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1.
PLoS One ; 15(7): e0235345, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32667930

RESUMO

This study was carried out to investigate the risks of simultaneous exposure to pesticide residues and bacteria contaminants in locally produced fresh vegetables and vegetables in Tanzania. A total of 613 samples were analyzed for pesticide residues, out of which 250 were also analyzed for bacterial contamination. Overall, 47.5% had pesticide residues, 74.2% exceeded Maximum Residue Levels (MRLs). Organophosphorus (95.2%), organochlorines (24.0%), pyrethroids (17.3%), and carbamates (9.2%) residues dominated. MRL values were mostly exceeded in tomatoes, onions, watermelons, cucumbers, Chinese cabbage, and sweet paper. Tetramethrin (0.0329-1.3733 mg/kg), pirimiphos-methyl (0.0003-1.4093 mg/kg), permethrin (0.0009-2.4537 mg/kg), endosulfan (beta) (0.0008-2.3416 mg/kg), carbaryl (0.0215-1.5068 mg/kg), profenofos (0.0176-2.1377 mg/kg), chlorpyrifos (0.0004-1.2549 mg/kg) and dieldrin (0.0011-0.5271 mg/kg) exceeded MRLs. The prevalence of bacteria contamination was high (63.2%). Enterobacter (55.6%) Pseudomonas aeruginosa (32.4%), E. coli (28.2%), Citrobacter (26.8%), Klebsiella oxytoca (14.8%), and Salmonella (7.7%) were isolated. Furthermore, 46.4% tested positive for both pesticide residues and bacterial contaminants. Vegetables from farms (60.7%) contained more dual contaminants than market-based vegetables (41.8%). This may have resulted from excessive pesticide use and unhygienic handling of fresh fruits and vegetables at production level. Binary logistic regression showed that fresh fruits and vegetables with pesticide residues were 2.231 times more likely to have bacteria contaminants (OR: 2.231; 95% CI: 0.501, 8.802). The contamination levels of pesticide residues and bacterial contaminants could be perceived as a serious problem as most fresh fruits and vegetables recorded values of pesticide residues far above the MRLs with pathogenic bacteria isolated in higher proportions. MRLs was higher in most vegetables consumed raw or semi-cooked such as watermelons, carrots, cucumber, tomatoes, onion and sweet paper. There is an urgent need to develop pesticide monitoring and surveillance systems at farmer level, educating farmers and promoting the use of greener pesticides to mitigate the health effects of pesticides and bacterial contaminants.


Assuntos
Contaminação de Alimentos/análise , Frutas/efeitos adversos , Praguicidas/efeitos adversos , Verduras/efeitos adversos , Citrobacter/isolamento & purificação , Citrobacter/patogenicidade , Enterobacter/isolamento & purificação , Enterobacter/patogenicidade , Frutas/química , Frutas/microbiologia , Humanos , Hidrocarbonetos Clorados/efeitos adversos , Hidrocarbonetos Clorados/química , Klebsiella oxytoca/isolamento & purificação , Klebsiella oxytoca/patogenicidade , Resíduos de Praguicidas/efeitos adversos , Resíduos de Praguicidas/química , Praguicidas/química , Pseudomonas aeruginosa/isolamento & purificação , Pseudomonas aeruginosa/patogenicidade , Piretrinas/efeitos adversos , Piretrinas/química , Salmonella/isolamento & purificação , Salmonella/patogenicidade , Verduras/química , Verduras/microbiologia
2.
PLoS One ; 15(7): e0235440, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32614915

RESUMO

BACKGROUND: Cholera remains a significant public health problem in more than one-third of the countries of the world. Cholera outbreak has become more common in Addis Ababa particularly in the rainy seasons; however, there is a paucity of data on risk factors associated with cholera outbreaks rendering interventions difficult. We investigated the outbreak to identify its etiology, source, risk factors and in order to control the outbreak. METHODS: We compared cases with health center-based unmatched controls (1:2). Cases were patients aged ≥5 years with acute watery diarrhea, with or without vomiting while controls were persons aged ≥5 years without history of acute watery diarrhea. We interviewed our study participants using structured questionnaire to collect demographic and cholera risk factors data. We described the outbreak over time, and then tested our hypotheses using unconditional logistic regression. RESULTS: The outbreak began on 7 September, 2017 reaching its peak on 23 September, 2017 and ended on 01 October, 2017. We identified a total of 25 cases (Median age: 38 years; IQR: 20 years) and recruited 50 controls (Median age: 35 years; IQR: 29 years). All case-patients had acute watery diarrhea and dehydration requiring intravenous fluids. All cases were admitted to cholera treatment center but there were no deaths. Stool and water samples yielded isolates of Vibrio cholerae O1 of serological subtype Ogawa. Consumption of contaminated holy water (AOR: 20.5, 95%CI: 3.50, 119.61) and raw vegetables (AOR: 15.3, 95%CI: 3, 81.51) were independent risk factors whereas washing hands with soap after visiting latrine (AOR: 0.04, 95%CI: 0.01, 0.25) was independent protective factor. CONCLUSION: Our findings demonstrated cholera foodborne transmission via consumption of raw vegetables, and its waterborne transmission via consumption of contaminated holy water. Washing hands with soap after visiting latrine was protective. We recommended cooking of vegetables and promoting hand washing.


Assuntos
Cólera/epidemiologia , Surtos de Doenças , Doenças Transmitidas por Alimentos/epidemiologia , Vibrio cholerae O1/isolamento & purificação , Estudos de Casos e Controles , Diarreia/epidemiologia , Diarreia/microbiologia , Água Potável/microbiologia , Etiópia , Fezes/microbiologia , Microbiologia de Alimentos , Desinfecção das Mãos , Fatores de Risco , Inquéritos e Questionários , Toaletes , Verduras/microbiologia , Verduras/envenenamento , Vômito/epidemiologia , Microbiologia da Água
3.
Chemosphere ; 251: 126408, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32171131

RESUMO

Water scarcity is emerging as a major problem in water stressed regions such as Middle East countries which highlights the importance of agricultural reuse of wastewater as a valid alternative source. However, consumption of wastewater-irrigated crops has been implicated as a vehicle for transmission of bacterial infections such as campylobacteriosis. Understanding and minimizing public health threats associated with agricultural reuse of treated wastewater (TWW) are crucial elements in sustainable water resource management. To address this need, the present study was carried out to determine Campylobacter risk for the consumers of TWW-irrigated vegetables by field experiments as well as quantitative microbial risk assessment (QMRA) model. Campylobacter was monitored in secondary treated wastewater, TWW-irrigated soil and harvested vegetables by nested real-time PCR assay. Campylobacter was detected in 64% (16/25) of TWW samples, whereas analysis of TWW-irrigated soil and vegetable samples yielded no positive result for Campylobacter. The estimated mean annual Campylobacter disease burden ranged from 2.37 × 10-5 to 6.6 × 10-5 disability-adjusted life years (DALYs) per person per year (pppy) for vegetable consumers which was lower than the less stringent reference level of 10-4 DALYs pppy has been recommended by world health organization (WHO). Our results in regard to the QMRA estimates and field experiments suggest that the reuse of TWW for irrigation of vegetables doesn't pose a considerable risk to human health from the viewpoint of Campylobacter infections in a semi-arid area.


Assuntos
Campylobacter/crescimento & desenvolvimento , Verduras/microbiologia , Águas Residuárias/microbiologia , Irrigação Agrícola/métodos , Agricultura/métodos , Produtos Agrícolas , Humanos , Oriente Médio , Medição de Risco , Solo , Microbiologia do Solo , Eliminação de Resíduos Líquidos/métodos
4.
Food Microbiol ; 89: 103416, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32138986

RESUMO

In this study the phenotypic and genomic characterization of two Arcobacter butzleri (Ab) strains (Ab 34_O and Ab 39_O) isolated from pre-cut ready-to-eat vegetables were performed. Results provided useful data about their taxonomy and their overall virulence potential with particular reference to the antibiotic and heavy metal susceptibility. These features were moreover compared with those of two Ab strains isolated from shellfish and a genotaxonomic assessment of the Ab species was performed. The two Ab isolated from vegetables were confirmed to belong to the Aliarcobacter butzleri species by 16S rRNA gene sequence analysis, MLST and genomic analyses. The genome-based taxonomic assessment of the Ab species brought to the light the possibility to define different subspecies reflecting the source of isolation, even though further genomes from different sources should be available to support this hypothesis. The strains isolated from vegetables in the same geographic area shared the same distribution of COGs with a prevalence of the cluster "inorganic ion transport and metabolism", consistent with the lithotrophic nature of Arcobacter spp. None of the Ab strains (from shellfish and from vegetables) metabolized carbohydrates but utilized organic acids and amino acids as carbon sources. The metabolic fingerprinting of Ab resulted less discriminatory than the genome-based approach. The Ab strains isolated from vegetables and those isolated from shellfish endowed multiple resistance to several antibiotics and heavy metals.


Assuntos
Arcobacter/genética , Frutos do Mar/microbiologia , Verduras/microbiologia , Arcobacter/isolamento & purificação , Biologia Computacional , Genômica , Tipagem de Sequências Multilocus , Fenótipo , RNA Ribossômico 16S/genética
5.
Int J Food Microbiol ; 322: 108562, 2020 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-32109682

RESUMO

Shiga toxin-producing Escherichia coli (STEC) in sprouts have caused large scale outbreaks in the past involving severe illness. The combination of this very diverse pathogen and a food matrix with high numbers of background microbiota poses a particular challenge for detection and isolation. An acid treatment of the enrichment before plating on agar has been shown to improve the recovery of STEC from sprouts. After enrichment in buffered peptone water (BPW) at 37 °C we applied an acid treatment, followed by plating on tryptone bile x-glucuronide (TBX) agar (acid bile method). An inter-laboratory study was organized with 21 laboratories taking part to evaluate the performance parameters and applicability of the acid bile method. A sample set of six sprout samples was prepared consisting of two uninoculated samples and four spiked samples, each containing one of two STEC strains at one of two concentrations (low and high). Analyzing a set of six samples at the National Reference Laboratory (NRL E. coli), we determined the relative abundance of STEC without, after acid-, after bile- and after acid-bile treatment using real-time PCR. The participating laboratories successfully applied the acid bile method and were better able to detect (sensitivity 92.9% vs. 70.0%) and isolate (sensitivity 87.5% vs. 31.3%) STEC from positive samples using the acid bile method compared to non-acid methods. The relative limit of detection (RLOD) after isolation using the acid bile method (vs. non-acid method) was <1 for both STEC strains used, BfR-EC-14434 O133:H25 (0.146) and BfR-EC-16015 O26:H11 (0.073). A collection of STEC (n = 71) of diverse type and characteristics was assessed for their resistance towards the acid bile treatment selection. The majority (n = 65) of STEC strains could be recovered after acid treatment on TBX plates. However, a few strains (n = 6), among them clinical isolates were (partly) sensitive. These results suggest that an acid bile method is a rapid and reasonable approach to improve the recovery of STEC from sprouts when used in combination with methods targeting other selection markers.


Assuntos
Ácidos e Sais Biliares/metabolismo , Microbiologia de Alimentos/métodos , Ácido Clorídrico/metabolismo , Escherichia coli Shiga Toxigênica/isolamento & purificação , Verduras/microbiologia , Ágar , Animais , Meios de Cultura/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Plântula/microbiologia , Escherichia coli Shiga Toxigênica/metabolismo
6.
Curr Pharm Biotechnol ; 21(10): 919-926, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32072900

RESUMO

X-ray is a non-thermal technology that has shown good efficacy in reducing pathogenic and spoilage bacteria, viruses and parasites. X-ray hygiene technology resulted in a high microbial loss in numerous food products, such as dairy products, ready-to-eat shrimp, oysters, fresh products, strawberries, shredded iceberg lettuce, and spinach leaves. Some X-ray studies on food safety have shown that X-ray is an effective technology and is also an appropriate alternative to the electron beam and gamma rays, and can be used in the food industry without side effects on human health. Besides, we reviewed the X-ray effect on the nutritional value of food. Therefore in this study, we aimed to review the available pros and cons of current studies regarding X-rays' effects on the food industry.


Assuntos
Contaminação de Alimentos/prevenção & controle , Microbiologia de Alimentos/normas , Parasitologia de Alimentos/normas , Valor Nutritivo/efeitos da radiação , Raios X , Microbiologia de Alimentos/métodos , Parasitologia de Alimentos/métodos , Frutas/microbiologia , Frutas/efeitos da radiação , Frutas/virologia , Humanos , Verduras/microbiologia , Verduras/efeitos da radiação , Verduras/virologia
7.
PLoS One ; 15(1): e0227250, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31910244

RESUMO

Oomycete plant pathogens are difficult to control and routine genetic research is challenging. A major problem is instability of isolates. Here we characterize >600 field and single zoospore isolates of Phytophthora capsici for inheritance of mating type, sensitivity to mefenoxam, chromosome copy number and heterozygous allele frequencies. The A2 mating type was highly unstable with 26% of 241 A2 isolates remaining A2. The A1 mating type was stable. Isolates intermediately resistant to mefenoxam produced fully resistant single-spore progeny. Sensitive isolates remained fully sensitive. Genome re-sequencing of single zoospore isolates revealed extreme aneuploidy; a phenomenon dubbed Dynamic Extreme Aneuploidy (DEA). DEA is characterized by the asexual inheritance of diverse intra-genomic combinations of chromosomal ploidy ranging from 2N to 3N and heterozygous allele frequencies that do not strictly correspond to ploidy. Isolates sectoring on agar media showed dramatically altered heterozygous allele frequencies. DEA can explain the rapid increase of advantageous alleles (e.g. drug resistance), mating type switches and copy neutral loss of heterozygosity (LOH). Although the mechanisms driving DEA are unknown, it can play an important role in adaptation and evolution and seriously hinders all aspects of P. capsici research.


Assuntos
Aneuploidia , Phytophthora/fisiologia , Doenças das Plantas/microbiologia , Reprodução Assexuada/genética , Verduras/microbiologia , Alelos , Evolução Biológica , Mapeamento Cromossômico , Cucumis sativus/microbiologia , Variação Genética , Genótipo , Perda de Heterozigosidade , Phytophthora/isolamento & purificação , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNA , Análise de Célula Única , Esporos/genética
8.
J Appl Microbiol ; 128(5): 1236-1247, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31922640

RESUMO

AIMS: To evaluate the inhibitory effect of five structurally different imidazolium salts on the in vitro growth of plant pathogenic bacteria that belong to divergent taxonomic genera as well as their ability to reduce the severity of common bacterial blight of common bean caused by Xanthomonas axonopodis pv. phaseoli and bacterial speck of tomato caused by Pseudomonas syringae pv. tomato. METHODS AND RESULTS: Growth inhibition of Xanthomonas, Pseudomonas, Erwinia, Pectobacterium and Dickeya strains by imidazolium salts was assessed in vitro by radial diffusion on agar medium and by ressazurin reduction in liquid medium. The reduction of common bacterial blight and bacterial speck symptoms and the area under de disease progress curves were determined by spraying two selected imidazolium salts on healthy plants 48 h prior to inoculation with virulent strains of the bacterial pathogens. All imidazolium salts inhibited the growth of all plant pathogenic bacteria when tested by radial diffusion on agar medium. The strength of inhibition differed among imidazolium salts when tested on the same bacterial strain and among bacterial strains when tested with the same imidazolium salt. In liquid medium, most imidazolium salts presented the same minimum inhibitory concentration (MIC) and minimum bactericidal concentration values (200 µmol l-1 ), the most notable exception of which was the MIC (at least 1000 µmol l-1 ) for the dicationic MImC10 MImBr2 . The imidazolium salts C16 MImBr and C16 MImCl caused significant reductions in the severity of common bacterial blight symptoms when compared with nontreated plants. CONCLUSION: Imidazolium salts inhibit the in vitro growth of plant pathogenic bacteria and reduce plant disease symptoms to levels comparable to an authorized commercial antibiotic product. SIGNIFICANCE AND IMPACT OF THE STUDY: New compounds exhibiting broad-spectrum antibacterial activity with potential use in agriculture were identified.


Assuntos
Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Imidazóis/farmacologia , Praguicidas/farmacologia , Doenças das Plantas/prevenção & controle , Bactérias/crescimento & desenvolvimento , Testes de Sensibilidade Microbiana , Doenças das Plantas/microbiologia , Verduras/microbiologia
9.
Int J Food Microbiol ; 319: 108472, 2020 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-31901751

RESUMO

The interaction of typical host adapted enteric bacterial pathogens with fresh produce grown in fields is complex. These interactions can be more pronounced in co-managed or sustainable farms where animal operations are, by design, close to fresh produce, and growers frequently move between the two production environments. The primary objectives of this study were to 1) determine the transmission of STEC or enteric pathogens from small and large animal herds or operations to fresh produce on sustainable farms in TN and NC, 2) identify the possible sources that impact transmission of AMR E. coli, specifically STEC on these systems, and 3) WGS to characterize recovered E. coli from these sources. Samples were collected from raw and composted manure, environment, and produce sources. The serotype, virulence, and genotypic resistance profile were determined using the assembled genome sequences sequenced by Illumina technology. Broth microdilution was used to determine the antimicrobial susceptibility of each isolate against a panel of fourteen antimicrobials. The prevalence of E. coli increased during the summer season for all sources tested. ParSNP trees generated demonstrated that the transmission of AMR E. coli is occurring between animal feeding operations and fresh produce. Ten isolates were identified as serotype O45, a serotype that is associated with the "Big Six" group that is frequently linked with foodborne outbreaks caused by non-O157 E. coli. However, these isolates did not possess the stx gene. The highest frequency of resistance was detected against streptomycin (n = 225), ampicillin (n = 190) and sulfisoxazole FIS (n = 140). A total of 35 (13.7%) isolates from two TN farms were positive for the blaCMY (n = 5) and blaTEM (n = 32) genes. The results of this study show the potential of AMR E. coli transmission between animal feeding operations and fresh produce, and more studies are recommended to study this interaction and prevent dissemination in sustainable farming systems.


Assuntos
Escherichia coli Enterotoxigênica/genética , Infecções por Escherichia coli/transmissão , Doenças Transmitidas por Alimentos/microbiologia , Esterco/microbiologia , Verduras/microbiologia , Ampicilina/farmacologia , Animais , Antibacterianos/farmacologia , Escherichia coli Enterotoxigênica/efeitos dos fármacos , Escherichia coli Enterotoxigênica/isolamento & purificação , Infecções por Escherichia coli/microbiologia , Fazendas , Genoma Bacteriano/genética , Testes de Sensibilidade Microbiana , Sorogrupo , Estreptomicina/farmacologia , Sulfisoxazol/farmacologia
10.
Int J Food Microbiol ; 319: 108509, 2020 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-31945714

RESUMO

The role of plant-based foods in the epidemiology of antimicrobial resistance has been inadequately studied. In this investigation, resistant organisms from vegetables, fruits and spices imported into Canada were identified and characterized. A total of 143 products imported from primarily Asian and African countries were purchased from international markets in Saskatoon, Saskatchewan. Samples were selectively cultured for bacterial species where resistance is known to be emerging. The proportions of samples positive for each organism were as follows: E. coli (n = 13, 9.1%), Salmonella spp. (n = 2, 1.4%), ESBL producing Enterobacter spp. (n = 2, 1.4%) and K. pneumoniae (n = 2, 1.4%), S. aureus (n = 7, 4.9%) and Enterococcus spp. (n = 66, 46.2%). Antimicrobial minimum inhibitory concentrations were determined by broth micro-dilution and agar-dilution. Based on the susceptibility of each organism, isolates were screened for resistance genes (ß-lactamases and plasmid mediated quinolones resistance determinants) by PCR. Extended-spectrum ß-lactamase producing Enterobacteriaceae and methicillin resistant S. aureus (MRSA) were identified from 6/143 (4.2%) and 2/143 (1.4%) of samples respectively. The qnrB, qnrS and aac(6')-Ib-cr plasmid mediated quinolone resistance determinants were identified in 2/143 (1.4%) of samples tested. None of the Enterobacteriaceae isolates were resistant to meropenem or colistin. Similarly, all Enterococcus isolates remained susceptible to ampicillin, penicillin and vancomycin. Finding multi-drug resistant bacteria which are frequently isolated from human infections is concerning, although the contribution of the global food trade to the dissemination of resistance remains cryptic. These results suggest that imported plant-based foods may be an underappreciated source of clinically relevant resistant organisms. Further study is required to address these gaps in our understanding of the epidemiology of resistance, and the magnitude of the risk posed to human health by these organisms.


Assuntos
Enterobacteriaceae/isolamento & purificação , Enterococcus/isolamento & purificação , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Plantas Comestíveis/microbiologia , Antibacterianos/farmacologia , Canadá , Farmacorresistência Bacteriana Múltipla/genética , Enterobacteriaceae/efeitos dos fármacos , Enterobacteriaceae/genética , Enterococcus/efeitos dos fármacos , Enterococcus/genética , Frutas/microbiologia , Humanos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/genética , Testes de Sensibilidade Microbiana , Plasmídeos/genética , Quinolonas/farmacologia , Especiarias/microbiologia , Verduras/microbiologia , beta-Lactamases/genética
11.
Lett Appl Microbiol ; 71(1): 54-60, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31930506

RESUMO

Emerging virulent and antibiotic-resistant pathogens present a global public health risk. Routine monitoring of prevalence within the clinical, environmental and food production setting is vital. Quantitative real-time PCR (qPCR) coupled with melting curve analysis can rapidly and accurately characterize pathogens. We evaluated commercial qPCR mixes based on SYBR Green l and EvaGreen for developing an assay for simultaneously detecting antibiotic resistance (extended-spectrum beta-lactamase, ESBL and blaCTX-M ) and virulence (stx1, stx2 and eae) genes in Escherichia coli (n = 12) isolated from irrigation water and irrigated vegetables. SYBR Green and EvaGreen detected two amplicons (stx1 and blaCTX-M ) and (stx2 and eae) in a single reaction. A higher mean melting temperature (Tm ) separation between targeted amplicons and smoother melting curves were observed with the EvaGreen suggesting better performance when targeting multiple amplicons. Through simple stepwise optimization of DNA, cycling, primers, reaction volume and melting curve scanning rate, we adopted a conventional PCR assay for detection of large amplicons (375-1580 bp) for qPCR. This may facilitate development of cost-effective tailor-made assays for rapid and accurate monitoring of emerging foodborne and environmental pathogens in resource constrained regions.


Assuntos
Antibacterianos/farmacologia , Cefotaxima/farmacologia , Farmacorresistência Bacteriana/genética , Escherichia coli/genética , beta-Lactamases/genética , Escherichia coli/efeitos dos fármacos , Infecções por Escherichia coli/tratamento farmacológico , Proteínas de Escherichia coli/genética , Doenças Transmitidas por Alimentos/microbiologia , Doenças Transmitidas por Alimentos/prevenção & controle , Água Doce/microbiologia , Humanos , Desnaturação de Ácido Nucleico/genética , Reação em Cadeia da Polimerase em Tempo Real , Verduras/microbiologia , Virulência/genética
12.
Int J Food Microbiol ; 317: 108442, 2020 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-31759181

RESUMO

Listeria monocytogenes is a foodborne pathogen which is a significant challenge in food production, particularly for ready-to-eat (RTE) products. Incidence of Listeria in food can be reduced by the application of multiple preservative factors or "hurdles", which include acids, water activity and salts. Studying the growth of Listeria in complex foods is often reliant on laborious plate-counting techniques, therefore alternative methodologies are required. In this study we investigated the use of bioluminescence produced by chromosomally integrated genes encoding luciferase and its substrate to determine microbial growth rates in media and complex food matrices. Five Listeria innocua strains, used as a non-pathogenic surrogate for L. monocytogenes, were transformed with plasmid pPL2luxPhelp, resulting in a collection of Lux-tagged strains. Three test matrices (BHI broth, zucchini purée and béarnaise sauce) were adjusted, testing various combinations of pH (4.7-5.3), water activity (0.96 & 0.98) and undissociated acetic and propionic acid concentrations (0-2 mM). Adjusted matrices were inoculated with a cocktail of Lux-tagged strains and growth monitored over time by both bioluminescence and viable plate counts. Specific growth rates were calculated using both the bioluminescence and plate count data and compared. Statistical analysis showed that specific growth rates determined by bioluminescence did not significantly differ from those determined by plate counts (t-test, P > 0.05), while measurements of bias and accuracy showed good agreement between growth rates determined by both methods. Although plate counts remain the method of choice for detection of very low specific growth rates, this study demonstrates the potential of bioluminescence as a rapid alternative to plate counts for determining microbial growth rates in complex foods.


Assuntos
Fast Foods/microbiologia , Contaminação de Alimentos/análise , Microbiologia de Alimentos/métodos , Listeria monocytogenes/crescimento & desenvolvimento , Medições Luminescentes/métodos , Contagem de Colônia Microbiana , Listeria monocytogenes/genética , Listeria monocytogenes/metabolismo , Luciferases/genética , Propionatos/análise , Sais/análise , Verduras/microbiologia
13.
Lett Appl Microbiol ; 70(2): 87-94, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31705681

RESUMO

Attiéké is the major fermented plant food in Côte d'Ivoire. The aim of this study was to identify hazards and critical control points (CCP) in order to implement a HACCP system for the production of attiéké. Physico-chemical and microbiological analyses were carried out. pH of the cossettes used as raw material for attieke process was slightly acidic (6·5 ± 0·23). But attiéké produced had an acid pH (4·55 ± 0·67). The very high amount of hydrocyanic acid in cassava roots (116 ± 9·42 mg kg-1 ) was reduced to a lower value (3·4 ± 0·14 mg kg-1 ) in attiéké. It was less than the Codex Alimentarus recommended dose (10 mg kg-1 ). Microbiological analysis of the samples revealed the presence of coliforms, bacillus, Staphylococcus aureus and moulds in the intermediate products, the packaged attieke, the utensils, environment and ingredients. During the fermentation and pressing stage, the coliforms disappeared and the loads of Bacillus cereus, S. aureus and moulds were reduced. Cooking eliminated all micro-organisms except B. cereus (spores) whose load was reduced to a value of (1·1 ± 0·4)102  CFU per gram. All these micro-organisms reappeared in attiéké just after packaging. The load of micro-organisms in the packaged attiéké was lower than the Codinorm standard, CCP were cassava roots, the crushing, fermentation, and drying, cooking and packaging stage. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrates the great need to carry out microbiological tests frequently on attieke and even more the need to apply correct HACCP system during the production. This study will make it possible to minimize the problems encountered by women producers of attiéké, ensure consumer safety, face competition from imported starch products (wheat, rice, etc.), contribute to the opening of a small and medium-scale industrialization path for the production of attiéké and strengthen standardization on attiéké to facilitate its export.


Assuntos
Bacillus cereus/isolamento & purificação , Alimentos e Bebidas Fermentados/microbiologia , Manihot/metabolismo , Manihot/microbiologia , Staphylococcus aureus/isolamento & purificação , Reatores Biológicos/microbiologia , Contagem de Colônia Microbiana , Costa do Marfim , Feminino , Fermentação , Microbiologia de Alimentos , Humanos , Verduras/metabolismo , Verduras/microbiologia
14.
Crit Rev Food Sci Nutr ; 60(5): 791-809, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-30582346

RESUMO

For a long time, food microbiota has been studied using traditional microbiological techniques. With the arrival of molecular or culture-independent techniques, a strong understanding of microbiota dynamics has been achieved. However, analyzing the functional role of microbial communities is not an easy task. The application of omics sciences to the study of fermented foods would provide the metabolic and functional understanding of the microbial communities and their impact on the fermented product, including the molecules that define its aroma and flavor, as well as its nutritional properties. Until now, most omics studies have focused on commercial fermented products, such as cheese, wine, bread and beer, but traditional fermented foods have been neglected. Therefore, the information that allows to relate the present microbiota in the food and its properties remains limited. In this review, reports on the applications of omics in the study of traditional fermented foods and beverages are reviewed to propose new ways to analyze the fermentation phenomena.


Assuntos
Bebidas/microbiologia , Alimentos e Bebidas Fermentados/microbiologia , Análise de Alimentos , Microbiota , Verduras/microbiologia , Fermentação
15.
Int J Infect Dis ; 92: 53-55, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31877351

RESUMO

Colistin is a last-resort antimicrobial against multidrug-resistant gram-negative bacteria. The occurrence and spread of colistin resistance in humans and animals have been reported globally. This study was performed to investigate the prevalence and antimicrobial susceptibility of mcr-harboring colistin-resistant Enterobacteriaceae from retail vegetables and food animals in South Korea in 2018. The mcr-1 gene was detected in Escherichia coli isolates from 0.076% (1/1324) of vegetables, 5.9% (2/34) of chickens, 6.8% (4/59) of pigs, and 0% (0/57) of cattle. Other mcr genes were not detected. All seven of the mcr-1-positive isolates showed multidrug resistance and co-produced ß-lactamases. Multilocus sequence typing analysis revealed five known E. coli sequence types (STs), including ST10 in the vegetable sample. The study findings demonstrated that the mcr-1 gene has emerged in vegetables and is increasingly detected in food animals in South Korea, highlighting the importance of continuous monitoring and control of colistin-resistant Enterobacteriaceae to prevent them from being transmitted to humans.


Assuntos
Colistina/farmacologia , Proteínas de Escherichia coli/biossíntese , Escherichia coli/isolamento & purificação , Microbiologia de Alimentos , Verduras/microbiologia , Animais , Antibacterianos/farmacologia , Bovinos , Galinhas , Farmacorresistência Bacteriana/genética , Escherichia coli/efeitos dos fármacos , Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Humanos , Tipagem de Sequências Multilocus , Prevalência , República da Coreia , Suínos , beta-Lactamases/metabolismo
16.
Arch Virol ; 165(3): 715-718, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31873766

RESUMO

In the present study, we evaluated the degree of contamination of fresh vegetables, cheeses and jellies from disaster area in Brazil with bacteria and enteric viruses. Food samples (n = 350) were tested for Escherichia coli, Salmonella spp., Listeria monocytogenes, Staphylococcus spp., and enteric viruses (rotavirus A (RVA), human adenovirus (HAdV), hepatitis A virus (HAV), and human norovirus (HNoV). E. coli was present in 56% of the samples, Salmonella spp. was present in 14% of the samples, L. monocytogenes and Staphylococcus spp. (coagulase-positive) were present in 36% of the samples. The enteric viruses RVA and HAdV were detected in cheeses and vegetables.


Assuntos
Queijo/microbiologia , Contaminação de Alimentos/análise , Verduras/microbiologia , Adenovírus Humanos/isolamento & purificação , Brasil , Escherichia coli/isolamento & purificação , Fazendas , Vírus da Hepatite A/isolamento & purificação , Humanos , Listeria monocytogenes/isolamento & purificação , Norovirus/isolamento & purificação , Rotavirus/isolamento & purificação , Salmonella/isolamento & purificação , Staphylococcus/isolamento & purificação
17.
Int J Food Microbiol ; 313: 108390, 2020 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-31678818

RESUMO

Growth of L. monocytogenes is among the most important factors affecting the risk of human listeriosis. In ready to eat leafy greens, the use of anti-Listeria treatments represents a good alternative to inhibit growth during storage. Several commercially available antimicrobial agents have been suggested as effective intervention strategies. Among them, phage preparations and bacteriocin-producing strains have shown promising results against L. monocytogenes. In this study, we investigate the efficacy of two commercially available surface treatments, the bacteriophage formulation PhageGuard Listex (Micreos Food Safety B.V., NL) and the bacteriocin-producing culture SafePro® (CHR Hansen, DK) to inactivate L. monocytogenes in fresh-cut curly endive after processing and during storage. Fresh-cut endive was inoculated with a cold-adapted L. monocytogenes cocktail of 6 strains (4.4 ±â€¯0.0 log cfu/g) and treated with the anti-Listeria treatments. The treatments were applied using a spray system at two different places within the processing line, on the conveyor belt and in the centrifuge. A total of 5 different treatments were applied: i) Untreated (CT); ii) PhageGuard Listex on the conveyor belt (Listex_Conveyor); iii) PhageGuard Listex during centrifugation (Listex_Centrifuge); iv) SafePro on the conveyor belt (SafePro_Conveyor); and v) SafePro during centrifugation (SafePro_Centrifuge). Samples were stored 3 days at 5 °C plus 5 days at 8 °C. PhageGuard Listex treatment reduced L. monocytogenes in fresh-cut endive by 2.5 logs, regardless of the place of treatment application (conveyor belt or centrifuge). On the other hand, SafePro only reduced L. monocytogenes by 0.2 and 0.4 logs, at the conveyor belt and centrifuge, respectively. Maximum L. monocytogenes reductions of about 3.5 log units were observed in fresh-cut endive treated with PhageGuard Listex after 3 days of storage. At the end of the shelf life (8 days), the initial trends were maintained and the fresh-cut curly endive treated with PhageGuard Listex showed the lowest L. monocytogenes concentration. However, by the end of the shelf-life, L. monocytogenes showed higher levels (1.3-fold) than immediately after the application of the treatment. One hypothesis could be that L. monocytogenes cells, which were able to survive the anti-Listeria treatments, were also able to proliferate under the specific storage conditions. Based on the obtained results, PhageGuard Listex seems to be a promising decontamination agent for leafy greens aiming to reduce growth of the bacteria but further work is needed.


Assuntos
Conservação de Alimentos/métodos , Listeria monocytogenes/crescimento & desenvolvimento , Verduras/microbiologia , Bacteriocinas/metabolismo , Bacteriófagos/fisiologia , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Conservação de Alimentos/instrumentação , Inocuidade dos Alimentos , Humanos , Listeria monocytogenes/metabolismo , Listeria monocytogenes/virologia , Projetos Piloto , Folhas de Planta/microbiologia , Temperatura
18.
Food Microbiol ; 86: 103341, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31703875

RESUMO

The genomic and metabolic features of Lactobacillus sakei were investigated using its pan-genome and by analyzing the metatranscriptome of kimchi fermentation. In the genome-based relatedness analysis, the strains were divided into the Lb. sakei ssp. sakei and Lb. sakei ssp. carnosus lineage groups. Genomic and metabolic pathway analysis revealed that all Lb. sakei strains have the capability of producing d/l-lactate, ethanol, acetate, CO2, formate, l-malate, diacetyl, acetoin, and 2,3-butanediol from d-glucose, d-fructose, d-galactose, sucrose, d-lactose, l-arabinose, cellobiose, d-mannose, d-gluconate, and d-ribose through homolactic and heterolactic fermentation, whereas their capability of d-maltose, d-xylose, l-xylulose, d-galacturonate, and d-glucuronate metabolism is strain-specific. All strains carry genes for the biosynthesis of folate and thiamine, whereas genes for biogenic amine and toxin production, hemolysis, and antibiotic resistance were not identified. The metatranscriptomic analysis showed that the expression of Lb. sakei transcripts involved in carbohydrate metabolism increased as kimchi fermentation progressed, suggesting that Lb. sakei is more competitive during late fermentation stage. Homolactic fermentation pathway was highly expressed and generally constant during kimchi fermentation, whereas expression of heterolactic fermentation pathway increased gradually as fermentation progressed. l-Lactate dehydrogenase was more highly expressed than d-lactate dehydrogenase, suggesting that l-lactate is the major lactate metabolized by Lb. sakei.


Assuntos
Brassica/microbiologia , Genoma Bacteriano , Lactobacillus sakei/genética , Lactobacillus sakei/metabolismo , Verduras/microbiologia , Aminas Biogênicas/metabolismo , Fermentação , Alimentos e Bebidas Fermentados/microbiologia , Microbiologia de Alimentos , Perfilação da Expressão Gênica , Genômica , Ácido Glucurônico/metabolismo , Ácido Láctico/metabolismo , Lactobacillus sakei/isolamento & purificação , Redes e Vias Metabólicas
19.
Food Microbiol ; 86: 103346, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31703876

RESUMO

This work aimed to study the effect of the combination of Sodium hypochlorite, the most used disinfectant by the vegetable industry, with a natural antimicrobial, benzyl-isothiocyanate (BITC), considering cutting surface and contact time, on the reduction of Salmonella in fresh-cut produce in washing operations under typical industrial conditions. Overall, the combinations of disinfectant and process parameters resulted in a mean reduction of Salmonella of 2.5 log CFU/g. According to statistical analysis, free chlorine and BITC concentrations, contact time and cut size exerted a significant effect on the Salmonella reduction (p ≤ 0.05). The optimum combination of process parameter values yielding the highest Salmonella reduction was a lettuce cut size of 15 cm2 washed for 110 s in industrial water containing 160 mg/L free chlorine and 40 mg/L BITC. A predictive model was also derived, which, as illustrated, could be applied to optimize industrial disinfection and develop probabilistic Exposure Assessments considering the effect of washing process parameters on the levels of Salmonella contamination in leafy green products. The present study demonstrated the efficacy of chlorine to reduce Salmonella populations in fresh-cut lettuce while highlighting the importance of controlling the washing process parameters, such as, contact time, cut size and concentration of the disinfectant to increase disinfectant efficacy and improve food safety.


Assuntos
Cloro/farmacologia , Desinfecção/métodos , Manipulação de Alimentos/métodos , Isotiocianatos/farmacologia , Alface/microbiologia , Salmonella/efeitos dos fármacos , Desinfetantes/farmacologia , Contaminação de Alimentos/análise , Microbiologia de Alimentos , Inocuidade dos Alimentos , Alface/crescimento & desenvolvimento , Salmonella/crescimento & desenvolvimento , Hipoclorito de Sódio/farmacologia , Fatores de Tempo , Verduras/crescimento & desenvolvimento , Verduras/microbiologia
20.
Food Microbiol ; 86: 103330, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31703878

RESUMO

Pickle is a type of mildly lactic acid fermented vegetable and is a traditional dish favored in China, Japan, and Korea. Corruption of spoilage bacteria and accumulation of nitrite during vegetable fermentation are common problems that affect the pickle industry and consumer health. In this work, cucumber juice was used as a vegetable model to study the dominant mesophilic aerobic bacteria (MAB) producing nitrite during pickle fermentation. Virulent phages infecting the dominant MABs combined with Lactobacillus plantarum M6 were used to control these bacteria. Enterobacter cloacae and Pseudomonas fluorescens are the dominant MABs in the fermentation of cucumber juice containing 4% or 8% NaCl, with isolation percentages reaching 30.6% and 23.1%, respectively. Virulent phages PspYZU5415 and EcpYZU01 were isolated using P. fluorescens J5415 and E. cloacae J01 as the host bacteria, respectively. These two phages show a broad host range and strong lytic activity, and their genomes contain no toxins and antibiotic resistance genes. PspYZU5415 and EcpYZU01 were combined into a cocktail (designated as Phage MIX) that effectively inhibits the growth of E. cloacae and P. fluorescens in cucumber juice with different salt concentrations. PhageMIX combined with L. plantarum M6 decreased the counts of P. mendocina and E. cloacae to undetectable levels at 48 h during the fermentation of cucumber juice artificially contaminated with P. mendocina and E. cloacae. In addition, nitrite content increased to 11.3 mg/L at 20 h and then degraded completely at 36 h. By contrast, P. mendocina and E. cloacae remained in the groups without PhageMIX during fermentation (0-48 h). Nitrite content rapidly increased to 65.7 mg/L at 12 h and then decreased to 21.6 mg/L at 48 h in the control group. This study suggests that PhageMIX combined with lactic acid bacterial strains can be used as an ecological starter for controlling the dominant MABs P. mendocina and E. cloacae and for reducing nitrate production during the early stage of pickle fermentation.


Assuntos
Bacteriófagos/fisiologia , Bacteriófagos/patogenicidade , Cucumis sativus/microbiologia , Enterobacter cloacae/virologia , Microbiologia de Alimentos/métodos , Pseudomonas fluorescens/virologia , Verduras/microbiologia , Aerobiose , Bacteriófagos/genética , Bacteriófagos/isolamento & purificação , Cucumis sativus/metabolismo , Enterobacter cloacae/metabolismo , Fermentação , Alimentos e Bebidas Fermentados/microbiologia , Especificidade de Hospedeiro , Lactobacillus plantarum/metabolismo , Nitritos/metabolismo , Pseudomonas fluorescens/metabolismo
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