Cargando…

Development of a real-time PCR assay and comparison to CHROMagar(TM) STEC to screen for Shiga toxin-producing Escherichia coli in stool, Cape Town, South Africa

INTRODUCTION: Shiga toxin-producing Escherichia coli (STEC) is an emerging infectious pathogen which could lead to haemolytic uremic syndrome. Even though previous studies have compared the performance of CHROMagar(TM)STEC to real-time polymerase chain reaction (PCR) in Europe, no study has been don...

Descripción completa

Detalles Bibliográficos
Autores principales: Kalule, John B., Keddy, Karen H., Smith, Anthony, Nicol, Mark P., Robberts, Lourens
Formato: Online Artículo Texto
Lenguaje:English
Publicado: AOSIS 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5803521/
https://www.ncbi.nlm.nih.gov/pubmed/29435423
http://dx.doi.org/10.4102/ajlm.v6i1.609
_version_ 1783298670806958080
author Kalule, John B.
Keddy, Karen H.
Smith, Anthony
Nicol, Mark P.
Robberts, Lourens
author_facet Kalule, John B.
Keddy, Karen H.
Smith, Anthony
Nicol, Mark P.
Robberts, Lourens
author_sort Kalule, John B.
collection PubMed
description INTRODUCTION: Shiga toxin-producing Escherichia coli (STEC) is an emerging infectious pathogen which could lead to haemolytic uremic syndrome. Even though previous studies have compared the performance of CHROMagar(TM)STEC to real-time polymerase chain reaction (PCR) in Europe, no study has been done to assess its performance on African isolates. OBJECTIVES: This project aimed to validate and test an in-house-developed duplex real-time PCR and use it as a reference standard to determine the performance of CHROMagar(TM)STEC on African isolates from diarrhoeic stool samples. METHODS: This study evaluated STEC diagnostic technology on African isolates. An in-house-developed duplex real-time PCR assay for detection of stx(1) and stx(2) was validated and tested on diarrhoeic stool samples and then used as a reference standard to assess the performance of CHROMagar(TM)STEC. Real-time PCR was used to screen for stx in tryptic soy broth and the suspected STEC isolates, while conventional PCR was used to detect the other virulence genes possessed by the isolates. RESULTS: The real-time PCR limit of detection was 5.3 target copies/μL of broth. The mean melting temperature on melt-curve analysis for detection of stx(1) was 58.2 °C and for stx(2) was 65.3 °C. Of 226 specimens screened, real-time PCR detected stx in 14 specimens (6.2%, 95% confidence interval = 3.43% – 10.18%). The sensitivity, specificity, negative predictive value and positive predictive value of the CHROMagar(TM)STEC were 33.3%, 77.4%, 95.3% and 11.3%. CONCLUSIONS: The in-house developed real-time PCR assay is a sensitive and specific option for laboratory detection of STEC as compared to CHROMagar(TM)STEC in this setting.
format Online
Article
Text
id pubmed-5803521
institution National Center for Biotechnology Information
language English
publishDate 2017
publisher AOSIS
record_format MEDLINE/PubMed
spelling pubmed-58035212018-02-12 Development of a real-time PCR assay and comparison to CHROMagar(TM) STEC to screen for Shiga toxin-producing Escherichia coli in stool, Cape Town, South Africa Kalule, John B. Keddy, Karen H. Smith, Anthony Nicol, Mark P. Robberts, Lourens Afr J Lab Med Original Research INTRODUCTION: Shiga toxin-producing Escherichia coli (STEC) is an emerging infectious pathogen which could lead to haemolytic uremic syndrome. Even though previous studies have compared the performance of CHROMagar(TM)STEC to real-time polymerase chain reaction (PCR) in Europe, no study has been done to assess its performance on African isolates. OBJECTIVES: This project aimed to validate and test an in-house-developed duplex real-time PCR and use it as a reference standard to determine the performance of CHROMagar(TM)STEC on African isolates from diarrhoeic stool samples. METHODS: This study evaluated STEC diagnostic technology on African isolates. An in-house-developed duplex real-time PCR assay for detection of stx(1) and stx(2) was validated and tested on diarrhoeic stool samples and then used as a reference standard to assess the performance of CHROMagar(TM)STEC. Real-time PCR was used to screen for stx in tryptic soy broth and the suspected STEC isolates, while conventional PCR was used to detect the other virulence genes possessed by the isolates. RESULTS: The real-time PCR limit of detection was 5.3 target copies/μL of broth. The mean melting temperature on melt-curve analysis for detection of stx(1) was 58.2 °C and for stx(2) was 65.3 °C. Of 226 specimens screened, real-time PCR detected stx in 14 specimens (6.2%, 95% confidence interval = 3.43% – 10.18%). The sensitivity, specificity, negative predictive value and positive predictive value of the CHROMagar(TM)STEC were 33.3%, 77.4%, 95.3% and 11.3%. CONCLUSIONS: The in-house developed real-time PCR assay is a sensitive and specific option for laboratory detection of STEC as compared to CHROMagar(TM)STEC in this setting. AOSIS 2017-12-14 /pmc/articles/PMC5803521/ /pubmed/29435423 http://dx.doi.org/10.4102/ajlm.v6i1.609 Text en © 2017. The Authors https://creativecommons.org/licenses/by/4.0/ Licensee: AOSIS. This work is licensed under the Creative Commons Attribution License.
spellingShingle Original Research
Kalule, John B.
Keddy, Karen H.
Smith, Anthony
Nicol, Mark P.
Robberts, Lourens
Development of a real-time PCR assay and comparison to CHROMagar(TM) STEC to screen for Shiga toxin-producing Escherichia coli in stool, Cape Town, South Africa
title Development of a real-time PCR assay and comparison to CHROMagar(TM) STEC to screen for Shiga toxin-producing Escherichia coli in stool, Cape Town, South Africa
title_full Development of a real-time PCR assay and comparison to CHROMagar(TM) STEC to screen for Shiga toxin-producing Escherichia coli in stool, Cape Town, South Africa
title_fullStr Development of a real-time PCR assay and comparison to CHROMagar(TM) STEC to screen for Shiga toxin-producing Escherichia coli in stool, Cape Town, South Africa
title_full_unstemmed Development of a real-time PCR assay and comparison to CHROMagar(TM) STEC to screen for Shiga toxin-producing Escherichia coli in stool, Cape Town, South Africa
title_short Development of a real-time PCR assay and comparison to CHROMagar(TM) STEC to screen for Shiga toxin-producing Escherichia coli in stool, Cape Town, South Africa
title_sort development of a real-time pcr assay and comparison to chromagar(tm) stec to screen for shiga toxin-producing escherichia coli in stool, cape town, south africa
topic Original Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5803521/
https://www.ncbi.nlm.nih.gov/pubmed/29435423
http://dx.doi.org/10.4102/ajlm.v6i1.609
work_keys_str_mv AT kalulejohnb developmentofarealtimepcrassayandcomparisontochromagartmstectoscreenforshigatoxinproducingescherichiacoliinstoolcapetownsouthafrica
AT keddykarenh developmentofarealtimepcrassayandcomparisontochromagartmstectoscreenforshigatoxinproducingescherichiacoliinstoolcapetownsouthafrica
AT smithanthony developmentofarealtimepcrassayandcomparisontochromagartmstectoscreenforshigatoxinproducingescherichiacoliinstoolcapetownsouthafrica
AT nicolmarkp developmentofarealtimepcrassayandcomparisontochromagartmstectoscreenforshigatoxinproducingescherichiacoliinstoolcapetownsouthafrica
AT robbertslourens developmentofarealtimepcrassayandcomparisontochromagartmstectoscreenforshigatoxinproducingescherichiacoliinstoolcapetownsouthafrica