SARS-CoV-2 surveillance with environmental surface sampling in public areas.

Contaminated surfaces are one of the ways that coronavirus disease 2019 (COVID-19) may be transmitted. SARS-CoV-2 can be detected on environmental surfaces; however, few environmental sampling studies have been conducted in nonclinical settings. The objective of this study was to detect SARS-CoV-2 RNA on environmental surfaces in public areas in Las Vegas, Nevada. In total, 300 surface samples were collected from high-touch surfaces from high-congregate public locations and from a public health facility (PHF) that was visited by COVID-19 patients. Environmental samples were analyzed with quantitative reverse-transcriptase polymerase chain reaction (RT-qPCR) using SARS-CoV-2 specific primers and probes for three target genes. Results showed that 31 out of 300 (10.3%) surface samples tested positive for SARS-CoV-2, 24 at the PHF and 7 in high-congregate public locations. Concentrations ranged from 102 to 106 viral particles per 3 ml sample on a wide variety of materials. The data also showed that the N gene assay had greater sensitivity compared to the S and ORF gene assays. Besides frequently touched surfaces, SARS-CoV-2 was detected in restrooms, on floors and surfaces in contact with floors, as well as in a mop water sample. The results of this study describe the extent and distribution of environmental SARS-CoV-2 contamination in public areas in Las Vegas, Nevada. A method using the N gene PCR assay was developed for SARS-CoV-2 environmental monitoring in public areas. Environmental monitoring with this method can determine the specific sites of surface contamination in the community and may be beneficial for prevention of COVID-19 indirect transmission, and evaluation and improvement of infection control practices in public areas, public health facilities, universities, and businesses.

Evaluation of two surface sampling methods for the detection of Bacillus atrophaeus aerosolized in a test chamber.

In response to the airborne release of biothreat agents, surface sampling is often used to provide information on bioaerosol dispersal and deposition, to identify biocontaminant sources, and determine the effectiveness of decontamination. The objective of this project was to use aerosolization and deposition of dry spores to evaluate the efficiency of the cellulose sponge wipe and 37-mm cassette micro vacuum surface sampling methods for the collection of microorganisms from two contaminated surfaces, metal and concrete. Aerosolization trials were performed in a room-sized test chamber with known airborne concentrations of Bacillus atrophaeus spores serving as a surrogate for a bioterrorism agent. Following each aerosolization trial, the chamber heating, ventilation, air conditioning (HVAC) system was turned off to allow airborne spores to settle onto the test materials. Surface sampling was conducted and culture analysis was used to determine the concentration of B. atrophaeus on the surfaces. Results were compared with reference samples to determine the collection efficiency of the sampling methods. The sponge wipe sampling method was significantly more effective than the vacuum method for the collection of B. atrophaeus from both metal and concrete surfaces (P < 0.001). The collection efficiency of the sponge wipe method was 39.5% for metal and 26.5% for concrete, while the collection efficiency of the vacuum method was 7.6% for metal and 9.3% for concrete. The results of this study provided data on the collection efficiencies of two surface sampling methods for detection and enumeration of biocontaminants and can aid in selection of sampling methods.