Colorimetric Screening of Antibiotic Resistance Biomarkers using Nucleic Acid Enzymes and Gold Nanoparticles

Mohamed, Mohamed 1, 3 ;  Kim, Jisung 1, 3 ;  Zagorovsky, Kyryl 1, 3 ;   Chan, Warren 1, 2, 3

1. Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2. Department of Chemistry, University of Toronto; 3. Department of Microbiology and Division of Infectious Diseases, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5, Canada; 4. Centre for Global Engineering, University of Toronto, Toronto, Ontario M5S 1A4, Canada 4Sandra Rotman Centre for Global Health, University Health Network, Toronto, Ontario M5G 1L7, Canada; 5. Terrence Donnelly Centre for Cellular and Bimolecular Research, University of Toronto, Toronto, Ontario M5S 3E1, Canada

Extensive and improper use of antibiotics have led to rapid evolution of antibiotic resistance (AR). In particular, there is an emerging trend of multi-drug resistant (MDR) pathogens, which have acquired resistances to multiple antibiotics. Rapid and accurate determination of bacterial susceptibility to antibiotics is critical to deliver effective treatments against infections and to reduce the risk of AR development and spread. Currently, the two major laboratory techniques for detection of AR are phenotypic culture-based tests and genotypic tests. Although phenotypic culture methods such as agar diffusion, microdilution, or selective chromogenic media are cost-effective, they take 24-72 hours for an accurate diagnosis. On the other hand, genotypic tests that uses polymerase chain reaction (PCR) can directly detect the presence of AR genes, are not affected by testing conditions, and are often used to confirm inconclusive phenotypic test results. However, PCR is expensive, uses complex equipment, and requires highly skilled technicians, precluding its use in resource-limited areas.

Here, we developed rapid, sensitive and an instrument free color-based test that can profile antibiotic resistance within 2 hours. Our assay achieved an analytical sensitivity of 10 2 -10 3 CFU/ml for detecting antibiotic resistance genes in methicillin resistant Staphylococcus aureus strains and can detect multiple antibiotic resistance genes in parallel without cross-reactivity from three different antibiotic resistant S. aureus strains. These results are equivalent to the common techniques such as PCR and agar diffusion methods but our method is significantly faster and more cost-effective. Our assay can be easily adapted to both centralized and remote testing locations to reduce the unnecessary overuse of antibiotics, and ensure that correct therapies are prescribed.