home Journal club New papers on Microbiology of the Built Environment, December 3, 2016

New papers on Microbiology of the Built Environment, December 3, 2016

Microbes and money

Dirty Money: A Matter of Bacterial Survival, Adherence, and Toxicity – Frank Vriesekoop – Microorganisms (OA)

Zone of inhibition around a UK 5 pence coin
Zone of inhibition around a UK 5 pence coin

In this study we report the underlying reasons to why bacteria are present on banknotes and coins. (…) We treated the various currencies used in this study as microcosms, and the bacterial loading from human hands as the corresponding microbiome. We show that the substrate from which banknotes are produced have a significant influence on both the survival and adherence of bacteria to banknotes. Smooth, polymer surfaces provide a poor means of adherence and survival, while coarser and more fibrous surfaces provide strong bacterial adherence and an environment to survive on. Coins were found to be strongly inhibitory to bacteria with a relatively rapid decline in survival on almost all coin surfaces tested. The inhibitory influence of coins was demonstrated through the use of antimicrobial disks made from coins. Despite the toxic effects of coins on many bacteria, bacteria do have the ability to adapt to the presence of coins in their environment which goes some way to explain the persistent presence of low levels of bacteria on coins in circulation.

Microbes in the kitchen

Video: Good Germs; Bad Germs. Microbes in the kitchen, 14 households, 500 swabs – University of Oxford – YouTube

Obtaining a kitchen sample
Obtaining a kitchen sample

Invisible to the naked eye, yet a constant presence, microbes (‘germs’) live in, on and around us. The researchers in this project collaborate with members of the public to explore and experiment on the microbial life in their kitchens (and in one instance – a cat) and starts to unpick what we really mean by ‘clean’ and ‘dirty’.

Microbes in heritage buildings

Application of biological growth risk models to the management of built heritage – Riccardo Paolini – Techne  (text in Italian with English translation at the end, Open Access)

Palazzo Reale in Milan, Italy
Palazzo Reale in Milan, Italy

The quality of the interior spaces is strongly related to the hygro-thermal conditions which affect the users’ comfort, and may yield to preservation risk for the built heritage. Moreover, careless management of exposition spaces with excessive occupancy may result in moisture loads that promote degradation. In this paper, as a case study, an exposition hall representative of the built heritage is considered. The microbiological growth risk is investigated at two different climate conditions, namely Milan and Barcelona, considering varying ventilation rates and number of visitors. The results outline the need of policies informed by advanced analyses to prevent hygro-thermal risk in the absence of dedicated building services, that cannot always be integrated in built heritage.

Microbes in the hospital

Microbiological surveillance of operation theatres, intensive care units and labor room of a teaching hospital in Telangana, India – S. Kiranmai – International Journal of Research in Medical Sciences

Swab sampling results
Swab sampling results

Hospital-associated infections are the major cause of patient morbidity and mortality. Environmental monitoring by the microbiological testing of surfaces and equipments is useful to detect changing trends of types and counts of microbial flora. The aims of the study were to count CFU (colony forming unit) rate of indoor air, to identify bacterial colonization of surface and equipments isolated from Operation theatres, ICUs and Labor room of a teaching hospital in Telangana, India. (…) The study shows that OTs were having bacterial CFU rate of air varying from 6-72 CFU/m3 and colonized by contaminants like Bacillus sp and pathogens like Klebsiella sp. ICUs were having bacterial CFU rate of air varying from 28-100 CFU/m3 and colonized with contaminant like Bacillus sp., as well as potential pathogens like Klebsiella, Pseudomonas etc. Fungal CFU were also seen both in OTs and ICUs. High level of microbial contamination indicates the needs for periodic surveillance aimed at early detection of bacterial contamination levels and prevention of hospital acquired infections.

Microbes in indoor air

Volatile organic compounds of possible microbial origin and their risks on childhood asthma and allergies within damp homes – Hyunok Choi – Environment International ($39.95)

Environment International cover
Environment International cover

Risk of indoor exposure to volatile organic compounds of purported microbial origin on childhood symptoms of wheezing, rhinitis, and/or eczema, and doctor-diagnosed asthma, rhinitis, and eczema, respectively, remain unclear. To test hypotheses that total sum of 28 microbial volatile organic compounds (Σ26 MVOCs): 1) poses independent risk on doctor-diagnosed asthma, rhinitis, and eczema, respectively, as well as multiple symptom presentation with a minimum of the two of the above conditions (i.e. case); 2) is associated with significant interaction with absolute humidity (AH) on additive scale. (…) Joint occurrence of high Σ28 MVOCs and AH was associated with a significant increase in the case status and asthma risks in an additive scale.

Viable airborne microbial counts from air-cooling units with and without complaints of urine and body odors – Ka Man Lai – Aerobiologia ($39.95)

Cannot read the paper, so here is the Aerobiologia cover
Cannot read the paper, so here is the Aerobiologia cover

Viable airborne microbial counts are commonly used in indoor air quality (IAQ) assessment, but studies linking the microbial counts to a specific type of indoor microbial contamination are limited. We hypothesize that the airborne microbial counts can differentiate air-cooling units with and without complaints of urine and body odors. The keratinolytic property of some isolated bacteria prompts to the hypothesis that keratinase is present in the units to break down keratins, structural proteins that form human skin scales, as sources of amino acids and ammonium to produce the odors. Seven bacterial species and four fungal species were identified in the units and room air. (…)  Viable airborne microbial counts can help IAQ inspectors to identify potential odor-causing air-cooling units. Keratins may be broken down in the units and associated with the odor complaints.

Laboratory experiments on indoor bioaerosol deposition onto various surface materials – Vuokko Lappalainen –  IAQVEC 2016 papers (Open Access)

The test chamber, coordinate system and surface sample points.
The test chamber, coordinate system and surface sample points.

Increasingly, people spend their time indoors and at the same time cases of unacceptable indoor air quality are on the rise. (…) In BITEFA project, bioaerosol deposition on various surface materials and flow fields were studied with Penicillium brevicompactum spores in a duct form test chamber. The air velocities of the system were similar to those in ventilated apartment buildings. Three commonly used materials were placed on horizontal and vertical surfaces at various flow field locations in the test chamber. Deposition was measured with cultural based and digital microscopic methods. As expected, clear differences were observed on deposition rates which was highest for horizontal upward facing surfaces and lowest for ceiling with low air velocity. Results indicate that viable bioaerosol deposition rate is highly dependent on particle size, air velocity and air flow direction towards the surface. Smaller non-viable particles are available deposit on all surfaces, vertical and horizontal. Because of smaller size of particles, the gravitation is not the major deposition mechanism. Small particles deposit by interception and diffusion. This study gives more information on practice of surface bioaerosol sampling in indoor environment investigations.

TAGS:

Elisabeth Bik

After receiving my PhD at Utrecht University in The Netherlands, I worked at the Dutch National Institute for Health and the St. Antonius Hospital in Nieuwegein. In 2001, I joined the Department of Microbiology and Immunology at Stanford, where I have worked on the characterization of the microbiome of human oral, gastric, and intestinal samples, as well as samples from marine mammals. Since November 2016, I am the new Science Editor at uBiome, a microbiome genomics company enabling citizen science. But you might also find me working on the detection of science misconduct, at my blog Microbiome Digest , an almost daily compilation of scientific papers in the rapidly growing microbiome field, on Twitter at @MicrobiomDigest.

Leave a Reply

%d bloggers like this: