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 l(-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 l(-1) of peracetic acid) and phages the lowest (ranging between 0.52 and 0.60 Log). Only a concentration of 1.5 mg l(-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.

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).

METHODS AND RESULTS

A total of 137 hot water samples were analysed: 59 from the same number of private apartments, 46 from 11 hotels and 32 from five hospitals, all using the same water supply. Legionella species were detected in 40.0% of the distribution systems, L. pneumophila in 33.3%. The highest colonization was found in the hot water systems of hospitals (93.7% of samples positive for L. pneumophila, geometric mean: 2.4 x 10(3) CFU l(-1)), followed by the hotels (60.9%, geometric mean: 127.3 CFU l(-1)) and the apartments with centralized heating (41.9%, geometric mean: 30.5 CFU l(-1)). The apartments with independent heating systems showed a lower level of colonization (3.6% for Legionella species), with no evidence of L. pneumophila. Correlation analysis suggests that copper exerts an inhibiting action, while the TOC tends to favour the development of L. pneumophila. No statistically significant association was seen with Pseudomonadaceae, which were found at lower water temperatures than legionellae and in individual distribution points rather than in the whole network.

CONCLUSIONS

The water recirculation system used by centralized boilers enhances the spreading of legionellae throughout the whole network, both in terms of the number of colonized sites and in terms of CFU count.

SIGNIFICANCE AND IMPACT OF THE STUDY

Differences in Legionella colonization between types of buildings are not due to a variation in water supply but to other factors. Besides the importance of water recirculation, the study demonstrates the inhibiting action of copper and the favourable action of TOC on the development of L. pneumophila.

Decontamination of dental unit water systems with hydrogen peroxide

AIMS

Transmission of microbial pathogens to patients from water in dental units is a concern. To reduce this risk, the decontaminating efficiency of hydrogen peroxide was evaluated.

METHODS AND RESULTS

Three percent hydrogen peroxide diluted 1 : 4 in distilled water (contact time 15 min) was used daily to disinfect the waterlines of a pilot unit previously contaminated with Pseudomonas aeruginosa or Staphylococcus aureus. The behaviour of the test bacteria was seen to differ over time. Staph. aureus numbers slowly decreased until only low numbers were recovered, after which the levels remained stable. Ps. aeruginosa abatement was more rapid and the density of the bacteria reached a peak when the circuit was empty.

CONCLUSIONS

Staph. aureus and Ps. aeruginosa treated with hydrogen peroxide fell from 6 to 4 log.

SIGNIFICANCE AND IMPACT OF THE STUDY

Treatment of dental unit waterlines with hydrogen peroxide was seen to be able to keep the number of the bacteria under control, as long as the treatment was repeated daily.

[Multicentric survey on hygienic aspects in private dental practice]

The aim of this research was to evaluate the knowledge of cross-infection hazards in private dental practices, and their control procedures. The survey, carried out by questionnaire in 11 Italian cities, showed that dental personnel do not completely follow the main procedures for infection control. The interviewed subjects usually wear gloves (95.5%), masks (90.1%) and glasses (91.2%), less frequently caps (23.9%) and coats (54.9%). They use steam sterilizers (92.9%) and periodically check the effectiveness (80.6%). Regarding individuals protection, 20.5% is not vaccinated against HBV and only 55.2% of those previously vaccinated has checked their immunity. Moreover, the majority of subjects underestimate the infection hazards especially for air-transmitted diseases.

[Tobacco smoking among nursing students: behaviour and knowledge of the correlated risks]

This study was designed to assess knowledge and consumption of tobacco, during the three years of the university course for nurses in Bologna. A questionnaire consisting of items about personal details, smoking habits, and one open question about knowledge of health risks linked to tobacco consumption 505 students. 43% of males and 33% of females were current smokers. The males were mostly medium and heavy smokers (>11 cigarettes/day) and the females light smokers (<10/day). As regards knowledge an increase in both number and accuracy of the answers given by the third year students was seen. Suggestions for educational programs are given considering that the population in question is part of an "example group" who are supposed to play a role in influencing the behavior of the general population.

[Environmental diffusion of Legionella spp and legionellosis frequency among patients with pneumonia: preliminary results of a multicentric Italian survey]

A multicentric Italian investigation on legionnaires' disease is in course to clarify host factors as well as pathogen associated characteristics involved in the infection/disease. The main goal of the research plan is to account for some critical aspects concerning identification and prevention of legionellosis. To improve knowledge on factors associated with Legionella spp colonisation in hot waters, to detect cases and to characterize risk factors in subjects which develop pneumonia are specific objectives of the research programme. Preliminary results show that hot waters of houses and hotels are frequently contaminated (22.6% and 54.6%, respectively), mainly by L. pneumophila. Microbial concentrations were low in domestic waters (<1.000 ufc/l), but higher in samples from the hotels (geom. mean 1.85 x 10(3) ufc/l). Warming system, age of the plant, type of building were risk factors significantly associated with Legionella spp positivity. The active surveillance on patients affected by pneumonia with search for Legionella urinary antigen allowed the identification of 34 cases, 3 of which of nosocomial origin, corresponding to 4.2% of the screened pneumonia. After informed consent, 26 subjects were recruited for a case-control-study to clarify risk factors for the disease.

[Hygiene education in the Laureate Course of Dentistry and Dental Prosthetics: evaluation of student knowledge about the risk of infection in a dental practice environment]

Hygiene education for dental students is crucial in order to control and reduce the risk of infections in their future professional practices. The aim of this study was to evaluate the improvement in university students' knowledge of infectious disease prevention, dental instruments and environmental decontamination following the Course in Dental Hygiene and Prevention. 595 questionnaires were submitted to dental students at twelve Italian Universities; 335 were filled out before the Course began and 260 at the end of the same course. The students in both the PRE-course and at the POST-course evaluations demonstrated adequate knowledge regarding the transmission of infections in dental practices, knowledge improved following the Hygiene course.

[Immigration and health: observational study concerning the foreign children attending the Bologna community pediatric service]

An analysis of the health situation of 2583 immigrant children examined by the Community Paediatric Service in the city of Bologna in 1999 and 2000 was made. The data were obtained from health records, from medical notes made in the districts or during school readmissions. Our investigation showed that: 68.8% of the children were of immigrant couples, 21.6% had at least one Italian parent, 6.0% had lost one or both parents and 3.6%, had been adopted by Italian couples; 68.8% were born in EU countries (1620 in Bologna and 133 in other regions). 99.6% of the children had received all compulsory vaccinations; 1853 subjects had also had one or more optional vaccinations: against whooping-cough 45.2%, measles 46.9% and mumps 33.8%. Only 38.5% of children had pathologies, and those most frequently encountered involved the respiratory and digestive systems. Diseases are more often infectious and allergic as in Italian population. Parasitic infections occurred more frequently than in Italian children; amoebiasis and cutaneous diseases were seen in 1.9% of the children (especially Indians). Cases of tuberculosis were limited. The children more often undergoing diagnostic investigations involving hospitalisation were from Asia and Africa. Only 10.1 of mothers and 7.6% of fathers reported medical problems; allergic pathologies were prevalent.

Immunomagnetic assay, classic culture method and fermentation tube test in the recovery of Escherichia coli O157 from sewage

The diffusion of E. coli O157 was studied in the effluents of a large sewage treatment plant. Three methods were used: the Culture Method, Immunomagnetic Separation (IMS) and Fermentation Tube Test. Vero cells assay and PCR were used to assess toxin production and the presence of virulence genes. E. coli O157 were only detected using IMS and the Fermentation Tubes Test: one strain in raw sewage and 2 in a sample of disinfected effluent. The latter resulted positive for the production of verocytotoxin and possessed genes coding for vt2 and type gamma intimin. The best results were obtained with SMAC-CT-BCIG medium. The use of various different recovery techniques confirmed the difficulty involved in isolating E. coli O157 from water samples.

Peracetic acid as an alternative wastewater disinfectant to chlorine dioxide

AIMS

The aim of this study was to compare the efficiency of peracetic acid with that of chlorine dioxide in the disinfection of wastewater from a sewage treatment plant (serving about 650 000 inhabitants) that has been using peracetic acid as a disinfectant since 1998.

METHODS AND RESULTS

A total of 23 samplings were made, each consisting of three samples: from secondary effluent, effluent disinfected with 2 mg l(-1) of peracetic acid and effluent disinfected with 2.2 mg l(-1) of chlorine dioxide (contact time 20 min). For each sample, measurements were made of the heterotrophic plate count at 36 degrees C, total and faecal coliforms, Escherichia coli, enterococci, pH, suspended solids and chemical oxygen demand (COD). During the first phase of the experiment the peracetic acid was seen to be less efficient than chlorine dioxide. To improve the disinfectant action a system of mechanical agitation was added which led to a greater efficiency in the inactivation of bacteria of faecal origin.

CONCLUSIONS

Both products were found to be influenced by the level of microbial contamination, the amount of suspended solids and COD but not by the pH of the effluent before disinfection. The immediate mixing of the wastewater and disinfectant caused a greater reduction in enterococci.

SIGNIFICANCE AND IMPACT OF THE STUDY

Since peracetic acid was seen to produce a high abatement of micro-organisms, it can be considered as a valid alternative to chlorine dioxide in the disinfection of wastewaters.

Tobacco consumption and sports participation: a survey among university students in northern Italy

Social-demographic information of a total of 1249 students attending the University of Bologna was analyzed by means of an anonymous questionnaire containing 33 questions with particular reference to tobacco smoking and sports activity. Results revealed that 31.6% of the students practise some form of sports regularly (6 hours a week or more), 40.5% occasionally (at least an hour a week for 8 months in a year) and 27.9% do not take part in any kind of sport. Significant differences were seen between those that practise sports (60.4% are non-smokers and 33.5% are habitual smokers) and those that do not (52.9% are non-smokers and 40.1% smoke habitually). The smokers who are active in sports smoke a lower mean number of cigarettes a day than the inactive group and thus belong to the category of light smokers. They also smoke fewer cigarettes on days when they take part in sports activity. As far as knowledge of health risks is concerned, 21.1% of those who practise sports obtained a score between good and excellent compared to 15.9% of those who do not. Although on the whole the results appear to show a certain influence of sports on smoking habits, the kind of study we led and the differences in the number of smokers are not sufficient to consider sports practitioners as a group not at risk for behaviour harmful to the health. Further studies are necessary to verify the cause-effect relationship between sports activity and smoking habits.

Airborne coagulase negative staphylococci produced by a sewage treatment plant

Since some coagulase-negative staphylococci species are involved in clinical and environmental situations, the authors carried out a study on the spread of these bacteria in the air of a sewage treatment plant. For these purposes a total of 196 samples were taken from 16 sampling stations, 11 during the day and 5 at night (only at 4 points), using the settle plate technique. Altogether 13 species of coagulase negative staphylococci were isolated: S. haemolyticus, S. xylosus and S. cohnii were particularly common. Station no. 2 (an area almost always kept closed containing the fine screens) was found to be the most contaminated. The presence of coagulase negative staphylococci was favoured by high temperatures and low humidity. No differences were found due to variations in wind speed and direction or between day and night.

Evaluation of the efficiency of peracetic acid in the disinfection of sewage effluents

AIMS

Evaluation of the efficiency of peracetic acid in the disinfection of wastewater in a large treatment plant.

METHODS AND RESULTS

Over a period of 18 months 30 sample collections were made, each consisting of three samples taken from: raw incoming sewage, secondary effluent (after 10-12 h) and secondary effluent disinfected with 1.5-2 mg l(-1) of peracetic acid (contact time: 20 min). Total coliforms and Escherichia coli declined from 10(7) MPN 100 ml(-1) in the raw sewage to 10(2) in the disinfected effluent and the enterococci fell from 10(6) MPN 100 ml(-1) to 702 MPN 100 ml(-1). The reduction of bacteria increased with the rise in temperature and decreased with the rise in BOD5.

CONCLUSIONS

Disinfection with peracetic acid reduced levels of faecal contamination by 97%, thus attaining the limit recommended by current Italian law (Escherichia coli <or= 5000 MPN 100 ml(-1)) for discharge into surface waters.

SIGNIFICANCE AND IMPACT OF THE STUDY

The process of disinfection with peracetic acid is easier to manage than other more common methods and the tests performed confirm that from the bacteriological point of view good results can be obtained for urban effluents.

Tobacco smoking among high school students in Romagna (Italy) and evaluation of a prevention campaign

The aim of this study was to investigate the smoking habits of a sample of second year high school students in Romagna (Northern Italy) by means of an anonymous self-administered questionnaire and the efficiency of a previous health education campaign. A sample of 2,691 16-year-old pupils (74% of the school population of this age) was randomly selected. Of these, 863 (32.1%) had participated in a prevention campaign while attending middle school. 19.1% of the students who had taken part in the campaign were smokers compared to 23.2% of those who had not. The students' smoking habits were found to be influenced by the type of school and by the role models (parents, siblings, friends, teachers). The campaign appears to have had good results, especially in places where it was carried out on a wide scale. Suggestions are made for making such campaigns more efficient.

Recovery of Burkholderia pseudomallei and B. cepacia from drinking water

Samples of drinking water were examined in order to evaluate the occurrence of two gram-negative bacteria: Burkholderia pseudomallei and B. cepacia. A total of 85 samples were collected from public and private buildings in the province of Bologna (Italy). Other bacteriological indicators (heterotrophic plate count at 22 and 36 degrees C) were also examined, together with physical and chemical parameters (temperature, pH, residual chlorine, total hardness and chemical oxygen demand (COD)). High levels of B. pseudomallei were recovered (mean value = 578 cfu/100 ml) in about 7% of samples, while B. cepacia was recovered in 3.5% (mean value = < 1) of the samples. The two microorganisms were found to correlate positively with heterotrophic plate counts at 22 and 36 degrees C, but not with the physical and chemical parameters taken into consideration.

Water characteristics associated with the occurrence of Legionella pneumophila in dental units

This study evaluated the incidence of Legionella pneumophila in dental unit water samples and investigated how the occurrence of these bacteria may be related to some physical, chemical and bacteriological characteristics of the water. The samples were taken from the incoming tap water, oral rinsing cup, air-water syringe, ultrasonic scaler, and the turbine of 23 dental units of private and public institutions. Apart from L. pneumophila (serogroup 1 and 3) isolated in 22 out of the 101 (21.8%) water samples tested, two other species were found: L. bozemanii and L. dumoffii. The highest densities and frequency of L. pneumophila were observed in the water coming into the units and in the dental units of public institutions. A negative association between L. pneumophila and 36 degrees C and 22 degrees C heterotrophic total plate counts and other gram-negative bacteria was found. An inverse association between the concentration of L. pneumophila and water temperature was also observed. The values of pH and total hardness did not show any significant difference in the L. pneumophila-positive and -negative dental unit waters. Finally, the chemical oxygen demand (COD) and residual chlorine were found to correlate positively with L. pneumophila.

Occurrence and seasonal variation of airborne gram negative bacteria in a sewage treatment plant

A study was carried out to determine the microbial density and the seasonal variation of airborne Gram negative bacteria in a sewage treatment plant. Sampling was made at 16 sites and the settle plate technique was used. Of the 201 samples examined, 43.2% revealed fecal coliforms (mean value = 14 cfu/p/h), 53% Pseudomonas spp. (mean value = 11 cfu/p/h), 46.5% Shigella spp. (mean value = 13 cfu/p/h), 3% Legionella spp. (mean value = 2 cfu/p/h) and 2% Salmonella (mean value = < 1 cfu/p/h). 72% of the samples contained "other" Gram negative bacteria such as Aeromonas hydrophila, Serratia marcescens, Enterobacter cloacae and others. With the exception of Legionella spp. and Salmonella, all other bacteria were more frequent and numerous in the October-March period, when temperatures were lower and humidity higher. Although the oxidation tanks were covered overall contamination was nevertheless high, thus presenting a potential health risk for plant workers.

Effect of heat and acid decontamination treatments on the recovery of Legionella pneumophila from drinking water using two selective media

Two different decontamination systems, heat and acid, and two isolation media, GVPC and MWY agar were tested for the recovery of Legionella pneumophila from drinking water. The samples were concentrated by filtration through 0.2 micron polyamide filter and the membranes were resuspended in the original water samples. The suspension was divided into three parts: the first was placed in a 50 degrees C water bath, the second was acidified in HCl-KCl solution and the third did not undergo any treatment. The isolation was made by means of media containing charcoal, yeast extract and glycine with cycloeximide (GVPC) or vancomycin, polimixin B, anysomicin and dyes (MWY). Heating at 50 degrees C for 30 minutes was seen to be the best decontamination system above all when used with GVPC agar. Moreover, with this pretreatment higher counts were obtained both on MWY and GVPC agar. The MWY agar produced the highest isolatin percentages and the highest counts.

Comamonas acidovorans contamination of dental unit waters

A study was carried out to evaluate the extent of the colonization of dental water systems by Comamonas acidovorans and to investigate how the occurrence of these bacteria is related to certain water characteristics. The 152 water samples were collected from the oral rinsing cup, air-water syringe, turbine and supply lines to dental units. Comamonas acidovorans was found most frequently and in greatest quantities in samples taken from water entering the units and in samples with a lower total bacterial count at 22 degrees C, higher temperature, lower content of organic matter and, in general, higher concentrations of residual chlorine.

Occurrence, removal and seasonal variation of thermophilic campylobacters and Arcobacter in sewage sludge

The presence of thermophilic campylobacters and Arcobacter was investigated in four types of sewage sludge taken from the treatment plant in Bologna (Italy): primary, activated, thickened and anaerobically digested sludge. Campylobacter jejuni and Campylobacter coli were more numerous during the March-September period and were found only in primary sludge (22.7%) with mean counts of 278 MPN/g dry matter and 1403 MPN/g dry matter respectively. Arcobacter butzleri were found in all types of sludge with frequencies of 80% in activated and thickened sludges and 41% in digested sludges. They were more numerous in the spring/summer period with peaks in April, May, June and September. They were less sensitive to anerobic digestion than fecal bacteria, probably due to their microaerophilic growth properties. However, since they are found in anaerobically digested sludges at mean values of 7649 MPN/g dry matter the land application of digested sludges may cause high risks infection.

Occurrence of Listeria monocytogenes in sewage sludge

The search for salmonella is the only bacteriological index included in Italian guidelines (in accordance with EU regulations) for the use of sewage sludge in agriculture. As a result, information regarding the presence of Listeria monocytogenes is rather limited. We therefore decided to carry out an investigation of Listeria in the sludge produced by the Bologna (Italy) treatment plant during the various phases of treatment. Five different types of sludge were analysed (primary raw, activated, thickened, digested and dewatered) in a total of 66 samples. The highest frequency and concentrations of Listeria species (100% and 2,743 MPN/g dry matter) and the lowest (63% and 6 MPN/g dry matter) were found in the activated and digested sludge respectively. These bacteria were mostly present in spring and autumn and positively correlated only with fecal streptococci. Four species were isolated: Listeria monocytogenes, Listeria innocua, Listeria welshimeri and Listeria grayi. Listeria monocytogenes (prevalent serotype 4b) was seen to be resistent to the biological oxidation but sensitive to anaerobic conditions during thickening and digestion. The dewatering process led to an increase in contamination. Since the sludge is used to fertilize land destined for vegetable farming our results show that it may represent a potential health risk.

Smoking habits, exposure to passive smoking and attitudes to a non-smoking policy among hospital staff

A survey was carried out into the smoking habits and exposure to passive smoking among health staff in the hospitals of Faenza, Forli and Rimini (Emilia-Romagna, Northern Italy), 2453 subjects answered anonymously a 41 question questionnaire. 53% of the subjects were professionals nurses, 16% doctors, 15% maintenance staff, 10% ancillary staff, 1% non-medical graduates, 2% were administrators and 3% were assigned to the category ¿other'. Of the subjects answering the questionnaire 39% were smokers, 19% ex-smokers and 42% non smokers. The highest number of smokers was found among women (41%) compared to men (37%) and among ancillary staff (48%) compared to nurses (41%) and doctors (31%). The males were mostly heavy smokers (> or = 20 cigarettes/d) and smoked strong cigarettes (> or = 12 mg/cig condensate content). The females were mostly light smokers (< 10 cigarettes/d) and smoked light cigarettes (1-6 mg/cig condensate content). A high percentage of subjects (87%) smoked at work especially in areas reserved for staff. 43% and 26% of shift workers and non-shift workers tended not to modify their habit when on morning or afternoon shifts. During night shifts the majority of them increased their tobacco consumption. Around 87% of hospital employees stated they were exposed to passive smoking inside the hospital especially in cooking areas, at information desks and corridors. Nurses, ancillaries and maintenance staff were those most exposed and for a greater number of hours per day compared to doctors. Almost all subjects were aware of the harm caused by passive smoking. 56% of smokers, 65% of ex-smokers and 72% of non smokers said they were willing to participate in future campaigns to limit smoking in their hospitals.

Characteristics of non-O1 Vibrio cholerae isolated from the effluents of a treatment plant

We report the results of a study concerning the characteristics of 19 Non-O1 Vibrio cholerae strains isolated from the incoming sewage and the effluents of the treatment plant in Bologna (Italy). These strains were compared to those of a strain of Vibrio cholerae biotype El Tor. The behaviour of the Non-O1 Vibrios was seen to be quite similar to those of the El Tor biotype in all aspects studied and antigenic correlations were found by means of immunoblotting and cytotoxin production on VERO cells. Since these bacterial strains may be pathogenic in humans, we believe it useful to describe some of their characteristics.

Occurrence of gram-negative bacteria in drinking water undergoing softening treatment

A study was carried out on the presence of Gram-negative bacteria in the municipal waters of Bologna (Italy) undergoing softening using domestic ion exchangers with an automatic disinfection mechanism. The softening process was seen to cause a 15 fold increase in 22 degrees C and 36 degrees C heterotrophic plate counts. There was a 30 fold increase in Gram-negative bacteria and their number correlated directly with temperature and inversely with active residual chlorine. Organic matter had no effect on bacterial growth. The most commonly found bacteria were various species of Pseudomonas (87.6%) (Ps. acidovorans, Ps. denitrificans, Ps. fluorescens and Ps. testosteroni) followed by Aeromonas hydrophila (5.6%) and Stenotrophomonas (Xantomonas) maltophilia (3.8% in outgoing water). Pseudomonas aeruginosa (present in 5.6% of incoming water samples and 0.4% of outgoing water) and Yersinia enterocolitica (present in 4.3% of incoming water samples and 1.1% of outgoing water) did not find favorable conditions for growth on the ion exchange resins.

Staphylococcus aureus in dairy products in the Bologna area

A study was carried out to evaluate the extent of contamination by Staphylococcus spp. and in particular by Staphylococcus aureus in dairy products on sale in the Bologna area. Staphylococcus aureus was found in 16.30% of the 135 cheese samples examined: 8.3% in soft cheese, 17.60% in blue cheese, 18.9% in semi-soft cheese and 25.0% in mozzarella-type cheese. The mean concentration was 2699 CFU/g in the 22 positive samples. The most commonly found species were Staphylococcus epidermidis (14.8%), Staphylococcus hominis (19.5%), Staphylococcus xylosus 2 (19.2%) and Staphylococcus cohnii (16.3%). Staphylococcus aureus was found mostly during the hot months while the other common species were found mostly in the period October-March.

Prevalence of thermophilic Campylobacter and Arcobacter butzleri in food of animal origin

Thermophilic campylobacters and Arcobacter butzleri were looked for in 57 manually shelled egg samples and 130 raw meat samples. No bacteria were found in the egg samples, but they were, however, found in 16.1% of meat samples with a frequency varying from 2.4% (port sausage) to 37.5% (poultry). A total of 21 strains were identified, one belonging to Arcobacter butzleri (pork) and 20 to Campylobacter. The most common species was C. jejuni (16/20) followed by C. coli (4/20) and in both species biotype I was the most frequently found. Regarding the methods employed for the isolation of bacteria, no substancial difference was seen between the three media (Butzler, CCDA and Preston) although CCDA medium gave better results than Butzler and Preston media. The variable which had the most influence was the incubation temperature. A higher number of strains was obtained at 42 degrees C than at 37 degrees C.

Comparative disinfection of secondary-treated sewage with chlorine dioxide and bromine chloride

A comparison was made of the inactivation rates of Arcobacter butzleri, coliphages, total coliforms, fecal coliforms, fecal streptococci and heterotrophic plate count in secondary sewage effluent using chlorine dioxide (2 and 4 ppm) and bromine chloride (4 or 8 and 12 ppm) as disinfecting agents. Using these doses the ClO2 gave higher reduction percentages (on average more than 99% at 4 ppm) than those obtained with BrCl. The average values of the fecal indicators are well within the legal limits. Arcobacter butzleri was more sensitive to the disinfectants than other bacteria while fecal streptococci were seen to be more resistant. From the chemical point of view no differences were seen between the two disinfectants except that the action of ClO2 was stronger regarding BOD5 than that of BrCl. With the exception of dichloromethane, the concentration of volatile halogenated compounds showed little variation and values were often lower than detection limits.

Effect of water softening and heating on microbial contamination of dental unit systems

This study regards the quality of the water used in 4 types of dental units making use of softened and heated water, softened but non-heated water, non-softened but heated water and non-softened and non-heated water. The samples were taken from the incoming tap water, from oral rinsing cup, the air-water syringe and the ultrasound descaling hand-piece. The results showed how the water underwent a notable growth in bacteria during its passage within the circuits of the units, reaching heterotrophic total counts greatly exceeding the guidelines set down by Italian laws regarding drinking water. While the influence of softening was evident, the bacteria in the samples taken from descaling handpiece, where there is more stagnation, found excellent growing conditions also at high temperatures. In the softened and heated waters a notable growth of Pseudomonas aeruginosa was found and it is likely that this was encouraged by the combined effect of the softening and heating. As far as the origin of the contamination is concerned, the bacteria present in the water systems seem to have come from the incoming water.

[Tobacco smoking among the students of professional nursing schools in the province of Bologna]

A study into the smoking habits of the Nursing School students of Bologna Province was carried out. 1077 (97.8%) of all students answered the self administered questionnaire and 44.6% of them were current or occasional smokers. 37.2% of males and 31.1% of females were current smokers. Overall nurse students smoked in a greater proportion in respect of coecal young people and females were generally lighter smokers and smokers of light cigarettes. Age, smoking habits of parents, siblings and partners were positively associated with smoking status of students while sex, civil status, education birth area, sport practice and parents profession did not show any significant association.

Consumption, behaviour and knowledge with respect to alcoholic drinks in student nurses in the province of Bologna, Italy

A study was carried out on alcohol intake among the students of the Schools for Trained Nurses in the province of Bologna by means of an anonymous especially prepared questionnaire. The series consisted of 1077 subjects: 753 females and 324 males aged between 16 and 40. 68.2% of males and 56.8% of females drank wine, l'81.3% of males and 61.8% of females drank beer and 65.3% of males and 46.2% of females drank spirits. While beer was the most popular drink, wine was on average drank in greater quantity. Alcohol intake was significantly related to sex (higher among males), area of origin (South) and cigarette smoking. The risk attributable to alcohol abuse are well known to almost all of the sample, above all those in the 2nd and 3rd years of their course. Nevertheless their alcohol consumption was not particularly different from that of students attending other High Schools. Regarding the sources, of their information about the risks, the 'mass media' was more quoted by the oldest students while 'family' was given by the younger students; the Nursing School was more often mentioned by both sexes in the 2nd and 3rd year of course. No relation however was found between the students knowledge of risks and actual consumption.

Arcobacter cryaerophilus and thermophilic campylobacters in a sewage treatment plant in Italy: two secondary treatments compared

Microaerophilic organisms were monitored in sewage effluent undergoing two secondary treatments: air and oxygen-activated sludge. The mean numbers of Arcobacter cryaerophilus and thermophilic campylobacters detected in incoming sewage were 5639/100 ml and 1720/100 ml respectively. Secondary treatment in air tanks reduced the population of A. cryaerophilus by 97.1% and of thermophilic campylobacters by 99.08%, whereas treatment in oxygen tanks reduced the bacteria 97.8% and 99.63% respectively, showing that oxygen-activated sludge treatment was more effective. Subsequent tertiary treatment with 2 p.p.m. chlorine dioxide evidenced the removal of A. cryaerophilus to 99.9% and eliminated thermophilic campylobacters. Campylobacter jejuni and C. coli constituted 54.1% and 45.9% of 74 thermophilic campylobacter strains isolated. In air-activated sludge effluent C. jejuni was found more often, thus appearing more sensitive to oxygen. The most probable number assay used for detection of campylobacters, blood medium for enrichment and blood-free medium for plating, also appeared to be fit for A. cryaerophilus, the high density of which in urban sewage may be due to inflows from slaughterhouses.

Occurrence, removal and seasonal variation of "thermophilic" campylobacters in a sewage treatment plant in Italy

Monitoring of "thermophilic" campylobacters in a sewage treatment plant in Bologna (Italy) has shown that incoming sewage contained a most probable number of 1630 campylobacters/100 ml. The secondary treatment in activated sludge tanks reduced 98.61% of campylobacters, 95.32% of fecal coliforms, 96.46% of fecal streptococci, 93.36% of salmonellas and 93.01% and 88.29% of BOD5 and COD respectively. Subsequent tertiary treatment with 3 ppm of chlorine dioxide for 15 min reduced 100% of campylobacters and salmonellas. Significant correlation coefficients were found in incoming sewage between campylobacters and salmonellas (p < 0.01) and between campylobacters and fecal coliforms (p < 0.02). Campylobacter jejuni and Campylobacter coli constituted 51.3% and 48.7% respectively of the 80 strains isolated. In incoming sewage 66% of the strains isolated were found to be Campylobacter jejuni whereas Campylobacter coli strains were prevalent in activated sludge effluent (69.7%). The greatest frequency of isolation and the higher counts were obtained during the Spring to Summer period with distinct peaks in May, June and July. This seasonability is probably due to the seasonal variation of campylobacter infections in man and animals.

[Comparative findings on the spread of healthy carriers of coagulase-positive staphylococci in a hospital milieu]

A comparative search was made for healthy carriers of pathogenic staphylococcus among the kitchen, canteen and scullery staff of the Malpighi Hospital and the paramedical personnel of its geriatrics, out-patient and nephrology sections. The following percentages of healthy carriers were observed: out-patient section 37.5%, nephrodialysis section 23%, kitchen 17.9%, and geriatrics section 14.2%. All staphylococcus strains were tested for their sensitivity to antibiotics. 25% were resistant to ampicillin, 21.8% to penicillin, and 21.8% to streptomycin.