Common Source Of Contamination Research Articles

Flame Atomic Absorption Spectrophotometric Determination of Heavy Metals in some Agricultural Soils of Kwali Area Council, Abuja, Nigeria

The concentrations of heavy metals Lead, Cadmium, Zinc, Copper and Nickel were determined in selected top agricultural soils of Kwali Area Council of Abuja, Nigeria using Flame Atomic Absorption Spectrophotometric technique. The HNO3-HCL method was used in the sample preparation and a precision of 5%,3%,4%, and 8% for Lead, Zinc, Copper, and Nickel were obtained respectively. The soil pH varied from mildly acidic to near neutral (5.53-6.95) from the various locations and these are considered as normal for agricultural production. The trend of the concentration is in order of Zn>Ni>Cu>Pb>Cd. The ranges of the concentrations are as follows:(N.D-7.25), (N.D-0.17), (3.10-22.90), (1.00-9.70), (1.95-32.80) for Pb, Cd, Zn, Cu and Ni respectively. Generally, all the metals in the study sites recorded higher levels than the control sites. Metal-metal correlation was carried out using Pearson’s product moments. Most elemental pairs show no significant correlation with each other. This revealed that each paired element has no common contamination sources. The metal levels in the soils of the study area were generally lower than most metal levels in soils approved for agricultural purposes. This shows that the area would not impact negatively on metal levels in crops. The study has provided a baseline study in the metals concentrations in the soils of the area.

Prevalence and Genetic Analysis of Salmonella enterica from a Cross-sectional Survey of the New Zealand Egg Production Environment

Epidemiological evidence suggests that Salmonella on New Zealand eggs is not an important pathway for human salmonellosis. However, robust nationally representative data for Salmonella contamination of eggs is not available to support this. To better understand the exposure of New Zealand commercial eggs to Salmonella, a cross-sectional survey collected data on prevalence and serotypes of Salmonella in the feed, laying sheds (feces, dust, and boot or manure belt swabs), and packhouses (egg contact surfaces) of New Zealand commercial egg layer farms. Salmonella was not detected on 16 of 28 surveyed farms, and 4 farms had only one positive sample. Of the 43 (13.3%) of 323 Salmonella-positive samples, dust samples had the highest prevalence (19 of 67, 28.4%), followed by boot or manure belt swabs (11 of 67, 16.4%), feces (7 of 67, 10.4%), packhouse egg contact surfaces (5 of 87, 5.7%), and feed (1 of 33, 3.0%). A significantly higher prevalence was from caged (33 of 75, 44.0%; P < 0.001) compared with cage-free (4 of 126, 3.2%) systems, yet multiple practices differ between laying systems, which could influence prevalence. Salmonella-positive packhouse samples were only identified on the three farms with the highest laying shed prevalence, and isolates were genetically related (as determined by single nucleotide polymorphism analyses) suggesting cross-contamination between the laying shed and packhouse surfaces. Serotypes isolated included Salmonella Infantis, Salmonella Thompson, Salmonella Typhimurium, Salmonella Anatum, and Salmonella Mbandaka. Importantly, Salmonella Enteritidis, which causes egg-associated outbreaks internationally, was not isolated. Genomic comparisons of isolates supported the presence of a common contamination source in the shed and farm environments rather than multiple sporadic contamination events. This survey establishes a benchmark of Salmonella prevalence and types in the New Zealand egg production environment and provides a reference point for assessing the impact of changes to practices on Salmonella prevalence.

Urban-rural gradients in the distribution of trace metals in sediments within temperate mangroves (New Zealand)

Abstract We investigated the sequestering capacity of mangrove sediments through better understanding of trace metal distributions within a temperate estuary. We selected two mangrove stands within Manukau Harbour, New Zealand, based on proximity to contaminant sources. Organic matter (OM), pH, and metal (Cd, Co, Cr, Cu, Fe, Mn, Pb, Zn) concentrations in sediments were analysed. Positive correlations between OM and most trace metals, and metals themselves suggest common contamination sources and sequestering capacity of organic sediments. Higher trace metals in urban versus rural mangrove sediments indicate that contamination source is a major factor controlling metal distribution in these temperate intertidal ecosystems. Specific seasonal trends in metal distributions were not observed due to complex weather patterns and possible fluctuations in anthropogenic inputs. Overall, we suggest that metal dynamics in mangrove sediments are controlled by interacting factors, and that mangroves modulate the ultimate distribution and magnitude of these inputs within temperate estuaries.

Outbreak Investigation of a Multipathogen Foodborne Disease in a Training Institute in Rabat, Morocco: Case-Control Study.

BackgroundOn June 18, 2017, the public health service was alerted about 43 students in the training institute in Rabat who were admitted to the emergency room for acute gastroenteritis following the uptake of a meal a day before.ObjectiveThis study aimed to investigate the foodborne disease outbreak by confirming the outbreak, identifying the source of contamination, and recommending control measures.MethodsWe conducted a case-control study. Cases and controls were selected in a ratio of 1:1. We defined a case as any member of the training institute who attended the Ramadan buffet in the institute’s restaurant and who had presented, in the weekend of June 16 to 20, 2017, symptoms of diarrhea or vomiting with at least one of the following signs: abdominal pain, fever, headache, nausea, and dizziness. A control was defined as anyone who attended the Ramadan buffet in the institute’s restaurant but had not presented any symptoms from June 16 to 20, 2017. We conducted a bivariate and multivariable analysis. Stools of ill students were collected, and a food specimen was collected for bacterial testing.ResultsA total of 50 cases and 50 controls were selected. Among the cases, males were predominant (43/50, 86%); the median age was 21 years. A total of 47 cases sought medical care. There were no hospitalizations and no deaths. The episode was short with an estimated average incubation period of 9 hours. The epidemic curve oriented toward a common source of contamination. Among food items, briwates were strongly associated with the illness with an odd ratio of 14.23 (95% CI 5.04-40.04; P<.001). Laboratory testing of briwates showed presence of Escherichia coli O157 and Staphylococcus aureus.ConclusionsThis foodborne disease outbreak was likely caused by briwates that was contaminated with S aureus and E coli. We recommended strengthening hygiene measures. Food handling techniques should be taught as part of continuous professional development for food handlers.

Public health risks associated with Salmonella contamination of imported edible betel leaves: Analysis of results from England, 2011–2017

Fresh betel leaves (Piper betle L.), imported into the UK are a traditional ready-to-eat food consumed by Asian populations. We report here the consolidation of routinely collected data to model the public health risks from consumption of this food. Amongst 2110 samples collected at Border Inspection, wholesale, catering or retail, Salmonella was detected in 488 (23%) of samples tested between 2011 and 2017 and was the most commonly Salmonella-contaminated ready-to-eat food examined by Public Health England during this period. Using data from multiple samples (usually 5) tested per consignment sampled at Border Inspection, contamination levels were calculated by most probable number: seasonal, temporal and country specific differences were detected. Quantitative contamination data was used to estimate the levels present at retail, and a β-Poisson dose response model the probability of illness was calculated. Using data for products imported from India, the probability of acquiring infection following a single exposure (comprising of a single leaf) was estimated to be between 0.00003 (January–March) and 0.0001 (July–September). Using British Asian population data for individuals over 30 years of age in England in 2011, two estimates of consumption were modelled as 2.1 and 12.8 million servings per annum. Results from the model estimated 160 cases (range 102 to 242) and 960 cases (range 612 to 1456) per year in England for the two consumption estimates and equated to 34 (range 22 to 51) and 204 (range 130 to 310) salmonellosis cases per year reported to national surveillance. Salmonella from 475 of the contaminated samples were further characterised which showed a heterogeneous population structure with 46 S. enterica subsp. Enterica serovars, together with S. enterica subs diarizonae and salamae identified. Isolates from individual consignments were diverse and close genetic relationships between independent isolates were very rare except from within an individual consignment. There were no outbreaks detected as associated with betel leaf consumption. However analysis by whole genome sequencing of the 2014–17 data identified two cases where the clinical isolate had <5 single nucleotide polymorphism differences to isolates from betel leaves which is indicative of a likely epidemiological link and common source of contamination. Due to the diversity of the Salmonella contaminating this product, associations between salmonellosis cases and betel leaf consumption will appear sporadic and unlikely to be detected by current surveillance strategies based on outbreak detection.

Chemical Speciation, Bioavailability and Risk Assessment of Potentially Toxic Metals in Highway Dusts as Indicators of Highway Pollution

This paper investigated concentrations of heavy metals in roadside soil dusts collected along Ife-Ibadan highway in Osun state, Nigeria with the aim of assessing the impacts of vehicular emissions on the environments. The soil dusts were analyzed for total metal concentrations and speciation using Atomic absorption spectrophotometry followed by the evaluation of the metal bioavailability. Results of the total metal analysis indicated that the concentrations of the metals (Pb, Zn, Cu, Fe and Mn) were higher in the contaminated soils than control soils and their WHO maximum allowable limits. The pattern of the total mean concentrations of the metals is in the order: Fe > Cu > Mn > Zn > Pb. The contamination factors of the metals showed that the soils suffered contamination. Analysis of variance (ANOVA) revealed that differences existed significantly in the mean values for all the metals across the study sites. Strong correlation among the metals signified common contamination sources. Cluster analysis produced two major groups: A (Fe and Cu) and B (Zn, Mn and Pb) which is subdivided into two sub-groups viz: Bi (Zn and Mn) and Bii (Pb), indicating similar chemical properties/or sources. The results of the T–test indicated that there were significant differences between the concentrations of the metals in contaminated and control soils. The chemical pools of the metals indicated that the metals were distributed into six fractions with most of the metals residing in the non-residual fractions, suggesting how readily the metals are released into the environment.

Detection of Legionella Anisa in Water from Hospital Dental Chair Units and Molecular Characterization by Whole-Genome Sequencing.

This study aims to assess contamination with Legionella spp. in water from dental chair units (DCUs) of a hospital dental ward and to perform its molecular characterization by whole-genome sequencing (WGS). We collect eight water samples (250 mL) from four DCUs (sink and water-syringe). Samples are tested for the presence of Legionella spp. (CFUs/mL) by culturing according to the Nederland Norm (NEN) 6265. Three DCUs are found positive for Legionella anisa, and four isolates are cultured (sink n = 2, water-syringe n = 1; two isolates from the same chair) with 1 × 102 CFU/mL. Whole-genome multi-locus sequence typing (wgMLST) results indicate that all strains belong to the same cluster with two to four allele differences. Classical culture combined with WGS allows the identification of a unique clone of L. anisa in several DCUs in the same hospital dental ward. This may indicate a common contamination source in the dental unit waterlines, which was fixed by replacing the chairs and main pipeline of the unit. Our results reveal tap water contamination in direct contact with patients and the usefulness of WGS to investigate bacterial molecular epidemiology.

Is blaCTX-M-1 Riding the Same Plasmid Among Horses in Sweden and France?

A predominance of the blaCTX-M-1/IncHI1 plasmid combination in horses has been reported in Czech-Republic, Denmark, and The Netherlands. To clarify a possible specific plasmid epidemiology of blaCTX-M-1 in horses in a European perspective, a collection of 74 extended-spectrum beta-lactamase-producing Escherichia coli recovered from diseased horses in France and Sweden during the period 2009-2014 was investigated in respect of their genetic relatedness, plasmid content, and molecular features. Overall, 80% of E. coli isolates from diseased horses harbored blaCTX-M-1 on large IncHI1 plasmids with plasmid sequence type (pST) 2 and pST9 more prevalent in Sweden and France, respectively. In French isolates, IncI1/pST3 plasmids were also identified. The CTX-M-1-producing E. coli belonged principally to the clonal complex 10. ST641, together with its single locus variant, and ST1730 constituted two other major groups. The rep-PCR clustering highlighted a clonal dissemination of E. coli CTX-M-1 producers in different regions of the same country and during several years. The STs found in our isolates were also reported in The Netherlands, suggesting a common source of contamination in Europe, although only further cooperative investigation will clarify this issue. On the other hand, the spread of IncI1/pST3 plasmids among horses constitutes another worrisome issue considering their successful spread in other animal hosts such as chicken or bovines. Monitoring evolution and propagation of antimicrobial resistance in equine environment is a priority to avoid further propagation of antimicrobial resistance mechanisms threatening human and animal health.

Recent actuality about Bacillus cereus and human milk bank: a new sensitive method for microbiological analysis of pasteurized milk.

Three cases of Bacillus cereus infection or colonization occurred in the same regionin France, and milk from the milk bank was suspected as a possible common source of contamination. All Batches delivered to the three cases complied with the requirements of the bacteriological reference method recommended bygood practices guidelines. Still, a retrospective analysis with a more sensitive method showed one batch to contain B. cereus, however straincomparison revealed no epidemiological link betweenisolates from patients and those from the milk. Consequently, in accordance with the precautionary principle, we developed a new sensitive method for the screening of pasteurized milk for pathogenic bacteria. From January 1 to August 31, 2017, 2526 samples of pasteurized milk were prospectively included in the study. We showed that a 20 mL sample of pasteurized milk incubated for 18h at 37°C under aerobic conditions was favoring the detection of B. Cereus. The nonconformity rate was 6.3% for the reference method and 12.6% for the improved method (p < 0.0001). Nonconformity was due to the presence of B. cereus in 88.5% of cases for the improved method and 53% of cases for the reference method (p < 0.0001). Thus our new method is improves the microbiological safety of the product distributedand only moderately increases the rate of bacteriological nonconformity.

Investigation of a Collective Foodborne Illness Shows a Multi-Pathogen Contamination in Training Institute in Rabat, June 2017, Morocco - A Case Control Study

Background: Foodborne diseases outbreaks are common worldwide and an important public health issue. According to WHO, approximatively 600 million of foodborne illness and 400 thousand related deaths per year. In Morocco, an average of 1500 cases is notified annually. On June 18, 2017, the public health service was alerted about 43 suspected students in a training Institute in Rabat admitted in emergency for collective foodborne disease following an uptake of meal a day before. Objective: We investigated this outbreak to confirm the outbreak, to identify the source of contamination and to recommend control measures. Methods: We conducted a case control study. We selected cases and controls in the ratio of 1:1. We defined a case as anyone who attended the meal served on 17 June 2017 at the Institute's restaurant and presented in the two days after diarrhea and one of the following signs: nausea, vomiting, abdominal pain, fever, and dizziness. A control was defined as anyone who had consumed the same meal and had not presented any digestive signs. We conducted bivariate and multivariable analysis. Stools of ill students were collected, and food specimen was collected for bacterial testing. Results: Among 100 students interviewed, we identified 50 cases. Among cases, males were predominant (86%), the median age was 21 years. 47 sought medical care. The episode was short with an estimated average incubation period of 9 hours. The epidemic curve oriented towards a common source of contamination. Among food items, Briwates were strongly associated with the illness with an odd ratio of 14.23 (5.04-40.04). Laboratory testing of Briwates found EColi O157 and Staphylococcus Aureus. Conclusions: This was an outbreak associated with the consumption of Briwates contaminated by two germs, which was the source of this episode. We recommended to strengthen hygiene measures and safe food handling, to raise awareness and educate the staff.

Isolation, molecular characterization and antimicrobial resistance of enterobacteriaceae isolated from fish and seafood

This current study attempted to examine the occurrence rates of Enterobacteriaceae in seafood samples collected from different fishmongers in the province of Constantine (Northeast Algeria) over a one-year period. Total and fecal coliforms were enumerated and selected Enterobacteriaceae colonies were identified. Escherichia coli (E. coli) and Salmonella isolates were serotyped, after which their antimicrobial susceptibility patterns were determined. Extended-spectrum beta-lactamases (ESBL) encoding genes, virulence genes (stx1, stx2 and eae) and plasmid-harboring were searched among E. coli isolates and their clonality was also assessed by pulsed-field gel electrophoresis (PFGE). Results showed that fecal coliform contamination levels are beyond the recommended limits. All strains of Salmonella (n = 2) isolated were of serovar infantis. One E. coli isolate from sardines belonged to serotype O127 and two others (one from sardines and one from shrimps) were identified as serotype O125. One E. coli isolate from sardines was characterized as enterohemorrhagic (EHEC) and six others as shiga toxin-producing (STEC) (three from sardines and three from shrimps). All tested strains were multidrug resistant, with five E. coli strains showing an ESBL phenotype and harboring the blaCTX-M-15 gene (four from sardines and one from shrimps). Plasmids of differents sizes were extracted from seven E. coli isolates (five from sardines and two from shrimps) with many strains carrying more than one plasmid. E. coli isolates belonged to two phylogenetic groups (B1 and, mainly, E) and scattered on eight distinct clones as defined by PFGE. Some strains are grouped within the same cluster regardless of their origin and characteristics, indicating a common source of contamination. These findings demonstrate that, in the study region, sardines and shrimp may play an important role in the dissemination of virulent and multi-drug resistant enterobacteria strains.

A transposon mutant library of Bacillus cereus ATCC 10987 reveals novel genes required for biofilm formation and implicates motility as an important factor for pellicle-biofilm formation.

Bacillus cereus is one of the most common opportunistic pathogens causing foodborne illness, as well as a common source of contamination in the dairy industry. B. cereus can form robust biofilms on food processing surfaces, resulting in food contamination due to shedding of cells and spores. Despite the medical and industrial relevance of this species, the genetic basis of biofilm formation in B. cereus is not well studied. In order to identify genes required for biofilm formation in this bacterium, we created a library of 5000 + transposon mutants of the biofilm‐forming strain B. cereus ATCC 10987, using an unbiased mariner transposon approach. The mutant library was screened for the ability to form a pellicle biofilm at the air‐media interface, as well as a submerged biofilm at the solid‐media interface. A total of 91 genes were identified as essential for biofilm formation. These genes encode functions such as chemotaxis, amino acid metabolism and cellular repair mechanisms, and include numerous genes not previously known to be required for biofilm formation. Although the majority of disrupted genes are not directly responsible for motility, further investigations revealed that the vast majority of the biofilm‐deficient mutants were also motility impaired. This observation implicates motility as a pivotal factor in the formation of a biofilm by B. cereus. These results expand our knowledge of the fundamental molecular mechanisms of biofilm formation by B. cereus.

Salad dressing spoilage by Bacillus amyloliquefaciens with gas formation

Abstract B. amyloliquefaciens is a Gram-positive, aerobic, motile rod, often found in soil, which has been described as a plant growth promoter and is used in several industrial processes. This study reports an episode involving the gassy spoilage of salad dressing caused by B. amyloliquefaciens in a production facility located in Rio de Janeiro, Brazil. Nine B. amyloliquefaciens strains were isolated from spoiled salad dressings, the sugar used as a raw material in the manufacture and from the production plant. A genotypic analysis of the isolates by Rep-PCR generated eight band profiles grouped in five Rep-PCR clusters. When re-inoculated into fresh salad dressing three B. amyloliquefaciens isolates belonging to the Rep-PCR clusters A, D and E were able to reproduce the gassy spoilage process, whereas the isolates belonging to the Rep-PCR clusters B and C did not produce any visible spoilage, suggesting that these isolates were not directly involved in the spoilage process. The predominant Rep-PCR cluster, cluster A, included strains isolated from barbecue and passion fruit seed salad dressings and from sugar (raw material), suggesting it is a common source of contamination for such salad dressings.

Salmonella Thompson outbreak associated with consumption of chicken shawarma and the usefulness of genome sequencing in the investigation.

A sudden increase in Salmonella Thompson (S. Thompson) cases distributed throughout three border regions in the province of Quebec in November 2016 triggered a provincial investigation to identify a common source of contamination and to put the appropriate control measures into place. To report on the outbreak and to describe the use of genomic sequencing to identify the salmonella serotype responsible. A descriptive survey of all reported cases of Salmonella serogroup C1 that had occurred between October 1, 2016 and February 15, 2017 was conducted. A case definition was developed. Pulsed field gel electrophoresis supplemented by analyses of genome sequences using the single nucleotide variant phylogenomics method were used to demarcate and manage the outbreak. Eighteen cases of S. Thompson were identified through whole genome sequencing. The onset dates of symptoms for the 16 cases that presented enteric symptoms were November 21-December 2, 2016. Two cases that presented with atypical symptoms were not reported until February 2017. Among the 18 cases, 16 had eaten or probably eaten chicken shawarma at the same restaurant chain and nine of these cases ate it at the same restaurant. In total, five restaurants from this chain, spread throughout three border regions of Quebec, were identified. Outbreaks associated with chicken shawarma have been identified in the past. Efforts must be made to ensure that the owners of this type of restaurant know the contamination risk associated with this type of cooking and take the necessary steps to reduce this risk. The use of the genome sequencing method was very useful in defining the outbreak.

Prevalence of Listeria spp. and characterization of Listeria monocytogenes isolated from food products in Tetouan, Morocco

A total of 1096 food samples were purchased in Tetouan, North-Western of Morocco, to examine the presence of Listeria spp. Eighty (7.3%) of the tested samples were found positive for the presence of Listeria spp., while L. monocytogenes was detected in 16 (1.5%) samples. L. monocytogenes isolates belonged to clonal complexes CC2 (PCR serogroup IVb) and CC199 (PCR serogroup IIa) and to 8 different combined AscI/ApaI pulsed-field gel electrophoresis profiles. Core genome multilocus sequence typing (cgMLST) allowed to distinguish 12 different cgMLST types and revealed the presence of 3 clusters of closely-related isolates from different samples, suggesting the existence of common sources of contamination. Isolates showed no resistance to the reference antibiotics used for the treatment of listeriosis. This study underlines the circulation of L. monocytogenes strains of clonal complex CC2 in Morocco and highlights the importance of microbiological surveillance in order to minimize consumers’ exposure to this foodborne pathogen.

Quantification of hygiene indicators and Salmonella in the tonsils, oral cavity and rectal content samples of pigs during slaughter

The tonsils, oral cavity and faeces of 94 pigs at slaughter were sampled to assess the numbers of total aerobic bacteria, Enterobacteriaceae and Escherichia coli in the rectal content, tonsils and oral cavity of pigs at time of evisceration. Moreover, the prevalence, numbers and types of Salmonella spp. were determined. Mean numbers of Enterobacteriaceae in tonsils and the oral cavity differed between slaughterhouses. The proportion of Enterobacteriaceae relative to total aerobic bacteria differed between the different tissues, though large variations were observed between animals. Salmonella spp. were mostly detected in oral cavity swabs (n = 51, 54%), of which six samples were contaminated in numbers over 2.0 log CFU/100 cm2. Salmonella spp. were also recovered from 17 tonsillar tissue samples (18%) and 12 tonsillar swabs (13%). Out of the 29 rectal content samples from which Salmonella was recovered (31%), most were lowly contaminated, in the range between −1 and 0 log CFU/g. The predominant serotypes were S. Typhimurium and its monophasic variant, which were recovered from 33 and 13 pigs, respectively. In most cases, the same serotypes and MLVA profiles were found in pigs slaughtered during the same day, thus suggesting a common source of contamination.

Assessment the Leachable Heavy Metals and Ecological Risk in the Surface Sediments inside the Red Sea Ports of Egypt

The concentrations and distributions of the leachable heavy metals (Co, Cu, Zn, Ni, Cd, Mn, Pb and Fe) were investigated in the fine sediment fractions (O3, O4 and O5) collected from the Egyptian Red Sea Harbors at Hurghada, Safaga and Qusier. The three fractions were the essential heavy metal carriers and were formed the main constituent of the marine sediments with percentages exceed 50% at the most of studied stations. The accumulation sequence of the metal carriers at Hurghada was O5 >O4> O3, however at Safaga and Qusier, it was O5 >O3> O4. Fe and Mn showed the highest values at Safaga (7483 and 306.3 µg/g, respectively) due to the high terrigenous inputs from the different shipment operations and the wastewater effluents. The highest values of Zn, Cu, Ni and Pb were recorded in the marine area off Hurghada ports (330.38, 298.40, 91.4 and 101.02 µg/g, respectively), which attributed to the coastal based activities at Hurghada shipyard and fishing berth. Meanwhile the highest levels of Co and Cd were observed at the old port of Qusier (5.85 and 4.19 µg/g, respectively). The correlation coefficient and principal component analysis (PCA) indicated the anthropogenic sources of Cu, Zn and Pb in front of Hurghada ports. Based on the SQGs, the concentrations of Co, Fe, Mn, Zn and Pb were below the lowest effect level (LEL) with limited severity for Cd, Cu and Ni at Hurghada shipyard but lower than the sever effect level (SEL). The principal component analysis (PCA) showed correlations between Fe, Mn and partially Cd as well as the strong positive correlations for Cu with Zn and Pb suggesting common source of contamination that is likely originated from the terrestrial materials associated with the shipping of ores and coastal activities. According to the Enrichment factor (EF) and the geo-accumulation factor (Igeo), Cu and Pb were the highest enriched elements due to anthropogenic contamination; consequently the studied ports were classified as moderately to highly contaminated by Cu and Pb at Hurghada.

Norovirus outbreak in a restaurant: investigation of the path of infection by sequence analysis of food and human samples

In September 2014, a small gastroenteritis outbreak occurred in a Greek restaurant. Primary investigations by official food surveillance revealed significant hygienic problems in the premises. Food samples and environmental samples were analyzed for the presence of bacterial and viral food pathogens. Norovirus genogroup I (GI) was detected in 2 environmental samples and in mixed salad. At the same time, stool samples from patients were analyzed and norovirus GI was detected. Further investigations revealed the presence of norovirus GI on some of the restaurant employees. Comparison of nucleic acid sequences revealed full sequence homology between norovirus RNA genotype 1.2 in food, environmental and stool samples, suggesting a common source of contamination and infection. Sequence analysis of food and environmental samples was facilitated by application of a system for total RNA amplification. Despite the fact that original source of contamination could be determined doubtlessly, observed weaknesses in the food production that caused this outbreak were discussed. The mixed salad could have been contaminated either by the lettuce contaminated at primary production or by one of the food-handlers. The investigation of the path of infection is necessary for the kind of legal consequences to be directed by authorities and may contribute to measures to eliminate possible sources of food contamination.

Sources, migration and transformation of antimony contamination in the water environment of Xikuangshan, China: Evidence from geochemical and stable isotope (S, Sr) signatures

The Xikuangshan (XKS) mine in central China is the largest antimony (Sb) mine in the world. The mining activity has seriously contaminated the waters in the area. To determine the sources, migration and transformation of Sb contamination, 32 samples from groundwater (aquifer water), surface water and mine water were collected for water chemistry, trace element and SSO4 and Sr stable isotope analyses. The results showed that the groundwater and surface water were in an oxidized environment. The SSO4 and Sr isotope compositions in the water indicated that dissolved Sb and SO42 originated from sulfide mineral (Sb2S3) oxidation, whereas radiogenic Sr may have been sourced from silicified limestone and stibnite in the Shetianqiao aquifer. Furthermore, a positive correlation between δ34SSO4 and δ87Sr values revealed that the Sr, S and Sb in the waters had a common contamination source, i.e., silicified limestone and stibnite, whereas the Sr, S and Sb in rock and ore were sourced from Proterozoic basement clastics. The analysis also indicated that the isotope composition of dissolved SO42− had been influenced by slight bacterial SO4 reduction in the Magunao aquifer. Mining or rock collapse may have caused Shetianqiao aquifer water to contaminate the Magunao aquifer water via mixing. This study has demonstrated that the stable isotopes of 34SSO4 and 87Sr, combined with hydrochemical methods, are effective in tracking the sources, migration and transformation of Sb contamination.

Practical toolkit for monitoring endoscope reprocessing effectiveness: Identification of viable bacteria on gastroscopes, colonoscopes, and bronchoscopes

Experts have recommended microbiologic surveillance by external reference laboratories for certain flexible endoscopes. There is currently insufficient evidence on the feasibility and utility of cultures. Researchers evaluated a preassembled toolkit for collecting and processing samples from endoscopes. A pilot study was performed in a large academic medical center. A toolkit was used to aseptically sample biopsy ports and suction/biopsy channels of 5 gastroscopes, 5 colonoscopes, and 5 bronchoscopes after full reprocessing. Blinded specimens were packaged and transported on icepacks to a reference laboratory that used standard methodologies for microbial cultures. The laboratory detected bacteria in samples from 60% of patient-ready endoscopes, including gram-positive and gram-negative species. Viable microbes (<10 CFU) were recovered from 2 gastroscopes, 3 colonoscopes, and 4 bronchoscopes. Stenotrophomonas maltophilia and Delftia acidovorans were recovered from all 3 endoscope types. Subsequent environmental testing detected S maltophilia in the reprocessing rinse water. A preassembled toolkit facilitated the aseptic collection of samples for culturing by a reference laboratory that detected viable microbes on fully reprocessed endoscopes. Speciation allowed identification of potential pathogens and a possible common contamination source, demonstrating that microbial cultures may have value even when colony counts are low.