Hygienic Relevance Research Articles

The evolutionary origin of human kissing.

A kiss has been a signal of special affection across continents and cultures for millennia. Between times and peoples, social norms invariably prescribe kissing to specific affiliations and contexts, implying deeper biological bases. Why the protruding of the lips and slight suction when touching another? Capuchin monkeys stick their fingers in their friends' eyes as sign of affection, why have humans developed kissing? Here I briefly review proposed hypotheses for the evolution of human kissing. Great ape social behavior suggests that kissing is likely the conserved final mouth-contact stage of a grooming bout when the groomer sucks with protruded lips the fur or skin of the groomed to latch on debris or a parasite. The hygienic relevance of grooming decreased over human evolution due to fur-loss, but shorter sessions would have predictably retained a final "kissing" stage, ultimately, remaining the only vestige of a once ritualistic behavior for signaling and strengthening social and kinship ties in an ancestral ape.

Genome Analysis of Enterobacter asburiae and Lelliottia spp. Proliferating in Oligotrophic Drinking Water Reservoirs and Lakes.

Surface waters are one of the main sources for drinking water production, and thus microbial contamination should be as minimal as possible. However, high concentrations of coliform bacteria were detected in reservoirs and lakes used for drinking water production during summer months due to autochthonous proliferation processes. Here, we present the genomic analyses of 17 strains of Enterobacter asburiae and Lelliottia spp. proliferating in reservoirs and lakes with special focus on the hygienic relevance, antibiotic resistance, and adaptations to the oligotrophic environments. The genomes contain neither genes for the type III secretion system nor cytotoxins or hemolysins, which are considered typical virulence factors. Examination of antibiotic resistance genes revealed mainly efflux pumps and β-lactamase class C (ampC) genes. Phenotypically, single isolates of Enterobacter asburiae showed resistance to fosfomycin and ceftazidime. The genome analyses further suggest adaptations to oligotrophic and changing environmental conditions in reservoirs and lakes, e.g., genes to cope with low nitrate and phosphate levels and the ability to utilize substances released by algae, like amino acids, chitin, alginate, rhamnose, and fucose. This leads to the hypothesis that the proliferation of the coliform bacteria could occur at the end of summer due to algae die-off. IMPORTANCE Certain strains of coliform bacteria have been shown to proliferate in the oligotrophic water of drinking water reservoirs and lakes, reaching values above 104 per 100 mL. Such high concentrations challenge drinking water treatment, and occasionally the respective coliform bacteria have been detected in the treated drinking water. Thus, the question of their hygienic relevance is of high importance for water suppliers and authorities. Our genomic analyses suggest that the strains are not hygienically relevant, as typical virulence factors are absent and antibiotic resistance genes in the genomes most likely are of natural origin. Furthermore, their presence in the water is not related to fecal contamination. The proliferation in reservoirs and lakes during stable summer stratification is an autochthonic process of certain E. asburiae and Lelliottia strains that are well adapted to the surrounding oligotrophic environment.

Minority report: small-scale metagenomic analysis of the non-bacterial kitchen sponge microbiota

Kitchen sponges are particularly well known to harbor a high number and diversity of bacteria, including pathogens. Viruses, archaea, and eukaryotes in kitchen sponges, however, have not been examined in detail so far. To increase knowledge on the non-bacterial kitchen sponge microbiota and its potential hygienic relevance, we investigated five used kitchen sponges by means of metagenomic shot-gun sequencing. Viral particles were sought to be enriched by a filter step during DNA extraction from the sponges. Data analysis revealed that ~ 2% of the sequences could be assigned to non-bacterial taxa. Each sponge harbored different virus (phage) species, while the present archaea were predominantly affiliated with halophilic taxa. Among the eukaryotic taxa, besides harmless algae, or amoebas, mainly DNA from food-left-overs was found. The presented work offers new insights into the complex microbiota of used kitchen sponges and contributes to a better understanding of their hygienic relevance.

Comprehensive Compositional Analysis of the Slit Lamp Bacteriota.

Slit lamps are routinely used to examine large numbers of patients every day due to high throughput. Previous, cultivation-based results suggested slit lamps to be contaminated with bacteria, mostly coagulase-negative staphylococci, followed by micrococci, bacilli, but also Staphylococcus aureus. Our study aimed at obtaining a much more comprehensive, cultivation-independent view of the slit lamp bacteriota and its hygienic relevance, as regularly touched surfaces usually represent fomites, particularly if used by different persons. We performed extensive 16S rRNA gene sequencing to analyse the bacteriota, of 46 slit lamps from two tertiary care centers at two sampling sites, respectively. 82 samples yielded enough sequences for downstream analyses and revealed contamination with bacteria of mostly human skin, mucosa and probably eye origin, predominantly cutibacteria, staphylococci and corynebacteria. The taxonomic assignment of 3369 ASVs (amplicon sequence variants) revealed 19 bacterial phyla and 468 genera across all samples. As antibiotic resistances are of major concern, we screened all samples for methicillin-resistant Staphylococcus aureus (MRSA) using qPCR, however, no signals above the detection limit were detected. Our study provides first comprehensive insight into the slit lamp microbiota. It underlines that slit lamps carry a highly diverse, skin-like bacterial microbiota and that thorough cleaning and disinfection after use is highly recommendable to prevent eye and skin infections.

Metatranscriptomic Analysis of Bacterial Communities on Laundered Textiles: A Pilot Case Study.

Microbially contaminated washing machines and mild laundering conditions facilitate the survival and growth of microorganisms on laundry, promoting undesired side effects such as malodor formation. Clearly, a deeper understanding of the functionality and hygienic relevance of the laundry microbiota necessitates the analysis of the microbial gene expression on textiles after washing, which—to the best of our knowledge—has not been performed before. In this pilot case study, we used single-end RNA sequencing to generate de novo transcriptomes of the bacterial communities remaining on polyester and cotton fabrics washed in a domestic washing machine in mild conditions and subsequently incubated under moist conditions for 72 h. Two common de novo transcriptome assemblers were used. The final assemblies included 22,321 Trinity isoforms and 12,600 Spades isoforms. A large part of these isoforms could be assigned to the SwissProt database, and was further categorized into “molecular function”, “biological process” and “cellular component” using Gene Ontology (GO) terms. In addition, differential gene expression was used to show the difference in the pairwise comparison of the two tissue types. When comparing the assemblies generated with the two assemblers, the annotation results were relatively similar. However, there were clear differences between the de novo assemblies regarding differential gene expression.

HYGIENIC BASIS FOR MONITORING OF PMD

A rational criterion for the hygienic relevance of the surface area of dust settling in the lungs is formulated in the article. 
 The differential parameters of airborne dust are determined by measuring the mass concentration of particular matter PM10 and PM2.5. A unified model of the behavior of dust in the lungs has been developed. It describes the deposition of particles on the walls of the airways when cleaning the inhaled air and the subsequent removal of settled dust from the lungs. 
 The adequacy of the model was verified by the compliance with the results of in vivo testing. The phenomenon of dust deposition in the lungs is described. It is typical for periodic dust exposure in the workplace. Dust exposure is acceptable if the surface area of the deposited dust does not exceed the area of the internal surface of the airways. With this approach, the concentration of dust in inhaled air is recomputed into the surface area of dust particles deposited in the lungs. As the initial data, the results of routine measurements of the mass concentration of particulate matter PM10 and PM2.5 are used. Permissible concentration for PM10 close to the WHO Recommendations and adopted in industrialized countries. Permissible concentration for PM2.5 should be a lot stiffer than currently accepted. 
 In reality, only the pair PM10 and РМ2,5 gives a quantitative characteristic of the danger of dust exposure. It determines the entering to the area of permissible dust exposure.

Microbiological examination of water and aerosols from four industrial evaporative cooling systems in regard to risk of Legionella emissions and methodological suggestions for surveillance.

The hygienic risk associated with evaporative cooling systems in Germany is currently only assessed by determining concentrations of Legionella spp. in the corresponding cooling waters. Relevant for the health risk is however the load of Legionella in emitted aerosols. In this work aerosol emissions from four industrial cooling systems (A - D) were analyzed. A microbiological air bioburden factor (MABF) is suggested to be useful to assess the overall microbiological load of emitted air and to judge the efficiency of droplet separation and overall microbiological retention. Whereas the MABF by itself only serves as a technical quality assurance (QA) parameter, the hygienic relevance has to be seen in combination with the assessment of Legionella either contained in the aerosol or in the cooling water. Plate counting of colonies was an appropriate method to quantify Legionella spp. in aerosols given the short time of flight at the chosen sampling locations and resulting low risk of desiccation. qPCR data on the other hand proved more reproducible than the culture approach to quantify Legionella spp. concentrations in cooling water-. The application of qPCR also allowed to assess the relative proportion of Legionella pneumophila within the total pool of Legionella which adds epidemiological relevance to risk assessment. A traffic light system was proposed to guide interpretation of qPCR data. The four industrial systems greatly differed in all measured parameters leading to different associated risks.

Influence of Sampling Site and other Environmental Factors on the Bacterial Community Composition of Domestic Washing Machines.

Modern, mainly sustainability-driven trends, such as low-temperature washing or bleach-free liquid detergents, facilitate microbial survival of the laundry processes. Favourable growth conditions like humidity, warmth and sufficient nutrients also contribute to microbial colonization of washing machines. Such colonization might lead to negatively perceived staining, corrosion of washing machine parts and surfaces, as well as machine and laundry malodour. In this study, we characterized the bacterial community of 13 domestic washing machines at four different sampling sites (detergent drawer, door seal, sump and fibres collected from the washing solution) using 16S rRNA gene pyrosequencing and statistically analysed associations with environmental and user-dependent factors. Across 50 investigated samples, the bacterial community turned out to be significantly site-dependent with the highest alpha diversity found inside the detergent drawer, followed by sump, textile fibres isolated from the washing solution, and door seal. Surprisingly, out of all other investigated factors only the monthly number of wash cycles at temperatures ≥ 60 °C showed a significant influence on the community structure. A higher number of hot wash cycles per month increased microbial diversity, especially inside the detergent drawer. Potential reasons and the hygienic relevance of this finding need to be assessed in future studies.

Bacteria on smartphone touchscreens in a German university setting and evaluation of two popular cleaning methods using commercially available cleaning products.

Smartphone touchscreens are known as pathogen carriers in clinical environments. However, despite a rapidly growing number of smartphone users worldwide, little is known about bacterial contamination of smartphone touchscreens in non-clinical settings. Such data are needed to better understand the hygienic relevance of these increasingly popular items. Here, 60 touchscreens of smartphones provided by randomly chosen students of a German university were sampled by directly touching them with contact agar plates. The average bacterial load of uncleaned touchscreens was 1.37 ± 0.33 CFU/cm(2). Touchscreens wiped with commercially available microfiber cloths or alcohol-impregnated lens wipes contained significantly less bacteria than uncleaned touchscreens, i.e., 0.22 ± 0.10 CFU/cm(2) and 0.06 ± 0.02 CFU/cm(2), respectively. Bacteria isolated from cleaned and uncleaned touchscreens were identified by means of MALDI Biotyping. Out of 111 bacterial isolates, 56 isolates (50 %) were identified to genus level and 27 (24 %) to species level. The vast majority of the identified bacteria were typical human skin, mouth, lung, and intestinal commensals, mostly affiliated with the genera Staphylococcus and Micrococcus. Five out of 10 identified species were opportunistic pathogens. In conclusion, the touchscreens investigated here showed low bacterial loads and a species spectrum that is typical for frequently touched surfaces in domestic and public environments, the general health risk of which is still under debate.

Microbial quality and nutritional aspects of Norwegian brand waters

The microbiological quality of the five leading brands of Norwegian bottled still waters was investigated. All brands were free for the enteric indicator organisms and named pathogens whose absence is demanded in current quality directives. The relatively nutrient-poor agar R2A revealed large heterogeneous bacterial populations which grew slowly, or not at all, on clinical media specified for use in substrate-utilization approaches to identification. The main approach used for identification was cultivation of microbes on R2A, followed by amplification and partial sequencing of 16S rDNA genes. The identity of the heterotrophic plate count of the brands differed significantly to that found in many other similar studies with respect to the dominating species. The bacterial flora was dominated by beta- and alphaproteobacteria most of which were psychrotolerant. Several brands contained Sphingomonas and large populations of Methylobacterium species which have been associated with a variety of opportunistic infections of immunocompromised hosts. Analysis of the isolated strains' nutritional capabilities using the Biolog GN2® system, gave in most instances low positive scores, and strain identifications using the system were generally inconclusive. Measures of assimilable organic carbon in the water revealed that some brands contained levels higher than those which have been associated with biological stability and restricted or no growth of heterotrophs in distribution systems. The relationship between assimilable organic carbon and R2A plate counts was significant and moderately positive for bottled waters. Assimilable organic carbon correlated strongly with the survival time of Escherichia coli when introduced into bottles as a contaminant. Those brands having high values (~100μg/L) supported protracted survival, but not growth of E. coli, whereas E. coli quickly became nonculturable in brands with low values. Thus measures of assimilable organic carbon may have a particular value in predicting the survival of this and nutritionally similar species of hygienic relevance. Only small numbers of fungi were found. However, one isolate (Aureobasidium pullulans) has been associated with infections of humans.

Occurrence and hygienic relevance of fungi in drinking water

Fungi, above all filamentous fungi, can occur almost everywhere, even in water. They can grow in such a quantity in water that they can affect the health of the population or have negative effects on food production. There are several reports of fungal growth in water from different countries, but to our knowledge none from Austria so far. The aim of this study was to gain an overview of the spectrum of filamentous fungi and yeasts in drinking water systems. Thirty-eight water samples from drinking water and groundwater were analysed. Fungi were isolated by using membrane filtration and plating method with subsequent cultivation on agar plates. The different taxa of fungi were identified using routine techniques as well as molecular methods. Fungi were isolated in all water samples examined. The mean value for drinking water was 9.1 CFU per 100 ml and for groundwater 5400 CFU per 100 ml. Altogether 32 different taxa of fungi were found. The taxa which occurred most frequently were Cladosporium spp., Basidiomycetes and Penicillium spp. (74.6%, 56.4% and 48.7%, respectively). This study shows that drinking water can be a reservoir for fungi, among them opportunists, which can cause infections in immunosuppressed patients.

25] Isolation and biochemical characterization of extracellular polymeric substances from Pseudomonas aeruginosa

This chapter discusses that Biofilms of Pseudomonas aeruginosa have been intensively studied during the last decade. Pseudomonas aeruginosa offers several advantages as a model organism in biofilm research. This gram-negative bacterium is well characterized with respect to its molecular genetics, biochemistry, and physiology; it is also of hygienic relevance as an opportunistic pathogen, because biofilms harboring this bacterium in technical water systems and on medical devices may be a source of human infections. The extracellular polymeric substances (EPS) of P. aeruginosa predominantly consist of different polysaccharides and proteins. Mucoid variants of P. aeruginosa are characterized by an overproduction of the viscous exopolysaccharide alginate, resulting in the production of large slimy colonies, when the bacteria are cultivated overnight on common agar-based media. Alginates from P. aeruginosa are high molecular weight unbranched copolymers consisting of (1→ 4)-linked uronic acid residues of β-D-mannuronate and α-L-guluronate. The formation of biofilms is regarded as part of a natural “life cycle” of mucoid P. aeruginosa. Alginates represent major components of the EPS of mucoid P. aeruginosa and have been implicated in the development as well as the maintenance of the mechanical stability of biofilms formed by P aeruginosa on living and abiotic surfaces. In this chapter, methods of isolation and biochemical characterization are described for both whole EPS and alginate from mucoid strains of P. aeruginosa grown as a confluent bacterial lawn on agar media as simple in vitro model systems for bacterial biofilms.

Studies on the stability of selected viruses in cosmetics

Synopsis Information concerning the risks emerging from the use of cosmetics contaminated with viruses is rarely reported. Therefore, we investigated the stability of viruses within different types of cosmetics. Test products were artificially contaminated with different viruses, which, due to the application of the products, have hygienic relevance. Virus persistence was observed by determining the reisolation rate. With this knowledge we were able to estimate the initial contamination of finished products and raw materials. Viruses with hygienic relevance could neither be detected in finished products nor in raw materials. We can conclude from this that cosmetics seem to be safe with regard to initial contamination. However, our results clearly showed that secondary contamination with viruses can have a persistence which is high enough to pose a hygienic risk through cross contamination.

Biological Degradation of Volatile Chlorinated Hydrocarbons in Groundwater

Chlorinated organic solvents - such as tetrachloroethene, trichloroethene and 1.1.1-trichloroethane - are the most frequently used compounds e.g. for degreasing in all branches of industries. Due to their widespread use, their large consumption quantities (Fed.Rep.of Germ. 180 × 103 t/a) and their physical properties, these organic solvents are the most important point-source of groundwater contamination. A serious case of soil, soil air and groundwater contamination by these organic solvents (maximum concentrations detected were 500 mg/kg, 7g/m3, 50 mg/l respectively) is reported, caused by the metal industry, rendering plant and paper production. A special effect is the comparatively rapid degradation sequence of tetrachloroethene to trichloroethene to cis-1,2-dichloroethene and to vinyl chloride. Concentrations of cis-1,2-dichloroethene observed in groundwater were up to 1600 µg/l and of vinyl chloride up to 120 µg/l, respectively, although none of these substances were primary pollutants in the investigated area. Results of laboratory tests give rise to the suggestion that degradation of chlorinated hydrocarbons in contaminated areas is mainly by microbiological means. This effect is of special hygienic relevance, due to the fact that one of the metabolites, vinyl chloride, is known to be a human carcinogen and the polluted area (approx. 4 km2) is located in a catchment area of a waterworks.