Hygiene, Volume 1, Issue 1 (June 2021) – 5 articles

Listeria monocytogenes is a food-borne bacterium that give rise to the potentially life-threatening disease listeriosis. Listeriosis has been mandatorily notifiable in Norway since 1991. All clinical L. monocytogenes isolates are sent to the Norwegian Institute of Public Health (NIPH) for typing. Since 2005 Multi-Locus Variable number tandem repeats Analysis (MLVA) has been used for typing but was recently replaced by whole genome sequencing using core genome Multi-Locus Sequence Typing (cgMLST). In the present study, L. monocytogenes isolates collected at salmon processing plants in Norway in 2007 (n = 12) and 2015 (n = 14) were first subject to MLVA. Twelve clinical L. monocytogenes isolates with matching MLVA profile and sampling time were selected from the strain collection at NIPH. Twenty-one isolates from the salmon processing plants and all clinical isolates (n = 12) were whole genome sequenced and compared using cgMLST and in silico detection of virulence genes. cgMLST revealed four pairs of environmental–human isolates with ≤10 allelic differences over 1708 genes, indicating that they may be assigned as clonal, with the implication that they are descended from the same recent ancestor. No relevant difference in carriage of virulence genes was found between environmental or human isolates. The present study shows that L. monocytogenes strains that genetically resemble contemporary isolates from human listeriosis circulate in Norwegian salmon slaughterhouses, and carry the same virulence genes. Full article

Contaminated surfaces have been discussed as a possible source of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Under experimental conditions, SARS-CoV-2 can remain infectious on surfaces for several days. However, the frequency of SARS-CoV-2 detection on surfaces in healthcare settings and the public is currently not known. A systematic literature review was performed. On surfaces around COVID-19 cases in healthcare settings (42 studies), the SARS-CoV-2 RNA detection rates mostly were between 0% and 27% (Ct values mostly > 30). Detection of infectious SARS-CoV-2 was only successful in one of seven studies in 9.2% of 76 samples. Most of the positive samples were obtained next to a patient with frequent sputum spitting during sampling. Eight studies were found with data from public surfaces and RNA detection rates between 0% and 22.1% (Ct values mostly > 30). Detection of infectious virus was not attempted. Similar results were found in samples from surfaces around confirmed COVID-19 cases in non-healthcare settings (7 studies) and from personal protective equipment (10 studies). Therefore, it seems plausible to assume that inanimate surfaces are not a relevant source for transmission of SARS-CoV-2. In public settings, the associated risks of regular surface disinfection probably outweigh the expectable health benefits. Full article

Wood materials are being adopted as nature-based architectural themes inside the healthcare buildings. Concern is raised that the organic and porous character of wood might support microbial survival. Therefore, this review discusses the hygienic properties of wood including the antimicrobial potential and its cleanability in comparison to smooth surface materials. In general, wood has antimicrobial properties owing to its chemical composition and physical structure. However, the hygienic potential of wood is influenced by the type of wood, age of wood, the cleaning method, surface treatment, and its moisture content. This information is intended to guide decision-makers regarding the use of wood in hygienically sensitive places and researchers to help them identify the variables for better utilizing the hygienic potential of this material. Full article

Fundamental rights are probably given back earlier to COVID-19 vaccinated individuals assuming that they cannot spread SARS-CoV-2 anymore. The objective of the study was to determine if COVID-19 vaccinated individuals can still be the source of SARS-CoV-2 transmission. PubMed was searched for studies on 4 April 2021. All studies with original data on COVID-19 cases among vaccinated individuals (phase III RCTs) and on viral load in the upper respiratory tract of vaccinated macaques after a SARS-CoV-2 challenge were included. Symptomatic COVID-19 cases were found in four trials among vaccinated participants although less frequently than among control subjects. One study revealed asymptomatic COVID-19 cases in a similar frequency among 2.168 AZD1222-vaccinated subjects (1.0%) compared to 2.223 control subjects (1.0%). In 15 studies with vaccinated macaques, it was found that the load of SARS-CoV-2 RNA, subgenomic RNA and infectious virus in the upper respiratory tract is variable. Sterilizing immunity was found in none of the animal studies. Major limitations of the animal studies are that the SARS-CoV-2 challenge took place within a few weeks of the final or only vaccine dose, that the viral challenge was often high and, in some studies, administered by up to four routes. Based on current knowledge it seems clear that COVID-19 vaccinated individuals can still be the source of SARS-CoV-2 transmission. Full article