scholarly journals Validation of selective agars for detection and quantification of Escherichia coli resistant to critically important antimicrobials

2021 ◽  
Author(s):  
Zheng Z Lee ◽  
Rebecca Abraham ◽  
Mark O'Dea ◽  
Ali Harb ◽  
Kelly Hunt ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Linear Models ◽  
Macconkey Agar ◽  
Generalised Linear Models ◽  
E Coli ◽  
Designed Experiments ◽  
Faecal Samples ◽  
Pure Cultures ◽  
Design Factors ◽  
Detection And Quantification

Success in the global fight against antimicrobial resistance (AMR) is likely to improve if surveillance can be performed more rapidly, affordably and on a larger scale. An approach based on robotics and agars incorporated with antimicrobials has enormous potential to achieve this. However, there is a need to identify the combinations of selective agars and key antimicrobials yielding the most accurate counts of susceptible and resistant organisms. A series of designed experiments involving 1,202 plates identified the best candidate-combinations from six commercially available agars and five antimicrobials using 18 Escherichia coli strains as either pure cultures or inoculums within faeces. The effect of various design factors on colony counts were analysed in generalised linear models. Without antimicrobials, Brilliance™ E. coli (Brilliance) and CHROMagar™ ECC (CHROMagar) agars yielded 28.9% and 23.5% more colonies than MacConkey agar. The order of superiority of agars remained unchanged when faecal samples with and without spiking of resistant E. coli were inoculated onto agars with or without specific antimicrobials. When incorporating antimicrobials at varying concentrations, it was revealed that ampicillin, tetracycline and ciprofloxacin are suitable for incorporation into Brilliance and CHROMagar agars at all defined concentrations. Gentamicin was only suitable for incorporation at 8 and 16 µg/mL while ceftiofur was only suitable at 1 µg/mL. CHROMagar™ ESBL agar supported growth of a wider diversity of extended-spectrum cephalosporin-resistant E. coli. The findings demonstrate the potential for combining robotics with agars to deliver AMR surveillance on a vast scale with greater sensitivity of detection and strategic relevance.

Low Specificity of the HEC O157™ ELISA in Screening Ground Beef for Escherichia coli O157:H7

1992 ◽  
Vol 55 (7) ◽  
pp. 545-547 ◽  
Author(s):  
LOREEN P. SERNOWSKI ◽  
STEVEN C. INGHAM
Keyword(s):  
Escherichia Coli ◽  
Ground Beef ◽  
Escherichia Coli O157 ◽  
Elisa Method ◽  
Macconkey Agar ◽  
Hafnia Alvei ◽  
Confirmatory Testing ◽  
E Coli ◽  
Elisa Kit ◽  
Pure Cultures

During January–August, 1991, 74 retail ground beef samples were tested for the presence of Escherichia coli O157:H7 using the commercial HEC O157™ ELISA kit. A total of 17 samples (23%) were presumptively positive for E. coli O157:H7. Twenty-nine isolates were taken from colonies corresponding to positive spots on the immunoreactive discs and 13 from colonies on sorbitol MacConkey agar No. 3 plates. Of these isolates, 30 were positive when retested as pure cultures with the ELISA (enzyme-linked immunoabsorbent assay). Only 15 of these 30 isolates were E. coli, 6 were identified as Hafnia alvei, and 9 were not identifiable. None of the E. coli isolates were serotype O157:H7. These results confirm that: a) the HEC O157™ ELISA method for detecting E. coli O157:H7 has low specificity, and b) use of the HEC O157™ ELISA necessitates thorough confirmatory testing.

An Improved Membrane Filtration Method for Enumeration of Faecal Coliforms and E. Coli by a Fluorogenic β-Glucuronidase Assay

1993 ◽  
Vol 27 (3-4) ◽  
pp. 267-270 ◽  
Author(s):  
M. T. Augoustinos ◽  
N. A. Grabow ◽  
B. Genthe ◽  
R. Kfir
Keyword(s):  
Escherichia Coli ◽  
Water Samples ◽  
Membrane Filtration ◽  
Faecal Coliforms ◽  
Environmental Waters ◽  
Filtration Method ◽  
E Coli ◽  
Wide Range ◽  
Pure Cultures ◽  
Glucuronidase Assay

A fluorogenic β-glucuronidase assay comprising membrane filtration followed by selective enumeration on m-FC agar at 44.5°C and further confirmation using tlie 4-metliylumbelliferyl-β-D-glucuronide (MUG) containing medium was evaluated for the detection of Escherichia coli in water. A total of 200 typical blue and non-typical blue colonies were isolated from sea and fresh water samples using initial selective enumeration on m-FC agar. Pure cultures of the selected colonies were further tested using the MUG assay and identified using the API 20E method. Of the colonies tested which were shown to be positive using the MUG assay 99.4% were Escherichia coli. The results of this study indicate the combination of the m-FC method followed by the MUG assay to be highly efficient for the selection and confirmation of E. coli from a wide range of environmental waters.

In Vitro Inhibition of the Growth of Salmonella typhimurium and Escherichia coli 0157:H7 by Bacteria Isolated from the Cecal Contents of Adult Chickens

1991 ◽  
Vol 54 (7) ◽  
pp. 496-501 ◽  
Author(s):  
ARTHUR HINTON ◽  
GEORGE E. SPATES ◽  
DONALD E. CORRIER ◽  
MICHAEL E. HUME ◽  
JOHN R. DELOACH ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Salmonella Typhimurium ◽  
Mixed Cultures ◽  
Enterococcus Durans ◽  
E Coli ◽  
Pure Cultures ◽  
In Vitro Inhibition ◽  
Lactic Acids

A Veillonella species and Enterococcus durans were isolated from the cecal contents of adult broilers. Mixed cultures of Veillonella and E. durans inhibited the growth of Salmonella typhimurium and Escherichia coli 0157:H7 on media containing 2.5% lactose (w/v). The growth of S. typhimurium or E. coli 0157:H7 was not inhibited by mixed cultures containing Veillonella and E. durans on media containing only 0.25% lactose or by pure cultures of Veillonella or E. durans on media containing either 0.25% or 2.5% lactose. The mixed cultures of Veillonella and E. durans produced significantly (P<0.05) more acetic, propionic, and lactic acids in media containing 2.5% lactose than in media containing 0.25% lactose. The inhibition of the enteropathogens was related to the production of lactic acid from lactose by the E. durans and the production of acetic and propionic acids from lactic acid by the Veillonella.

scholarly journals A novel report of colistin-resistant Escherichia coli carrying mcr-1 gene from animal and human feacal samples in Nigeria

2018 ◽  
Vol 1 (1) ◽  
pp. 7-10 ◽  
Author(s):  
Olugbenga A. Olowe ◽  
Rita A. Olowe ◽  
Adeolu S. Oluremi ◽  
Olusolabomi J. Adefioye
Keyword(s):  
Escherichia Coli ◽  
Animal Husbandry ◽  
Multiple Drug ◽  
Colistin Resistance ◽  
Pcr Assay ◽  
Southwestern Nigeria ◽  
E Coli ◽  
Multiple Drug Resistant ◽  
Microbiological Methods ◽  
Faecal Samples

Background: The mobilized colistin resistance (m cr)-1 gene confers transferable colistin resistance. Reports of mcr-1-positive Escherichia coli (MCRPE) have attracted substantial attention. However, in Nigeria, there is no report of mcr-1 gene resistance. Since colistin is a last resort for multiple drug-resistant isolates, this study therefore report the prevalence of mcr-1 gene among E. coli isolated from human and animal sources. Methods: Out of a total of 280 samples collected from animal and hum an faecal samples from selected farms in Oyo and Osun States, Southwestern Nigeria between July 2015 and June 2016, 60 E. coli were identified using standard microbiological methods. The mcr-1 gene was detected in the isolates by conventional PCR assay. Results: The m cr-1 gene was low and not statistically significant (p≥0.05). It was detected in 5 (8.3%) of 60 E. coli isolates (4= animals; 1= human) Conclusion: This study is the first report of mcr -1 gene from E. coli from human and animal sources in Nigeria. This calls for urgent caution in the use of colistin in animal husbandry.

Comparison of a New Enrichment Procedure for Shiga Toxin–Producing Escherichia coli with Five Standard Methods

2005 ◽  
Vol 68 (8) ◽  
pp. 1593-1599 ◽  
Author(s):  
MICHAEL A. GRANT
Keyword(s):  
Escherichia Coli ◽  
Real Time ◽  
Shiga Toxin ◽  
Real Time Pcr ◽  
Target Cells ◽  
Macconkey Agar ◽  
Standard Methods ◽  
E Coli ◽  
Canadian Health ◽  
Health Products

A new procedure for enrichment of Escherichia coli O157:H7 and other Shiga toxin–producing E. coli was compared to five standard methods: the British Public Health Laboratory Service, International Standard Method, U.S. Department of Agriculture, Canadian Health Products and Food Branch, and U.S. Food and Drug Administration. The new procedure was comparable to the standard methods in its ability to detect target cells inoculated into foods at approximately 1 CFU g−1. Comparisons were also made of the ability of the six enrichment procedures to detect E. coli O157:H7 against a large background of competitor microorganisms. In these experiments the new procedure yielded more target cells than the other five enrichments by two to three orders of magnitude as determined by enumeration on sorbitol MacConkey agar with tellurite and cefixime and Rainbow agar with tellurite and novobiocin and by verification of presumptive colonies by real-time PCR. For example, the population of enterohemorrhagic E. coli strain 6341 recovered on sorbitol MacConkey agar with tellurite and cefixime after enrichment with the experimental method was 2.42 × 108 CFU ml−1 and 1.80 × 106 CFU ml−1 after enrichment with the Canadian Health Products and Food Branch method, the second most effective in this experiment. In addition, broth cultures resulting from each of the six enrichment procedures were used to prepare templates for real-time PCR detection of stx1/stx2. Resulting threshold cycle (Ct) values after the experimental enrichment were similar to positive control values, whereas the five standard methods produced delayed Ct values or were not detected.

scholarly journals Sampling considerations for herd-level measurement of faecal Escherichia coli antimicrobial resistance in finisher pigs

1999 ◽  
Vol 122 (3) ◽  
pp. 485-496 ◽  
Author(s):  
R. H. DUNLOP ◽  
S. A. McEWEN ◽  
A. H. MEEK ◽  
R. M. FRIENDSHIP ◽  
W. D. BLACK ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Resistance ◽  
Membrane Filter ◽  
Filter Method ◽  
Animal Testing ◽  
E Coli ◽  
Level Measurement ◽  
Faecal Samples ◽  
Membrane Filter Method ◽  
Estimate Prevalence

The objective of this study was to determine the most efficient means of sampling faeces of finisher pigs for accurate and precise farm-level estimates of antimicrobial resistance among faecal Escherichia coli. Resistance to tetracycline and gentamicin of 8250 isolates of E. coli from 55 finisher pigs on one farm was measured with a hydrophobic grid membrane filter method. The between-pig, within-pen component of variance in resistance was large (97·5%), while between-pen, within-room and between-room components were small (2·5% and 0%, respectively). Using these resistance data, the abilities of two sampling strategies to estimate prevalence were modelled with a Monte Carlo ‘bootstrap’ procedure. Compositing faecal samples from several pigs before testing produced unbiased and precise estimates of prevalence and is simpler technically than individual animal testing.

Inactivation of Escherichia coli by Ultrasound Combined with Nisin

2018 ◽  
Vol 81 (6) ◽  
pp. 993-1000 ◽  
Author(s):  
ZUWEN WANG ◽  
XIUFANG BI ◽  
RUI XIANG ◽  
LIYI CHEN ◽  
XIAOPING FENG ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Synergistic Effect ◽  
Linear Models ◽  
Treatment Time ◽  
Nutrient Broth ◽  
Inactivation Kinetics ◽  
Growth Phases ◽  
E Coli ◽  
Kinetics Of ◽  
Inactivation Effect

ABSTRACT The aim of this study was to investigate the inactivation of nonpathogenic Escherichia coli in nutrient broth and milk through the use of either ultrasound (US) alone or US combined with nisin (US + nisin) treatments. The E. coli cells were treated at 0 to 55°C, 242.04 to 968.16 W/cm2 for 0 to 15 min. The results showed that the inactivation of E. coli by US and US + nisin increased when the temperature, US power density, and treatment time were increased. The inactivation kinetics of E. coli in nutrient broth by US and US + nisin both conformed to linear models. The largest reductions of 2.89 and 2.93 log cycles by US and US + nisin, respectively, were achieved at 968.16 W/cm2 and at 25°C for 15 min. The suspension media of the E. coli cells influenced the inactivation effect of US, while the growth phases of E. coli cells did not affect their resistance to US. Under all experiment conditions of this study, the differences between US and US + nisin in their respective inactivation effects on E. coli were not obvious. The results suggested that nisin had either no effect at all or a weak synergistic effect with US and that the E. coli cells were inactivated mainly by US, thus indicating that the inactivation of E. coli by US is an “all or nothing” event.

scholarly journals Frequency of Detection ofEscherichia coli,Salmonellaspp., andCampylobacterspp. in the Faeces of Wild Rats (Rattusspp.) in Trinidad and Tobago

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Comfort Nkogwe ◽  
Juliah Raletobana ◽  
Alva Stewart-Johnson ◽  
Sharianne Suepaul ◽  
Abiodun Adesiyun
Keyword(s):  
Antimicrobial Agents ◽  
Diffusion Method ◽  
Disc Diffusion ◽  
Macconkey Agar ◽  
Disc Diffusion Method ◽  
O157 Strain ◽  
E Coli ◽  
Faecal Samples ◽  
Wild Rats

The study was conducted to determine the frequency of isolation ofSalmonella,CampylobacterandE. coliO157 in the faecal samples of rats trapped across the regional corporations in Trinidad and to assess their resistance to antimicrobial agents. A total of 204 rats were trapped for the detection of selected bacteria. Standard methods were used to isolateSalmonella,CampylobacterandE. coliO157. Characterization ofE. coliwas done on sorbitol MacConkey agar to determine non-sorbitol fermentation, blood agar to determine haemolytic and mucoid colonies and by usingE. coliO157 antiserum to determine O157 strain. The disc diffusion method was used to determine resistance to nine antimicrobial agents. Of the 204 rats, 4 (2.0%), 7 (3.4%) and 171 (83.8%) were positive forSalmonellaspp.,Campylobacterspp. andE. coli, respectively. Of the 171 isolates ofE. colitested 0 (0.0%), 25 (14.6%) and 19 (11.1%) were haemolytic, mucoid and non-sorbitol fermenters, respectively. All isolates were negative for the O157 strain. The frequency of resistance to the 9 antimicrobial agents tested was 75% (3 of 4) forSalmonella, 85.7% (6 of 7) ofCampylobacterspp. and 36.3% (62 of 171) forE. coli(;χ2).

scholarly journals In Vitro Activity of Trovafloxacin against Bacteroides fragilis in Mixed Culture with either Escherichia coli or a Vancomycin- Resistant Strain of Enterococcus faecium Determined by an Anaerobic Time-Kill Technique

2001 ◽  
Vol 45 (1) ◽  
pp. 243-251 ◽  
Author(s):  
Lorna E. T. Stearne ◽  
Clarissa Kooi ◽  
Wil H. F. Goessens ◽  
Irma A. J. M. Bakker-Woudenberg ◽  
Inge C. Gyssens
Keyword(s):  
Escherichia Coli ◽  
Resistant Strain ◽  
Enterococcus Faecium ◽  
Mixed Cultures ◽  
E Coli ◽  
Abdominal Abscesses ◽  
Pure Cultures ◽  
Vancomycin Resistant ◽  
Time Kill

ABSTRACT To determine the efficacy of trovafloxacin as a possible treatment for intra-abdominal abscesses, we have developed an anaerobic time-kill technique using different inocula to study the in vitro killing ofBacteroides fragilis in pure culture or in mixed culture with either Escherichia coli or a vancomycin-resistant strain of Enterococcus faecium (VREF). With inocula of 5 × 105 CFU/ml and trovafloxacin concentrations of ≤2 μg/ml, a maximum observed effect (E max) of ≥6.1 (log10 CFU/ml) was attained with all pure and mixed cultures within 24 h. With inocula of 108CFU/ml, a similar E max and a similar concentration to produce 50% of E max(EC50) for B. fragilis were found in both pure cultures and mixed cultures with E. coli. However, to produce a similar killing of B. fragilis in the mixed cultures with VREF, a 14-fold increase in the concentration of trovafloxacin was required. A vancomycin-susceptible strain of E. faecium and a trovafloxacin-resistant strain of E. coli were also found to confer a similar “protective” effect on B. fragilis against the activity of trovafloxacin. Using inocula of 109 CFU/ml, the activity of trovafloxacin was retained for E. coli and B. fragilis and was negligible against VREF. We conclude that this is a useful technique to study the anaerobic killing of mixed cultures in vitro and may be of value in predicting the killing of mixed infections in vivo. The importance of using mixed cultures and not pure cultures is clearly shown by the difference in the killing of B. fragilis in the mixed cultures tested. Trovafloxacin will probably be ineffective in the treatment of infections involving large numbers of enterococci. However, due to its ability to retain activity against large cultures of B. fragilis and E. coli, trovafloxacin could be beneficial in the treatment of intra-abdominal abscesses.

Evaluation of Three Commercially Available Enzyme-Linked Immunosorbent Assay Kits for Detection of Shiga Toxin

2009 ◽  
Vol 72 (4) ◽  
pp. 741-747 ◽  
Author(s):  
JOHN WILLFORD ◽  
KENNETH MILLS ◽  
LAWRENCE D. GOODRIDGE
Keyword(s):  
Escherichia Coli ◽  
Immunosorbent Assay ◽  
Shiga Toxin ◽  
Screening Method ◽  
Enzyme Linked Immunosorbent Assay ◽  
Microplate Assay ◽  
E Coli ◽  
Elisa Kit ◽  
Pure Cultures ◽  
Order Of Magnitude

Three commercially available Shiga toxin (Stx) enzyme-linked immunosorbent assay (ELISA) kits were evaluated for their ability to detect Stx in pure cultures of Stx-producing Escherichia coli (specificity). The detection limits (sensitivity) of each ELISA kit were also evaluated. Seventy-eight Stx-producing E. coli (STEC) isolates that produced Stx1, Stx2, or Stx1 and Stx2 variants were examined in this study. The specificities of the tests were comparable, and the sensitivities of two of the tests (Premier EHEC and rBiopharm Ridascreen Verotoxin Enzyme Immunoassay) were within the same order of magnitude. The ProSpecT Shiga Toxin E. coli Microplate Assay was approximately 10-fold less sensitive. The inability of all three tests to detect the Stx2d and Stx2e variants indicated that some STEC strains may not be detected by Stx ELISA. The ability of the Premier EHEC ELISA to detect toxin in artificially inoculated bovine fecal samples (following enrichment) indicated that this kit may be used to screen cattle for the presence of Stx as an indicator of the presence of STEC. In particular, such a screening method could be useful during the summer, when the number of STEC-positive animals and the number of STEC that they shed increase.

Sign in / Sign up

Export Citation Format

Share Document