Adherence to the Mediterranean Diet in Children and Adolescents and Association with Multiple Outcomes: An Umbrella Review.

The Mediterranean Diet (MD) has been linked to numerous health benefits. This umbrella review aims to synthesize evidence from systematic reviews on the MD's impact on children and adolescents aged 6 to 19 years. Following Joanna Briggs Institute guidelines, we included 11 systematic reviews focusing on the MD's effects on health outcomes, such as asthma, anthropometric measures, physical fitness, and inflammatory markers. The results indicate a protective role of the MD against childhood asthma due to its antioxidant-rich components. However, evidence for its impact on allergic conditions like rhinitis and eczema is inconclusive. Findings regarding anthropometric outcomes, particularly BMI, are limited and inconsistent. A positive correlation was observed between MD adherence and increased physical activity, improved physical fitness, quality of life, and reduced sedentary behavior. Additionally, the MD showed an inverse relationship with pro-inflammatory biomarkers, suggesting anti-inflammatory benefits. The inconsistency in BMI findings and the potential anti-inflammatory properties of the MD warrant further longitudinal research. Future studies should explore the MD's impact on cognitive functions, academic performance, and mental health in this age group, highlighting the significance of establishing healthy eating habits early in life.

Consumption of Energy Drinks among Italian University students: a cross-sectional multicenter study.

PURPOSE: The aim of the study was to evaluate the caffeinated Energy Drinks (EDs) consumption among a large sample of Italian undergraduates and its association with some of the major lifestyle risk factors. METHODS: Students attending twelve public Italian universities were involved between October 2021 and May 2022. Information on socio-demographic characteristics, ED consumption, and on health-related behaviors of participants was collected by the use of a web-based questionnaire. RESULTS: A total of 2165 students participated in the study and 15.2% of them reported having used caffeinated EDs in the last six months, mainly once a month (41.5%). In comparison with non-users, ED users showed a higher proportion of males (p < 0.001) and a higher father's educational level (p = 0.003), came mainly from Northern universities (p = 0.004) and life sciences degree courses (p < 0.001). Besides, ED users reported higher BMI values (p = 0.003), more particular dietary regimens (p < 0.001), higher levels of weekly moderate-vigorous physical activity (p < 0.001) and participation in sports (p < 0.001) and in team sports (p = 0.003), and higher proportion of smokers (p < 0.001) and alcohol drinkers (p = 0.005). ED use was negatively related with female gender (OR 0.546; 95% CI 0.374-0.798), the Mediterranean diet (OR 0.587; 95% CI 0.362-0.951) and coming from the center of Italy (OR 0.500; 95% CI 0.275-0.909) and positively associated with tobacco smoke (OR 1.712; 95% CI 1.176-2.492) and participation in a team sport (OR 1.686; 95% CI 1.051-2.707). CONCLUSION: These findings could encourage figures engaged in education to increase the students' awareness on this issue in order to prevent the excessive use of EDs and associated unhealthy behaviors, especially in the most interested subgroups.

Cross-Sectional Analysis of Family Factors Associated with Lifestyle Habits in a Sample of Italian Primary School Children: The I-MOVE Project.

The acquisition of healthy dietary and exercise habits during childhood is essential for maintaining these behaviors during adulthood. In early childhood, parents have a profound influence on a child's lifestyle pursuits, serving as both role models and decision-makers. The present study examines family factors as potential contributors to healthy lifestyle habits and their child's overall diet quality among a sample of primary school children. A secondary aim is to evaluate several aspects of diet quality using the Mediterranean adaptation of the Diet Quality Index-International (DQI-I). This cross-sectional study involved 106 children enrolled in a primary school located in Imola, Italy. Data were collected from October to December 2019 using an interactive tool used to assess parent characteristics, children's lifestyle, food frequency (ZOOM-8 questionnaire), and actigraph accelerometers to capture children's physical activity and sedentary behavior. Adherence to the Mediterranean Diet (expressed by KIDMED Index) was positively associated with fathers' educational level, parental sport participation, and the parent's overall nutritional knowledge. Higher mothers' educational level was inversely associated with children's leisure screen time. Parents' nutritional knowledge was positively related to children's average daily minutes of organized sport activities. The better score for DQI-I was for consumption adequacy, followed by variety and moderation. The lowest score was for overall balance. The present study reinforces the importance of family factors in young children's lifestyle choices, particularly their dietary, leisure time, and exercise habits.

Assessment of dietary supplement consumption among Italian university students: The multicenter DiSCo study.

OBJECTIVES: The aim of this study was to analyze the consumption of dietary supplements (DSs) and related sociodemographic characteristics or behaviors in Italian undergraduates. METHODS: A questionnaire-based, cross-sectional study was carried out between October 2021 and May 2022 involving undergraduates from 12 public universities. The use of DSs in the previous 6 mo, the aim and reason for use, the purchasing channel, and related adverse effects were explored and compared by sex. A logistic regression was performed to highlight possible associations between sociodemographic, anthropometric, and behavioral characteristics of participants and supplement consumption. RESULTS: The use of DSs was reported by 71.5% of the 2165 respondents. Supplementation was related to sex (odds ratio [OR] 0.690; 95% confidence interval [CI], 0.516-0.924, for men), vegetarian or vegan (OR 4.814; 95% CI, 1.669-13.887) and other particular diet regimens (OR 1.819; 95% CI, 1.282-2.580), sport (OR 1.688; 95% CI, 1.116-2.553), and type of sport (OR 0.629; 95% CI, 0.423-0.936, for team sports). Women were more likely to use DSs following a doctor's prescription and to buy them in a pharmacy (P < 0.001) but reported more adverse effects (P = 0.018) than men. The main aim pursued was general health; proteins, amino acids, and non-caffeinated energy supplements were consumed to improve physical performance and caffeinated energy supplements for mental performance. CONCLUSIONS: Diet supplementation was common in the sample examined, especially in women, and associated with particular dietary regimens and sports, especially individual sports. Female consumers follow specialists' indications more than males. These results highlight the need for educational interventions about diet supplementation for this category of users.

Mediterranean diet, physical activity, and family characteristics associated with cognitive performance in Italian primary school children: analysis of the I-MOVE project.

Working memory (WM) is a multicomponent system that supports cognitive functioning. It has been linked to a wide variety of outcomes including academic success and general well-being. The present study examined the relations between adherence to the Mediterranean diet (MD) and WM among Italian children, adjusting for important parent characteristics and children's lifestyle habits. Data for this study was obtained from 106 children attending primary school in Imola (Italy) who were part of the I-MOVE study emphasizing school-based physical activity. Children's adherence to the MD was calculated using the KIDMED index (KI) based on the ZOOM-8 questionnaire. Physical activity (PA) levels were assessed using an actigraph accelerometer and WM using the backward digit span test. Univariate regression was used to select significant child-level and family measures associated with WM, which were then tested in a single multivariate regression model. Older age is positively associated with higher WM (ß = 0.36; 95% CI 0.25, 0.47). Dietary adherence (KI) (ß = 0.07; 95% CI 0.01, 0.14) and engagement in organized PA outside school hours (ß = 0.58; 95% CI 0.09, 1.10) are positively related to WM. Among the family measures, father's education was positively associated with WM for high school education and for university vs. middle school or lower, respectively. CONCLUSION: Adherence to the MD was associated with better WM capacity in primary school children. These findings can be used to guide policymakers in designing health promotion programs and instituting policies emphasizing healthy nutrition to improve physical health and boost cognitive functioning. WHAT IS KNOWN: • The development of working memory involves the entire childhood with a rapid spurt between 2 and 8 years of age. • Working memory plays a critical role in children's learning and academic performance and underlies higher-order cognitive abilities. WHAT IS NEW: • Adherence to the Mediterranean Diet was associated with higher working memory capacity in primary school children. • Health promotion interventions based on PA and sound nutrition involving children benefit not only physical and mental health, but also cognitive health.

Weekday and Weekend Differences in Eating Habits, Physical Activity and Screen Time Behavior among a Sample of Primary School Children: The "Seven Days for My Health" Project.

BACKGROUND: Healthy eating and active lifestyle habits are essential for a child's development, wellbeing, and health. School setting and family environment play a crucial role in shaping these habits and this could be reflected in different behavior patterns during weekdays and weekends. METHODS: We investigated primary school children's lifestyle habits through a cross-sectional analysis of 428 Italian primary school children, with a mean age of 8.99 years (±1.43). Data were collected from May to June 2017 using a weekly diary to assess children's lifestyles. RESULTS: Children who eat their morning snack and lunch at school three or more times during the weekdays were 5.47 times more likely (95% CI 3.02, 10.2) to consume adequate snacks and 7.79 times more likely (95% CI 4.43, 14.5) to have adequate meals than those who did not. CONCLUSION: Consumption of vegetables, lunch, and snacks are significantly more adequate during the weekdays as compared to the weekends. Physical activity levels did not differ between weekdays and weekends. Moreover, children spent more time engaged in physical activities than in front of a screen during both the weekdays and the weekends. The present results are good indicators of the importance of the school canteen in defining correct eating habits. Family-based and school-based interventions could represent valuable integrative strategies for promoting a healthy lifestyle in children.

What about Your Body Ornament? Experiences of Tattoo and Piercing among Italian Youths.

BACKGROUND: tattooing and piercing are increasingly common, especially among youths. However, several health complications may be associated with these practices if basic hygiene rules are not respected. This multicenter study was aimed at exploring tattoo and piercing experiences reported by a large sample of Italian undergraduate students through a public health perspective. METHODS: tattooed and/or pierced students attending 12 Italian universities were asked to complete a web-based questionnaire regarding their body art experience. RESULTS: out of 1472 respondents, 833 (56.6%) were tattooed and 1009 (68.5%) were pierced. The greatest proportion of tattooed students (93.9%) got her/his first tattoo in a tattoo studio, while most of the pierced were serviced in a jewelry store (48.0%). The pierced ones were less informed on health issues related to the procedure (56.0% versus 77.8% of tattooed p < 0.001), and tattooists were reportedly more attentive to hygiene rules (instrument sterilization 91.5% versus 79.1% of piercers, p < 0.001; use of disposable gloves 98.2% versus 71% of piercers, p < 0.001). CONCLUSIONS: educational interventions for both professionals and communities are needed to improve the awareness and the control of health risks related to body art throughout the Italian territory.

Assessing Undergraduates' Perception of Risks Related to Body Art in Italy: The SUPeRBA Multicenter Cross-Sectional Study.

Tattooing and piercing may lead to health complications. The present multicenter cross-sectional study aimed to assess awareness and knowledge of health risks related to body art and to identify their possible determinants among a large sample of undergraduates in Italy. A web-based questionnaire collecting information on socio-demographic characteristics, awareness, knowledge, and some potential predictors was administered to undergraduates attending twelve Italian universities. The level of knowledge was expressed as the number of correct answers (0-11 for tattooing, 0-14 for piercing). A total of 2985 participants (mean age 23.15 ± 3.99, 73.9% F) participated in the study. Although 95.4% of the respondents were aware of possible health consequences of body art, a low level of specific knowledge was registered for both tattooing (mean number of correct answers 5.38 ± 2.39) and piercing (5.93 ± 3.12) consequences. Lower knowledge was associated with the attendance of non-life science course and with lower duration of academic education for both tattoo and piercing. Lower knowledge of tattooing risks was related with commuter status, while lower knowledge of piercing risks was associated with lower father's education. These findings highlight the need to enhance information campaigns targeted to youths to increase their awareness of possible health risk of body art.

Quality of Drinking Water Treated at Point of Use in Residential Healthcare Facilities for the Elderly.

Municipal tap water is increasingly treated at the point of use (POU) to improve the acceptability and palatability of its taste. The aim of this study was to assess the bacteriologic and nutritional characteristics of tap water treated at the point of use in residential healthcare facilities for the elderly. Two types of POU devices were used: microfiltered water dispensers (MWDs) and reverse-osmosis water dispensers (ROWDs). All samples of water entering the devices and leaving them were tested for the bacteriological parameters set by Italian regulations for drinking water and for opportunistic pathogens associated with various infections in healthcare settings; in addition, the degree of mineralization of the water was assessed. The results revealed widespread bacterial contamination in the POU treatment devices, particularly from potentially pathogenic species. As expected, the use of ROWDs led to a decrease in the saline content of the water. In conclusion, the use of POU treatment in healthcare facilities for the elderly can be considered advisable only if the devices are constantly and carefully maintained.

Occurrence of non-fermenting gram negative bacteria in drinking water dispensed from point-of-use microfiltration devices.

INTRODUCTION AND OBJECTIVE: Many devices have been marketed in order to improve the organoleptic characteristics of tap water resulting from disinfection with chlorine derivates. The aim of the presented study was to assess the degree of contamination by non-fermenting Gram-negative bacteria (NF-GNB) of drinking water dispensed from microfiltration devices at point-of-use. METHODS: Water samples were collected from 94 point-of-use water devices fitted with a filter (0.5 µm pore size) containing powdered activated carbon. The microbiological contamination of water entering and leaving the microfiltered water dispensers was compared. The NF-GNB loads were correlated to Total Heterotrophic Counts (HPCs) at 37 and 22 °C, residua chlorine, and some structural and functional features of the devices. RESULTS: NF-GNB were detected from 23% of supply water samples, 33% of still unchilled water, 33% of still chilled water and 18% of carbonated chilled water. The most frequent isolates were Pseudomonadaceae: Steno.maltophilia 30.2% of isolates, Pseudomonas 20.5%, Delftia acidovorans 13.4%, while the species more largely distributed was Ps. aeruginosa recovered from 13% of samples. The distribution of the various NF-GNB was different in the water entering and in that leaving the devices. Ps.aeruginosa and Steno.maltophilia were the predominant species in water leaving the microfiltration dispensers, probably due to their capacity to colonize the circuits and to prevail over the others. Recovery of NF-GNB was favoured by the reduction in residual chlorine of the supply water, occasional use, the absence of a bacteriostatic element in the filter and inadequate disinfection of the water lines. CONCLUSIONS: The presence of high concentrations of potentially pathogenic species of NF-GNB (Ps.aeruginosa, Steno. maltophilia, Burkhol.cepacia) in the water dispensed from microfiltration devices represents a risk of waterborne infections for vulnerable individuals. When these devices are used in environments such as hospitals, nursing homes for the elderly, etc., microbiological monitoring for the detection of NF-GNB is advisable.

Effects of a 2-year school-based intervention of enhanced physical education in the primary school.

BACKGROUND: This study aimed to assess whether a school-based physical education intervention was effective in improving physical abilities and influencing daily physical activity habits in primary school children. The possible effect on body mass index (BMI) was also considered. METHODS: Twenty-six 3rd-grade classes were randomly selected stratifying by geographic location (city, plain, hills) and were assigned either to an intervention (127 boys; 120 girls) or to a traditional (129 boys; 121 girls) physical education program. At baseline (age: 8-9 years) and after a 2-year follow-up (age: 10-11 years), information was collected about sport participation and daily activity habits using a self-administered questionnaire. Height, weight, and BMI were measured and physical performance was assessed by means of standardized tests. RESULTS: The enhanced program of physical education was effective in improving physical abilities of children and determining a decrease (boys: 10%; girls: 12%) in daily sedentary activities (preintervention versus postintervention, p < .05; intervention versus control group, p < .01). The percentages of overweight and obese children did not vary significantly, but the experimental group showed a significantly lower rise in BMI compared to the control group (p < .001). CONCLUSION: The school proved to be an ideal setting for promoting physical activity and achieving the required daily activity levels.

Removal of indicator bacteriophages from municipal wastewater by a full-scale membrane bioreactor and a conventional activated sludge process: implications to water reuse.

The effectiveness of a full scale membrane bioreactor (MBR) in the removal of bacteriophages and bacterial fecal indicators from municipal wastewater was compared with that obtained by conventional activated sludge process (CASP). Somatic coliphages (SOMCPH) and F-RNA specific bacteriophages (FRNAPH) were always detected in the pre-treated effluent (mean: 6Log10), while phages infecting Bacteroides fragilis were not always present (mean: 3.9Log10). The MBR process was able to achieve respectively 2.7 and 1.7Log10 higher reductions of SOMCPH and FRNAPH compared to CASP (significant differences: P<0.05). SOMCPH were found to be the most suitable indicators for assessing MBR performance, since they showed greater resistance to biofiltration than FRNAPH and a more regular distribution in pre-treated effluent than BFRAGPH. Moreover, since the traditional bacterial indicators were almost totally removed by biofiltration, SOMCPH proved to be the best indicators to evaluate the microbiological risk when MBR effluent is discharged into natural waters or reused.

Physical fitness of primary school children in relation to overweight prevalence and physical activity habits.

A cross-sectional study was carried out to analyse, through a limited number of fitness tests, the main conditioning and coordinative abilities in children aged 8-9 years, and their relationship with gender, anthropometric variables and physical activity habits. The height and weight of 256 boys and 241 girls were measured and information about physical activity habits was collected using a self-administered questionnaire. Physical performance was assessed by means of a few standardised tests: 'sit & reach', medicine-ball forward throw, standing long jump, 20 m running speed, and forward roll test. In both boys and girls, body weight and body mass index (BMI) were positively correlated with the medicine-ball throw performances and negatively correlated for the standing long jump and speed tests, while no association was found with tests measuring back flexibility and total body coordination. Daily physical activity and participation in sport were not significantly correlated with body weight and BMI, but were positively associated with children's motor performance. The standardised fitness tests selected in the current study have been found to be suitable to identify fitness levels of primary school children. Thanks to their limited number and ease of measurement, they can be used in any school context to classify children and for monitoring the effects of targeted interventions promoting physical activity.

Performance of a full-scale membrane bioreactor system in treating municipal wastewater for reuse purposes.

The microbial removal efficacy of membrane bioreactor (MBR) technology in a full-scale municipal wastewater treatment plant was evaluated. Total and faecal coliforms, thermo-tolerant coliforms, Escherichia coli, enterococci, somatic coliphages, F-RNA specific bacteriophages and bacteriophages infecting Bacteroides fragilis (BFRPH) were used as bacterial and viral indicators. Reclamation and reuse of MBR effluent were considered. The average Log(10) reductions of the bacterial indicators range from 6 Log(10) for enterococci to 7 Log(10) for E. coli and faecal coliforms. The average removal of FRNA coliphages was similar to that of enterococci. Complete removal of BFRPH was observed. Log(10) reductions of somatic coliphages were significantly lower than those of all other indicators. Somatic coliphages appear to be better indicators of the microbial removal efficiency of the MBR system than faecal bacterial indicators. The quality of the MBR permeate conforms largely with the microbiological standards for urban (e.g. street cleaning, vehicle washing) and agricultural reuse.

Control of Pseudomonas aeruginosa and Stenotrophomonas maltophilia contamination of microfiltered water dispensers with peracetic acid and hydrogen peroxide.

The abilities of peracetic acid and hydrogen peroxide to remove or reduce Pseudomonas aeruginosa and Stenotrophomonas maltophilia in output water from microfiltered water dispensers (MWDs) were investigated. Two MWDs were inoculated with strains of P. aeruginosa and S. maltophilia isolated from water. Dispensers A and B were disinfected with 10% (v/v) peracetic acid (PAA) and 3% (v/v) hydrogen peroxide (HP) respectively. Each dispenser was disinfected three times at monthly intervals with contact times of 10, 30 and 40 min. Water dispensed by the MWDs was collected immediately before and after each treatment and then twice weekly for the remaining period. Once a week a sample of the tap water entering the dispensers was tested. P. aeruginosa and S. maltophilia were enumerated in the 90 samples collected during 6 months. In the output water from the dispensers before the first treatment, the number of the bacteria was 3 to 4 log cfu/100 mL. Treatment with PAA greatly reduced the numbers of P. aeruginosa and S. maltophilia in the dispensed water initially. However, by 2 days after treatment, the numbers increased and remained high. In the case of disinfection with HP for 40 min, P. aeruginosa was not detected in most of the samples (73.7%). Numbers of S. maltophilia decreased with increasing time after treatment.

Control of bacterial contamination in microfiltered water dispensers (MWDs) by disinfection.

Three microfiltered water dispensers (MWDs) for domestic use were bacteriologically monitored over a period of 1 year to evaluate their hygienic status and to compare the ability of two disinfectants (peracetic acid and hydrogen peroxide) to ensure adequate bacteriological quality of the dispensed water. To this end, two dispensers were purposely contaminated with a strain of Pseudomonas aeruginosa of environmental origin. A total of 324 samples of input and output water were analyzed. Heterotrophic plate count (HPC) bacteria at 22 degrees C and 36 degrees C, total coliforms (CT), Escherichia coli (EC), enterococci (ENT), P. aeruginosa and Staphylococcus aureus were enumerated. Throughout the study period, the supply water was always of excellent bacteriological quality. All water samples taken from the MWDs complied with the legal requirements for drinking water: CT, EC, ENT and S. aureus were all consistently absent. P. aeruginosa was never isolated from the uncontaminated dispenser. However, an increase in HPCs up to levels of 10(3)-10(4) cfu/mL was found in the dispensed water. Under the present operative conditions, hydrogen peroxide was seen to be more effective than peracetic acid in controlling bacterial contamination in the water circuits. Periodic disinfection with hydrogen peroxide made it possible to obtain water with HPC levels conforming to Italian regulations for drinking water (< or =100 cfu/mL) as well as to the levels recommended by the American Dental Association (ADA) (< or =200 cfu/mL). Furthermore, in the contaminated circuits, H(2)O(2) disinfection led to a reduction in the concentrations of P. aeruginosa to only a few colony forming units/100 mL or to a complete, albeit temporary, disappearance of the microorganism. In conclusion, hydrogen peroxide at 3% can be proposed as a suitable product for periodic disinfection of domestic MWDs, taking into consideration also its low cost and easy availability.

Comparative study on the efficiency of peracetic acid and chlorine dioxide at low doses in the disinfection of urban wastewaters.

A comparison was made between the efficiency of low doses of peracetic acid (PAA: 1.5 mg/l) and chlorine dioxide (ClO(2): 1.5 and 2.0 mg/l) in the disinfection of secondary effluents of a wastewater treatment plant. Peracetic acid was seen to be more active than chlorine dioxide and less influenced by the organic content of the waste. Both PAA and ClO(2) (2.0 mg/l) lead to a higher reduction in total and faecal coliforms and E. coli than in phages (somatic coliphages and F-specific RNA bacteriophages) and enterococci. Detection of faecal coliforms and E. coli should therefore be accompanied by a search for these more resistant microorganisms when assessing the conformity of wastewater for irrigation use, or for discharge into surface waters. Coliphages are also considered suitable indicators of the presence of enteric viruses. Although the application of low doses of both disinfectants offers advantages in terms of costs and produces not significant quantities of byproducts, it is not sufficient to obtain wastewater suitable for irrigation according to the Italian norms (E. coli < 10/100 ml in 80 % of samples and <100/100 ml in the remaining samples). Around 65 % of the samples, however, presented concentrations of E. coli lower than the limit of 5,000/100 ml established by Italian norms for discharge into surface waters.

Rapid and sensitive detection of MS2 coliphages in wastewater samples by quantitative reverse transcriptase PCR.

Coliphage MS2 is used in place of pathogens in many studies and is considered one of the indicators of pathogenetic viruses in wastewater. We developed a quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) assay to quantify MS2 coliphages in treated wastewater samples. The format used was SYBR Green. The assay included an internal control to disclose the presence of PCR-product inhibitors. The method had a wide dynamic range (8 logs) with a correlation coefficient of 0.999 and is capable of detecting as few as 4x10(2) genome equivalents/100 ml of wastewater sample. The method was validated by using artificially contaminated water samples. The validated method was then applied to naturally contaminated samples collected in a wastewater treatment plant and the results were compared with those obtained by a plaque assay. In comparison with the plaque assay the PCR-method yielded viral counts about 1.5 orders of magnitude higher. The entire detection method, including sample processing and real-time PCR amplification, was completed within 4 hours, making it a rapid single-day method.

Active surveillance of legionnaires disease during a prospective observational study of community- and hospital-acquired pneumonia.

A prospective surveillance study of legionnaires disease and an environmental survey of Legionella species were performed simultaneously in a general hospital. During a period of 3 years, 705 patients with pneumonia were screened with a Legionella urinary antigen test, and pneumonia was confirmed by culture and serological tests. Twelve cases of legionnaires disease were identified, none of which were hospital acquired, despite the fact that 60% of hospital water samples were contaminated with Legionella pneumophila at a concentration of more than 10(3) colony-forming units/L. The probable source of infection was identified for only 2 community-acquired cases. The results show that environmental contamination alone is not able to predict the risk of legionnaires disease. If no cases are present, monitoring of hospital water systems is of little significance; clinical surveillance is much more important.

Influence of material and tube size on DUWLs contamination in a pilot plant.

Numerous studies have shown that the water discharged from dental unit waterlines (DUWLs) contains high densities of bacteria, especially non-fermenting Gram negative bacteria. The aim of the present study was to investigate how the material (polyethylene-PE and polytetrafluorethylene-PTFE) and size (1.6 and 4.0 mm) of 4 waterlines in a pilot plant influence the level of contamination in the output water. The water contamination was assessed by analyzing the trend of the heterotrophic plate counts at 22 degrees C as a function of time and by testing for non-fermenting Gram negative bacteria. In all waterlines, the bacterial density increased exponentially during the first months and thereafter remained between 10(4) and 10(6) cfu/ml. However, the plate count at 22 degrees C was lower in the water from PTFE tubes and from larger size tubes. Comamonas acidovorans, Pseudomonas aeruginosa and Pseudomonas fluorescens were isolated. Pseudomonas aeruginosa, responsible for infections associated with dental practice, was never isolated in the output water from PTFE tubes. In order to control bacterial contamination the results suggest the use of waterlines made of PTFE on account of their ability to inhibit the colonization and growth of Pseudomonas aeruginosa.