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.

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

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph16152648 ◽

2019 ◽

Vol 16 (15) ◽

pp. 2648 ◽

Cited By ~ 7

Author(s):

Anna Maria Spagnolo ◽

Marina Sartini ◽

David Di Cave ◽

Beatrice Casini ◽

Benedetta Tuvo ◽

...

Keyword(s):

Legionella Pneumophila ◽

Tap Water ◽

Microbiological Quality ◽

Coliform Bacteria ◽

Dental Staff ◽

Plate Counts ◽

Dental Unit Waterlines ◽

Heterotrophic Plate Counts

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.

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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

Journal of Water and Health ◽

10.2166/wh.2017.137 ◽

2017 ◽

Vol 16 (3) ◽

pp. 346-358

Author(s):

Toru Iyo ◽

Keiko Asakura ◽

Makiko Nakano ◽

Kazuyuki Omae

Keyword(s):

Pseudomonas Aeruginosa ◽

Tap Water ◽

Viable Count ◽

Warm Water ◽

Water Heater ◽

Reservoir Water ◽

Advantages And Disadvantages ◽

On Demand ◽

Plate Counts ◽

Heterotrophic Plate Counts

Abstract 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.

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Chlorine requirement for biologically stable drinking water after nanofiltration

Water Science & Technology Water Supply ◽

10.2166/ws.2013.214 ◽

2013 ◽

Vol 14 (3) ◽

pp. 405-413

Author(s):

Y. Ohkouchi ◽

Y. Yata ◽

R. Bun ◽

S. Itoh

Keyword(s):

Drinking Water ◽

Water Distribution ◽

Flow Reactor ◽

Heterotrophic Bacteria ◽

Tap Water ◽

Biological Stability ◽

Bacterial Regrowth ◽

Chlorine Residual ◽

Plate Counts ◽

Heterotrophic Plate Counts

There is considerable interest in minimizing the chlorine residual in Japan's tap water because of increasing consumer complaints about the chlorinous odor of drinking water. However, minimization of the chlorine residual requires stricter control of biodegradable organics in finished water to ensure biological stability during water distribution. In this context, we investigated the improvement of biological stability of drinking water by nanofiltration (NF). The removal of assimilable organic carbon (AOC) was 52% on average, but showed large seasonal variation. It was found to be difficult to maintain the acceptable AOC level for biologically stable water by NF. In addition, significant bacterial regrowth in NF permeates was still observed without chlorination, although 52% AOC was removed. Then, the chlorine concentration required to prevent bacterial regrowth during distribution of nanofiltrated water was determined using continuous-flow reactor systems. The heterotrophic plate counts (HPC) densities in biofilm were monitored at different chlorine conditions. The results indicated that the NF process could significantly reduce the chlorine requirement of the finished water. The relationship between free chlorine residual and HPC in biofilm formed from 1 μgC AOC showed that a trace level of chlorine residual, <0.1 mg/L, could inactivate heterotrophic bacteria and prevent biofilm formation.

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Evaluation of Microbiological Quality of Commercially Available Bottled Water in the City of Dhaka, Bangladesh

Stamford Journal of Microbiology ◽

10.3329/sjm.v1i1.9099 ◽

1970 ◽

Vol 1 (1) ◽

pp. 24-30 ◽

Cited By ~ 7

Author(s):

Ahmad Kamruzzaman Majumder ◽

KM Nazmul Islam ◽

Rezwanun Naher Nite ◽

Rashed Noor

Keyword(s):

Water Samples ◽

Tap Water ◽

Microbiological Quality ◽

Bottled Water ◽

Fecal Coliforms ◽

Plate Counts ◽

Human Illness ◽

New Treatment ◽

Heterotrophic Plate Counts

Bottled water has become one of the most popular drinks in Bangladesh. Now a days it is easily available in the market. Due to lack of confidence on municipal supply water, people now prefer to drink bottled water instead of tap water, mostly when they are outside the home, and in many occasions. In the present study, the presence of total coliforms (TC) and fecal coliforms (FC) from nine commercially available lacal Bangladeshi bottled water samples were examined. The obtained results indicated that most of the studied bottled water were out of their safety guidelines and hence some chronic diseases (renal failure, liver cirrhosis and anemia) are expected in the area understudy, because 68.89% and 31.11% of the bottled water sampled in the current study showed heterotrophic plate counts (HPC) within a range of 1-500 (cfu/ml) and greater than 500 (cfu/ml), respectively and 0% samples showed less than 1 (cfu/ml) in heterotrophic plate counts. The results also revealed the ill performance and poor drinking water quality of the purification systems of the investigated water samples. 28% of the respondents considered that the quality of bottled water was satisfactory, in contrast to the 26% of the respondent, who judged that the quality of bottled water was not that satisfactory. However, the highest (34%) number of the respondents did not know whether the quality of the bottled water is good or not satisfactory. Recommendation was suggested for new treatment systems of the investigated suspicious water to prevent human illness. DOI: http://dx.doi.org/10.3329/sjm.v1i1.9099Stamford Journal of Microbiology, Vol.1(1), July 2011, p.24-30

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UV ability to inactivate microorganisms combined with factors affecting radiation

Water Science & Technology ◽

10.2166/wst.1997.0718 ◽

1997 ◽

Vol 35 (11-12) ◽

pp. 107-112 ◽

Cited By ~ 7

Author(s):

A. M. Shaban ◽

G. E. El-Taweel ◽

G. H. Ali

Keyword(s):

Microbial Communities ◽

Uv Radiation ◽

Contact Time ◽

Tap Water ◽

Scenedesmus Obliquus ◽

Morphological Characters ◽

The Other ◽

Bacterial Cells ◽

Dark Repair ◽

Nile Water

In the present study, the effect of UV radiation on the inactivation of a range of microorganisms was studied. Each organism was seeded into sterile tap water and exposed to UV in batch experiments with changing turbidities. In addition, the effect of UV on microbial communities in river Nile water was examined. It was found that 1min contact time (0.5L/min flow rate) was effective against vegetative cells levels almost reaching zero (except with Staphylococcus aureus). On the other hand, spore-forming bacteria, Candida albicans and coliphage were more resistant to UV. This contact time caused coenobia cells in single form with Scenedesmus obliquus while for Microcystis aeruginosa colonies broke into smaller groups. Exposure of Nile water microbial communities to UV showed that yeasts and Aeromonas survived better than the other organisms while in the phytoplankton partial fragmentation occurred in some algal groups. The protective effect of turbidity differed between organisms, with increased contact time under conditions of stable turbidity having no effect on the organisms. At 20 NTU the UV radiation had no effect on the morphological characters of algal cells. In reactivation experiments, it is clear that photoreactivation, and not dark repair, takes place with bacterial cells. Only coliphage had no photoreactivation and dark repair responses although with coliphage and host, both reactivation processes worked well. Moreover, the irradiated algae regained their normal shape after 3 days in suitable media and enough light.

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Endotoxin contamination in the dental surgery

Journal of Medical Microbiology ◽

10.1099/jmm.0.47231-0 ◽

2007 ◽

Vol 56 (9) ◽

pp. 1230-1234 ◽

Cited By ~ 14

Author(s):

M. K. Huntington ◽

J. F. Williams ◽

C. D. Mackenzie

Keyword(s):

Bacterial Load ◽

Dental Surgery ◽

Paired Samples ◽

Dental Procedures ◽

Large Numbers ◽

Endotoxin Exposure ◽

Endotoxin Contamination ◽

Plate Counts ◽

High Concentrations ◽

Heterotrophic Plate Counts

Dental waterlines contain large numbers of Gram-negative bacteria. Endotoxin, a component of such organisms, has significant health implications. Paired samples of dental unit water and the aerosols generated during dental procedures were collected, and assayed for bacteria and endotoxin levels, using heterotrophic plate counts and the Limulus amoebocyte lysate test. Consistent with published studies, the extent of bacterial contamination in the dental waters sampled for this investigation surpassed the levels associated with potable water, with counts in excess of 2.0×106 c.f.u. ml−1 in some samples. Correspondingly high concentrations of endotoxin [up to 15 000 endotoxin units (EU) ml−1] were present in the water. A statistically significant Spearman correlation coefficient of ρ=0.94 between endotoxin (EU ml−1) and bacterial load (c.f.u. ml−1) was demonstrated. All of the aerosol samples contained detectable endotoxin. Further studies of the consequences of dental endotoxin exposure, and evaluation of means to prevent exposure, are warranted.

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Sausage Casings as a Model for Attachment of Salmonella to Meat

Journal of Food Protection ◽

10.4315/0362-028x-56.5.390 ◽

1993 ◽

Vol 56 (5) ◽

pp. 390-394 ◽

Cited By ~ 3

Author(s):

ISABEL WALLS ◽

PETER H. COOKE ◽

ROBERT C. BENEDICT ◽

ROBERT L. BUCHANAN

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Bacterial Attachment ◽

Bacterial Cells ◽

Inoculum Level ◽

Plate Counts ◽

Increasing Temperature ◽

Convenient Model ◽

Sausage Casing ◽

Scanning Electron

Artificial sausage casings were used as a model for studying bacterial attachment to meat connective tissue. Sausage casings of known mass were exposed to suspensions of Salmonella typhimurium in 0.15 M NaCl under various time, temperature, and inoculum level regimes, then washed to remove unattached bacteria. Attached bacterial cells were enumerated using both plate counts and scanning electron microscopy. Bacterial cells attached to sausage casing surfaces within 1 min of incubation. Numbers of attached cells increased with increasing temperature and inoculum levels and with time. Rates of attachment of S. typhimurium to sausage casings were comparable with those reported for attachment to meat surfaces. Sausage casings appear to be a convenient model for examining mechanisms of bacterial attachment to meats.

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Parameters predictive of Legionella contamination in hot water systems: Association with trace elements and heterotrophic plate counts

Water Research ◽

10.1016/j.watres.2011.01.009 ◽

2011 ◽

Vol 45 (6) ◽

pp. 2315-2321 ◽

Cited By ~ 63

Author(s):

Annalisa Bargellini ◽

Isabella Marchesi ◽

Elena Righi ◽

Angela Ferrari ◽

Stefano Cencetti ◽

...

Keyword(s):

Trace Elements ◽

Water Systems ◽

Hot Water ◽

Plate Counts ◽

Heterotrophic Plate Counts

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

Microorganisms ◽

10.3390/microorganisms8071075 ◽

2020 ◽

Vol 8 (7) ◽

pp. 1075 ◽

Cited By ~ 1

Author(s):

Domenico Cicciarella Modica ◽

Massimo Maurici ◽

Gian Loreto D’Alò ◽

Cinzia Mozzetti ◽

Alessandra Messina ◽

...

Keyword(s):

Mobile Phones ◽

Staphylococcus Epidermidis ◽

Univariate Analysis ◽

Clinical Settings ◽

Linear Regression Models ◽

Biochemical Tests ◽

E Coli ◽

Plate Counts ◽

Healthcare Professions ◽

Heterotrophic Plate Counts

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.

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Coliforms and other microbial indicators occurrence in water and biofilm in full-scale distribution systems

Water Science & Technology ◽

10.2166/wst.2006.446 ◽

2006 ◽

Vol 54 (3) ◽

pp. 41-48 ◽

Cited By ~ 7

Author(s):

M. Batté ◽

C. Féliers ◽

P. Servais ◽

V. Gauthier ◽

J.-C. Joret ◽

...

Keyword(s):

Water Quality ◽

Residence Time ◽

Distribution Systems ◽

Full Scale ◽

Bacterial Indicators ◽

Total Coliforms ◽

E Coli ◽

Plate Counts ◽

Microbiological Water Quality ◽

Heterotrophic Plate Counts

Biofilm and microbial water quality were studied in four middle size full-scale distribution systems (DS) in France serving 5,000–30,000 inhabitants (maximum residence time 23–160 h) through three sampling campaigns over 1 year. Three of these DSs were chosen because of a quite high occurrence of bacterial indicators (i.e. total coliforms), the last DS was considered as a reference. Biofilm was studied on cast iron coupons incubated for more than 1 month in devices continuously fed with water from the DS in conditions imitating those met in DS. The devices were located at different points (4–6) along each DS. The abundance of bacteria in biofilm was estimated by heterotrophic plate counts (HPC) after detachment of the biofilm from the support by sonication. Microbiological water quality was estimated in parallel; analysis of total coliforms, E. coli, enterococci and anaerobic sulphide-reducing bacteria spores (ASRB spores) was carried out in biofilm and water. Over the period of the study, 171 water samples and 57 biofilm samples were collected. Over these 171 waters, 19 (11%) were positive for at least one of the measured indicators while two biofilm samples were positive (3.5%). Significant differences were observed in the levels of contamination between the DSs. High residence time in the DS, low disinfectant residual and high temperature increased the risk of indicator occurrence in the water phase. Due to the low number of biofilm samples positive for bacterial indicators, the data collected in the present study did not allow observation of a direct association between biofilm and water contaminations, even if the occurrence of indicators in water appeared on DSs with the highest density of biofilm (HPC).

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