Safety of the Surrogate Microorganism
            <i>Enterococcus faecium</i>
            NRRL B-2354 for Use in Thermal Process Validation

Kopit, Lauren M.; Kim, Eun Bae; Siezen, Roland J.; Harris, Linda J.; Marco, Maria L.

doi:10.1128/aem.03859-13

Cited by 97 publications

(41 citation statements)

References 81 publications

(97 reference statements)

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“…Beyond these preliminary tests, more extensive evaluations need to be performed for surrogate evaluations (35,42). For example, wash water obtained from a lettuce processing plant could be used to provide additional realistic conditions for evaluation, with results verified in a scaled-up washing system (15,31), and a safety assessment should be made (27). Nevertheless, the compar ison of traits as performed in this study may serve as a starting point for selecting surrogates that could be used in validating antimicrobial washing processes.…”

Section: Resultsmentioning

confidence: 99%

Behavior Of Shiga Toxigenic Escherichia coli Relevant to Lettuce Washing Processes and Consideration Of Factors for Evaluating Washing Process Surrogates

Deng

Wang

Yen

et al. 2014

Journal of Food Protection

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Postharvest processes for fresh produce commonly include washing in water containing antimicrobial chemicals, such as chlorine; however, if the antimicrobials are not present in sufficient levels, washing can promote the spread of contamination that might be present. To understand cross-contamination risk during washing, we tested a collection of Shiga toxigenic Escherichia coli (STEC), including O157:H7 and other non-O157 strains, for certain traits during washing of fresh-cut lettuce, i.e., sensitivity to sublethal chlorine levels and ability to cross-contaminate (detach from and attach to) lettuce in the presence of sublethal chlorine levels. Nonpathogenic E. coli Nissle 1917 (EcN) and Pediococcus pentosaceus lactic acid bacterial species (LAB) were included as potential washing process validation surrogates. As measured by extension of the lag phase of growth in media containing 0.15 ppm of chlorine, chlorine sensitivity varied among the STECs. Cross-contamination was assessed by evaluating transfer of bacteria from inoculated to uninoculated leaves during washing. Without chlorine, similar transfer to wash water and uninoculated leaves was shown. In 1 ppm of chlorine, cross-contamination was not detected with most strains, except for the substantial transfer by a STEC O111 strain and EcN in some replicates. Strain O111 and EcN showed less inactivation in 0.25 ppm of chlorine water compared with O157 (P < 0.05). LAB showed similar transfer and similar chlorine inactivation to O157. Considering together the sublethal chlorine sensitivity and detachment/attachment traits, neither EcN nor LAB displayed optimal characteristics as washing process surrogates for the STEC strains, although further evaluation is needed. This work demonstrated a range of behaviors of STEC strains during lettuce washing and may be helpful in hazard characterization, identifying factors to consider for evaluating washing process efficacy, and identifying phenotypic traits to select surrogates to validate washing processes.

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Section: Resultsmentioning

confidence: 99%

Behavior Of Shiga Toxigenic Escherichia coli Relevant to Lettuce Washing Processes and Consideration Of Factors for Evaluating Washing Process Surrogates

Deng

Wang

Yen

et al. 2014

Journal of Food Protection

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“…We selected these 37 strains to represent the E. faecium phylogeny. Together with three additional strains (DO [TX16], NRRL B-2354 [33,35], and E1293 [GenBank accession no. NZ_AHWU00000000]), the set of 40 strains used for building the cgMLST scheme included clade A1 (9 isolates), clade A2 (18 isolates), clade B (12 isolates), and one strain that appears to be a hybrid of clades A and B.…”

Section: Resultsmentioning

confidence: 99%

“…An E. faecium cgMLST scheme was set up using SeqSphereϩ version 2.3 (Ridom GmbH, Münster, Germany [http://www.ridom.de /seqsphere/]) using 40 E. faecium whole-genome sequences publicly available in GenBank (ftp://ftp.ncbi.nih.gov/genomes/) as of August 2014 (see Table S1 in the supplemental material) (17,(32)(33)(34)(35). This set included three completed genome sequences, of which E. faecium strain Aus0004 (36) (GenBank accession no.…”

Section: Methodsmentioning

confidence: 99%

Core Genome Multilocus Sequence Typing Scheme for High-Resolution Typing of Enterococcus faecium

et al. 2015

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Enterococcus faecium, a common inhabitant of the human gut, has emerged in the last 2 decades as an important multidrugresistant nosocomial pathogen. Since the start of the 21st century, multilocus sequence typing (MLST) has been used to study the molecular epidemiology of E. faecium. However, due to the use of a small number of genes, the resolution of MLST is limited. Whole-genome sequencing (WGS) now allows for high-resolution tracing of outbreaks, but current WGS-based approaches lack standardization, rendering them less suitable for interlaboratory prospective surveillance. To overcome this limitation, we developed a core genome MLST (cgMLST) scheme for E. faecium. cgMLST transfers genome-wide single nucleotide polymorphism (SNP) diversity into a standardized and portable allele numbering system that is far less computationally intensive than SNPbased analysis of WGS data. The E. faecium cgMLST scheme was built using 40 genome sequences that represented the diversity of the species. The scheme consists of 1,423 cgMLST target genes. To test the performance of the scheme, we performed WGS analysis of 103 outbreak isolates from five different hospitals in the Netherlands, Denmark, and Germany. The cgMLST scheme performed well in distinguishing between epidemiologically related and unrelated isolates, even between those that had the same sequence type (ST), which denotes the higher discriminatory power of this cgMLST scheme over that of conventional MLST. We also show that in terms of resolution, the performance of the E. faecium cgMLST scheme is equivalent to that of an SNP-based approach. In conclusion, the cgMLST scheme developed in this study facilitates rapid, standardized, and high-resolution tracing of E. faecium outbreaks. In the last 2 decades, Enterococcus faecium has emerged as an important multidrug-resistant nosocomial pathogen causing an increasing number of bloodstream infections, mainly in debilitated patients (1-3). Currently, Ͼ90% of the E. faecium strains causing infections have acquired ampicillin resistance, and an increasing number of health care-associated infections and outbreaks are caused by E. faecium strains that are resistant to both ampicillin and vancomycin (4). The global emergence of ampicillin-and vancomycin-resistant E. faecium (VRE) as nosocomial pathogens started in the United States in the late 1980s/early 1990s and occurred in other parts in the world 1 or 2 decades later. In Europe, more particularly in France, Germany, Denmark, and the Netherlands, VRE first spread among livestock due to the use of the vancomycin analog avoparcin as a growth promoter, and it only relatively recently became an important nosocomial pathogen (5, 6). Different molecular typing methods have been used to study the epidemiology of E. faecium, ranging from fingerprint-based methods, like pulsed-field gel electrophoresis (PFGE) (7), ribotyping (8), and amplified fragment length polymorphism (9), to PCR-based methods, like multilocus variable-number tandemrepeat analysis (10) and the sequenced-bas...

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“…Concerns about the use of enterococci as a double-edged sword have led to an increasing number of studies intended to evaluate the safety of certain enterococci strains (Kopit et al, 2014; Zhang et al, 2016; Peng et al, 2017). …”

Section: Discussionmentioning

confidence: 99%

“…Biofilm formation was evaluated using a previously described method (Kopit et al, 2014) with some modifications. Briefly, bacteria was grown overnight in M17 broth at 37°C.…”

Section: Methodsmentioning

confidence: 99%

Evaluating the Safety of Potential Probiotic Enterococcus durans KLDS6.0930 Using Whole Genome Sequencing and Oral Toxicity Study

Zhan

Evivie

et al. 2018

Front. Microbiol.

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Enterococcus durans KLDS6.0930 has previously been shown to have probiotic potential. However, being a potential clinical pathogen, it becomes necessary to evaluate its safety status for novel potential probiotic use. The purpose of this study is to systematically evaluate the safety of E. durans KLDS6.0930 based on its genomics, phenotypic characteristics and oral toxicity. The complete genome of E. durans KLDS6.0930 was sequenced and analyzed for safety-related genes. Antibiotic susceptibility and the production of harmful metabolites were tested. A 28-day repeated oral dose toxicity test was implemented in rats. In vitro, E. durans KLDS6.0930 was resistant to five antibiotics, with intrinsic resistances to four antibiotics and no identified genes for the last. E. durans KLDS6.0930 was not hemolytic and virulence factors were non-functional in its genome. E. durans KLDS6.0930 produced a small amount of tyramine and phenethylamine; genes encoding tyramine decarboxylase were identified. In addition, genotype and phenotype analyses showed that the strain did not have the ability to generate D-lactic acid, indole, or nitroreductase. In vivo, E. durans KLDS6.0930 did not induce adverse effects on the organs, hematological and serum biochemical parameters, or cecal bacterial populations in the oral toxicity test. These results indicate that E. durans KLDS6.0930 can be safely used as a potential probiotic for human consumption and animal feed.

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Safety of the Surrogate Microorganism Enterococcus faecium NRRL B-2354 for Use in Thermal Process Validation

Cited by 97 publications

References 81 publications

Behavior Of Shiga Toxigenic Escherichia coli Relevant to Lettuce Washing Processes and Consideration Of Factors for Evaluating Washing Process Surrogates

Behavior Of Shiga Toxigenic Escherichia coli Relevant to Lettuce Washing Processes and Consideration Of Factors for Evaluating Washing Process Surrogates

Core Genome Multilocus Sequence Typing Scheme for High-Resolution Typing of Enterococcus faecium

Evaluating the Safety of Potential Probiotic Enterococcus durans KLDS6.0930 Using Whole Genome Sequencing and Oral Toxicity Study

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