Daniela Tufi

The evaluation of the microbial safety of fresh ready-to-eat vegetables produced by different technologies in Italy

Aims:  The study was performed to evaluate the safety of whole and RTE vegetables and to investigate the effectiveness of different preventive strategies for the quality assurance of RTE vegetables collected from three Italian production systems. Producer 1, applied a strict system in compliance with GAP‐ GMP – HACCP, Producer 2 used chlorine disinfection at a second washing step, and Producer 3 using a physical microbial stabilization.

Legionella control in the water system of antiquated hospital buildings by shock and continuous hyperchlorination: 5 years experience

BackgroundTo control the presence of Legionella in an old hospital water system, an integrated strategy of water disinfection-filtration was implemented in the university hospital Umberto I in Rome.MethodsDue to antiquated buildings, hospital water system design and hospital extension (38 buildings), shock hyperchlorination (sodium hypochlorite, 20–50 ppm of free chlorine at distal points for 1–2 h) followed by continuous hyperchlorination (0.5-1.0 mg/L at distal points) were adopted, and microbiological and chemical monitoring of the water supply was carried out in the university hospital (December 2006-December 2011).ResultsOverall, 1308 samples of cold <20°C (44.5%), mixed ≥20°C ≤ 45°C (37.7%) and hot >45°C (17.8%) water were collected, determining residual free chlorine (0.43 ± 0.44 mg/L), pH (7.43 ± 0.29) and trihalomethanes (8.97 ± 18.56 μg/L). Legionella was isolated in 102 (9.8%) out of 1.041 water samples without filters (L. pneumophila sg 1 17.6%, L. pneumophila sg 2–14 28.4%, L. non pneumophila 53.9%), and in none of the 267 samples with filters. Legionella was recovered in 23 buildings out of 38 and 29 samples (28.4%) exceeded 103 cfu/L. When considering the disinfection treatment Legionella was isolated: before shock hyperchlorination (21.1%), 15 days after shock hyperchlorination (7.8%), 30 days after shock hyperchlorination (3.5%), during continuous hyperchlorination (5.5%) and without continuous hyperchlorination (27.3%). Continuous hyperchlorination following the shock treatment achieved >70% reduction of positive samples, whereas no continuous hyperchlorination after shock treatment was more frequently associated to Legionella isolation (OR 6.41; 95% CI 3.10–13.26; p <0.001). Independent risk factors for Legionella isolation were: residual free chlorine <0.5 mg/L (OR 13.0; 95% CI 1.37 – 123.2; p <0.03), water T° ≥20°C ≤ 45°C (OR 12.0; 95% CI 1.28 – 111.48; p <0.03) and no continuous hyperchlorination after shock treatment (OR 10.3; 95% CI 1.06 – 100.05; p <0.05).ConclusionsShock and continuous hyperchlorination achieved significant Legionella reduction, but effective chlorine levels (>0.5 < 1.0 mg/L) deteriorated water quality (organoleptic and chemical). However, shock and continuous hyperchlorination remains a valid-term option in old buildings with no water system rational design, managing problems due to hospital extension and absence of a proper hot water recirculation system.

Epidemiology of emerging foodborne pathogens

Foodborne diseases still represent an important global public health issue, including Europe and Italy, which endangers the health of the population and leads to socio-economic costs and a threat to the market trend. In developed countries it is estimated that up to one third of the population are affected by microbiological foodborne diseases each year. In these countries, it has been observed that traditional infectious foodborne diseases have decreased while re-emerging and emerging pathogens like Escherichia coli O157, Listeria monocytogenes, Campylobacter jejuni, Norovirus and Hepatitis A virus have increased. In 2004, in Italy the incidence for Listeriosis was 0.06 per 100,000 population and is included among the statutory notifiable diseases. E. coli O157:H7 is not subject to statutory notification in Italy; however, a voluntary national surveillance system for HUS in paediatric patients and for VTEC, has lead to the notification of 429 paediatric HUS cases and 344 clinical cases of VTEC from 1988 to 2004. Data on campylobacteriosis are available thanks to the voluntary notifications received from the Enternet Laboratories: 582 cases were isolated from human clinical specimens in 2004. Furthermore, data from a specific surveillance system for acute viral hepatitis (SEIEVA) shows that the incidence of reported cases in Italy is declining. The necessity to alert the authorities responsible for epidemiological surveillance nationally remains paramount. Communication as well as educational campaigns aimed at different target groups, for example consumers, will play an important role in the prevention of foodborne diseases.

FoodBioTimerAssay: a new microbiological biosensor for detection of Escherichia coli food contamination

Background : Prevention of foodborne diseases is a fundamental goal for public health and industries engaged in food preparation and distribution. The correct procedure to ensure an effective prevention of foodborne diseases consists essentially in microbiological monitoring and enumeration of indicator microorganisms of faecal contamination at critical control points along the food producing procedures. Here, we propose a new microbiological biosensor, called FoodBioTimerAssay (FBTA), for rapid and reliable detection of Escherichia coli as indicator of faecal contamination in food and surface samples. Methods : A total of 122 samples were analysed using both experimental FBTA and Reference method. FBTA employs FBTM medium and counts bacteria through microbial metabolism measure: the time required for colour switch (red-to-yellow) of FBTM, due to E. coli metabolism, is correlated to initial bacterial concentration. Results : FBTA results showed an overall agreement percentage with Reference method equal to 97.54%. Discrepancies concerned three samples (1 food and 2 surface samples). Moreover, the time required to perform FBTA method was 3-fold shorter than Reference one. Conclusions : FBTA method may be considered a useful tool for detection of E. coli contamination in food and surface samples. Therefore, FBTA method may be successfully employed in risk analysis of foodborne diseases.

Prevalence of Staphylococcus aureus colonization and antibiotic susceptibility: A survey among biomedical students

Staphylococcus aureus is a major human pathogen, causing both hospital and community-acquired infections. It is responsible for 25% of healthcare-associated infections and contributes substantially to morbidity and cost of hospital stays. The source of many of these infections is thought to be the patients’ endogenous flora. The ecological niche of S. aureus is the anterior nostrils, and 25e30% of individuals are colonized at a given time. Numerous studies have linked nasal carriage of S. aureus with increased risk of infection with S. aureus in various settings. A study conducted in central Italy to establish the rates of nasal carriage of S. aureus and antibiotic susceptibility patterns in the community showed that the prevalence of nasal carriage of S. aureus was 30 5%, with only one subject identified as a carrier of meticillin-resistant S. aureus (MRSA) (prevalence 0 12%). In another Italian study conducted in injection drug users, the prevalence of nasal colonization with S. aureus was 8.83%, and 12.5% of isolates were found to be meticillin resistant. Recently, concern has increased regarding the spread of MRSA in the community and schools. Students with weakened immune systemsmay be at risk formore severe illness if

Temporal pattern of microbial indicators of ready-to-eat rocket salads during shelf life

INTRODUCTION From 2001-2009 there have been numerous community alerts and notifications about the rocket salad produced in Italy and distributed in Europe. Our study describes the evolution of the microbial quality of ready to eat rocket salad during shelf life among three different Italian producers. MATERIAL AND METHODS Total Mesophilic Count (TMC) and Escherichia coli (EC) count were measured in 248 samples. We used Wilcoxon test to compare the median values of TMC and EC counts and Kruskal Wallis test to compare the producers. RESULTS The TMC and EC values differed among producers at the stages of raw material and in the finished product (Kruskall Wallis test, p < 0.05). The evolution of bacterial charges had significant differences among producers at expiration date (Wilcoxon test, p < 0.05). More than half of the samples (54.8%) exceed reference standard for TMC after 48 h from packaging. CONCLUSION Differences among producers may linked to the different minimal processing technologies adopted after harvesting.

Detection of Escherichia coli O157 in raw and cooked meat: comparison of conventional direct culture method and Enzyme Linked Fluorescent Assay (ELFA)

Abstract Background : Verocytotoxin Escherichia coli is a frequent and important cause of diarrhea and haemolytic uremic syndrome all over the world. Consumption of ground beef, lettuce, and other kinds of food have been associated with outbreaks. The aim of this study was to detect the presence of E. coli O157 in meat products collected from hospital food catering services in Rome, using a rapid detection method in comparison with a standard culture method to verify the effectiveness of HACCP system. Methods : Three hundred and ten food samples (80 of cooked and 230 of raw meat) were screened for E.coli O157 by ISO culture method and by enzyme-linked-fluorescent-assay (ELFA)-based methods (VIDAS®system, bioMerieux). All isolates obtained were tested for VT1 and VT2 genes by PCR. The statistical analysis considered absolute frequencies and percentages. The K statistic was applied to assess agreement between direct culture method and the VIDAS system. Results : A total of 6 (1,9%) E.coli O157 isolates were recovered from raw meat samples by the culture method; of these only four were identified by PCR as VTEC producers. A total of 9 (2,9%) E.coli O157 isolates were recovered from raw meat samples by the VIDAS® system. No E.coli O157 was detected in cooked products. All comparisons between the direct culture method and the VIDAS system were statistically significant (K= 0,795; p<0.001). Conclusions : The present study showed how ELFA-based methods are highly specific and rapid for the detection of E.coli O157 in food samples compared with the direct culture method. ELFA method is useful to verify the effectiveness of the HACCP system in the risk management of potential contaminating hazards during the preparation of foods for susceptible persons.

A New Biosensor to Enumerate Bacteria in Planktonic and Biofilm Lifestyle

Remarkable interest for human health concerns the microbiological risk assessment due infections by bacteria possessing the ability to adhere to host cell or abiotic surfaces as well as to live in aggregated and biofilm lifestyle. Biofilm is multicellular bacterial community held together by a self-produced extracellular matrix in response to several factors. These factors may include recognition of specific or non-specific attachment sites on cell surfaces, electrostatic interactions on abiotic surfaces, nutritional cues, or in some cases, exposure to stress conditions in the environment as well as into the host. Biofilm lifestyle is comparatively more common than the planktonic one and it has been shown that biofilm plays a crucial role in human health (Brady et al., 2008; Bryers, 2008). As matter of fact, the eradication of bacterial biofilm by administration of antibiotics often fails due to the high drug resistance of bacteria in this lifestyle. Since 2008, European Centre for Disease Prevention and Control reports epidemiological data on the increasing of antimicrobial resistance constituting an important concern in public health hazard. For this reason, rapid assays to determine biofilm susceptibility to antibacterial drugs can significantly improve the outcome of infected patients by enabling a fast selection of efficient antibiotic treatments, thus decreasing the period and the related costs of hospitalization, as well as the incidence of morbidity and mortality ( Gfeller et al., 2005). Therefore, a fundamental prerequisite in studying, counteracting and eradicating biofilm is the possibility to quantify the actual number of bacteria involved. Bacterial counts have deep implications in microbiological diagnosis and therapeutic treatments (Bryers, 2008), in water and food quality analysis (Ramalho et al., 2001; Lee et al., 2007; Rueckert et al., 2005), in environmental applications and consumers’ safety. The standard method used to evaluate the number of bacteria, based on determination of Colony Forming Units (CFUs) (ISO method), can be considered fully appropriate only when bacteria are in planktonic lifestyle but it is unreliable to count bacteria in aggregated, adherent and biofilm lifestyle (Berlutti et al., 2003, Pantanella, 2008; Berlutti, 2008 a; Frioni,

Commercial nonindustrial production of pastries and ice cream in Naples, Italy: results from the inspection of 34 food businesses during a 2-year surveillance study

Background : Ice cream and cream-based pastries are an excellent media for the growth of pathogenic microorganisms. Foods that are prepared without due respect to the rules of food hygiene can carry microorganisms and/or toxins and could be responsible of toxinfections. The main objective of this study was to obtain an overall picture of the hygiene/sanitation conditions found in businesses that produce hand-made pastries and/or ice cream in Naples, Italy. Methods : We inspected 34 businesses to assess the following aspects: hygiene/sanitation conditions of the work area and equipment, implementation of good food hygiene principles, evaluation of HACCP plans, licensing/authorization, quality control and sampling protocols, as well as systems for ensuring food traceability. In 28 of the businesses, samples (environment, foods, workers) were collected for microbiological analysis. Results : Sanctions were issued for nonconformities in 8 businesses (23.5%), and 25 businesses (73.5%) received warnings with orders to correct minor nonconformities (inadequate documentation of compliance with current regulations, incorrect implementation of the quality-control protocol) within specified time periods. Microbiological analyses revealed irregularities in 24/28 businesses (85.7%), and 138 of the 280 samples collected displayed contamination levels exceeding the limits adopted for this study (49.3%). In particular, 80% of the surfaces sampled and 23.8% of the hand swabs collected were shown to be contaminated. All food samples collected met the process-hygiene and food-safety standards prescribed by the European Community. Results obtained were statistically significant (p < 0.05). Conclusions : Our experience of food safety surveillance system indicates that Neapolitan food business operators involved in the production of hand-made ice cream or pastries do not fully understand the importance of the general preventive measures such as Good Hygienic Practices, Good Manufacturing Practice and Hazard Analysis Critical Control Point Codex requirements for providing consumers with safe, high-quality food products.

Verifica di qualitá dei prodotti del legame caldo nella ristorazione ospedaliera

Obiettivi : valutare l’efficacia del legame caldo in un sistema di ristorazione ospedaliera. Metodi : sono stati monitorati negli ultimi tre anni, parametri di temperatura, Carica Mesofila Totale (CMT), indicatori di inquinamento fecale e patogeni, in prodotti del legame caldo preparati e distribuiti dalla ristorazione di un ospedale romano nelle fasi: T0 (centro cottura), T1 (primo reparto servito) e T2 (ultimo reparto servito), per un totale di 337 rilevazioni. Parametri di riferimento per la valutazione: (a) T°C › 60°C (limite critico HACCP); (b) CMT ‹1x106 ufc/g (Delibera Giunta Regionale n. 5575 del 27/10/1998). Risultati: l’analisi dei valori medi di temperatura rilevati al T0 ha evidenziato, nel tempo, una riduzione delle inidoneita (dal 20% del 2000 al 4% del 2002). Le temperature riscontrate nei tempi T1 e T2 appaiono sempre inferiori ai valori rilevati al tempo T0 mostrando una tendenza alla diminuzione rispetto il limite critico. Le riduzioni percentuale delle temperature al T1 ed al T2 rispetto al T0 sono risultate statisticamente significative e piu marcate per l’anno 2002 (16,8%) rispetto al 2001 (2,9%) ed al 2000 (7,5%). Non sono state riscontrate inidoneita per i parametri microbiologici considerati. Conclusione : l’analisi dei risultati evidenzia come l’introduzione di nuove tecnologie di conservazione a caldo del vitto al T0 ha sensibilmente migliorato la rispondenza dei prodotti alle specifiche dell’HACCP. Contrariamente, a seguito della sostituzione/ ottimizzazione della tecnologia di trasporto del vitto ai reparti, si e registrato un peggioramento della qualita del servizio in termini di non conformita dei prodotti rispetto al limite di temperatura, mai accompagnato da non conformita microbiologiche. Gli aspetti organizzativi e gestionali del ciclo lavorativo, unitamente agli aspetti tecnologici, sono stati individuati quali elementi ostacolanti il processo di qualita sui quali intervenire attraverso un’azione combinata di formazione/ coinvolgimento degli operatori della filiera produttiva, nonche di ottimizzazione della performance della tecnologia di trasferimento del vitto.