BackgroundLegionella pneumophila is increasingly recognised as a significant cause of sporadic and epidemic community-acquired and nosocomial pneumonia. Many studies describe the frequency and severity of Legionella spp. contamination in spa pools, natural pools, hotels and ships, but there is no study analysing the environmental monitoring of Legionella on board trains. The aims of the present study were to conduct periodic and precise environmental surveillance of Legionella spp. in water systems and water tanks that supply the toilet systems on trains, to assess the degree of contamination of such structures and to determine the effectiveness of decontamination.MethodsA comparative pre-post ecological study was conducted from September 2006 to January 2011. A total of 1,245 water samples were collected from plumbing and toilet water tanks on passenger trains. The prevalence proportion of all positive samples was calculated. The unpaired t-test was performed to evaluate statistically significant differences between the mean load values before and after the decontamination procedures; statistical significance was set at p ≤ 0.05.ResultsIn the pre-decontamination period, 58% of the water samples were positive for Legionella. Only Legionella pneumophila was identified: 55.84% were serogroup 1, 19.03% were serogroups 2–14 and 25.13% contained both serogroups. The mean bacterial load value was 2.14 × 103 CFU/L. During the post-decontamination period, 42.75% of water samples were positive for Legionella spp.; 98.76% were positive for Legionella pneumophila: 74.06% contained serogroup 1, 16.32% contained serogroups 2–14 and 9.62% contained both. The mean bacterial load in the post-decontamination period was 1.72 × 103 CFU/L. According to the t-test, there was a statistically significant decrease in total bacterial load until approximately one and a half year after beginning the decontamination programme (p = 0.0097).ConclusionsThis study indicates that systematic environmental surveillance could be a useful approach for assessing the risk of exposure to Legionella bacteria, which still represents a public health threat. According to the study results, an environmental surveillance programme, followed by decontamination procedures where necessary, would decrease the total bacterial count, protecting the health of travellers and workers.
Foodborne diseases and antibiotic resistance are serious widespread health problems in the contemporary world. In this study, we compared the microbiological quality of ready-to-eat (RTE) foods found in community canteens versus hospital canteens in Rome, Italy, focusing on detection and quantification of Enterobacteriaceae and the antibiotic resistance of these bacteria. Our findings show a remarkable difference in Enterobacteriaceae contamination between RTE foods distributed in community canteens (33.5% of samples) and those distributed in hospital canteens (5.3% of samples). This result highlights greater attention to good manufacturing practices and good hygiene practices by the food operators in hospitals compared with food operators in community canteens. As expected, a higher percentage of cold food samples (70.9%) than of hot food samples (10.8%) were positive for these bacteria. Excluding the intrinsic resistance of each bacterial strain, 92.3% of the isolated strains were resistant to at least one antibiotic, and about half of the isolated strains were classified as multidrug resistant. The prevalence of multidrug-resistant strains was 50% in the community samples and 33.3% in hospital canteens. Our results indicate that approximately 38% of RTE foods provided in community canteens is not compliant with microbiological food safety criteria and could be a special risk for consumers through spread of antibiotic-resistant strains. Hygienic processing and handling of foods is necessary for both hospital and community canteens.
Objective: The aim of the present study is to evaluate the presence of Salmonella spp. and Listeria monocytogenes in ready-to-eat foods by comparing the performance and sensitivity of BIO-RAD commercial Kits based on real-time PCR detection with traditional culture (ISO) procedures. Materials and methods: Sixty-five samples of ready-to-eat foods were analysed as described above. In order to verify the validity of both culture and biomolecolar methods and to compare the sensitivity of real-time PCR versus conventional culture (ISO) procedures, five food samples were artificially contaminated with the Salmonella enteritidis ATCC strain by using scalar concentration from 103 to 10-1 cfu/g while one food sample was artificially contaminated with the Listeria monocytogenes ATCC strain. Finally, statistical analyses of the results were performed using the statistics “K” to confirm the agreement between the compared methods.
Results: Both procedures showed the absence of Salmonella spp. and Listeria monocytogenes in the processed samples; results in agreement appeared both for the five food samples artificially contaminated with Salmonella enteritidis ATCC strain and for the food sample artificially contaminated with Listeria monocytogenes ATCC strain. The sensitivity of the biomolecolar test was 1 cfu/g. Therefore full agreement between the two methods was detected, with a K value of 1.
Conclusions: The real-time PCR system appears to be extremely useful in the rapid screening of food samples, allowing for the rapid identification of Salmonella spp. and L. monocytogenes.
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