Interlaboratory Validation of a Real-Time PCR 24-Hour Rapid Method for Detection of Salmonella in Foods

2009 ◽  
Vol 72 (5) ◽  
pp. 945-951 ◽  
Author(s):  
CHORNG-MING CHENG ◽  
KHANH T. VAN ◽  
WEN LIN ◽  
RICHARD M. RUBY
Keyword(s):  
Real Time ◽  
Screening Method ◽  
Rapid Screening ◽  
Selective Enrichment ◽  
Manual Method ◽  
Qpcr Method ◽  
Peptone Water ◽  
Interlaboratory Validation ◽  
Chili Powder ◽  
The One

The efficacy of a 24-h Salmonella real-time, or quantitative, PCR (qPCR) detection method was assessed through a collaborative effort involving eight Federal and state laboratories. Eleven foods including mashed potatoes, soft cheese, chili powder, chocolate, eggs, sprouts, apple juice, fish, shrimp, ground beef, and ground chicken were tested. For each food, seven blind samples were distributed to each participant for testing. These included six samples equivalently inoculated with 1 to 5 CFU/25 g of various serotypes of Salmonella (Gaminara, Weltevreden, Heidelberg, Senftenberg, Enteritidis, Newport, Typhimurium, and Kentucky for each food) and 10 to 50 CFU/25 g of the competitor Enterobacter cloacae. The seventh sample was inoculated with 10 to 50 CFU/25 g of the competitor, E. cloacae, only. These samples were tested for Salmonella by using four methods in parallel: (i) 24-h qPCR method detecting Salmonella from modified buffered peptone water enrichment medium; (ii) 48-h qPCR method detecting Salmonella from a secondary selective enrichment broth; (iii) modified Bacteriological Analytical Manual method; and (iv) VIDAS, an immunoassay system. The results of the statistical analysis showed there was no significant (P ≥ 0.05) difference between either of the qPCR methods and the modified Bacteriological Analytical Manual method for 10 of 11 foods. For the one exception, sprouts, detection by qPCR required 48 h. Both qPCR methods showed a detection limit of 0.08 to 0.2 CFU/g. These results provide a solid basis for using this 24-h qPCR rapid screening method to detect Salmonella in foods.

scholarly journals Evaluation of a novel and rapid screening method for the detection of contaminated colistin-resistant bacteria in food

2020 ◽  
Author(s):  
Hanh Vu ◽  
Cornelia Appiah-Kwarteng ◽  
Kaori Tanaka ◽  
Ryuji Kawahara ◽  
Diep Thi Khong ◽  
...  
Keyword(s):  
Real Time ◽  
Rapid Method ◽  
High Speed ◽  
Screening Method ◽  
Rapid Screening ◽  
Resistant Bacteria ◽  
Practical Utility ◽  
E Coli ◽  
Retail Meat ◽  
Meat Samples

Abstract Background: The dissemination of colistin-resistant bacteria carrying the colistin-resistant mobile gene, mcr-1 threatens medical care worldwide. In particular, contamination of food with colistin-resistant bacteria accelerates the community dissemination of colistin-resistant bacteria. Therefore, monitoring of colistin-resistant bacteria in food is important for controlling resistant bacteria. Unfortunately, the conventional culture methods for detecting colistin-resistant bacteria are not practical for monitoring food saftey. Therefore, development of a simple and rapid method to detect food contamination with colistin-resistant bacteria is desirable as an effective means for preventing the dissemination of resistant bacteria, particularly colistin-resistant bacteria.Findings: We developed a simple and rapid method for detecting Escherichia coli harboring the mcr-1 colistin resistance gene using a high-speed real-time polymerase chain reaction (PCR). The entire procedure, from sample processing to finals results, was performed within one hour. The practical utility of this method was verified by analyzing 27 retail meat samples for the presence of colistin-resistant bacteria. The results of the developed method were in agreement with the results of culturing colistin-resistant E. coli from the meat samples, demonstrating its efficacy and usefulness.Conclusions: A simple and rapid real-time PCR-based screening method was developed for detecting E. coli harboring mcr-1 in food samples. The practical utility of the procedure was confirmed using retail meat samples, indicating its potential as a convenient and rapid method to detect bacterial contamination of food items, especially in developing communities.

A novel rapid screening method for health monitoring of building structures from earthquake records

2019 ◽  
Vol 22 (16) ◽  
pp. 3544-3557
Author(s):  
Ging-Long Lin ◽  
Jer-Fu Wang ◽  
Chi-Chang Lin ◽  
Jim Lin
Keyword(s):  
Real Time ◽  
Health Monitoring ◽  
Screening Method ◽  
Nonlinear Behavior ◽  
Relative Displacement ◽  
Rapid Screening ◽  
Building Structures ◽  
Detection Techniques ◽  
Earthquake Records ◽  
Rapid Screening Method

This study presents a rapid screening method for health monitoring of building structures based on earthquake records. Compared with conventional damage detection techniques, the rapid screening system with few sensors is more attractive and cost-effective in assessing the global behaviors of a building structure. Only two tri-axial accelerometers are required for a building. One is mounted at the ground level, and another one is mounted at the top floor. First, the relative displacement of top floor to ground is calculated by on-line integration. Then, the diagram of absolute acceleration versus relative displacement of top floor is used to determine the pseudo stiffness of the whole building by linear regression. The decrease of pseudo stiffness denotes the occurrence and degree of damage in the building. A novel real-time damage technique is also proposed to detect nonlinear behavior of a building. A five-story shear-type building under earthquake excitations was illustrated for sensitivity analysis of pseudo stiffness considering different damage cases. Shaking-table-test data of a three-story benchmark building were used to verify the accuracy of the proposed damage assessment technique. In addition, the proposed method was also applied to evaluate a new eight-story residential building equipped with accelerometers in Taipei, Taiwan. Finally, the acceleration response records of a real building, which experienced moderate damages caused by the main shock of 1999 Taiwan Chi-Chi earthquake ( ML = 7.3), were considered to examine the applicability of the proposed method to generate a real-time damage indicator for a building with nonlinear behavior. All of the results show that the proposed method is reliable and effective for rapid diagnosis of building health.

scholarly journals Rapid Screening Method for Compounds That Affect the Growth and Germination of Candida albicans, Using a Real-Time PCR Thermocycler

2011 ◽  
Vol 77 (22) ◽  
pp. 8193-8196 ◽  
Author(s):  
Lucja M. Jarosz ◽  
Bastiaan P. Krom
Keyword(s):  
Candida Albicans ◽  
Real Time ◽  
Real Time Pcr ◽  
Fluorescent Protein ◽  
Screening Method ◽  
Rapid Screening ◽  
Content Type ◽  
Wide Range ◽  
Hyphal Formation ◽  
Green Fluorescent

ABSTRACTWe propose a screening method for compounds affecting growth and germination inCandida albicansusing a real-time PCR thermocycler to quantify green fluorescent protein (GFP) fluorescence. Using PACT1-GFPand PHWP1-GFPreporter strains, the effects of a wide range of compounds on growth and hyphal formation were quantitatively assessed within 3 h after inoculation.

scholarly journals Real-Time PCR Method for Detection of Salmonella spp. in Environmental Samples

2017 ◽  
Vol 83 (14) ◽  
Author(s):  
Kuppuswamy N. Kasturi ◽  
Tomas Drgon
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Environmental Samples ◽  
False Negative ◽  
Screening Method ◽  
Reference Method ◽  
Rapid Screening ◽  
Content Type ◽  
Pcr Method ◽  
Group D

ABSTRACT The methods currently used for detecting Salmonella in environmental samples require 2 days to produce results and have limited sensitivity. Here, we describe the development and validation of a real-time PCR Salmonella screening method that produces results in 18 to 24 h. Primers and probes specific to the gene invA, group D, and Salmonella enterica serovar Enteritidis organisms were designed and evaluated for inclusivity and exclusivity using a panel of 329 Salmonella isolates representing 126 serovars and 22 non-Salmonella organisms. The invA- and group D-specific sets identified all the isolates accurately. The PCR method had 100% inclusivity and detected 1 to 2 copies of Salmonella DNA per reaction. Primers specific for Salmonella-differentiating fragment 1 (Sdf-1) in conjunction with the group D set had 100% inclusivity for 32 S. Enteritidis isolates and 100% exclusivity for the 297 non-Enteritidis Salmonella isolates. Single-laboratory validation performed on 1,741 environmental samples demonstrated that the PCR method detected 55% more positives than the Vitek immunodiagnostic assay system (VIDAS) method. The PCR results correlated well with the culture results, and the method did not report any false-negative results. The receiver operating characteristic (ROC) analysis documented excellent agreement between the results from the culture and PCR methods (area under the curve, 0.90; 95% confidence interval of 0.76 to 1.0) confirming the validity of the PCR method. IMPORTANCE This validated PCR method detects 55% more positives for Salmonella in half the time required for the reference method, VIDAS. The validated PCR method will help to strengthen public health efforts through rapid screening of Salmonella spp. in environmental samples.

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