RESUMO
Campylobacter continues to be the number one cause of bacterial gastroenteritis in Europe. Poultry, and especially broiler chickens, is considered an important reservoir for Campylobacter spp. Poultry producers prioritize to identify and reduce the number of Campylobacter contaminated chicken flocks by tightening biosecurity and mitigation actions at slaughter. Campylobacter-positive flocks must therefore be identified as close to slaughter as possible, and rapid detection methods are needed. Here we evaluated the applicability, sensitivity, and specificity of four commercially available rapid methods to detect Campylobacter in naturally contaminated chicken cecal droppings on-farm before slaughter against an established qPCR method. The Biofire® FilmArray® Gastrointestinal Panel assay, the VIDAS Campylobacter assay, the Singlepath® Campylobacter test, and OptiGenes' Genie Campylobacter isothermal DNA amplification were assessed in a pilot-study. The OptiGenes' Genie Campylobacter isothermal DNA amplification was also tested under field conditions. The Biofire® FilmArray® showed superior sensitivity and specificity compared to the three other rapid tests but had a lower throughput and a higher cost. While the VIDAS Campylobacter, Singlepath® Campylobacter and the isothermal DNA amplification were affordable, their unsatisfactory sensitivity (10%-71%) left these unsuitable to monitor Campylobacter carriage in chickens. An additional finding of this study is that 38% of flocks positive for Campylobacter at slaughter became contaminated during the last week of rearing. Therefore, increased efforts to develop suitable methods to detect Campylobacter rapidly and reliably in chickens close to slaughter are needed.
Assuntos
Infecções por Campylobacter , Campylobacter , Doenças das Aves Domésticas , Animais , Biosseguridade , Campylobacter/genética , Infecções por Campylobacter/diagnóstico , Infecções por Campylobacter/veterinária , Galinhas , Projetos Piloto , Doenças das Aves Domésticas/diagnósticoRESUMO
We describe an outbreak of Salmonella Agbeni sequence type (ST)2009 infections in Norway. Between 31 December 2018 and 16 March 2019, 56 cases (33 female and 23 male; median age: 50 years, range: 2-91) were reported, of which 21 were hospitalised. Cases were defined as people living in Norway, with laboratory-confirmed infection with S. Agbeni ST2009 and cluster type (CT)2489, reported between 31 December 2018 and 30 March 2019. We conducted a case-control study, with three controls per case (matched by age, sex and municipality), using the Norwegian National Registry. Cases were more likely to have consumed a commercial mix of dried exotic fruits than controls (cases = 8, controls = 31; odds ratio: 50; 95% confidence interval: 3-2,437). The outbreak strain was confirmed by whole genome sequencing (WGS) and was isolated from the fruit mix consumed by cases, resulting in withdrawal from the market on 6 March 2019.The fruit mix consisted of fruits from different countries and continents. It was packed in Italy and distributed to several European countries, including Norway. However, no other countries reported cases. This outbreak highlights that dried fruits could represent a risk in terms of food-borne infections, which is of particular concern in ready-to-eat products.
Assuntos
Frutas , Intoxicação Alimentar por Salmonella , Estudos de Casos e Controles , Surtos de Doenças , Europa (Continente) , Feminino , Humanos , Itália , Masculino , Pessoa de Meia-Idade , Noruega/epidemiologia , Salmonella/genética , Intoxicação Alimentar por Salmonella/diagnóstico , Intoxicação Alimentar por Salmonella/epidemiologiaRESUMO
The present multicenter study aimed at assessing the performance of air sampling as a novel method for monitoring Campylobacter in biosecure poultry farms. We compared, using a harmonized procedure, the bacteriological isolation protocol (ISO 10272-1:2017) and a real-time PCR method used on air filter samples. Air samples and boot swabs were collected from 62 biosecure flocks from five European countries during the summer of 2019. For air filters, the frequency of PCR-positive findings was significantly higher (n = 36; 58%) than that obtained with the cultivation methods (P < 0.01; standardized residuals). The cultivation protocols (one with Bolton enrichment and one with Preston enrichment) were comparable to each other but returned fewer positive samples (0 to 8%). The association between type of sample and frequency of PCR-positive findings was statistically confirmed (P < 0.01; Fisher´s exact test), although no culture-positive air filters were detected using direct plating. For the boot swabs, the highest number of positive samples were detected after enrichment in Preston broth (n = 23; 37%), followed by direct plating after homogenization in Preston (n = 21; 34%) or Bolton broth (n = 20; 32%). It is noteworthy that the flocks in Norway, a country known to have low Campylobacter prevalence in biosecure chicken flocks, tested negative for Campylobacter by the new sensitive approach. In conclusion, air sampling combined with real-time PCR is proposed as a multipurpose, low-cost, and convenient screening method that can be up to four times faster and four times more sensitive than the current boot-swab testing scheme used for screening biosecure chicken production.IMPORTANCECampylobacter bacteria are the cause of the vast majority of registered cases of foodborne illness in the industrialized world. In fact, the bacteria caused 246,571 registered cases of foodborne illness in 2018, which equates to 70% of all registered cases in Europe that year. An important tool to prevent campylobacters from making people sick is good data on where in the food chain the bacterium is present. The present study reports a new test method that quadruples the likelihood of identifying campylobacter-positive chicken flocks. It is important to identify campylobacter-positive flocks before they arrive at the slaughterhouse, because negative flocks can be slaughtered first in order to avoid cross-contamination along the production line.
Assuntos
Infecções por Campylobacter/veterinária , Campylobacter/isolamento & purificação , Galinhas , Doenças das Aves Domésticas/diagnóstico , Animais , Infecções por Campylobacter/diagnóstico , Infecções por Campylobacter/microbiologia , República Tcheca , Dinamarca , Itália , Noruega , Polônia , Doenças das Aves Domésticas/microbiologiaRESUMO
The present pilot study aimed at evaluating air sampling as a novel method for monitoring Campylobacter in poultry farms. We compared the bacteriological isolation of Campylobacter from boot swabs and air filter samples using ISO 10272-1:2017. A secondary aim was to evaluate the use of molecular methods, i.e. real time PCR, on the same sample set. Samples from 44 flocks from five European countries were collected, and included air samples, in parallel with boot swabs. Campylobacter spp. was isolated from seven of 44 boot swabs from three of five partners using the enrichment method. Two of these positive boot swab samples had corresponding positive air samples. Using enrichment, one positive air sample was negative in the corresponding boot swabs, but Campylobacter spp. was isolated from direct plating of the boot swab sample. One partner isolated Campylobacter spp. from six of 10 boot swabs using direct plating. Overall, 33 air filter samples were screened directly with PCR, returning 14 positive results. In conclusion, there was a lack of correspondence between results from analysis of boot swabs and air filters using ISO 10272-1:2017. In contrast, the combination of air filters and direct real-time PCR might be a way forward. Despite the use of the detailed ISO protocols, there were still sections that could be interpreted differently among laboratories. Air sampling may turn into a multi-purpose and low-cost sampling method that may be integrated into self-monitoring programs.
Assuntos
Microbiologia do Ar/normas , Infecções por Campylobacter/veterinária , Campylobacter/isolamento & purificação , Galinhas/microbiologia , Doenças das Aves Domésticas/prevenção & controle , Animais , Campylobacter/genética , Europa (Continente) , Fazendas/estatística & dados numéricos , Fezes/microbiologia , Internacionalidade , Projetos Piloto , Aves Domésticas/microbiologia , Doenças das Aves Domésticas/microbiologia , Doenças das Aves Domésticas/transmissãoRESUMO
Only a few studies concerning Shiga toxin-producing E. coli (STEC) detection in bivalves and their harvesting areas have been reported, and to the best of our knowledge there are no outbreaks associated with STEC from bivalves described. The aim of the present study was to investigate the occurrence of STEC in Norwegian bivalves, and to characterize potential STEC isolated from the samples. A total of 269 samples of bivalves were screened for the presence of stx and eae genes, and markers for the serogroups O26, O103, O111, O145 and O157 by using ISO TS 13136 (2012). The screening returned 19 samples that were positive for stx and eae, and attempts of isolation of STEC were made from these samples. Presumptive STEC were obtained from three samples, and three isolates (one from each sample) were subjected to whole-genome-sequencing (WGS). The WGS revealed that one of the isolates did not carry the stx genes, while the other two were identified as stx2i positive E. coli O9:H19 and stx2g positive E. coli O96:H19. Neither of the two STEC isolates were positive for virulence markers such as eae and ehx. The results suggest that the occurrence of STEC in Norwegian bivalves is low.
Assuntos
Bivalves/microbiologia , Alimentos Marinhos/microbiologia , Escherichia coli Shiga Toxigênica/genética , Escherichia coli Shiga Toxigênica/isolamento & purificação , Animais , Proteínas de Escherichia coli/genética , Fezes/microbiologia , Noruega , Sorogrupo , Sorotipagem , Virulência/genéticaRESUMO
In September 2017, a cluster of monophasic Salmonella Typhimurium isolates was identified at the National Reference Laboratory for Enteropathogenic Bacteria in Norway. We investigated the cluster to identify the source and implement control measures. We defined a case as a person with laboratory-confirmed salmonellosis with the outbreak strain multiple locus variable-number tandem repeat analysis type. We conducted descriptive epidemiological and environmental investigations and performed whole genome sequencing (WGS) with core and accessory genome multilocus sequence typing of all isolates from cases or the environment connected with this outbreak. We identified 21 cases, residing in 10 geographically dispersed counties, all of whom had consumed food or drinks from a café at Oslo Airport. Case distribution by date of symptom onset suggested that a point source was introduced in mid-August followed by continued environmental contamination. The incubation periods ranged 0-16 days and increased as the outbreak progressed, likely due to increasingly low-dose exposure as control measures were implemented. WGS confirmed an identical cluster type-944 in all cases and six environmental specimens from the café. Control measures, including temporary closure and kitchen refurbishment, failed to eliminate the environmental source. We recommend strengthened hygiene measures for established environmental contamination during an outbreak.
Assuntos
Aeroportos , Surtos de Doenças/estatística & dados numéricos , Período de Incubação de Doenças Infecciosas , Intoxicação Alimentar por Salmonella/diagnóstico , Infecções por Salmonella/diagnóstico , Salmonella typhimurium/isolamento & purificação , Adolescente , Adulto , Criança , DNA Bacteriano/genética , Notificação de Doenças , Poluição Ambiental , Contaminação de Alimentos , Doenças Transmitidas por Alimentos/epidemiologia , Genoma Bacteriano , Humanos , Pessoa de Meia-Idade , Repetições Minissatélites , Tipagem de Sequências Multilocus , Noruega/epidemiologia , Intoxicação Alimentar por Salmonella/epidemiologia , Infecções por Salmonella/epidemiologia , Infecções por Salmonella/microbiologia , Salmonella typhimurium/genética , Sequenciamento Completo do Genoma , Adulto JovemRESUMO
In May 2014, a cluster of Yersinia enterocolitica (YE) O9 infections was reported from a military base in northern Norway. Concurrently, an increase in YE infections in civilians was observed in the Norwegian Surveillance System for Communicable Diseases. We investigated to ascertain the extent of the outbreak and identify the source in order to implement control measures. A case was defined as a person with laboratory-confirmed YE O9 infection with the outbreak multilocus variable-number tandem repeat analysis (MLVA)-profile (5-6-9-8-9-9). We conducted a case-control study in the military setting and calculated odds ratios (OR) using logistic regression. Traceback investigations were conducted to identify common suppliers and products in commercial kitchens frequented by cases. By 28 May, we identified 133 cases, of which 117 were linked to four military bases and 16 were civilians from geographically dispersed counties. Among foods consumed by cases, multivariable analysis pointed to mixed salad as a potential source of illness (OR 10.26; 95% confidence interval (CI): 0.85-123.57). The four military bases and cafeterias visited by 14/16 civilian cases received iceberg lettuce or radicchio rosso from the same supplier. Secondary transmission cannot be eliminated as a source of infection in the military camps. The most likely source of the outbreak was salad mix containing imported radicchio rosso, due to its long shelf life. This outbreak is a reminder that fresh produce should not be discounted as a vehicle in prolonged outbreaks and that improvements are still required in the production and processing of fresh salad products.
Assuntos
Diarreia/epidemiologia , Surtos de Doenças , Contaminação de Alimentos/análise , Verduras/microbiologia , Yersiniose/diagnóstico , Yersinia enterocolitica/isolamento & purificação , Estudos de Casos e Controles , Busca de Comunicante , Diarreia/microbiologia , Notificação de Doenças , Doenças Transmitidas por Alimentos/epidemiologia , Doenças Transmitidas por Alimentos/microbiologia , Humanos , Modelos Logísticos , Masculino , Militares , Repetições Minissatélites , Análise Multivariada , Noruega/epidemiologia , Razão de Chances , Vigilância da População , Yersiniose/epidemiologia , Yersinia enterocolitica/classificação , Yersinia enterocolitica/genéticaRESUMO
Pathways for exposure and dissemination of antimicrobial-resistant (AMR) bacteria are major public health issues. Filter-feeding shellfish concentrate bacteria from the environment and thus can also harbor extended-spectrum ß-lactamaseproducing Escherichia coli (ESBL E. coli) as an example of a resistant pathogen of concern. Is the short steaming procedure that blue mussels (Mytilus edulis) undergo before consumption enough for food safety in regard to such resistant pathogens? In this study, we performed experiments to assess the survival of ESBL E. coli in blue mussel. Consequently, a predictive model for the dose of ESBL E. coli that consumers would be exposed to, after preparing blue mussels or similar through the common practice of brief steaming until opening of the shells, was performed. The output of the model is the expected number of colony forming units per gram (cfu/g) of ESBL E. coli in a meal as a function of the duration and the temperature of steaming and the initial contamination. In these experiments, the heat tolerance of the ESBL-producing E. coli strain was indistinguishable from that of non-ESBL E. coli, and the heat treatments often practiced are likely to be insufficient to avoid exposure to viable ESBL E. coli. Steaming time (>3.5−4.0 min) is a better indicator than shell openness to avoid exposure to these ESBL or indicator E. coli strains.
RESUMO
Shiga toxin-producing Escherichia coli (STEC) are important food-borne pathogens with Shiga toxins as the main virulence factor. Shiga toxins are encoded on Shiga toxin-encoding bacteriophages (Stx phages). Stx phages may exist as free bacteriophages in the environment or in foods or as prophages integrated into the host genome. From a food safety perspective, it is important to have knowledge on the survival and persistence of Stx phages in food products since these may integrate into the bacterial hosts through transduction if conditions are right. Here, we present the results from a study investigating the survival of a Stx phage in minced meat from beef stored at a suboptimal temperature (8°C) for food storage along with modifications and optimizations of the methods applied. Minced meat from beef was inoculated with known levels of a labeled Stx phage prior to storage. Phage filtrates were used for plaque assays and DNA extraction, followed by real-time PCR and digital droplet PCR (ddPCR). The results from the pilot study suggested that the initial DNA extraction protocol was not optimal, and several modifications were tested before a final protocol was defined. The final DNA extraction protocol comprised ultra-centrifugation of the entire phage filtrate for concentrating phages and two times phenol-chloroform extraction. The protocol was used for two spiking experiments. The DNA extraction protocol resulted in flexibility in the amount of DNA available for use in PCR analyses, ultimately increasing the sensitivity of the method used for quantification of phages in a sample. All three quantification methods employed (i.e., plaque assays, real-time PCR, and ddPCR) showed similar trends in the development of the phages during storage, where ddPCR has the benefit of giving absolute quantification of DNA copies in a simple experimental setup. The results indicate that the Stx phages persist and remain infective for at least 20 days under the storage conditions used in the present study. Stx phages in foods might represent a potential risk for humans. Although it can be speculated that transduction may take place at 8°C with subsequent forming of STEC, it can be expected to be a rare event. However, such an event may possibly take place under more optimal conditions, such as an increase in storage temperature of foods or in the gastrointestinal tract of humans.
RESUMO
EN ISO 10273 method for the detection of pathogenic Yersinia enterocolitica in foods was validated in the project Mandate M/381 funded by European Commission. A total of 14 laboratories from five European countries participated in the interlaboratory study (ILS) organized during 2013 and 2014. Before the ILS, the method was revised by an international group of experts and the performance of the revised method was assessed in an ILS study. The results are published as a part of the standard EN ISO 10273 revision. The study included three rounds with different sample types; raw milk, iceberg lettuce and minced meat, inoculated with a low and high level of pathogenic Y. enterocolitica strains representing major pathogenic bioserotypes 4/O:3 and 2/O:9. The homogeneity and stability of the samples were verified before dispatching them to the laboratories. The results demonstrated the method sensitivity of 96% in raw milk, 97% in minced meat, and 98% in lettuce at high inoculation level of pathogenic Y. enterocolitica. The specificity was 100% in raw milk, 96% in minced meat, and 98% in lettuce. The level of detection, LOD50, varied between study rounds, being 9.4â¯CFU/25â¯ml in raw milk, 9.9â¯CFU/25â¯g in minced meat and 63â¯CFU/25â¯g in lettuce samples. During the study, confirmation by using real-time PCR method ISO/TS 18867 together with pyrazinamidase testing was also validated, as alternative to conventional biochemical confirmation. When comparing different isolation steps used in the revised method during the study rounds, PSB enrichment and plating on CIN after alkaline (KOH) treatment showed the highest sensitivity (52-92%) in raw milk and minced meat samples. In lettuce samples, however, ITC with KOH treatment before plating on CIN showed higher sensitivity (64% at low level; 82% at high level) than plating on CIN from PSB with KOH treatment (44% at low level; 74% at high level). Statistical analysis of different isolation steps supported the use of two enrichment media, PSB and ITC, in the revised method. Recovery of pathogenic Y. enterocolitica on CIN was most efficient after KOH treatment and, based on the analysis, plating on CIN agar without KOH treatment could be left as optional procedure in the method.
Assuntos
Microbiologia de Alimentos/métodos , Yersinia enterocolitica/fisiologia , Animais , Europa (Continente) , União Europeia , Lactuca/microbiologia , Limite de Detecção , Carne/microbiologia , Leite/microbiologia , Reprodutibilidade dos Testes , Yersinia enterocolitica/isolamento & purificaçãoRESUMO
High-throughput sequencing (HTS) is becoming the state-of-the-art technology for typing of microbial isolates, especially in clinical samples. Yet, its application is still in its infancy for monitoring and outbreak investigations of foods. Here we review the published literature, covering not only bacterial but also viral and Eukaryote food pathogens, to assess the status and potential of HTS implementation to inform stakeholders, improve food safety and reduce outbreak impacts. The developments in sequencing technology and bioinformatics have outpaced the capacity to analyze and interpret the sequence data. The influence of sample processing, nucleic acid extraction and purification, harmonized protocols for generation and interpretation of data, and properly annotated and curated reference databases including non-pathogenic "natural" strains are other major obstacles to the realization of the full potential of HTS in analytical food surveillance, epidemiological and outbreak investigations, and in complementing preventive approaches for the control and management of foodborne pathogens. Despite significant obstacles, the achieved progress in capacity and broadening of the application range over the last decade is impressive and unprecedented, as illustrated with the chosen examples from the literature. Large consortia, often with broad international participation, are making coordinated efforts to cope with many of the mentioned obstacles. Further rapid progress can therefore be prospected for the next decade.
RESUMO
Bacteriophages that carry the Shiga toxin gene (stx) represent an additional hazard in cattle manure-based fertilizers in that their survival could lead to toxigenic conversion of Escherichia coli and other bacteria post-composting. A Stx-phage in which the Shiga toxin (stx(2)) gene was inactivated by insertion of a chloramphenicol resistance gene was used in combination with a rifampicin-resistant E. coli host where RecA is constitutively activated so that all infectious phage particles could be enumerated by plaque assay. PCR-based confirmation methods and the additional application of a host enrichment protocol ensured that very low numbers of surviving bacteriophage could be detected and unequivocally identified. Stx-bacteriophage numbers declined rapidly over the first 48 h and none could be detected after 3 days. The host enrichment method was applied after 6 days and no bacteriophages were recovered. While addition of fresh E. coli cells at intervals after the compost temperature had reduced below 40 degrees C demonstrated that E. coli growth could be supported in the compost, Stx-phages or their lysogens were never detected. Here, we demonstrate that composting animal manure for 40 days during which a temperature of >60 degrees C is maintained for at least 5 days is effective at removing both E. coli and a model infectious Stx-encoding bacteriophage.
Assuntos
Colífagos/fisiologia , Escherichia coli/virologia , Toxina Shiga II/genética , Microbiologia do Solo , Solo , Colífagos/genética , DNA Viral/análise , Reação em Cadeia da Polimerase , Prófagos/genética , Prófagos/fisiologia , Temperatura , Fatores de Tempo , Ensaio de Placa Viral , Inativação de VírusRESUMO
Surface water is used for irrigation of food plants all over the World. Such water can be of variable hygienic quality, and can be contaminated from many different sources. The association of contaminated irrigation water with contamination of fresh produce is well established, and many outbreaks of foodborne disease associated with fresh produce consumption have been reported. The objective of the present study was to summarize the data on fecal indicators and selected bacterial pathogens to assess the level of fecal contamination of a Norwegian river used for irrigation in an area which has a high production level of various types of food commodities. Sources for fecal pollution of the river were identified. Measures implemented to reduce discharges from the wastewater sector and agriculture, and potential measures identified for future implementation are presented and discussed in relation to potential benefits and costs. It is important that the users of the water, independent of intended use, are aware of the hygienic quality and the potential interventions that may be applied. Our results suggest that contamination of surface water is a complex web of many factors and that several measures and interventions on different levels are needed to achieve a sound river and safe irrigation.
Assuntos
Irrigação Agrícola , Monitoramento Ambiental/normas , Rios/microbiologia , Qualidade da Água , Doenças Transmitidas por Alimentos/prevenção & controle , Noruega , Microbiologia da Água , Poluição da Água/análiseRESUMO
Leafy greens, including fresh herbs, have repeatedly been involved in outbreaks of foodborne disease. Although much effort has been put into studying leafy greens and products such as head lettuce and baby leaves, less is known about fresh leafy herbs, such as basil. The goal of this study was to investigate the survival of Salmonella on basil plants and in pesto. A mix of three Salmonella strains (Reading, Newport, and Typhimurium) was inoculated onto basil leaves and pesto and survived during the experimental period. Whereas the mix of Salmonella survived in pesto stored at 4°C for 4 days, Salmonella was recovered from inoculated leaves for up to 18 days at 20 to 22°C. Although the steady decline of Salmonella on leaves and in pesto suggests a lack of growth, it appears that pesto is a hostile environment for Salmonella because the rate of decline in pesto was faster (0.29 log CFU/g/day) than on leaves (0.11 log CFU/g/day). These findings suggest that the dilution of contaminated ingredients and the bactericidal effect of the pesto environment helped to further reduce the level of enteric organisms during storage, which may have applications for food safety.
Assuntos
Viabilidade Microbiana , Ocimum basilicum/microbiologia , Folhas de Planta/microbiologia , Salmonella/crescimento & desenvolvimento , Microbiologia de Alimentos , Ocimum basilicum/química , Salmonella/isolamento & purificaçãoRESUMO
The aim of this study was to investigate the bacteriological quality of strawberries at harvest and to study risk factors such as irrigation water, soil and picker's hand cleanliness. Four farms were visited during the harvest season in 2012. Samples of strawberries, irrigation water, soil and hand swabs were collected and analyzed for E. coli, Campylobacter, Salmonella and STEC Although fecal indicators and pathogens were found in environmental samples, only one of 80 samples of strawberries was positive for E. coli (1.0 log10 cfu/g) and pathogens were not detected in any of the strawberry samples. The water samples from all irrigation sources were contaminated with E. coli in numbers ranging from 0 to 3.3 log10 cfu/g. Campylobacter (8/16 samples) and Salmonella (1/16 samples) were isolated from samples with high numbers of E. coli. The water samples collected from a lake had lower numbers of E. coli than the samples from rivers and a stream. The present study indicated continuous background contamination in the primary production environment. Although the background contamination was not reflected on the strawberries tested here, the results must be interpreted with caution due to the limited number of samples.
Assuntos
Campylobacter/isolamento & purificação , Fragaria/química , Salmonella/isolamento & purificação , Escherichia coli Shiga Toxigênica/isolamento & purificação , Fragaria/crescimento & desenvolvimento , NoruegaRESUMO
The microbiological sanitary quality and safety of leafy greens and strawberries were assessed in the primary production in Belgium, Brazil, Egypt, Norway and Spain by enumeration of Escherichia coli and detection of Salmonella, Shiga toxin-producing E. coli (STEC) and Campylobacter. Water samples were more prone to containing pathogens (54 positives out of 950 analyses) than soil (16/1186) and produce on the field (18/977 for leafy greens and 5/402 for strawberries). The prevalence of pathogens also varied markedly according to the sampling region. Flooding of fields increased the risk considerably, with odds ratio (OR) 10.9 for Salmonella and 7.0 for STEC. A significant association between elevated numbers of generic E. coli and detection of pathogens (OR of 2.3 for STEC and 2.7 for Salmonella) was established. Generic E. coli was found to be a suitable index organism for Salmonella and STEC, but to a lesser extent for Campylobacter. Guidelines on frequency of sampling and threshold values for E. coli in irrigation water may differ from region to region.
Assuntos
Campylobacter/isolamento & purificação , Fragaria/microbiologia , Salmonella/isolamento & purificação , Escherichia coli Shiga Toxigênica/isolamento & purificação , Verduras/microbiologia , Brasil , Egito , Europa (Continente) , Microbiologia de Alimentos , Humanos , Fatores de RiscoRESUMO
A total of 890 samples of fresh produce obtained from Norwegian markets were examined in order to assess the bacteriological quality of the products and their potential public health risk. The samples comprised lettuce, pre-cut salads, growing herbs, parsley and dill, mushrooms and strawberries. The samples were analysed for the presence of thermotolerant coliform bacteria (TCB), Escherichia coli O157, Salmonella spp., Listeria monocytogenes, Staphylococcus spp., and Yersinia enterocolitica. Neither Salmonella spp. nor E. coli O157 were isolated. For all product groups included, TCB were isolated from a small proportion of samples. Three samples harboured L. monocytogenes; one of the isolates belonging to serogroup 1 (champignons) and two of the isolates belonging to serogroup 4 (Chinese leaves and strawberries). Staphylococci were isolated from a relatively large proportion of the samples of strawberries and mushrooms. However, only four isolates were identified as S. aureus (non-toxinogenic). By the use of PCR, the presence of Y. enterocolitica was indicated in a few of the samples of lettuce, whilst no positive samples were found using a culturing method. The study shows that the occurrence of pathogenic bacteria and TCB in the products analysed was quite low. Nevertheless, the results indicate that the type of products analysed may contain pathogenic bacteria and thereby represent a risk to the consumers in regard to food-borne diseases.
Assuntos
Bactérias/isolamento & purificação , Frutas/microbiologia , Verduras/microbiologia , Agaricales , Anethum graveolens/microbiologia , Bactérias/classificação , Contagem de Colônia Microbiana , Qualidade de Produtos para o Consumidor , Contaminação de Alimentos/análise , Contaminação de Alimentos/prevenção & controle , Microbiologia de Alimentos , Frutas/normas , Humanos , Lactuca/microbiologia , Noruega , Petroselinum/microbiologia , Reação em Cadeia da Polimerase , Saúde Pública , Verduras/normasRESUMO
As part of larger survey of microbial contamination of fruits and vegetables in Norway, four different sprouted seed products were analysed for bacterial and parasitic contaminants (n = 300 for bacterial analyses and n = from 17 to 171 for parasite analyses, depending on parasite). Escherichia coli O157, Salmonella, Listeria monocytogenes, Cyclospora oocysts, Ascaris eggs and other helminth parasites were not detected in any of the sprout samples. Thermotolerant coliform bacteria (TCB) were isolated from approximately 25% of the sprout samples, with the highest percentage of TCB positive samples in alfalfa sprouts. Most TCB were Enterobacter spp. and Klebsiella. E. coli was isolated from 8 of 62 TCB positive mung bean sprout samples. Cryptosporidium oocysts were detected in 8% of the sprout samples and Giardia cysts were detected in 2% of the samples. All the Cryptosporidium positive samples, and most of the Giardia positive samples, were mung bean sprouts. Parasite concentrations in positive samples were low (between 1 and 3 oocysts/cysts per 50 g sprouts). Sprout irrigation water was also analysed for microbial contaminants. E. coli O157 and L. monocytogenes were not detected. TCB were isolated from approximately 40% of the water samples. Salmonella reading was isolated from three samples of spent irrigation water on 3 consecutive days. Cryptosporidium and Giardia were also isolated from spent irrigation water. Additionally, eight samples of unsprouted mung bean seed were analysed for Cryptosporidium oocysts and Giardia cysts. One or both of these parasites were detected in six of the unsprouted seed samples at concentrations of between 1 and 5 oocysts/cysts per 100 g unsprouted seed. Whilst our results support spent irrigation water as the most suitable matrix for testing for bacteria, unsprouted seed is considered the more useful matrix for analysing for parasite contaminants.