Issue 22, 2020

Paper-based analytical devices for colorimetric detection of S. aureus and E. coli and their antibiotic resistant strains in milk

Abstract

Animal derived milk which is an important part of human diet due to its high nutritional value not only supports humans but also presents a growth environment for pathogenic bacteria. Milk may become contaminated with bacteria through udder infections or through contact within the dairy farm environment. Infections are treated with antibiotics, with β-lactams most commonly used in veterinary medicine. However, their frequent use leads to the emergence of β-lactam resistant bacterial strains, which causes difficulties in the treatment of infections in both humans and animals. Detection of pathogens as well as their antibiotic sensitivity is a pre-requisite for successful treatment and this is generally achieved with laboratory-based techniques such as growth inhibition assays, enzyme-linked immunosorbent assays (ELISA) or polymerase chain reactions (PCRs), which are unavailable in resource-limited settings. Here, we investigated paper-based analytical devices (μPADs) for the presumptive detection of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) and their antibiotic resistant bacterial strains in milk samples. The μPADs were fabricated on filter paper using wax printing, and then impregnated with chromogenic substrates, which reacted with bacterial enzymes to form coloured products. Limits of detection of S. aureus and E. coli and their antibiotic resistant strains in milk samples were found to be 106 cfu mL−1. Enrichment of milk samples in a selective medium for 12 h enabled detection as low as 10 cfu mL−1. The paper devices tested on a set of 640 milk samples collected from dairy animals in Pakistan demonstrated more than 90% sensitivity and 100% selectivity compared to PCR, showing promise to provide inexpensive and portable diagnostic solutions for the detection of pathogenic bacteria in resource-limited settings.

Graphical abstract: Paper-based analytical devices for colorimetric detection of S. aureus and E. coli and their antibiotic resistant strains in milk

Supplementary files

Article information

Article type
Paper
Submitted
28 May 2020
Accepted
09 Aug 2020
First published
10 Aug 2020
This article is Open Access
Creative Commons BY-NC license

Analyst, 2020,145, 7320-7329

Paper-based analytical devices for colorimetric detection of S. aureus and E. coli and their antibiotic resistant strains in milk

M. Asif, F. R. Awan, Q. M. Khan, B. Ngamsom and N. Pamme, Analyst, 2020, 145, 7320 DOI: 10.1039/D0AN01075H

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