall 1, wall 2, window, window frame, door knob, call button, blood pressure cuff, ventilator, and patient monitor. Swabs from the following tested positive on PCR but negative on viral culture: air outlet fan, floor far from the patient, restraint, high-flow oxygen generator, telephone, thermometer, and cup. Swabs from the following tested positive on culture: nasal prong, floor near the patient, bed rails, bedsheets, non-invasive ventilator masks, bedside table, and remote controller. The solid lines radiating from the large green circle indicate the angle of observation used for illustration of the patient's room.