Rossella Sacchetti

Legionella waterline colonization: detection of Legionella species in domestic, hotel and hospital hot water systems

Aims:  An evaluation was made of the prevalence of Legionella species in hot water distribution systems in the city of Bologna (Italy) and their possible association with bacterial contamination (total counts and Pseudomonadaceae) and the chemical characteristics of the water (pH, Ca, Mg, Fe, Mn, Cu, Zn and Total Organic Carbon, TOC).

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.

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.

Detection of Escherichia coli O157 in bovine meat products in northern Italy

Tests for Escherichia coli and E. coli O157 were carried out on meat samples collected from randomly chosen stores throughout the city of Bologna and suburban areas. The samples consisted of 25 g of loose minced beef, sometimes already shaped into meatballs or hamburgers, some of which were mixed with vegetables. The meat was purchased from retail outlets, open market stalls, and supermarket chains during 25 sampling visits from October 2000 to December 2001. For E. coli detection, Tryptone soya broth (TSB) supplemented with novobiocin and C-EC agar were used. Immunomagnetic separation with SMAC-BCIG-CT agar and chromogenic E. coli O 157 agar, API 20E system and agglutination latex test were used to detect E. coli O157; Vero cell assay and polymerase chain reaction (PCR) were used to assess toxin production and the presence of virulence genes.E. coli were detected in 45 (30.2%) of the 149 samples examined, mainly in the hamburger samples mixed with vegetables and in the loose minced beef. E. coli O157 was found in one sample of hamburger and two samples of hamburger mixed with vegetables (2%) collected from three different butchers stores between July and October. All the strains of E. coli O157 and most cases of E. coli were found in meat from small retailers. The three strains of E. coli O157 were positive for verocytotoxin production. PCR analysis revealed genes coding for vt2 and one strain possessed the gene for eae A. Chromogenic E. coli O157 agar was found to be more selective and differential, allowing easier identification of suspected colonies with mixed flora and producing less false-positive colonies.

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

Abstract 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 childrens 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.

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.

Disinfection efficiency of peracetic acid (PAA): inactivation of coliphages and bacterial indicators in a municipal wastewater plant.

The aim of the study was to assess the efficiency of low doses of peracetic acid against viral and bacterial indicators in wastewater and to evaluate if the treatment allows regulatory requirements to be satisfied. A total of 31 samplings were carried out, each involving the collection of secondary effluent and of effluent disinfected with 1.2 or 1.5 mg 1−1 of peracetic acid (contact time 20 minutes). In each sample were measured: somatic coliphages, F-specific RNA bacteriophages, Escherichia coli, total and faecal coliforms, enterococci. Peracetic acid disinfection showed significant differences between the reductions of the microorganisms tested: E. coli showed the highest reduction (1.78 and 2.43 Log respectively with 1.2 and 1.5 mg 1−1 of peracetic acid) and phages the lowest (ranging between 0.52 and 0.60 Log). Only a concentration of 1.5 mg 1−1 of peracetic acid would enable the effluent to be discharged into surface waters in compliance with Italian regulations. The variability of microbial resistance against the peracetic acid disinfection treatment, underlines the importance of assessing disinfection efficiency by using more than one indicator microorganism. The detection of E. coli could be usefully accompanied by tests for more resistant microorganisms such as enterococci or coliphages. In conclusion, peracetic acid can be used for the disinfection of effluents even at low doses, with the advantage of reducing costs and preventing the formation of significant amounts of genotoxic by-products.

Control of Legionella pneumophila contamination in a respiratory hydrotherapy system with sulfurous spa water.

OBJECTIVE To evaluate the effectiveness of different disinfection treatments in a spa water system contaminated by Legionella pneumophila and associated with a case of Legionella pneumonia. DESIGN During an 18-month period, the spa water was analyzed by taking samples from the well, the recirculation line, and the final distribution devices (nebulizers and nasal irrigators). Various attempts were made to eradicate Legionella organisms by chemical and thermal shock. The final protocol consisted of heat shock treatment at 70 degrees C-75 degrees C for 3 hours, 2 nights per week, followed by a lowering of the water temperature to 30 deg C+/-1 deg C for use in the plant. In addition, 3 times a week superheated steam (at a pressure of 1 atmosphere) was introduced for 1 hour into the nebulization machines. SETTING A spa at which sulfurous water was used for hydrotherapy by means of aerosol and nasal irrigation. PATIENT A 74-year-old woman with legionnaires disease. RESULTS After the case of infection occurred, L. pneumophila was isolated from the recirculation line at a concentration of 400,000 cfu/L and from the nebulizers and nasal irrigators at levels ranging from 3,300 to 1,800,000 cfu/L. The colonizing organisms consisted of a mixture of L. pneumophila serogroup 1 (12%) and serogroup 5 (88%). The shock treatment with chlorine dioxide and peracetic acid resulted in the eradication of Legionella organisms from the recirculation line but not from the water generated from the final distribution devices. After the restructuring of the plant and the application of thermal shock protocol, an evaluation after 12 months revealed no evidence of Legionella contamination. CONCLUSION To prevent Legionella colonization, disinfection treatment is effective if associated with carefully selected materials, good circuit design, and good maintenance practices.

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.