We use cookies to understand how you use our site and to improve your experience. This includes personalizing content and advertising. To learn more, click here. By continuing to use our site, you accept our use of cookies. Cookie Policy.

Features Partner Sites Information LinkXpress hp
Sign In
Advertise with Us
Sekisui Diagnostics

Download Mobile App




Immunofluorescence Assay Detects Virulent Escherichia coli

By LabMedica International staff writers
Posted on 15 Oct 2013
A sensitive and specific detection method for identifying enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. More...
coli (EHEC) has been reported.

Among the methods for detection of virulence factor expression, immunoassays for which polyclonal and or monoclonal antibodies are raised, can be considered the first alternative to either animal use or in vitro culture cells assays.

Scientists at Instituto Butantan (Sao Paulo, SP, Brazil) developed a recombinant antibody using the single-chain variable fragment (scFv) approach. They evaluated the sensitivity and specificity of an intimin recombinant antibody (scFv-intimin) using an immunofluorescence assay. A synthetic gene was designed using the scFv-intimin. The intimin adherence-protein gene (eae) encodes for intimin, a 94-kDa outer membrane protein.

The evaluation of scFv-intimin by an indirect immunofluorescence assay test performance implied the use of eae-positive isolates displaying intimin variants, specifically typical EPEC (tEPEC), atypical EPEC (aEPEC), and EHEC, to assess test sensitivity and eae-negative and other Enterobacteriaceae isolates. The prototype tEPEC E2348/69 and enterotoxigenic (ETEC) H10407/E. coli K-12 isolates acted as positive and negative controls, respectively, for assay standardization.

Anti-histidine mouse antibody and goat anti-mouse immunoglobulin G- Fluorescein isothiocyanate (IgG-FITC, Sigma-Aldrich; St. Louis, MO, USA) conjugate were also included as immunofluorescence controls. In all isolates, the eae gene was first assayed by PCR, and the eae positive isolates were confirmed by fluorescent actin staining analysis. A drop of the manipulated bacterial suspension that had also been resuspended with scFv-intimin was placed on a glass slide and observed with a fluorescence microscope (Axioskop-Zeiss; Munich, Germany).

The scFv-intimin immunoassay detected typical EPEC, atypical EPEC, and EHEC isolates with 100% sensitivity and did not detect eae negative isolates, indicating 100% specificity. The authors conclude that immunofluorescence is an effective and rapid method, and scFv-intimin, an excellent tool for the diagnosis of diarrhea caused by EPEC and EHEC and also can be employed in case-control epidemiological surveys. The study was published on October 2, 2013, in the journal Diagnostic Microbiology and Infectious Disease.

Related Links:

Instituto Butantan
Sigma-Aldrich
Axioskop-Zeiss



Platinum Member
Automated Coagulation Analyzer
Hemolumi H6
Gold Member
Clinical Chemistry Assay
Sorbitol Dehydrogenase (SDH)
Hematology Consumables
Bioblood Devices
Platinum Member
Integrated Biochemical & Immunological System
Biolumi CX Solution X10+C10
Read the full article by registering today, it's FREE! It's Free!
Register now for FREE to LabMedica.com and get access to news and events that shape the world of Clinical Laboratory Medicine.
  • Free digital version edition of LabMedica International sent by email on regular basis
  • Free print version of LabMedica International magazine (available only outside USA and Canada).
  • Free and unlimited access to back issues of LabMedica International in digital format
  • Free LabMedica International Newsletter sent every week containing the latest news
  • Free breaking news sent via email
  • Free access to Events Calendar
  • Free access to LinkXpress new product services
  • REGISTRATION IS FREE AND EASY!
Click here to Register








Channels

Clinical Chemistry

view channel
Image Credit: 123RF

Screening After Pneumococcal Disease May Reveal Undiagnosed Blood Cancer or Immune Disorders

Severe pneumococcal disease requiring hospitalization often presents as pneumonia, particularly in older adults and people with cancer or compromised immune function. Because M protein testing and antibody... Read more

Technology

view channel
Image: The laser-based photoacoustic spectroscopy setup consists of a Mid-IR laser equipped with three QCL modules covering wavelengths from 5.6 μm to 12.9 μm, two silver coated mirrors (SCM), a dichroic mirror (DM) with a transmittance of 90%, a thermal power sensor head (PM) to monitor the output laser power, a mechanical chopper (MC) for frequency modulation and a CEPAS-detector with a self-designed swab holder (SH). (Credit: Graunke, T., Scholz, T., Pieniak, M. et al. Scientific Reports (2026). https://doi.org/10.1038/s41598-026-68298-9)

Laser-Based Swab Analysis Shows Promise for Detecting Disease-Linked Odor Patterns

Disease-related changes in volatile organic compounds can alter body odor, producing measurable patterns in exhaled breath and bodily fluids. Current analytical methods can be complex, time-consuming,... Read more

Industry

view channel
Image

Collaboration Combines AI Cognitive Assessment and RNA Blood Testing for Earlier Alzheimer’s Detection

Alzheimer’s disease is often identified only after substantial neurodegeneration, partly because current diagnostic pathways are fragmented and difficult to scale. As treatment shifts toward earlier intervention,... Read more
Copyright © 2000-2026 Globetech Media. All rights reserved.