home Journal club New papers on Microbiology of the Built Environment, January 7, 2017

New papers on Microbiology of the Built Environment, January 7, 2017

Microbes around the house

EditorialAn emerging paradox: Toward a better understanding of the potential benefits and adversity of microbe exposures in the indoor environment – J. Mensah-Attipoe – Indoor Air (OA)

Alfred P. Sloan Foundation logo

In order to further explore indoor microbial exposures and their associated health effects, and to help establish research agenda priorities, a two-day workshop to discuss the key challenges in recognizing and resolving the emerging paradox of indoor microbe exposures, sponsored by the Alfred P. Sloan Foundation, was held in Kuopio, Finland. The workshop brought together 50 researchers/experts in the field of indoor microbiology, environmental engineering, asthma and allergy research, toxicology, and epidemiology, from North America and Europe. The workshop consisted of podium presentations from invited speakers and a breakout group discussion session, with the outcomes from these groups being reported to the general assembly in the course of a final discussion. We highlight here the key recommendations that stemmed from the group discussions and the final discussion, structured based on a set of questions (in italics) that were provided to guide the process.

Sandpits as a reservoir of potentially pathogenic fungi for children – Anna Wójcik – Annals of Agricultural and Environmental Medicine (OA)

Children playing in sandbox. Source: Artaxerxes, Wikipedia.

Fungi belonging to various physiological and morphological groups present in the environment are potential human pathogens. Some of them are considered as emerging pathogens. Therefore, their presence in children’s playgrounds should be regarded as health risk factor. Sixty-eight samples of sand collected from 17 sandpits of different localities in Łódź, Poland, in autumn 2010 and 2011, and in spring 2011 and 2012 were evaluated. The fungi were isolated with classical mycological methods and identified on the basis of morphological and biochemical features. The prevalence of fungi in spring was 94.1% of sandpits in both layers of sand (depth 0–3 cm and 10–15 cm) and in one kindergarten sandpit, but only in a deeper layer. In autumn, fungi occurred in both layers in all sandpits (100%). (…). There were important causes of allergies, among them Cladosporium herbarum and Alternaria alternata, as well as of opportunistic mycoses: Cryptococcus neoformans, Aspergillus fumigatus and new and ‘emerging’ fungal pathogens e.g., Trichosporon, Rhodotorula, Fusarium and Scedosporium species.

Mold and dampness exposure and allergic outcomes from birth to adolescence: data from the BAMSE cohort – J. D. Thacher – Allergy (OA)

Association between exposure to mold or dampness indicators during infancy and the overall risk of asthma, rhinitis, or sensitization

Exposure to moldy or damp indoor environments is associated with allergic disease in young children, but it is unclear whether the effects persist to adolescence. Our objective was to assess whether exposure to mold or dampness during infancy increases the risk of asthma, rhinitis, or IgE sensitization in children followed from birth to 16 years of age. We collected questionnaire derived reports of mold or dampness indicators and allergic outcomes from 3798 children in a Swedish birth cohort (BAMSE). Sensitization was assessed from blood samples in 3293 children. Longitudinal associations between prevalent asthma, rhinitis, and IgE sensitization and mold or dampness indicators were assessed using generalized estimating equations. (…) Exposure to mold or dampness during infancy increased the risk of asthma and rhinitis up to 16 years of age, particularly for nonallergic disease. Early exposure to mold or dampness appeared particularly associated with persistent asthma through adolescence.

Using soil microbial inoculations to enhance substrate performance on extensive green roofs – Chloe J. Molineux – Science of the Total Environment ($41.95)

Graphical abstract

(…)  Extensive green roofs are lightweight systems generally constructed with a specialised growing medium that tends to be biologically limited and as such can be a harsh habitat for plants to thrive in. Thus, this investigation aimed to enhance the soil functioning with inoculations of soil microbes to increase plant diversity, improve vegetation health/performance and maximise access to soil nutrients. Manipulations included the addition of mycorrhizal fungi and a microbial mixture (‘compost tea’) to green roof rootzones, composed mainly of crushed brick or crushed concrete. The study revealed that growing media type and depth play a vital role in the microbial ecology of green roofs, with complex relationships between depth and type of substrate and the type of microbial inoculant applied, with no clear pattern being observed. (…)

Microbes in public places

Indoor fungal contamination of traditional public baths (Hammams) – Leyla Benammar – International Biodeterioration & Biodegradation ($35.95)

Graphical abstract

This study was carried out to provide an overview of the fungal load in Algerian traditional baths (Hammams) as well as to isolate and identify the main pathogenic fungi. Over a period of four months, ten baths were examined and screened for fungal contamination from several parts of the hot steamy rooms (floor, wall, door, air and marble massage platform). In total, 7157 fungi isolates were recovered from the surveyed Hammams and the most abundant molds were Penicillium spp. (45.12%) followed by Aspergillus spp. (28.80%). (…) ANCOVA revealed a significant increase in fungal loads related to the average number of customers and mean opening year of the Hammams, in contrast with locality (favored or popular district). This study indicates that Hammams present a potential source of pathogenic fungi which may impose a real threat on public health.

Resistance of Aerosolized Bacterial Viruses to Four Germicidal Products – Nathalie Turgeon – PLOS ONE (OA)

Effect of Pledge®, Eugenol, MiST®, and H2O2 on the infectivity of airborne phage ϕ6.

Viral diseases can spread through a variety of routes including aerosols. Yet, limited data are available on the efficacy of aerosolized chemicals to reduce viral loads in the air. Bacteriophages (phages) are often used as surrogates for hazardous viruses in aerosol studies because they are inexpensive, easy to handle, and safe for laboratory workers.  (…)  The resistance levels of the four phages varied depending on the relative humidity (RH) and germicidal products tested. Phage MS2 was the most stable airborne virus under the environmental conditions tested while phage PR772 was the least stable. Pledge® and Eugenol reduced the infectivity of all airborne phages tested. At 25% RH, Pledge® and Eugenol were more effective at reducing infectivity of RNA phages ϕ6 and MS2. At 50% RH, Pledge® was the most effective agent against phage MS2. These findings illustrate that various airborne viruses should be tested to demonstrate the effectiveness of germicidal treatments. This research also provides a set of parameters for testing germicidal products in large-scale settings to reduce the risk of virus transmission.

Microbes and city birds

Plumage micro-organisms and preen gland size in an urbanizing context – Mathieu Giraudeau – Science of The Total Environment ($41.95)

Graphical abstract

(…) Birds carry a large variety of microorganisms on their plumage and some of them have the capacity to degrade feather keratin and alter plumage integrity. To limit the negative effects of these feather-degrading bacteria, birds coat their feathers with preen gland secretions containing antibacterial substances. Here we examined urban-rural variation in feather microbial abundance and preen gland size in house finches (Haemorhous mexicanus). We found that, although urban and rural finches carry similar total-cultivable microbial loads on their plumage, the abundance of feather-degrading bacteria was on average three times higher on the plumage of urban birds. We also found an increase in preen gland size along the gradient of urbanization, suggesting that urban birds may coat their feathers with more preen oil to limit the growth or activity of feather-degrading microbes. (…)

Microbes on ships

Molecular methods resolve the bacterial composition of natural marine biofilms on galvanically coupled stainless steel cathodes – Athenia L. Oldham – Journal of Industrial Microbiology & Biotechnology ($39.95)

Navy vessel. Source: Wikipedia.

Navy vessels consist of various metal alloys and biofilm accumulation at the metal surface is thought to play a role in influencing metal deterioration. To develop better strategies to monitor and control metallic biofilms, it is necessary to resolve the bacterial composition within the biofilm. This study aimed to determine if differences in electrochemical current could influence the composition of dominant bacteria in a metallic biofilm, and if so, determine the level of resolution using metagenomic amplicon sequencing. (…) Following 3 months of exposure, the bacterial composition of biofilms collected from the SSCs was determined and compared. Dominant bacterial taxa from the two higher current SSCs were different from that of the low-current SSC as determined by DGGE and verified by Illumina DNA-seq analysis. These results demonstrate that electrochemical current could influence the composition of dominant bacteria in metallic biofilms and that amplicon sequencing is sufficient to complement current methods used to study metallic biofilms in marine environments.

Microbes in drinking water

Biofilm composition and threshold concentration for growth of Legionella pneumophila on surfaces exposed to flowing warm tap water without disinfectant – Applied and Environmental Microbiology ($25 for 1 day)

Legionella bacterium (green) caught by a Vermamoeba amoeba (orange). Source: Wikipedia.

Legionella pneumophila in potable-water installations poses a potential health risk, but quantitative information about its replication in biofilms in relation to water quality is scarce. Therefore, biofilm formation on surfaces of glass and chlorinated polyvinyl chloride (CPVC) in contact with tap water at 34-39°C was investigated under controlled hydraulic conditions in a model system inoculated with biofilm-grown L. pneumophila. (…) An elevated biofilm concentration and growth of L. pneumophila were also observed with tap water at the laboratory. The Betaproteobacteria Piscinibacter and Methyloversatilis and amoeba-resisting Alphaproteobacteria predominated in the clones and isolates retrieved from the biofilms. In the biofilm, the Legionella colony counts correlated significantly with total cell count (TCC), heterotrophic plate count, ATP concentration and Vermamoeba vermiformis. (…)

PressDutch scientists discover favorable conditions for growth of Legionella bacteria – News Medical

“Drinking water prepared from aerobic groundwater with a low concentration of dissolved natural organic matter induced a very low biofilm concentration that did not support growth of L. pneumophila,” said van der Kooij. “Drinking water from two other sources with higher concentrations of organic matter induced higher biofilm concentrations that supported Legionella growth.” Legionella bacteria grew exponentially in relation to biofilm concentration, said van der Kooij. Below a threshold concentration of biofilm, Legionella did not multiply.

Spatial and temporal analogies in microbial communities in natural drinking water biofilms – I. Douterelo – Science of The Total Environment (OA)

Graphical abstract

Biofilms are ubiquitous throughout drinking water distribution systems (DWDS), playing central roles in system performance and delivery of safe clean drinking water. However, little is known about how the interaction of abiotic and biotic factors influence the microbial communities of these biofilms in real systems. Results are presented here from a one-year study using in situ sampling devices installed in two operational systems supplied with different source waters. Independently of the characteristics of the incoming water and marked differences in hydraulic conditions between sites and over time, a core bacterial community was observed in all samples suggesting that internal factors (autogenic) are central in shaping biofilm formation and composition. From this it is apparent that future research and management strategies need to consider the specific microorganisms found to be able to colonise pipe surfaces and form biofilms, such that it might be possible to exclude these and hence protect the supply of safe clean drinking water.

Microbes and food production

Microbial Quality, Safety, and Pathogen Detection by Using Quantitative PCR of Raw Salad Vegetables Sold in Dhanbad City, India – Sujeet K. Mritunjay – Journal of Food Protection (restricted access, no price listed)

Tossed salad. Source: Wikipedia.

Consumption of ready-to-eat fresh vegetables has increased worldwide, with a consequent increase in outbreaks caused by foodborne pathogens. In the Indian subcontinent, raw fresh vegetables are usually consumed without washing or other decontamination procedures, thereby leading to new food safety threats. In this study, the microbiological quality and pathogenic profile of raw salad vegetables was evaluated through standard protocols. In total, 480 samples (60 each of eight different salad vegetables) of cucumber, tomato, carrot, coriander, cabbage, beetroot, radish, and spinach were collected (…). The samples were analyzed for total plate count, total coliforms, Escherichia coli, E. coli O157:H7, Listeria monocytogenes, and Salmonella spp. Incidences of pathogens were detected through quantitative PCR subsequent to isolation. Results showed that 46.7% (for total plate counts) and 30% (for total coliforms) of samples were unacceptable for consumption per the Food Safety and Standards Authority of India.(…)

Microbes and cultural heritage objects

About a Sloth: Survey of the state of conservation of the Mylodon listai (Xenarthra-Mylodontidae) skin fragment from the Pleistocene of Argentina kept at the Museum of La Plata (Argentina) – Daniela Silvana Nitiu – Ge-conservación (OA)

Showcase in the La Plata Museum where the skin fragment is kept

The aim of the present study was to assess the state of conservation of the fossilized skin fragment assigned to Mylodon listai preserved in a showcase of the Paleontology Hall of the Museum of La Plata. To this end, we conducted a volumetric aerobiological sampling both inside the showcase and in the hall to detect the presence of fungal load that could alter its preservation. We also determined the environmental parameters both inside and outside the showcase. The aerobiological sampling inside the showcase showed 3061.50 spores/m3 corresponding to 22 fungal types, while in the hall, 2283.20 spores/m3 corresponding to 14 fungal types where detected. Cladosporium was the most important type in all the sampling points. The temperatures recorded were lower than those recommended for the conservation of leather and the relative humidity values were acceptable in 70% of the record for this material.

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