Preenrichment Conditions for Effective Recovery of Salmonella in Foods and Feed Ingredients

1979 ◽  
Vol 42 (2) ◽  
pp. 153-157 ◽  
Author(s):  
J. Y. D'AOUST ◽  
C. MAISHMENT
Keyword(s):  
Brilliant Green ◽  
False Negative ◽  
Food Samples ◽  
Contamination Level ◽  
Experimental Conditions ◽  
Feed Ingredients ◽  
Selective Enrichment ◽  
Negative Results ◽  
False Negative Results ◽  
The Cost

The efficacy of Clausen, EE, Eugon, GN, Tergitol 7, lactose and nutrient broths as Salmonella preenrichment media was evaluated using 165 food samples with an incident contamination level ranging from 1.5 to 460 salmonellae/100 g. Replicate food samples (100 g) were preenriched in each of seven media (900 ml) for 6 h and 24 h at 35 C; various amounts (10, 1.0 and 0.1 ml) of preenriched cultures were selectively enriched in tetrathionate brilliant green (43 C) and selenite cystine (35 C) broths and plated on bismuth sulfite and brilliant green sulfa agars. Short (6 h) and 24-h preenrichment conditions resulted in 26 (16%) and 8 (5%) false negative results, respectively. Recovery of Salmonella from 6-h but not 24-h preenrichment cultures also varied directly with the portion of culture inoculated into selective enrichment broths. None of the preenrichment media tested performed satisfactorily at 6 h of incubation where levels of recovery ranged from 32 to 62%; at 24 h, good recovery was obtained with all media (95 to 100%) except EE broth (74%). The incidence of competitive flora was significantly higher on selenite + brilliant green sulfa than on tetrathionate + bismuth sulfite; transfer volumes (10 and 1.0 ml) and preenrichment media did not contribute significantly to the presence of non-salmonellae on plating media. Characteristics of preenrichment media were found to be less critical than preenrichment incubation time for effective recovery of Salmonella in foods and feed ingredients. The use of 1.0- rather than 10-ml preenrichment transfer volume is indicated because it proved to be completely reliable under our experimental conditions and reduced the cost of analyses.

Surfactants for the Effective Recovery of Salmonella in Fatty Foods

1982 ◽  
Vol 45 (3) ◽  
pp. 249-252 ◽  
Author(s):  
J.-Y. D'AOUST ◽  
C. MAISHMENT ◽  
P. STOTLAND ◽  
A. BOVILLE
Keyword(s):  
Salmonella Enteritidis ◽  
Brilliant Green ◽  
False Negative ◽  
Tween 80 ◽  
Food Samples ◽  
Nutrient Broth ◽  
Tween 20 ◽  
Negative Results ◽  
False Negative Results ◽  
Tween 60

Inhibitory concentrations of 8 surfactants were determined for Salmonella typhimurium and Salmonella enteritidis. Pure culture work resulted in the exclusion of Tween 20, Teepol 610 and Brij 35 and retention of Tergitol-7 (T-7), Tween 80 (TW 80), Triton X-100 (TX), Myrj 52S (M), and Arlacel 80 + Tween 60 (AT) for a study on the quantitative recovery of Salmonella in 45 naturally contaminated fatty foods. Replicate food samples (100 g) were preenriched overnight at 35 C in nutrient broth supplemented with 3%(w/v) surfactant except AT (10%). Serial dilutions of preenrichment cultures were selectively enriched overnight in tetrathionate brilliant green (43 C) and selenite cystine (35 C) broths and streaked on bismuth sulfite and brilliant green sulfa agar media. Recovery with all test surfactants was comparable to that obtained with nutrient broth controls; of 270 preenrichment cultures tested, only 7 false-negative results attributable to TX (3), AT (2), M (1), and nutrient broth control (1) were obtained. None of the surfactants consistently yielded greater populations of Salmonella for given foods or food categories; median counts for preenrichment cultures were 104–105 salmonellae/ml for low and high moisture foods and 106–107 salmonellae/ml for animal feeds. These results suggest that use of surfactants to facilitate detection of Salmonella in fatty foods is not warranted.

Update on Preenrichment and Selective Enrichment Conditions for Detection of Salmonella in Foods

1981 ◽  
Vol 44 (5) ◽  
pp. 369-374 ◽  
Author(s):  
JEAN-YVES D'AOUST
Keyword(s):  
Nutritional Value ◽  
Brilliant Green ◽  
False Negative ◽  
Sterility Testing ◽  
Selective Enrichment ◽  
Cultural Methods ◽  
Negative Results ◽  
Limited Success ◽  
False Negative Results ◽  
Transfer Volumes

The search for short and sensitive cultural methods for detection of Salmonella in foods has met with limited success. Short (3–8 h) incubation of non-selective enrichment media do not provide conditions for effective resuscitation of stressed or injured salmonellae and result in unacceptably high numbers of false-negative results. Isolation of Salmonella is not dependent on the nutritional value of preenrichment media; simple media such as lactose and nutrient broths are equally reliable as highly nutritive sterility testing media. The need for detergents in non-selective enrichment of fatty foods and use of preenrichment transfer volumes greater than 1 ml is not indicated. Although selective enrichment in tetrathionate brilliant green (TBG) broth at an elevated temperature (43 C) increases method sensitivity, use of Mueller-Kauffman TBG under similar analytical conditions may be inhibitory to Salmonella. Refrigeration of preenrichment and selective enrichment broth cultures has been used successfully to provide greater analytical flexibility by increasing the number of days on which analyses can be initiated without engendering weekend work.

scholarly journals Evaluation of a widely used culture-based method for detection of livestock-associated meticillin-resistant Staphylococcus aureus (MRSA), Denmark and Norway, 2014 to 2016

2017 ◽  
Vol 22 (28) ◽  
Author(s):  
Jesper Larsen ◽  
Marianne Sunde ◽  
Md Zohorul Islam ◽  
Anne Margrete Urdahl ◽  
Aina Steihaug Barstad ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Environmental Samples ◽  
False Negative ◽  
High Ratio ◽  
Selective Enrichment ◽  
Negative Results ◽  
False Negative Results

We evaluated a widely used culture-based method for detection of livestock-associated meticillin-resistant Staphylococcus aureus (LA-MRSA) in samples collected from pigs and the environment inside pig stables in Denmark and Norway. Selective enrichment in tryptic soy broth containing cefoxitin and aztreonam led to a high ratio of false-negative results (26%; 57/221). On this basis, we recommend reconsidering the use of selective enrichment for detection of LA-MRSA in animal and environmental samples.

scholarly journals 667. Next Generation Sequencing of Microbial Cell Free DNA in the Diagnosis and Treatment of Infectious Disease in Children: When Does the Result Justify the Cost?

2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S436-S436
Author(s):  
Rachel Downey Quick ◽  
Kelli A Martinez ◽  
Susan M Russo ◽  
Sarah E McGwier ◽  
Rachel A Quirt ◽  
...  
Keyword(s):  
Next Generation Sequencing ◽  
Antimicrobial Resistance ◽  
False Negative ◽  
Next Generation ◽  
Cell Free Dna ◽  
Negative Results ◽  
Free Dna ◽  
False Negative Results ◽  
The Cost ◽  
Generation Sequencing

Abstract Background Pathogen testing using next-generation sequencing of microbial cell-free DNA (NGS cfDNA) is a promising diagnostic tool to identify pathogens that might not be detected using conventional lab evaluation. Considering the cost of this test, it is important to determine when it is most useful to the plan of care (POC). Figure 1. Unit of admission among cases Figure 2. Patient characteristics in cases determined to be valuable and not valuable to the plan of care (POC) Methods In this retrospective study, we collected data from the medical charts of 50 consecutive NGS cfDNA tests in a free-standing children’s hospital. We evaluated patients for demographics, underlying conditions, diagnosis at time of testing, conventional laboratory testing and timing, medical treatment, and NGS cfDNA test results for clinical relevance or false negative results compared to conventional testing. The primary goal was to identify patients for whom the NGS cfDNA testing affected the POC. Charts were reviewed, and determinations regarding whether the result influenced the POC were confirmed by a provider. Results We were unable to differentiate patients with clinically valuable NGS cfDNA results (Fig 1 & 2). Among those with NGS cfDNA results valuable to the POC (n=22), both negative and positive testing guided POC (13 valuable negative vs. 9 diagnostic cases). In the total sample, 5 cases (10%) had a clinically relevant pathogen identified through conventional testing, but not through NGS cfDNA and 2 cases had antimicrobial resistance on culture, which is not detected by NGS cfDNA. Conclusion While we did not find a specific clinical profile for NGS cfDNA use, positive results were essential to the diagnosis in 18% of cases with otherwise negative laboratory evaluation for the pathogen identified in NGS cfDNA. Negative tests affected the POC in 26% of cases by avoiding unnecessary antimicrobials in high risk immunocompromised patients and patients that presented with low-risk of infection, but unclear disease process. Caution must be exercised with reliance on this test with respect to antimicrobial resistance and risk of false negative results. Disclosures All Authors: No reported disclosures

Rapid Detection of Salmonellae in Foods Using Immunoassay Systems

1986 ◽  
Vol 49 (2) ◽  
pp. 92-98 ◽  
Author(s):  
GEORGE F. IBRAHIM ◽  
MARY J. LYONS ◽  
RETA A. WALKER ◽  
GRAHAM H. FLEET
Keyword(s):  
Solid Phase ◽  
False Negative ◽  
Food Samples ◽  
Negative Results ◽  
Cultural Method ◽  
False Negative Results ◽  
Salmonella Serotypes ◽  
Cost Efficient ◽  
Positive Results ◽  
Additional Sample

A standard cultural method, radioimmunometric (RIMA) and enzyme immunometric (EIMA) assays were compared for detection of salmonellae in 235 food samples. The immunoassays used titanous hydroxide as the solid-phase, commercial Spicer-Edwards salmonella polyvalent H antisera (SEA) or pooled antisera produced against 10 salmonella flagellins (PFA). Nineteen food samples were positive for Salmonella by the standard cultural method. These as well as one additional sample were also positive for Salmonella by RIMA and EIMA. No false-negative results were obtained from the immunoassays using PFA, whereas two false-negative results were observed when SEA was used. The incidence of false-positive results when SEA and PFA were used were, respectively, 3.0 and 0.9% with RIMA and 2.6 and 0.9% with EIMA. The immunoassays were also able to detect 77 Salmonella serotypes when grown alone or in association with other species of Enterobacteriaceae, in mannitol selenite cystine broth. Both immunoassays performed reliably on enrichment cultures stored under refrigeration for up to 9 d. Also, of 6 non-motile salmonellae, 5 were detectable by the immunoassays. The immunoassays were simple, rapid and cost-efficient.

Efficacy of an International Method for Detection of Salmonella in Chocolate and Cocoa Products

1984 ◽  
Vol 47 (2) ◽  
pp. 111-113 ◽  
Author(s):  
J.-Y. D'AOUST ◽  
A. SEWELL
Keyword(s):  
Brilliant Green ◽  
False Negative ◽  
Positive Sample ◽  
Negative Results ◽  
False Negative Results ◽  
Toxic Agents ◽  
Cocoa Products ◽  
Agar Media ◽  
Limited Sensitivity

The methods of the International Office of Cocoa and Chocolate and International Sugar Confectionery Manufacturers' Association (IOCC/ISCMA), and of the Health Protection Branch (HPB) were compared for their ability to detect Salmonella in chocolate and cocoa products. Of 152 samples tested, 13 contaminated samples were identified, 10 by the HPB and 8 by the IOCC/ISCMA method. Prolonged (48 h) incubation of enrichment media produced two false-negative results each with the Muller-Kauffman tetrathionate and the selenite cystine broths, exerted no effect on tetrathionate brilliant green, and identified one additional positive sample with the selenite brilliant green broth. More samples were found positive on bismuth sulfite than on brilliant green and brilliant green sulfa agar media. The present study underlines the limited sensitivity of both standard methods and questions the determinant role of casein in the neutralization of toxic agents in cocoa products.

Comparison of Selective Enrichment Broths for Isolation of Campylobacter jejuni/coli from Freshly Deboned Market Chicken

1992 ◽  
Vol 55 (5) ◽  
pp. 333-336 ◽  
Author(s):  
ALEJANDRO CASTILLO-AYALA
Keyword(s):  
Campylobacter Jejuni ◽  
False Negative ◽  
Polymyxin B ◽  
Similar Distribution ◽  
Retail Markets ◽  
Selective Enrichment ◽  
Negative Results ◽  
False Negative Results ◽  
Two Samples ◽  
Elevated Rate

The efficiency of Brucella broth supplemented with vancomycin-trimethoprim-polymyxin B (VTP) at the same concentration as Skirrow agar and bacitracin-colistin-cephalothincycloheximide-novobiocin (BCN) at the same concentration as Butzler agar was evaluated in the recovery of Campylobacter jejuni/coli from fresh retail chicken. Ninety-two samples were acquired from retail markets in Guadalajara, Mexico, and analyzed by enrichment in VTP and BCN broths, each streaked on Skirrow and Butzler agars. Thirty-three (36%) of the samples were positive by any route of analysis. The recovery of Campylobacter (19.6% in VTP alone, 25.0% in BCN, and 35.9% in VTP+BCN) was enhanced by simultaneously using two instead of only one enrichment broth, especially when VTP broth was used (p<0.05). There was an elevated rate of samples containing Campylobacter which gave false-negative results on VTP (45.2% of false-negatives) and on BCN (30.3%). While isolation on Butzler agar showed a similar distribution between samples derived from VTP or BCN broths, Skirrow agar was effective only when the inoculum was derived from BCN broth. Our results indicated that vancomycin-trimethoprim-polymyxin B mixture was not a suitable agent for use in an enrichment-plating procedure to recover Campylobacter from chicken, and that by simultaneously using two enrichment broths the ability to recover Campylobacter was enhanced significantly.

Effect of non-fat dry milk on recovery of staphylococcal thermonuclease from foods

1979 ◽  
Vol 25 (1) ◽  
pp. 44-46 ◽  
Author(s):  
C. E. Park ◽  
H. B. El Derea ◽  
M. K. Rayman
Keyword(s):  
False Negative ◽  
Ground Beef ◽  
Acid Precipitation ◽  
Food Samples ◽  
Assay Method ◽  
Negative Results ◽  
False Negative Results ◽  
Dry Milk ◽  
Egg Products ◽  
Subsequent Acid

Modification of the method of Tatini et al. (1976) by addition of non-fat dry milk (NFDM) to food samples and subsequent acid precipitation at pH 3.8 enhanced the recovery of staphylococcal thermonuclease (TNase) from most of 37 foods tested. The modified TNase assay method allowed detection of 10 ng (0.002 units) of the enzyme per gram of each of the following foods: ground beef, boiled egg products, whey powder, fruit-containing yogurt, dressings and spreads, potato and egg salads, and pastas, all of which gave false-negative results without NFDM.

Rapid Cultural Method to Detect Salmonella in Foods

1984 ◽  
Vol 47 (1) ◽  
pp. 46-48 ◽  
Author(s):  
HELLMUT RAPPOLD ◽  
ROBERT F. BOLDERDIJK ◽  
JOZEF M. DE SMEDT
Keyword(s):  
Incubation Time ◽  
False Negative ◽  
Selective Enrichment ◽  
Negative Results ◽  
Cultural Method ◽  
False Negative Results ◽  
Selective Agar ◽  
Agar Media

The influence of reduced incubation time (8 h) on productivity of the Muller Kauffman tetrathionate and modified Rappaport broths incubated at 43°C was studied using naturally and artificially contaminated dry foods. Inoculation of selective enrichments from pre-enrichments and streaking on selective agar media were carried out on the same day, thus providing presumptive evidence of Salmonella one day earlier than with conventional cultural techniques. With modified Rappaport broth, the number of Salmonella-positive samples was the same after 8 and 24 h of selective enrichment. With Muller Kauffman tetrathionate, 3 false-negative results were obtained after 8 h of incubation. Salmonellae were detected at a level of less than 1 cell per 500 g of product (MPN).

scholarly journals Ecotoxicological testing of sediments and dredged material: an overlooked opportunity?

2020 ◽  
Vol 20 (12) ◽  
pp. 4218-4228 ◽  
Author(s):  
Susanne Heise ◽  
Marc Babut ◽  
Carmen Casado ◽  
Ute Feiler ◽  
Benoit J. D. Ferrari ◽  
...  
Keyword(s):  
False Negative ◽  
Added Value ◽  
Management Decision ◽  
Dredged Material ◽  
Negative Results ◽  
False Negative Results ◽  
Management Decision Making ◽  
Chemical Sediment ◽  
The Cost

Abstract Purpose Basing decisions for the management of contaminated sediments on ecotoxicological data is still often met with skepticism by European stakeholders. These concerns are discussed as they pertain to bioassays to show how ecotoxicological data may provide added value for the sustainable management of sediment in aquatic systems. Materials and methods Five “concerns” are selected that are often raised by stakeholders. The ecotoxicological practice is discussed in light of the knowledge gained in recent decades and compared with chemical sediment analysis and chemical data. Results and discussion Common assumptions such as a higher uncertainty of biotest results for sediments compared to chemical analyses are not supported by interlaboratory comparisons. Some confusion also arises, because the meaning of biotest data is often misunderstood, questioning their significance in light of a limited number of organisms and altered test conditions in the lab. Because biotest results describe a sediment property, they should not be directly equated with an impact upon the biological community. To identify a hazard, however, the possibility of false-negative results due to the presence of contaminants that are not analyzed but are toxic is lower. Conclusions The cost of increased investment in ecotoxicological tests is, in our view, small compared with that of making false-negative assessments of sediment/dredged material that can ultimately have long-term environmental costs. As such, we conclude that ecotoxicological testing is an opportunity for sediment management decision-making that warrants more attention and confidence in Europe.

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