Detection and enumeration of E. coli O157:H7 in water samples by culture and molecular methods

Ngwa, G.A.; Schop, R.; Weir, Susan C.; León-Velarde, Carlos G.; Odumeru, Joseph A.

doi:10.1016/j.mimet.2012.11.018

Cited by 50 publications

(42 citation statements)

References 33 publications

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“…In accordance with Ngwa et al (2013), our results showed that CHROMagar ™ O157 exhibited a higher r e c o v e r y p e r c e n t a g e o f v i a b l e c e l l s t h a n c h r o m I D ™ O 1 5 7 : H 7 a g a r . H o w e v e r , CHROMagar ™ O157 could never exceed the 80 % of recovery, and this percentage was decreasing significantly over time that the cells remain in water (Fig.…”

Section: Discussionsupporting

confidence: 89%

“…Consequently, there is no recognized standard for the detection of E. coli O157:H7 in water samples. Ngwa et al (2013) reported that CT-SMAC, commonly recommended for the isolation of E. coli O157:H7 from foodstuffs, had a very low recovery of E. coli O157:H7 from water samples, principally when the cells have stayed in water for several days. The same authors pointed to the chromogenic medium CHROMagar ™ O157 as one that exhibited the better recovery capacity from inoculated tap water over 29 days.…”

Section: Discussionmentioning

confidence: 99%

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Strategies for recovering of planktonic and sessile cells of Escherichia coli O157:H7 from freshwater environment

Marucci

Cubitto

2016

Environ Monit Assess

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The experiments were performed with Escherichia coli O157:H7 EDL 933 in freshwater microcosms at 12 °C. At 35, 45, and 70 days, samples were taken and filtered through 0.45 μm membrane filters. The following alternatives were tested to evaluate the recovery percentage of injured cells: (1) selective media CHROMagar(™)O157 and chromID(™)O157:H7 agar, at 37 °C for 24 h; (2) tryptic soy agar supplemented with yeast extract (TSAE), incubated at 25 °C for 2 or 4 h, then transferred to CHROMagar(™)O157 or chromID(™)O157:H7 agar at 37 °C (TSAE2h-CHROM, TSAE4h-CHROM and TSAE2h-ID, TSAE4h-ID); (3) thin agar layer (TAL) method, TSAE was overlaid on CHROMagar(™)O157 or chromID(™)O157:H7 agar (TALCHROM and TALID, respectively) and incubated at 37 °C for 24 h; and (4) TALCHROM at 25 °C for 4 h, then continued up to complete 24 h at 37 °C (TALCHROM4h). Furthermore, the recovery of E. coli O157:H7 cells adhering to glass coverslips were evaluated to mimic biofilm conditions. The recovery percentages obtained from each alternative were calculated relative to TSAE counts. After 70 days, TSAE4h-CHROM and TALCHROM4h showed the highest recovery percentage (>90 %) from water microcosms. Despite the improved recovery of cell adhering to glass surfaces, the percentages obtained with TSAE4h-CHROM were low. Further studies for the recovery of biofilm-forming E. coli O157:H7 are required. Pre-incubation on TSAE at 25 °C for 4 h, combined with CHROMagar(™)O157, or by thin agar layer method (TALCHROM) enhanced significantly the recovery of viable cells of E. coli O157:H7 after prolonged stay in water microcosms.

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Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Strategies for recovering of planktonic and sessile cells of Escherichia coli O157:H7 from freshwater environment

Marucci

Cubitto

2016

Environ Monit Assess

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“…These often labor intensive, consisting of sampling, separation, amplification and detection stages, taking days or weeks 4,9,10,14 to perform. With the recent advances in droplet microfluidics 18,34,[46][47][48][49] , multi-functional nano-composites [18][19][20][21][22] and software design 35 it is now possible digitize each of these stages and very accurately quantitate the entire process in a fraction of the time.…”

Section: Discussionmentioning

confidence: 99%

Recent trends in the detection of pathogenic Escherichia coli O157 : H7

Hulme

2015

BioChip J

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The rapid and accurate detection of pathogenic Escherichia coli (E. coli) poses a significant health problem in both developed and developing countries around the world. Conventional microbial detection methods can take more than 48 hours to identify a pathogenic organism. Recently new types of nucleic acid chip based methods, microfluidic devices, signal amplification methods, immunoassays and biosensors have been developed capable of detecting very low concentrations of pathogenic E. coli in a few hours. This review examines the current limitations and recent advances in methodologies employed in the rapid detection of pathogenic E. coli O157 : H7.

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“…For the isolation of the strains present in the pre‐enrichment broth, the most traditional media used are methylene blue eosin (Levine) and MacConkey agars with sorbitol supplemented with tellurium and cefixime (TC‐SMAC). Other media have been developed with the inclusion of chromogenic substrates, such as Rainbow O157 agar, Biosynth culture media O157, Fluorocult E. coli O157:H7, HICrome EC O157, O157:H7 ID agar, and CHROMagar O157 (Manafi and Kremsmaier ; Park and others ; Tzschoppe and others ; Ngwa and others ). For the isolation of STEC O26, the use of Rhamnose‐MacConkey agar (RMAC) is preferred, due to the inability of this strain to ferment Rhamnose (Hiramatsu and others ).…”

Section: Bacteriological Methods For E Coli Stec Screeningmentioning

confidence: 99%

Shiga‐toxin Producing Escherichia coli: Pathogenicity, Supershedding, Diagnostic Methods, Occurrence, and Foodborne Outbreaks

Castro

Carvalho

Conté-Júnior

et al. 2017

Comp Rev Food Sci Food Safe

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Historically, Escherichia coli is among the most studied organisms and serves as the basis for understanding many fundamental biochemical and genetic concepts. In addition, it displays 9 pathogenesis groups, with the Shiga toxin-producing (STEC) group being the main representative regarding foodborne pathogenesis. Its typical characteristic is the presence of 2 distinct toxins and variants: stx1 (stx1a, stx1c, and stx1d), and stx2 (stx2a, stx2b, stx2c, stx2d, stx2e, stx2f, and stx2g). The main challenge regarding the study of E. coli is the standardization of a high sensitivity method including all pathotypes, that allows for enrichment of STEC cells and a decrease of background microbiota. The ability of some E. coli cells belonging to other pathogenic groups, such as O104:H4, to acquire genes unique to the STEC group, increases the pathogenic power and the risk of new outbreaks related to these bacteria. In addition, animals with a high concentration of pathogenic E. coli cells present in feces (above 10 4 CFU/g), designated as supershedding animals, may be the primary transmission factor among ruminants. Therefore, the purpose of this review is to address pathogenicity factors and the importance of supershedding animals in the transmission of this pathogen, discussing the main methods currently applied, to focus on the occurrence of STEC in beef.

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Detection and enumeration of E. coli O157:H7 in water samples by culture and molecular methods

Cited by 50 publications

References 33 publications

Strategies for recovering of planktonic and sessile cells of Escherichia coli O157:H7 from freshwater environment

Strategies for recovering of planktonic and sessile cells of Escherichia coli O157:H7 from freshwater environment

Recent trends in the detection of pathogenic Escherichia coli O157 : H7

Shiga‐toxin Producing Escherichia coli: Pathogenicity, Supershedding, Diagnostic Methods, Occurrence, and Foodborne Outbreaks

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