SSEL , a selective enrichment broth for simultaneous growth of Salmonella enterica , Staphylococcus aureus , Escherichia coli O157 : H7 , and Listeria monocytogenes

2020 ◽  
Vol 40 (5) ◽  
Author(s):  
Yang Qu ◽  
Yalong Bai ◽  
Yanhong Liu ◽  
Changyan Zhou ◽  
Xiujuan Zhou ◽  
...  
2008 ◽  
Vol 74 (15) ◽  
pp. 4853-4866 ◽  
Author(s):  
Hyochin Kim ◽  
Arun K. Bhunia

ABSTRACT Multipathogen detection on a single-assay platform not only reduces the cost for testing but also provides data on the presence of pathogens in a single experiment. To achieve this detection, a multipathogen selective enrichment medium is essential to allow the concurrent growth of pathogens. SEL broth was formulated to allow the simultaneous growth of Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes. The results were compared to those obtained with the respective individual selective enrichment broths, Rappaport-Vassiliadis (RV) for S. enterica, modified E. coli broth with 20 mg of novobiocin/liter for E. coli O157:H7, and Fraser broth for L. monocytogenes, and a currently used universal preenrichment broth (UPB). The growth of each pathogen in SEL inoculated at 101 or 103 CFU/ml was superior to that in the respective individual enrichment broth, except in the case of RV, in which Salmonella cells inoculated at both concentrations grew equally well. In mixed-culture experiments with cells of the three species present in equal concentrations or at a 1:10:1,000 ratio, the overall growth was proportional to the initial inoculation levels; however, the growth of L. monocytogenes was markedly suppressed when cells of this species were present at lower concentrations than those of the other two species. Further, SEL was able to resuscitate acid- and cold-stressed cells, and recovery was comparable to that in nonselective tryptic soy broth containing 6% yeast extract but superior to that in the respective individual selective broths. SEL promoted the growth of all three pathogens in a mixture in ready-to-eat salami and in turkey meat samples. Moreover, each pathogen was readily detected by a pathogen-specific immunochromatographic lateral-flow or multiplex PCR assay. Even though the growth of each pathogen in SEL was comparable to that in UPB, SEL inhibited greater numbers of nontarget organisms than did UPB. In summary, SEL was demonstrated to be a promising new multiplex selective enrichment broth for the detection of the three most prominent food-borne pathogens by antibody- or nucleic acid-based methods.


2018 ◽  
Vol 19 (0) ◽  
Author(s):  
Priscila Alves Dias ◽  
Daiani Teixeira Silva ◽  
Cláudio Dias Timm

Resumo Kefir é o produto da fermentação do leite pelos grãos de kefir. Esses grãos contêm uma mistura simbiótica de bactérias e leveduras imersas em uma matriz composta de polissacarídeos e proteínas. Muitos benefícios à saúde humana têm sido atribuídos ao kefir, incluindo atividade antimicrobiana contra bactérias Gram positivas e Gram negativas. A atividade antimicrobiana de 60 microrganismos isolados de grãos de kefir, frente à Escherichia coli O157:H7, Salmonella enterica subsp. enterica sorotipos Typhimurium e Enteritidis, Staphylococcus aureus e Listeria monocytogenes, foi estudada através do teste do antagonismo. A ação antimicrobiana dos sobrenadantes das bactérias ácido-lácticas que apresentaram atividade no teste do antagonismo foi testada. O experimento foi repetido usando sobrenadantes com pH neutralizado. Salmonella Typhimurium e Enteritidis sobreviveram por 24 horas no kefir em fermentação. E. coli O157:H7, S. aureus e L. monocytogenes foram recuperados até 72 horas após o início da fermentação. Todos os isolados apresentaram atividade antimicrobiana contra pelo menos um dos patógenos usados no teste do antagonismo. Sobrenadantes de 25 isolados apresentaram atividade inibitória e três mantiveram essa atividade com pH neutralizado. As bactérias patogênicas estudadas sobreviveram por tempo superior àquele normalmente utilizado para a fermentação do kefir artesanal, o que caracteriza perigo em potencial para o consumidor quando a matéria-prima não apresentar segurança sanitária. Lactobacillus isolados de grãos de kefir apresentam atividade antimicrobiana contra cepas de E. coli O157:H7, Salmonella sorotipos Typhimurium e Enteritidis, S. aureus e L. monocytogenes além daquela exercida pela diminuição do pH.


2013 ◽  
Vol 11 (2) ◽  
pp. 210-223 ◽  
Author(s):  
Taryn-Ann Standing ◽  
Erika du Plessis ◽  
Stacey Duvenage ◽  
Lise Korsten

The internalisation potential of Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O157:H7 and Salmonella enterica subsp. enterica serovar Typhimurium in lettuce was evaluated using seedlings grown in vermiculite in seedling trays as well as hydroponically grown lettuce. Sterile distilled water was spiked with one of the four human pathogenic bacteria (105 CFU/mL) and used to irrigate the plants. The potential for pathogen internalisation was investigated over time using light microscopy, transmission electron microscopy and viable plate counts. Additionally, the identities of the pathogens isolated from internal lettuce plant tissues were confirmed using polymerase chain reaction with pathogen-specific oligonucleotides. Internalisation of each of the human pathogens was evident in both lettuce seedlings and hydroponically grown mature lettuce plants. To our knowledge, this is the first report of S. aureus internalisation in lettuce plants. In addition, the levels of background microflora in the lettuce plants were determined by plate counting and the isolates identified using matrix-assisted laser ionisation–time of flight (MALDI–TOF). Background microflora assessments confirmed the absence of the four pathogens evaluated in this study. A low titre of previously described endophytes and soil inhabitants, i.e., Enterobacter cloacae, Enterococcus faecalis, Lysinibacillus fusiformis, Rhodococcus rhodochrous, Staphylococcus epidermidis and Staphylococcus hominis were identified.


Author(s):  
Na Yue ◽  
Zichao Jia

The emergence of outbreaks of foodborne illness is closely associated with food contamination caused by various enteric pathogens, such as Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica serovar Enteritidis, and Staphylococcus aureus. The control of enteric pathogens poses a challenge due to the fact that these pathogens can persist for a long period of time in the environment. The rapid detection of pathogenic organisms plays a crucial role in the prevention and identification of crises related to health, safety, and well-being. Improper sample handling and processing may influence the diagnostic efficacy and accuracy. The aim of the present study was to compare the preservation capacity for enteric bacteria between Whatman Flinders Technology Associates (FTA) cards and swabs for reverse transcription-quantitative PCR (RT-qPCR) detection. It was found that Whatman FTA cards exhibited an improved preservation capacity for five types (both laboratory and environmental strains) of enteric bacteria, including Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica serovar Enteritidis, and Staphylococcus aureus for RT-qPCR detection. Hence, Whatman FTA cards may be a suitable tool for the routine isolation of foodborne bacteria for molecular diagnosis. Therefore, the use of Whatman FTA cards for sample collection and preservation may increase sensitivity and accuracy for bacteria isolation and diagnosis.


2010 ◽  
Vol 56 (7) ◽  
pp. 585-597 ◽  
Author(s):  
Yi-Gang Yu ◽  
Hui Wu ◽  
Yuan-Yuan Liu ◽  
Su-Long Li ◽  
Xiao-Quan Yang ◽  
...  

A selective enrichment broth (SSL) was formulated to allow concurrent growth of 3 prominent food-borne pathogens: Salmonella enterica serovar Enteritidis, Staphylococcus aureus , and Listeria monocytogenes . Nalidixic acid, lithium chloride, and potassium tellurite were added as the selective agents, while sodium pyruvate and mannitol were employed as the supplemented elements. In the individual growth trial, the target pathogens were capable of growing in SSL to as high as 7–8 log10colony-forming units (CFU)/mL after 24 h incubation at 37 °C when being inoculated at 50–100 CFU/mL. In the simultaneous growth trial, the 3 combined target pathogens showed similar growth rates. The results show that SSL could support the successful simultaneous enrichment of 3 pathogens; however, SSL inhibited the growth of nontarget bacteria. In the artificial contaminated raw beef and ready-to-eat chicken, a high recovery of these 3 target pathogens was obtained in SSL. Finally, Salmonella Enteritidis, Staphylococcus aureus, and L. monocytogenes were detected from 710 suspicious food samples by SSL with real-time PCR, and no false-positive or -negative results were reported. In summary, SSL has been shown to be a suitable broth for the simultaneous detection of the 3 prominent food-borne pathogens by multipathogen detection on a single-assay platform.


2008 ◽  
Vol 71 (10) ◽  
pp. 2110-2114 ◽  
Author(s):  
P. ELIZAQUÍVEL ◽  
R. AZNAR

Four commercial DNA extraction methods, PrepMan Ultra (Applied Biosystems), InstaGene Matrix (BioRad), DNeasy Tissue kit (Qiagen), and UltraClean (MoBio), were tested for PCR detection of Listeria monocytogenes, Escherichia coli O157: H7, Salmonella, and Staphylococcus aureus in fresh, minimally processed vegetables. For comparative purposes, sensitivity assays with specific PCRs were carried out after DNA extraction with the four methods in green pepper, broccoli, and onion artificially inoculated with the four pathogens separately. As confirmed by statistical analysis, the DNeasy Tissue kit rendered the highest sensitivity values in the three matrices assayed for Salmonella, L. monocytogenes, and E. coli O157:H7 and in onion for S. aureus. Despite being the most expensive of the methods compared, the DNeasy Tissue Kit can be successfully applied for any of the four most commonly studied pathogens, thus saving time and overall reducing the cost of the analysis.


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