Paper-Based Assay for Antimicrobial Resistant Bacteria Detection

Identifying AMR bacteria in water sources

At a Glance

Antimicrobial resistance (AMR), the ability of a bacterial species to resist the action of an antimicrobial drug, has been on the rise due to the widespread use of antimicrobial agents, and one of the many ways AMR can spread is through contaminated water sources. To monitor these water sources, we have developed an inexpensive, fast assay using a paper-based analytical device (PAD) that can test for the presence of β-lactamase-mediated resistance as one major form of AMR that has reliably detected resistance in sewage water.


The introduction of antimicrobial agents in the early 20th century revolutionized medicine, significantly decreasing morbidity and mortality.  However, due to the widespread use of antimicrobial agents and the genetic plasticity of bacteria, more pathogens have developed the ability to resist these drugs, giving rise to antimicrobial resistant (AMR) bacteria.  According to the World Health Organization (WHO), AMR costs approximately $2 IB to $34B annually within the United States alone and is predicted to surpass heart disease as the number one cause of death worldwide by 2050.

Contaminated water is a significant source of infection and outlet for the spread of AMR bacteria. AMR propagation in water is further advanced through contamination by antimicrobial agents, which results in the selective proliferation of AMR bacteria, and the horizontal gene transfer of resistance from AMR bacteria to non-AMR bacteria. Due to its significant role, many bodies of water have been studied for the presence of AMR bacteria including urban wastewater, irrigation water, and drinking water in China to name a few.


Researchers at Colorado State University developed a straightforward and accurate paper-based colorimetric assay to detect bacteria resistant to β-lactam antibiotics. The assay costs approximately $0.20 per test and gives similar sensitivity to more expensive microtiter plate methods. Further, the group demonstrated that non-AMR bacteria do not interfere with the assay performance and cell lysis is not required.

Tests to detect β-lactamase-expressing bacteria in community sewage water were conducted to identify resistance in various species of bacterial isolates, demonstrating the practicality of this method. All tests were confirmed and compared to traditional culturing methods, antibiotic susceptibility testing, and PCR gene analysis.

Bacterial samples were shown to react with nitrocefin whether in solution or dried into the paper, also demonstrating its potential for a field-ready module. It was confirmed that using a paper-based test and a camera phone for quantification yielded the same LOD as using an expensive and non-transportable plate reader and microtiter plate.

While traditional methods are also quantitative of resistance, this paper-based method is a rapid, cost-effective surveillance tool with a yes/no informed decision outcome prior to establishing a need for additional testing.


  • Rapid, disposable, and inexpensive device
  • Does not require instrumentation or training laboratory personnel
  • Field-ready module


  • Detection of antimicrobial (AMR) bacteria in water sources
Last Updated: September 2021
Illustration of bacteria fighting off Penicillin

Collaboration and Funding Welcome

IP Status

US Patent: US 2020/0131558


Chuck Henry
Katherine Boehle
Brian Geiss

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