Evaluation of a Method for Rapid Detection of Listeria monocytogenes in Dry-Cured Ham Based on Impedanciometry Combined with Chromogenic Agar

2018 ◽  
Vol 81 (5) ◽  
pp. 705-712 ◽  
Author(s):  
MIRIAN LABRADOR ◽  
MARÍA C. ROTA ◽  
CONSUELO PÉREZ ◽  
ANTONIO HERRERA ◽  
SUSANA BAYARRI
Keyword(s):  
Listeria Monocytogenes ◽  
Comparative Study ◽  
Pure Culture ◽  
Food Industry ◽  
Reference Method ◽  
Agar Culture ◽  
Promising Alternative ◽  
Dry Cured Ham ◽  
Study Results ◽  
Chromogenic Agar

ABSTRACT The food industry is in need of rapid, reliable methodologies for the detection of Listeria monocytogenes in ready-to-eat products, as an alternative to the International Organization of Standardization (ISO) 11290-1 reference method. The aim of this study was to evaluate impedanciometry combined with chromogenic agar culture for the detection of L. monocytogenes in dry-cured ham. The experimental setup consisted in assaying four strains of L. monocytogenes and two strains of Listeria innocua in pure culture. The method was evaluated according to the ISO 16140:2003 standard through a comparative study with the ISO reference method with 119 samples of dry-cured ham. Significant determination coefficients (R2 of up to 0.99) for all strains assayed in pure culture were obtained. The comparative study results had 100% accuracy, 100% specificity, and 100% sensitivity. Impedanciometry followed by chromogenic agar culture was capable of detecting 1 CFU/25 g of food. L. monocytogenes was not detected in the 65 commercial samples tested. The method evaluated herein represents a promising alternative for the food industry in its efforts to control L. monocytogenes. Overall analysis time is shorter and the method permits a straightforward analysis of a large number of samples with reliable results.

Comparative Evaluation of Veriflow®Listeria monocytogenes to USDA and AOAC Culture Based Methods for the Detection of Listeria monocytogenes in Food

2015 ◽  
Vol 98 (5) ◽  
pp. 1325-1334
Author(s):  
Adam C Joelsson ◽  
Ashley S Brown ◽  
Amrita Puri ◽  
Martin P Keough ◽  
Zara E Gaudioso ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Pcr Amplification ◽  
Reference Method ◽  
Probability Of Detection ◽  
Complex Data ◽  
Detection Analysis ◽  
Environmental Surfaces ◽  
Study Results ◽  
Significant Difference ◽  
Inspection Service

Abstract Veriflow®Listeria monocytogenes (LM) is a molecular based assay for the presumptive detection of Listeria monocytogenes from environmental surfaces, dairy, and ready-to-eat (RTE) food matrixes (hot dogs and deli meat). The assay utilizes a PCR detection method coupled with a rapid, visual, flow-based assay that develops in 3 min post PCR amplification and requires only 24 h of enrichment for maximum sensitivity. The Veriflow LM system eliminates the need for sample purification, gel electrophoresis, or fluorophore-based detection of target amplification, and does not require complex data analysis. This Performance Tested MethodSM validation study demonstrated the ability of the Veriflow LM method to detect low levels of artificially inoculated L. monocytogenes in seven distinct environmental and food matrixes. In each unpaired reference comparison study, probability of detection analysis indicated no significant difference between the Veriflow LM method and the U.S. Department of Agriculture, Food Safety and Inspection Service Microbiology Laboratory Guidebook 8.08 or AOAC 993.12 reference method. Fifty strains of L. monocytogenes were detected in the inclusivity study, while 39 nonspecific organisms were undetected in the exclusivity study. The study results show that Veriflow LM is a sensitive, selective, and robust assay for the presumptive detection of L. monocytogenes sampled from environmental, dairy, or RTE (hot dogs and deli meat) food matrixes.

A STUDY OF ENDOMETRIAL THICKNESS IN TRANS VAGINAL SONOGRAPHY IN RELATION WITH HISTOPATHOLOGY REPORT IN DILATION & CURRATAGE IN AUB WOMEN

2019 ◽  
pp. 1-2
Keyword(s):  
Comparative Study ◽  
Endometrial Thickness ◽  
P Value ◽  
First Line ◽  
Non Invasive ◽  
Dilation And Curettage ◽  
Study Results ◽  
Vaginal Sonography ◽  
In Trans

A study of of endometrial thickness on TVS in relation with histopathology report on dilation and curettage. AIM AND OBJECTIVE-To set a cut off limit of endometrial thickness on TVS for differtiating between normal and abnormal endometrium. MATERIAL AND METHOD-hospital based comparative study. RESULTS-TVS is non invasive ,simple first line procedure in AUB women. Mean endometrial thickness in normal endometrial group was 8.00±2.44 mm and in abnormal endometrial group was 15.16±33 mm.The difference was found highly significant (p value<.001)

scholarly journals Methods to extract the exopolymeric matrix from biofilms: a comparative study

1999 ◽  
Vol 39 (7) ◽  
pp. 243-250 ◽  
Author(s):  
Joana Azeredo ◽  
Valentina Lazarova ◽  
Rosário Oliveira
Keyword(s):  
Organic Carbon ◽  
Comparative Study ◽  
Mixed Culture ◽  
Pure Culture ◽  
Cell Walls ◽  
Extraction Method ◽  
Extraction Methods ◽  
Suitable Method ◽  
The Matrix ◽  
Biofilm Matrix

To study the composition of a biofilm a previous extraction method is required to separate cells from the matrix. There are several methods reported in the literature; however they are not efficient or promote leakage of intracellular material. In this work several extraction methods were assayed in mixed culture and pure culture biofilms and their efficiency was evaluated by the amount of organic carbon, proteins and intracellular material extracted. The results showed that the extraction with glutaraldehyde 3% (w/v) was the most suitable method, extracting great amounts of organic carbon without promoting cell lysis or permeabilization. Glutaraldehyde is a bifunctional reagent that binds to cell walls avoiding their permeabilization and the biofilm matrix is solubilized in the solution.

Astra Tech and Brånemark System Implants: A Prospective 5-Year Comparative Study. Results after One Year

1999 ◽  
Vol 1 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Per Astrand ◽  
Bo Engquist ◽  
Simon Dahlgren ◽  
Eva Engquist ◽  
Hartmut Feldmann ◽  
...  
Keyword(s):  
Comparative Study ◽  
Study Results ◽  
One Year

Compliment Strategies Employed by Japanese and Malaysian Tour Guides during Tour Sessions

2020 ◽  
Author(s):  
Roswati Abdul Rashid ◽  
◽  
Roslina Mamat ◽  
Rokiah Paee ◽  
◽  
...  
Keyword(s):  
Comparative Study ◽  
Native Speakers ◽  
Japanese Language ◽  
Tourist Attractions ◽  
Tour Guides ◽  
Japanese Speakers ◽  
Study Results ◽  
Language Communication ◽  
Research Goal ◽  
Tourist Guides

This research is a comparative study of Japanese language communication between the Japanese and Malay tourist guides during tourism tour sessions. The research goal is to examine patterns of compliment strategies implemented throughout the interactions of the tour sessions. The study results acquired are in the form of four recordings of a dialogue between the tourist guides and the tourists, in audio and video modes. The conversations are transcribed and coded. The tour guides included two Japanese native speakers and two Malaysian-Japanese speakers. In contrast, the tourists are Japanese native speakers who visited Malaysia, and Malaysians who attended the tourist attractions in Japan. The study reveals that the frequency of compliments applied by both Japanese and Malaysian tour guides are alike, or in other words, there are no significant differences. Nevertheless, category, function and topic or theme of compliment utterance present ssubstantial distinction.

Behavior of Listeria monocytogenes in a Pseudomonas putida Biofilm on a Condensate-Forming Surface

2004 ◽  
Vol 67 (2) ◽  
pp. 322-327 ◽  
Author(s):  
ASHRAF N. HASSAN ◽  
DAWN M. BIRT ◽  
JOSEPH F. FRANK
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Pseudomonas Putida ◽  
Microscopic Observation ◽  
Pure Culture ◽  
Extracellular Polymeric Substances ◽  
Plate Count ◽  
Free Surfaces ◽  
Processing Plants ◽  
Humidity Chamber

Listeria monocytogenes has been isolated from condensate-forming surfaces in food processing plants. The objective of this research was to observe the behavior of L. monocytogenes on condensate-covered stainless steel with a Pseudomonas putida biofilm. L. monocytogenes–containing biofilms, either with or without added chicken protein, were incubated in a high humidity chamber at 12°C to allow formation of condensate. Samples were analyzed for attached and unattached L. monocytogenes and total plate count periodically for 35 days. Samples were also taken for microscopic observation of Listeria and bacterial extracellular polymeric substances (EPS). L. monocytogenes attached in significantly greater numbers (&gt;3-log difference) to surfaces with preexisting P. putida biofilms than to Pseudomonas-free surfaces. L. monocytogenes survived in the presence or absence of P. putida with no added nutrients for 35 days, with numbers of survivors in the range of 3 to 4 log CFU/cm2 in the presence of P. putida and less than 2.9 log CFU/cm2 in pure culture. Attached and unattached L. monocytogenes were at similar levels throughout the incubation under all conditions studied. The addition of protein to the biofilms allowed growth of L. monocytogenes in pure culture during the first 7 days of incubation. Numbers of L. monocytogenes were not affected by the presence of P. putida when protein was present. Unattached L. monocytogenes were at levels of 3.6 to 6.7 log CFU/cm2 on the protein-containing surfaces. Microscopic observation of the condensate-covered biofilms indicated that L. monocytogenes formed microcolonies embedded within an EPS matrix over a 28-day period. This research demonstrates that L. monocytogenes can survive on condensate-forming stainless steel in low and high nutrient conditions, with or without the presence of Pseudomonas biofilm. The Listeria can detach and, therefore, have the potential to contaminate product.

Sign in / Sign up

Export Citation Format

Share Document