Development and Validation of Shiga Toxin-Producing Escherichia coli Immunodiagnostic Assay

Abstract

Shiga toxin (Stx)–producing Escherichia coli (STEC) and its subgroup enterohemorrhagic E. coli are important pathogens involved in diarrhea, which may be complicated by hemorrhagic colitis and hemolytic uremic syndrome, the leading cause of acute renal failure in children. Early diagnosis is essential for clinical management, as an antibiotic treatment in STEC infections is not recommended. Previously obtained antibodies against Stx1 and Stx2 toxins were employed to evaluate the sensitivity and specificity of the latex Agglutination test (LAT), lateral flow assay (LFA), and capture ELISA (cEIA) for STEC detection. The LAT (mAb Stx1 plus mAb stx2) showed 99% sensitivity and 97% specificity. Individually, Stx1 antibodies showed 95.5% and 94% sensitivity and a specificity of 97% and 99% in the cEIA and LFA assay, respectively. Stx2 antibodies showed a sensitivity of 92% in both assays and a specificity of 100% and 98% in the cEIA and LFA assay, respectively. These results allow us to conclude that we have robust tools for the diagnosis of STEC infections.

Diversity of Hybrid- and Hetero-Pathogenic Escherichia coli and Their Potential Implication in More Severe Diseases

“…Some researchers classify any STEC strain as EHEC based only on the patients' clinical manifestations, including hemorrhagic colitis or HUS due to Stx production (Doughty et al, 2002 ; Navarro-Garcia, 2014 ; Krause et al, 2018 ; Lang et al, 2018 ; Torres et al, 2018 ). Others, instead, use molecular criteria based on the simultaneous presence of Stx and the locus of enterocyte effacement (LEE) pathogenicity island (PAI) to classify as EHEC (Kaper et al, 2004 ; Croxen et al, 2013 ; Sadiq et al, 2014 ; Silva et al, 2019 ).…”

“…As STEC strains can cause diarrhea and HUS in human subjects independently of the presence of LEE (Luck et al, 2005 ; Croxen et al, 2013 ; Krause et al, 2018 ), this PAI is an accessory set of virulence genes that enhances STEC pathogenicity; thus, we can consider it as a hetero-pathogen. Nevertheless, LEE PAI is the major factor associated with the occurrence of attaching and effacing (A/E) lesion and diarrhea by EPEC strains (Croxen et al, 2013 ; Silva et al, 2019 ). LEE bears several virulence genes encoding, e.g., intimin ( eae ), a type 3 secretion system, and other effectors involved in A/E lesion formation, which are used to clinically classify pathogenic E. coli strains as EPEC ( Table 1 ).…”

“…The EPEC pathotype is sub-grouped based on the presence of the bundle-forming pilus (BFP) in the strains classified as typical and, on its absence, in the strains classified as atypical. In general, EPEC/STEC hetero-pathogens comprise atypical EPEC carrying Stx (Croxen et al, 2013 ; Eichhorn et al, 2015 ; Gomes et al, 2016 ; Silva et al, 2019 ). The first description of a typical EPEC strain bearing Stx was reported by Gioia-Di Chiacchio et al ( 2018 ), who identified eight E. coli strains isolated from birds that carried Stx2, LEE, and BFP simultaneously.…”

Special Issue: Shiga Toxin-Producing Escherichia coli

“…Many questions remain about STEC virulence factors, pathogenesis, detection, and other aspects that necessitate a continuation of basic and applied research on a wide front. This Special Issue includes 14 papers (nine articles, two communications, one review, one comment, and one reply) that collectively provide novel information on the epidemiology [ 4 , 5 , 6 , 7 ], virulence factors [ 7 , 8 , 9 , 10 ], and pathogenesis [ 11 , 12 , 13 ] of STEC, and the molecular structure or toxicity [ 14 , 15 , 16 ] and immunodetection [ 17 ] of Shiga toxin.…”

“…A study evaluating three immunological diagnostic assays for STEC (latex agglutination, lateral flow, and capture ELISA) found that all were highly sensitive and specific, indicating that robust tools for the diagnosis of STEC infections are available [ 17 ]. Collectively, the papers in this Special Issue on STEC reveal significant progress in the understanding of these pathogens, but they also highlight their complexity with the realization that more work is necessary to enable the development of more specific preventive measures and therapies.…”