Optimization of Quantitative Analysis of Biofilm Cell from Pipe Materials

The quantitative analysis of biofilm can be used not only to assess the microbiological stability of tap water but also on its basis can assess: the degree of colonization of materials by bacterial cells, the rate of biofilm formation on the surfaces of pipes and determine their composition and number. The article presents the results of research on the development of an effective method of biofilm detachment from the surface of the galvanized steel. The number of biofilm cells was determined by methods: (1) luminometric ATP determination, (2) flow cytometry and (3) heterotrophic plate counts (HPC). The presence of the biofilm was confirmed by SEM and fractal analysis. The analysis of the obtained results showed that the most effective method of detaching the biofilm cells from the galvanized steel surface was the mechanical separation with a sterile cotton swab. The variant with the use of a sterile swab enables rapid collection of the biofilm from the surface of the ducts forming internal installations or water supply networks. Due to the simplicity and speed of obtaining results, the luminometric ATP measurement has been established as the best method for the quantification of biofilm cells. The results of this study were intended to provide reliable and useful data on the quantification of biofilm cells.

Mycological Investigation of Bottled Water Dispensers in Healthcare Facilities

The usage of bottled water dispensers (BWDs) has spread worldwide. Despite their popularity, few studies have dealt with their microbial contaminants, and little attention is given to their fungal contamination. To our knowledge this is the first mycological study of BWDs in Europe. 36 devices have been examined in Budapest, Hungary. Despite of the strictly regulated water hygiene system in Hungary, molds and yeasts were detected in 86.8% of the samples, 56.76% were highly contaminated. Elevated heterotrophic plate counts were also observed in all samples compared to that of Hungarian drinking water. As all physical and chemical water quality characteristics have met the relevant national and European parametric values and neither totally explained the results of microbial counts, the effect of usage and maintenance habits of the devices were examined. Fungal concentrations were affected by the time elapsed since disinfection, days remaining until expiration of bottles, month of sampling and exposure to sunlight during storage. Microbes are able to proliferate in the bottled water and disperse inside the BWDs. Many of the detected fungal species (Sarocladium kiliense, Acremonium sclerotigenum/egyptiacum, Exophiala jeanselmei var. lecanii-corni, Exophiala equina, Meyerozyma guilliermondii, Cystobasidium slooffiae, Aspergillus jensenii, Bisifusarium biseptatum) are opportunistic pathogens for subpopulations of sensitive age groups and patients with immunodeficient conditions, including cystic fibrosis. Thus BWDs may pose a health risk to visitors of healthcare institutions, especially to patients with oral lesions in dental surgeries. The study draws attention to the need to investigate microbial contamination of these devices in other countries as well.

Characterization of Autochthonous Bacterial Isolates with The Potentiality to Degrade Spent Engine Oil from Contaminated Soil Area Enriched with Glycine max

This study was conducted to identify and characterize bacteria capable of degrading spent oil contaminated soil. The physicochemical parameters of used engine oil were analyzed according to existing standards, while the total heterotrophic plate counts (HBC) and hydrocarbon utilizing bacteria counts were ascertained with the pour plate methods using nutrient agar and minimal salt agar (MSA) media respectively. The results indicated a mean total HBC ranging from 2.86 ± 0.08 to 5.76 log10 CFU/g and mean hydrocarbon utilizing bacterial counts from 1.32 ± 0.09 to 3.82 ± 0.25 log10 CFU/g, with samples enriched with Glycine max (Soybean) recorded to have the highest bacterial counts. The phenotypic identification of the hydrocarbon utilizing bacteria as sources of carbon and energy showed the presence of two primary bacterial genera: Bacillus and Micrococcus.However, from the overall 50 counted colonies, the frequency of occurrence for Bacillus was 41 (82 %) whereas, the Micrococcus was (9) 18%. The obtained data, confirmed the breakdown capacity of autochthonous (indigenous) organisms notably; Bacillus in the reduction of pollutants linked with oil spillage. This provides for reliable and promising approach of ameliorating crude oil pollutants and its inherent threats. Keywords: Soil, spent oil, Glycine max, degrading bacteria, isolation and bioremediation

Talk2clean: application of probiotics to control biofilm in industrial water circuits – a innovative application

<p>Biofilms are omnipresent in industrial cooling water circuits and frequently lead to technical and economic problems. Yet, methods to remove biofilms may be inefficient, due to the EPS layer, which provides a protective layer against penetration of disinfectants. In combination with stricter legislation and increased environmental awareness, this has opened the search for alternative strategies to control biofilms in cooling water systems.</p> <p>In this study we implement a novel biofilm removal strategy, in which we target the intercellular language involved in the formation of biofilm structures. This language consists of signalling molecules (autoinducers) excreted by biofilm forming bacteria, a process referred to as quorum sensing (QS). We aim to alter QS via the activation of an antagonistic process called quorum quenching (QQ). Quorum quenching is a process that naturally occurs in bacterial communities; hence the final product is environment, - and user-friendly and thus a valuable alternative to the oxidising chemical products that are often used to clean cooling water circuits.</p> <p>Here we present the first application of a QQ-product tested on pilot scale using parameters that resemble industrial evaporative cooling towers. This setting is particularly interesting as it an open system, fed with various types of make-up water, and comprised of biofilms adjusted to high operating temperatures.</p> <p>The QQ product was tested using a closed, tube-like system, under continuous flow, fed with a propionic, - and acetic acid rich synthetic medium. Hydraulic retention time (HRT) was gradually shifted over a time span of 6 weeks. Heterotrophic plate counts were acquired once per week from the planktonic and biofilm phase. A pilot without the addition of QQ was ran in parallel as a control.</p> <p>Our results show that the QQ product reduced and delayed the formation of biofilm compared to the control. Interestingly, this difference diminished when the HRT was modified. Metagenomic analysis of the biofilm phase, revealed that 16S rRNA sequences corresponding to the QQ were also strongly reduced during this shift, indicating a wash-out of the QQ product. The exact interaction of HRT and presence of QQ will be analysed in more depth using QQ specific qPCR primers.</p>

Taking Screenshots of the Invisible: A Study on Bacterial Contamination of Mobile Phones from University Students of Healthcare Professions in Rome, Italy

Mobile phones (MPs) are commonly used both in the personal and professional life. We assessed microbiological contamination of MPs from 108 students in healthcare professions (HPs), in relation to their demographic characteristics and MPs handling habits, collected by means of a questionnaire. Cultural and biochemical tests were performed, and statistical analyses were carried out. Staphylococci were present in 85% of MPs, Enterococci in 37%, Coliforms in 6.5%; E. coli was never detected. Staphylococcus epidermidis was the most frequently isolated staphylococcal species (72% of MPs), followed by S. capitis (14%), S. saprophyticus, S. warneri, S. xylosus (6%), and by S. aureus (4%). Heterotrophic Plate Counts (HPC) at 37 °C, ranged from 0 to 1.2 × 104 CFU/dm2 (mean = 362 CFU/dm2). In univariate analysis, the male gender only was significantly associated with higher HPCs and enterococcal contamination. Multiple linear regression models explained only 17% and 16% of the HPC 37 °C and staphylococcal load variability, respectively. Developing specific guidelines for a hygienic use of MPs in clinical settings, for preventing cross-infection risks, is advisable, as well as introducing specific training programs to HP students. MPs decontamination procedures could also be implemented in the community.

Evaluation of Microbiological and Free-Living Protozoa Contamination in Dental Unit Waterlines

Studies conducted over the last 40 years have demonstrated that the water output from dental unit waterlines (DUWLs) is often contaminated with high densities of microorganisms. It has been monitored the microbiological quality of the water in 30 public dental facilities in northern Italy in order to assess the health risk for patients and dental staff. In each facility, samples of water both from taps and from DUWLs were analyzed in order to evaluate heterotrophic plate counts (HPCs) at 22 °C and 36 °C, and to detect coliform bacteria, Pseudomonas aeruginosa, Legionella pneumophila and amoebae. In 100% of the samples taken from the DUWLs, the concentration of HPCs was above the threshold as determined by the Ministère de la Santé et des Solidarités (2007). The concentration of P. aeruginosa was greater than the indicated threshold in 16.67% of the hand-pieces analyzed. A total of 78.33% of samples were contaminated by L. pneumophila, while in the samples taken from the DUWLs alone, this percentage rose to 86.67%. Amoebae were detected in 60% of the samples taken from hand-pieces; all belonging to the species V. vermiformis. This study documented the presence of various microorganisms, including Legionella spp., at considerably higher concentrations in water samples from DUWLs than in samples of tap water in the same facilities, confirming the role of the internal DUWLs in increasing microbial contamination, especially in the absence of proper management of waterborne health risks.

Evaluation of disinfection processes for water heater devices used for extracorporeal life support

The Maquet Heater Unit 35 (HU35) is widely used to maintain patient body temperature during extracorporeal life support. Water is used as a medium for heat transfer though it also provides a medium for the growth of pathogens. Thus, the use of a heating unit presents a risk for transmission of water-borne pathogens in critically ill patients. Recently, a Mycobacterium chimaera outbreak in cardiac surgery has been linked to the production of bioaerosols by heater-cooler devices. Consequently, manufacturers have revised cleaning recommendations, with significant impact on staff, budget and environment. Heterotrophic plate counts (HPC) and non-tuberculous mycobacterium growth were assessed following three disinfection processes over a 16-month period. It was found that water quality was acceptable in HU35s when disinfecting with a lower concentration of Chloramine-T than currently recommended, provided exposure of the device to potential pathogens was minimised by the use of a 0.2 μm water filter.

Microorganism levels in spray from warm-water bidet toilet seats: factors affecting total viable and heterotrophic plate counts, and examination of the fluctuations and origins of Pseudomonas aeruginosa

The objectives of this study were to conduct an appropriate microbial evaluation of warm-water bidet toilet seats. Health-related advantages and disadvantages have been associated with using warm-water bidet toilet seats, which are classified according to the tank type, including tanks equipped with reservoir water heaters and on-demand tankless systems equipped with an instantaneous water heater. However, related bacterial research is sparse. Here, we performed a long-term survey of the behavior of microorganisms (i.e., the total viable count (TVC), heterotrophic plate counts (HPCs), and Pseudomonas aeruginosa count) in a university campus. We also examined the differences between the tank and on-demand types, and the origins of P. aeruginosa. A low TVC (≤1/mL) in the spray waters from both on-demand and tank-type warm-water bidet toilet seats showed low bacterial contamination, although there was an increase in HPC, i.e., growth of biofilms, inside in the warm-water bidet toilet seats. When P. aeruginosa was detected in spray water over an extended duration, the P. aeruginosa origin was considered as either from feces or tap water. Collectively our findings demonstrate that hygienic safety of warm-water bidet toilet seats is being maintained overall.

Membrane Fouling and Chemical Cleaning in Three Full-Scale Reverse Osmosis Plants Producing Demineralized Water

Membrane fouling and cleaning were studied in three reverse osmosis (RO) plants. Feed water was secondary wastewater effluent, river water, and surface water. Membrane autopsies were used for fouling characterization. Fouling layer measurements included total organic carbon (TOC), adenosine triphosphate, polysaccharides, proteins, and heterotrophic plate counts. In all locations, membrane and spacer fouling was (bio)organic. Plant chemical cleaning efficiencies were evaluated from full-scale operational data and cleaning trials in a laboratory setup. Standard cleaning procedures were compared to two cleaning procedures specifically adapted to treat (bio)organic fouling using commercial blend cleaners (mixtures of active substances). The three RO plants were impacted by irreversible foulants causing permanently decreased performance in normalized pressure drop and water permeability even after thorough chemical cleaning. The standard plant and adapted cleaning procedures reduced the TOC by 45% on average, with a maximum of ~80%. In general, around 20% higher biomass removal could be achieved with adapted procedure I compared to adapted procedure II. TOC measurements and SEM showed that none of cleaning procedures applied could remove foulants completely from the membrane elements. This study underlines the need for novel cleaning approaches targeting resistant foulants, as none of the procedures applied resulted in highly effective membrane regeneration.