Effect of Listeria seeligeri or Listeria welshimeri on Listeria monocytogenes detection in and recovery from buffered Listeria enrichment broth

Dailey, Rachel C.; Welch, Lacinda J.; Hitchins, Anthony D.; Smiley, R. Derike

doi:10.1016/j.fm.2014.09.008

Cited by 20 publications

(23 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The second proposed mode of action is that the rapid growth of a competitor microorganism and resulting depletion of one or more essential nutrients in the enrichment broth causes Listeria to enter stationary phase at a population much lower than the generally accepted maximum of approximately 9 log CFU/ml. This is also supported by several published studies (5, 8, 16). In actuality, both of these modes of action probably contribute to varying degrees, depending on the matrix and the competitors present in that matrix, to the suppression of the Listeria population.…”

Section: Resultssupporting

confidence: 88%

“…L. monocytogenes sensitivity to acriflavine·HCl has been previously reported and was attributed to an increase in lag time and a decrease in the specific growth rate of the test strains (3). To confirm this for our test strains, we performed a growth rate analysis, as described in previous studies (7, 8, 16). The mean generation times were 150 ± 23 min ( n = 9), 160 ± 18 min ( n = 9), and 204 ± 43 min ( n = 9) in nonselective basal BLEB, acriflavine·HCl–supplemented basal BLEB, and fully selective BLEB, respectively.…”

Section: Resultsmentioning

confidence: 78%

“…When multiple species of Listeria are present in the test sample, competitive growth during selective enrichment will frequently result in an intraspecies population differential that is sufficiently large to prevent the recovery of L. monocytogenes during subsequent selective plating steps. This has been shown for the FDA Listeria- selective enrichment method (8, 16), the U.S. Department of Agriculture Food Safety and Inspection Service (USDA-FSIS)–recommended method (6, 19), and the European Union International Organization for Standardization (EN ISO 11290-1) method (5, 22). The added presence of non- Listeria species competitors also contributes to large postenrichment population differentials (17).…”

mentioning

confidence: 77%

See 2 more Smart Citations

Contribution of Selective Conditions to Microbial Competition in Four Listeria Selective Enrichment Formulations

Keys

Hitchins

Smiley

2016

Journal of Food Protection

Self Cite

View full text Add to dashboard Cite

Microbial competition during selective enrichment negatively affects Listeria monocytogenes populations and may hinder the subsequent detection or recovery of this organism. Competition assays among 10 selected strains of Listeria and Citrobacter braakii were performed in buffered Listeria enrichment broth, 3-(N-morpholino)propanesulfonic acid–buffered Listeria enrichment broth, University of Vermont medium–modified Listeria enrichment broth, and Fraser broth. The individual contributions of each selective agent in these media were also assessed, as well as the contribution of incubation temperature. Acriflavine hydrochloride and sodium nalidixate were ineffective at preventing the overgrowth of C. braakii; this resulted in substantially lower populations of Listeria than when the competitor was absent. At the higher levels, both of these selective agents were detrimental to Listeria populations. The highest enrichment populations of Listeria were observed when either NaCl or LiCl was present. In the absence of selective agents, the final populations of Listeria following competitive growth with C. braakii were not substantially affected by temperature; however, in the presence of selective agents, the Listeria populations were statistically higher at the higher incubation temperature. There are a limited number of selective agents available for use in Listeria-specific enrichment media, resulting in formulations that are only somewhat selective for this species. The optimization of current formulations may help researchers to improve Listeria recovery, particularly from products with a high microbial load. The understanding of the behavior and interactions between target and nontarget microorganisms in the presence of these available selective agents is a necessary step in the optimization of Listeria selective enrichment formulations.

show abstract

Section: Resultssupporting

confidence: 88%

Section: Resultsmentioning

confidence: 78%

mentioning

confidence: 77%

See 1 more Smart Citation

Contribution of Selective Conditions to Microbial Competition in Four Listeria Selective Enrichment Formulations

Keys

Hitchins

Smiley

2016

Journal of Food Protection

Self Cite

View full text Add to dashboard Cite

show abstract

“…The interference of background food microflora (9,10) or other Listeria spp. (particularly L. innocua) may mask the presence and diminish the detectability of L. monocytogenes (11)(12)(13)(14)(15)(16)(17). Recent studies have addressed the issue of L. monocytogenes strain competition as a factor related to enrichment bias (18,19).…”

mentioning

confidence: 99%

Listeria monocytogenes Strains Underrepresented during Selective Enrichment with an ISO Method Might Dominate during Passage through Simulated Gastric Fluid and In Vitro Infection of Caco-2 Cells

Zilelidou

Karmiri

Ζουμποπούλου

et al. 2016

Appl Environ Microbiol

View full text Add to dashboard Cite

Various Listeria monocytogenes strains may contaminate a single food product, potentially resulting in simultaneous exposure of consumers to multiple strains. However, due to bias in strain recovery, L. monocytogenes strains isolated from foods by selective enrichment (SE) might not always represent those that can better survive the immune system of a patient. We investigated the effect of cocultivation in tryptic soy broth with 0.6% yeast extract (TSB-Y) at 10°C for 8 days on (i) the detection of L. monocytogenes strains during SE with the ISO 11290-1:1996/Amd 1:2004 protocol and (ii) the in vitro virulence of strains toward the Caco-2 human colon epithelial cancer cell line following exposure to simulated gastric fluid (SGF; pH 2.0)-HCl (37°C). We determined whether the strains which were favored by SE would be effective competitors under the conditions of challenges related to gastrointestinal passage of the pathogen. Interstrain competition of L. monocytogenes in TSB-Y determined the relative population of each strain at the beginning of SE. This in turn impacted the outcome of SE (i.e., favoring survival of competitors with better fitness) and the levels exposed subsequently to SGF. However, strong growth competitors could be outcompeted after SGF exposure and infection of Caco-2 cells by strains outgrown in TSB-Y and underdetected (or even missed) during enrichment. Our data demonstrate a preferential selection of certain L. monocytogenes strains during enrichments, often not reflecting a selective advantage of strains during infection. These findings highlight a noteworthy scenario associated with the difficulty of matching the source of infection (food) with the L. monocytogenes isolate appearing to be the causative agent during listeriosis outbreak investigations. IMPORTANCEThis report is relevant to understanding the processes involved in selection and prevalence of certain L. monocytogenes strains in different environments (i.e., foods or sites of humans exposed to the pathogen). It highlights the occurrence of multiple strains in the same food as an important aspect contributing to mismatches between clinical isolates and infection sources during listeriosis outbreak investigations. Selective enrichment (SE) for detection of foodborne pathogens has been a fundamental tool in the food industry, critical for hygiene control and safety monitoring (1) while providing crucial information during trace-back investigations of foodborne outbreaks. However, selective culture-based enrichment procedures are associated with inherent bias since the use of selective agents and the presence of competing background microorganisms in food samples sometimes obstruct the isolation of a target pathogen and lead to false-negative results (2, 3).Listeria monocytogenes stands out among the pathogens of major concern for food safety. This Gram-positive bacterium causes the rare but life-threatening disease listeriosis and manifests the interplay between saprophytic lifestyle and virulence (4, 5). Its ubiquity allows...

show abstract

“…Despite the use of selective agents in these enrichment methods, species-specific growth is not achieved. When more than one species of Listeria is present in the test sample each may respond differently to selective enrichment conditions (Petran and Swanson, 1993; Curiale and Lewus, 1994; Carvalheira et al, 2010; Cornu et al, 2002; Ganou Besse et al, 2005; Keys et al, 2013; Dailey et al, 2015; Ganou Besse et al, 2016). The importance of this observation is that recovery of only L. innocua or any other non-pathogenic Listeria species does not preclude the presence of L. monocytogenes .…”

Section: Introductionmentioning

confidence: 99%

Comparison of Listeria monocytogenes recoveries from spiked mung bean sprouts by the enrichment methods of three regulatory agencies

2017

Self Cite

View full text Add to dashboard Cite

Three selective enrichment methods, the United States Food and Drug Administration’s (FDA method), the United States Department of Agriculture Food Safety Inspection Service’s (USDA method), and the EN ISO 11290-1 standard method, were assessed for their suitability for recovery of Listeria monocytogenes from spiked mung bean sprouts. Three parameters were evaluated; the enrichment L. monocytogenes population from singly-spiked sprouts, the enrichment L. monocytogenes population from doubly-spiked (L. monocytogenes and Listeria innocua) sprouts, and the population differential resulting from the enrichment of doubly-spiked sprouts. Considerable L. monocytogenes inter-strain variation was observed. The mean enrichment L. monocytogenes populations for singly-spiked sprouts were 6.1 ± 1.2, 4.9 ± 1.2, and 6.9 ± 2.3 log CFU/mL for the FDA, USDA, and EN ISO 11290-1 methods, respectively. The mean L. monocytogenes populations for doubly-spiked sprouts were 4.7 ± 1.1, 5.5 ± 1.3, and 4.6 ± 1.4 log CFU/mL for the FDA, USDA, and ISO 11290–1 enrichment methods, respectively. The corresponding mean population differentials were 2.8 ± 1.1, 3.3 ± 1.3, and 3.6 ± 1.4 Δlog CFU/mL for the same three enrichment methods, respectively. The presence of L. innocua and resident microorganisms on the sprouts negatively impacted final levels of L. monocytogenes with all three enrichment methods.

show abstract

Effect of Listeria seeligeri or Listeria welshimeri on Listeria monocytogenes detection in and recovery from buffered Listeria enrichment broth

Cited by 20 publications

References 15 publications

Contribution of Selective Conditions to Microbial Competition in Four Listeria Selective Enrichment Formulations

Contribution of Selective Conditions to Microbial Competition in Four Listeria Selective Enrichment Formulations

Listeria monocytogenes Strains Underrepresented during Selective Enrichment with an ISO Method Might Dominate during Passage through Simulated Gastric Fluid and In Vitro Infection of Caco-2 Cells

Comparison of Listeria monocytogenes recoveries from spiked mung bean sprouts by the enrichment methods of three regulatory agencies

Contact Info

Product

Resources

About