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Understanding the particle size distribution in the air and patterns of environmental contamination of SARS-CoV-2 is essential for infection prevention policies. Here we screen surface and air samples from hospital rooms of COVID-19 patients for SARS-CoV-2 RNA. Environmental sampling is conducted in three airborne infection isolation rooms (AIIRs) in the ICU and 27 AIIRs in the general ward. 245 surface samples are collected. 56.7% of rooms have at least one environmental surface contaminated. High touch surface contamination is shown in ten (66.7%) out of 15 patients in the first week of illness, and three (20%) beyond the first week of illness ( p  = 0.01, χ 2 test). Air sampling is performed in three of the 27 AIIRs in the general ward, and detects SARS-CoV-2 PCR-positive particles of sizes >4 µm and 1–4 µm in two rooms, despite these rooms having 12 air changes per hour. This warrants further study of the airborne transmission potential of SARS-CoV-2. Here, the authors sample air and surfaces in hospital rooms of COVID-19 patients, detect SARS-CoV-2 RNA in air samples of two of three tested airborne infection isolation rooms, and find surface contamination in 66.7% of tested rooms during the first week of illness and 20% beyond the first week of illness.

Campylobacteriosis is common in both developing and developed countries. Although there had been numerous studies performed to gain a better understanding of the disease, much still remains to be unravel. In this project, the interactions between the bacteria and host cells or organisms were interrogated. Raman based imaging was initially investigated using an established Salmonella Typhimurium and cell infection model. The results obtained showed the potential for real-time imaging. However, due to the instability of the laser system of the microscope, reproducible results could not be obtained. Therefore, this technique was not applied to Campylobacter jejuni. Zebrafish embryo was established as a new infection model suitable for C. jejuni studies. C. jejuni strains and mutants were screened using this model to determine their virulence. This model was used to screen two type six secretion system mutants constructed in this study. The results obtained showed that one of the mutants, Cj1∆tssM(syn)::kanR _cas, was attenuated in the ZFE model. Subsequent competitive index challenges performed in piglets with C. jejuni wild-type and the two T6SS mutants, also showed that Cj1∆tssM(syn)::kanR _cas was attenuated. Both T6SS mutants had shown increased adherence to macrophages and Cj1∆tssM(syn)::kanR_cas also showed increased cell invasion. Together, these findings suggested that the T6SS is involved in establishment of infection in ZFE and piglet and as well as in adhesion and invasion of macrophages.