The systematic study of circulating tumor cell isolation using lithographic microfilters

Circulating tumor cells (CTCs) disseminated into peripheral blood from a primary, or metastatic, tumor can be used for early detection, diagnosis and monitoring of solid malignancies. CTC isolation by size exclusion techniques have long interested researchers as a simple broad based approach, which is methodologically diverse for use in both genomic and protein detection platforms. Though a variety of these microfiltration systems are employed academically and commercially, the limited ability to easily alter microfilter designs has hindered the optimization for CTC capture. To overcome this problem, we studied a unique photo-definable material with a scalable and mass producible photolithographic fabrication method. We use this fabrication method to systematically study and optimize the parameters necessary for CTC isolation using a microfiltration approach, followed by a comparison to a "standard" filtration membrane. We demonstrate that properly designed microfilters can capture MCF-7 cancer cells at rate of 98 ± 2% if they consist of uniform patterned distributions, ≥160 000 pores, and 7 μm pore diameters.

Involvement of CRH and hCG in the induction of aromatase by cortisol in human placental syncytiotrophoblasts

INTRODUCTION

Increased estrogen production in placenta towards the end of gestation plays a pivotal role in the onset of human labor. Estrogen transforms myometrium from a quiescent to a contractile status. Glucocorticoids have been shown to induce estrogen production through the transcription factor specificity protein 1 (Sp1)-mediated induction of aromatase transcription upon elevation of cyclic adenosine mono-phosphate (cAMP) level in human placental syncytiotrophoblasts. However, it is unclear how glucocorticoids activate cAMP pathway thereby inducing aromatase expression in human placental syncytiotrophoblasts.

MATERIAL AND METHODS

We investigated this issue in cultured primary human placental syncytiotrophoblasts prepared from placentas collected at term without labor.

RESULTS

We demonstrated that cortisol (0.01-1 μM) dose-dependently increased corticotropin-releasing hormone (CRH) and human chorionic gonadotropin (hCG) α/β subunit expression and their production in the syncytiotrophoblasts. The induction of intracellular cAMP level, Sp1 expression, Sp1 enrichment at the aromatase promoter as well as aromatase expression by cortisol could be partially attenuated by either hCG antibody (1:100) or CRH receptor antagonist α-helical-CRH (1 μM), and further attenuated by combination of hCG antibody and α-helical-CRH.

CONCLUSIONS

Cortisol increases aromatase expression via induction of CRH and hCG production and subsequent elevation of cAMP level and enrichment of Sp1 at the aromatase promoter in human placental syncytiotrophoblasts. These findings may account for the parallel increases of cortisol and estrogen production prior to the onset of parturition.

Chinese SLE Treatment and Research group (CSTAR) registry: I. Major clinical characteristics of Chinese patients with systemic lupus erythematosus

The Chinese systemic lupus erythematosus (SLE) treatment and research group (CSTAR) provides major clinical characteristics of SLE in China and establishes a platform to provide resources for future basic and clinical studies. CSTAR originated as a multicentre, consecutive, and prospective design. The data were collected online from 104 rheumatology centers, which covered 30 provinces in China. The registered patients were required to meet four or more of the American College of Rheumatology (ACR) criteria for the classification of SLE. All CSTAR centers use the same protocol-directed methods to provide uniform evaluations, which included demographic data, clinical features, laboratory examinations, and disease activity evaluations. The patient samples, including DNA samples and sera, were also collected for further quality controls and additional studies. Preliminary analysis from 2104 baseline evaluations was available for this analysis. Of 1914 female and 190 male patients (F:M=10.1), the mean age at onset was 29.2 y with confirmed diagnosis one year later at the age of 30.3 y. Eighty four (4.2%) of 2002 patients had a family history of rheumatic diseases, including 34 (1.7%) cases with SLE. In addition, one hundred and seven (5.2%) abnormal pregnancies were recorded among 2026 experiences. The characteristics of the CSTAR cohort were compared to similarly sized cohorts from other studies. We found that 56.1% of patients presented with concurrent hematological disorders compared to only 18.2% of European patients. Moreover, 47.4% of patients presented with nephropathy compared to 27.9% of European patients. Conversely, neurological manifestations were only seen in 4.8% of Chinese SLE patients compared to 19.4% of European patients, 12.1% of U.S. patients, 22.8% of Malaysian patients and 26.4% of Latin Americans. Pulmonary arterial hypertension and interstitial lung diseases were complications identified in 3.8% and 4.2% of Chinese lupus patients, respectively. The CSTAR registry has provided epidemiological data and phenotypes of Chinese patients with SLE, and has demonstrated several differences between ethnicities. Clinical data and biologic samples would be valuable resources for future translational studies with national and international collaboration.

Plasmoid formation in current sheet with finite normal magnetic component

Current sheet configurations in natural and laboratory plasmas are often accompanied by a finite normal magnetic component that is known to stabilize the two-dimensional resistive tearing instability in the high Lundquist number regime. Recent magnetohydrodynamic simulations indicate that the nonlinear development of ballooning instability is able to induce the formation of X lines and plasmoids in a generalized Harris sheet with a finite normal magnetic component in the high Lundquist number regime where the linear two-dimensional resistive tearing mode is stable.

Low cytokeratin- and low EpCAM-expressing circulating tumor cells in pancreatic cancer

11046

Background: To date, detecting circulating tumor cells (CTCs) in the peripheral blood of pancreatic patients using standard immuno-capture techniques has met with limited success. As pancreatic cancer is prone to metastasize at distant sites, and therefore should have high numbers of CTCs, it is possible that immuno-capture methods are not suitable for this disease. Using a microfiltration approach, we show that CTCs are present in the peripheral blood in over 75% of pancreatic cancer patients, and that two distinct subtypes can be identified. Methods: Pancreatic patient samples were provided by Medical College of Wisconsin, Milwaukee, WI. CellSieve microfilters, with precision 7 micron diameter pores distributed in uniform arrays were employed. 7.5 mL of whole blood was diluted in pre-fixation solution and filtered through CellSieve microfilters. CTCs collected by this size exclusion technique were fixed, permeabilized, and stained with DAPI, an antibody cocktail against cytokeratin 8, 18 and 19 (FITC), EpCAM (PE), and CD45 (Cy5). CTCs, defined as cytokeratin positive and CD45 negative, were found in two distinct subtypes. One subtype had the “classic” characteristics of a CTC, with high EpCAM and cytokeratin expression, identifiable cytokeratin filamentation, and a cancer-like nuclear structure. The second subtype is indicative of a CTC undergoing epithelial-mesenchymal transition (EMT), with low or no EpCAM, weak cytokeratin expression, and a smooth oval nuclear structure. Results: The “classic” CTCs were found in ~20% (n=40) of patient samples. The EMT-like CTCs were found in ~75% of the same patient cohort. Neither cell was present in any healthy subjects (n=30). EMT-like CTCs consistently lacked EpCAM expression and commonly presented as multi-cell clusters, or microemboli, in ~40% of the cases. Conclusions: We show that two distinct CTC subtypes circulate in the blood of most pancreatic patients. The low expression of cytokeratin and EpCAM of the EMT-like subtype implies that immuno-capture based CTC isolation methods have limited utility for pancreatic cancer. Further, this subtype provides a useful strategy for tracking pancreatic CTCs over the course of treatment.

Novel EDA p.Ile260Ser mutation linked to non-syndromic hypodontia

Hypodontia, a tooth developmental disease, can affect chewing and pronunciation. Mutations in the ectodysplasin-A (EDA) gene can lead to both X-linked hypohidrotic ectodermal dysplasia (XLHED) and non-syndromic hypodontia (NSH). However, the mechanism by which these 2 related but different disorders are caused by the distinct mutations in EDA is unknown. In this study, we identified a novel missense mutation (c.779 T>G) in a Chinese family with NSH via a direct sequencing approach. This mutation results in an Ile260Ser substitution in the tumor necrosis factor (TNF) homology domain. Homology modeling suggests that this alteration may induce a conformational change in the hydrophobic center of the TNF homology domain. Furthermore, by exploring systematic 3D conformation analysis and calculation of residue relative solvent accessibility (RSA) for all the reported mutated amino acid sites on EDA's TNF homology domain, we found that the site mutations at the interior may be linked to XLHED, while those at the surface are more likely to be associated with NSH. These findings may aid in the discovery of unidentified functionally significant mutation sites in the EDA gene and provide a new way to clarify the mechanisms by which the XLHED and NSH phenotypes arise from mutations in the same gene.

Abstract 1448: Identifying and subtyping circulating tumor cells from breast, prostate, and pancreatic cancer patients based on distinct morphology

Background: Isolation of circulating tumor cells (CTCs) from peripheral blood based on size exclusion is rapid and straight-forward using precision microfilters. We describe the use of CellSieveTM microfilters to isolate CTCs from the peripheral blood of breast, prostate, and pancreatic cancer patients. It is accepted that CTCs isolated from patient samples represent a highly heterogeneous population with varying degrees of epithelial mesenchymal differentiation. We hypothesized that the CTCs from three different epithelial malignancies can be identified and grouped into distinct subtypes by morphological characterization.

Methods: Prostate, breast, and pancreatic patient blood samples were provided by Northwestern University, Fox Chase Cancer Center, University of Maryland, and Medical College of Wisconsin and analyzed by Creatv MicroTech. The CellSieveTM microfilters have 8 micron diameter pores in a uniform array, with 160,000 pores in a 9 mm diameter area. 7.5 mL of whole blood was diluted in fixative and drawn through a microfilter. CTCs collected by this size exclusion technique were post-fixed, permeabilized, and stained with DAPI, cytokeratin 8, 18 and 19 (FITC), EpCAM (PE), PSMA (Texas Red), and CD45 (Cy5). CTCs were CD45 negative cells identified by their morphology, nuclear profile, and expression of cytokeratin, PSMA, and EpCAM.

Results: Each patient sample was found to have a number of phenotypic CTC subtypes. Distinct morphological patterns emerged in the three malignancies. CTCs from breast cancer patients demonstrated high expression of cytokeratin signal with web-like cytokeratin filamentation. Prostate cancer CTCs had less defined filamentation, but intense PSMA and cytokeratin signal and mottled cytokeratin morphology. Pancreatic CTCs had extremely fine filamentation, with spindle-like morphology and little or no EpCAM expression. Within each cancer, CTCs could be grouped into distinct subtypes. Additional markers, such as vimentin (PE), are used to further analyze the cells after bleaching the original PE.

Conclusions: In addition to enumeration and identification, the phenotypic analysis of CTCs provides new information that can be used to characterize disease status for personalized treatment of cancer patients. We have shown that CTCs can have multiple distinct phenotypes. These phenotypic morphologies may implicate definable traits which can be exploited while tracking site directed treatment of metastatic cancer patients.

Citation Format: Daniel Adams, R. Katherine Alpaugh, Massimo Cristofanilli, Stuart Martin, Saranya Chumsri, Monica Charpentier, Raymond C. Bergan, Irene May Ogden, Susan Tsai, Peixuan Zhu, Olga V. Makarova, Shuhong Li, Platte T. Amstutz, Cha-Mei Tang. Identifying and subtyping circulating tumor cells from breast, prostate, and pancreatic cancer patients based on distinct morphology. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1448. doi:10.1158/1538-7445.AM2013-1448

A new technology for separation and recovery of materials from waste printed circuit boards by dissolving bromine epoxy resins using ionic liquid

Recovery of valuable materials from waste printed circuit boards (WPCBs) is quite difficult because WPCBs is a heterogeneous mixture of polymer materials, glass fibers, and metals. In this study, WPCBs was treated using ionic liquid (1-ethyl-3-methylimizadolium tetrafluoroborate [EMIM+][BF4-]). Experimental results showed that the separation of the solders went to completion, and electronic components (ECs) were removed in WPCBs when [EMIM+][BF4-] solution containing WPCBs was heated to 240 °C. Meanwhile, metallographic observations verified that the WPCBs had an initial delamination. When the temperature increased to 260 °C, the separation of the WPCBs went to completion, and coppers and glass fibers were obtained. The used [EMIM+][BF4-] was treated by water to generate a solid-liquid suspension, which was separated completely to obtain solid residues by filtration. Thermal analyses combined with infrared ray spectra (IR) observed that the solid residues were bromine epoxy resins. NMR (nuclear magnetic resonance) showed that hydrogen bond played an important role for [EMIM+][BF4-] dissolving bromine epoxy resins. This clean and non-polluting technology offers a new way to recycle valuable materials from WPCBs and prevent environmental pollution from WPCBs effectively.

Treatment of waste printed circuit board by green solvent using ionic liquid

Recycling of waste printed circuit boards (WPCBs) is an important subject not only for the protection of environment but also for the recovery of valuable materials. A feasibility study was conducted to dissolve bromine epoxy resins of WPCBs using ionic liquid (IL) of 1-ethyl-3-methylimizadolium tetrafluoroborate [EMIM(+)][BF(4)(-)] (nonaqueous green solvent) for recovering copper foils and glass fibers. Experimental results indicated that the initial delamination had seen from the cross-section of the WPCBs by mean of metallographic microscope and digital camera when WPCBs were heated in [EMIM(+)][BF(4)(-)] at 240°C for a duration of 30 min. When temperature was increased to 260°C for a duration of 10 min, the bromine epoxy resins of WPCBs were throughout dissolved into [EMIM(+)][BF(4)(-)] and the separations of copper foils and glass fibers from WPCBs were completed. This clean and non-polluting technology offers a new way to recycle valuable materials from WPCBs and prevent the environmental pollution of WPCBs effectively.

Quantitative detection of zeta-chain-associated protein 70 expression in chronic lymphocytic leukemia

Overexpression of zeta-chain-associated protein 70 (ZAP-70) was recently recognized as an independent prognostic marker for the aggressive form of chronic lymphocytic leukemia (CLL). The objective of this study was to demonstrate the feasibility and implementation of quantitative detection of ZAP-70 protein in B cells to clearly distinguish patients with CLL with the aggressive form of the disease. B cells were isolated from patient blood and lysed. Released ZAP-70 protein was detected using an immunomagnetic fluorescence assay. The assay protocol was developed using Jurkat cells and recombinant ZAP-70 (rZAP-70). The limit of detection was determined to be lower than 125 Jurkat cells and 39 pg of rZAP-70 protein. The signal response was linear over a wide dynamic range, from 125 to 40 000 Jurkat cells per test (R(2) = 0.9987) and from 0 to 40 000 pg rZAP-70 protein per test (R(2) = 0.9928). The results from 20 patients with CLL correlated strongly with flow cytometry analysis. Concordance between the two methods for positive and negative results was 100% (7/7) and 92% (12/13), respectively, while the overall concordance between the two methods was 95%. The assay reported here is a simple, reliable and reproducible method for quantitative detection of ZAP-70 in patient leukemic cells, without the need for cell fixation or permeabilization. The ZAP-70 signal was linear over a wide dynamic range, which we believe enables quantitative assessment of small changes in ZAP-70 expression over the course of the disease and in response to therapeutic intervention.

Perianal necrotizing fasciitis treated with a loose-seton technique

AIM

The study evaluated the effect of a loose-seton technique for perianal necrotizing fasciitis.

METHOD

The medical records of seven patients with perianal necrotizing fasciitis treated by the loose-seton technique between December 2005 and June 2010 were reviewed. Age, gender, status of diabetes mellitus, duration of symptoms, the length of hospital stay and number of debridements were investigated.

RESULTS

Five of the patients were men. The mean age was 53 years and the range was 43-79 years. All seven patients had a past history of acute perianal abscess. Six (85.7%) patients had diabetes mellitus. The mean time for removal of the seton was 24 (14-32) days and the mean hospitalization time was 31 (23-45) days. All patients had primary wound healing. There was no mortality. At a median follow-up 18 (6-60) months one patient required inpatient treatment with cutting-seton for complex anal fistula after 11 months. All patients had normal faecal continence and none of them required a reconstructive procedure during the follow-up.

CONCLUSION

The loose-seton technique is an effective treatment for perianal necrotizing fasciitis. The advantages include inhibiting the spread of inflammation, reducing the frequency of debridements, decreasing the area of the wound and limiting extensive scar formation.

Quantitative detection of ZAP-70 expression in chronic lymphocytic leukemia

6581

Background: Intracellular ZAP-70 protein was recently recognized as prognostic marker in chronic lymphocytic leukemia (CLL). The specific objective of this study was to develop a simple and sensitive assay, for the quantitative detection of ZAP-70 protein in leukemic cells. Methods: Components of the assay system include sample preparation, immunomagnetic fluorescence assay, Signalyte-II spectrofluorometer. The leukemic cells were isolated from CLL patient blood samples and lysed to release the intracellular ZAP-70 protein. ZAP-70 protein was captured by magnetic beads coated with anti-ZAP70 capture antibody, and recognized by a fluorescent detector antibody, forming an immuno-sandwich complex. This complex was dissociated for measurement of the fluorescence signal, which was proportional to ZAP-70 concentration, using the spectrofluorometer. Results: The assay conditions were extensively optimized by selecting an optimal pair of capture/detector antibodies, conjugation of fluorescence dye, cell lysis condition and excitation/emission wavelengths. The protocol was further validated with two positive controls, Jurkat cell lysate and recombinant ZAP70 protein (rZAP70). The limit of detection was determined to be lower than 125 Jurkat cells and 39 pg of rZAP70 protein. The signal response was linear over a wide range of concentration, from 625 to 40,000 Jurkat cells per test (R2=0.9987) and from 0 to 40,000 pg rZAP70 protein per test (R2=0.9928). The results from 20 CLL patients correlated strongly with flow cytometry analysis. The concordance between the two methods for positive and negative results was 100% (7/7) and 92% (12/13), respectively, while the overall concordance between the two methods was 95%. Conclusions: The assay is a simple, reliable, and reproducible method for quantitative detection of ZAP-70 in patient leukemic cells, without the need for cell fixation or permeabilization. The entire assay could be completed in 5.5 hours. The ZAP-70 signal was linear over a wide dynamic range, which we believe enables quantitative assessment of small changes in ZAP-70 expression over the course of the disease and in response to therapeutic intervention.

Morphologic variation of circulating tumor cells in metastatic breast cancer patients visualized by immunofluorescent stain pattern

e21079

Background: Isolation of circulating tumor cells (CTCs) using microfiltration is a growing utility in the field of CTC detection. The microfiltration approach can be used on peripheral blood as a non-invasive liquid biopsy for cancer detection and subtyping. We present a utilization of the CellSieve microfilter to subtype CTCs based on immunofluorescent staining pattern of cytokeratin filamentation and EpCAM surface marker expression. Our initial study on CTCs in patient blood indicates that disseminated CTC populations have high rates of phenotypic heterogeneity. Further detailed molecular analysis and patient tracking of these phenotypes may lead to individualized patient assessment based on CTC characterization. Methods: 7.5 mL of whole blood collected from metastatic breast cancer patients were diluted in a fixative solution. An 8 µm CellSieve precision microfilter was placed into a filter holder and the samples were passed through the filter (~ 90 seconds). The cells captured on the filter were fixed, permeabilized, and stained with DAPI, cytokeratin (FITC), EpCAM (PE), and CD45 (Cy5). Cells without CD45 staining were classified by their morphology, nuclear integrity and the presence of cytokeratin and EpCAM staining. Results: In our initial assessment, patient samples were found to have a number of phenotypic CTC subtypes. Cytokeratin filamentation was clearly seen on a number of CTCs while other cells presented with spotted patterns, implying CTCs in various stages of apoptosis. Later stage apoptosis, with segmented nuclear signature, was also seen in various samples. Cell clusters and cells in division were DAPI positive, while EpCAM positivity was negligible, 0-3 cells/sample, correlating with established data from the CellSearch CTC assay. Conclusions: In addition to enumeration, phenotypic variation of CTCs may be a valuable tool for the personalized care of cancer patients. We have shown that individual breast cancer patients have overlapping phenotypes of CTCs circulating in their peripheral blood. We have begun categorizing patients based on these phenotypes and plan to correlate them with overall prognosis.

Synovial fluid dynamics with small disc perforation in temporomandibular joint

The articular disc plays an important role as a stress absorber in joint movement, resulting in stress reduction and redistribution in the temporomandibular joint (TMJ). The flow of synovial fluid in the TMJ may follow a regular pattern during movement of the jaw. We hypothesised that the regular pattern is disrupted when the TMJ disc is perforated. By computed tomography arthrography, we studied the upper TMJ compartment in patients with small disc perforation during jaw opening-closing at positions from 0 to 3 cm. Finite element fluid dynamic modelling was accomplished to analyse the pattern of fluid flow and pressure distribution during the movements. The results showed that the fluid flow in the upper compartment generally formed an anticlockwise circulation but with local vortexes with the jaw opening up to 2 cm. However, when the jaw opening-closing reached 3 cm, an abnormal flow field and the fluid pressure change associated with the perforation may increase the risk of perforation expansion or rupture and is unfavourable for self-repair of the perforated disc.

Measurement of the neutron radius of 208Pb through parity violation in electron scattering

We report the first measurement of the parity-violating asymmetry A(PV) in the elastic scattering of polarized electrons from 208Pb. A(PV) is sensitive to the radius of the neutron distribution (R(n)). The result A(PV)=0.656±0.060(stat)±0.014(syst) ppm corresponds to a difference between the radii of the neutron and proton distributions R(n)-R(p)=0.33(-0.18)(+0.16) fm and provides the first electroweak observation of the neutron skin which is expected in a heavy, neutron-rich nucleus.

Randomized clinical trial comparing infrahepatic inferior vena cava clamping with low central venous pressure in complex liver resections involving the Pringle manoeuvre

BACKGROUND

Control of bleeding remains key to successful hepatic resection. The present randomized clinical trial compared infrahepatic inferior vena cava (IVC) clamping with low central venous pressure (CVP) during complex hepatectomy using portal triad clamping (PTC).

METHODS

Consecutive patients undergoing complex hepatectomy were allocated randomly to PTC combined with infrahepatic IVC clamping or to PTC with low CVP. Primary outcome was blood loss during parenchymal transection. Secondary outcomes were intraoperative surgical and haemodynamic parameters, postoperative recovery of liver and renal function, postoperative morbidity and mortality, and duration of hospital stay.

RESULTS

Between January 2008 and September 2010, 192 patients were randomized. Compared with low CVP, infrahepatic IVC clamping significantly decreased blood loss during parenchymal transection (mean(s.e.m.) 243(158) versus 372(197) ml; P < 0·001), was associated with faster recovery of liver function, and caused less impairment in renal function and fewer haemodynamic changes. The degree of cirrhosis correlated positively with CVP (R(2) = 0·963, P = 0·019) and with infrahepatic IVC pressure (R(2) = 0·950, P = 0·025). For patients with moderate or severe cirrhosis, infrahepatic IVC clamping was more efficacious in controlling blood loss during parenchymal transection (mean(s.e.m.) 2·9(1·8) versus 6·1(2·4) ml/cm(2); P < 0·001).

CONCLUSION

PTC combined with infrahepatic IVC clamping is more efficacious in controlling bleeding during complex hepatectomy than PTC with low CVP, especially in patients with moderate to severe cirrhosis.

REGISTRATION NUMBER

NCT01355887 (http://www.clinicaltrials.gov).

Detection of E. coli O157:H7 by immunomagnetic separation coupled with fluorescence immunoassay

Conventional culture-based methods for detection of E. coli O157:H7 in foods and water sources are time-consuming, and results can be ambiguous, requiring further confirmation by biochemical testing and PCR. A rapid immunoassay prior to cultivation to identify presumptive positive sample would save considerable time and resources. Immunomagnetic separation (IMS) techniques are routinely used for isolation of E. coli O157:H7 from enriched food and water samples, typically in conjunction with cultural detection followed by biochemical and serological confirmation. In this study, we developed a new method that combines IMS with fluorescence immunoassay, termed immunomagnetic fluorescence assay (IMFA), for the detection of E. coli O157:H7. E. coli O157:H7 cells were first captured by anti-O157 antibody-coated magnetic beads and then recognized by a fluorescent detector antibody, forming an immunosandwich complex. This complex was subsequently dissociated for measurement of fluorescence intensity with Signalyte™-II spectrofluorometer. Experiments were conducted to evaluate both linearity and sensitivity of the assay. Capture efficiencies were greater than 98%, as determined by cultural plating and quantitative real-time PCR, when cell concentrations were <10(5) cells/mL. Capture efficiency decreased at higher cell concentrations, due to the limitation of bead binding capacity. At lower cell concentrations (10-10(4) cells/mL), the fluorescence intensity of dissociated Cy5 solution was highly correlated with E. coli 157:H7 cell concentrations. The detection limit was 10 CFU per mL of water. The assay can be completed in less than 3 h since enrichment is not required, as compared to existing techniques that typically require a 24 h incubation for pre-enrichment, followed by confirmatory tests.