Portable Device Lights Up for Resistant Bacteria Detection

Researchers at the Indian Institute of Science (IISc) and Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) have created a paper-based platform that may make finding antibiotic-resistant bacteria that cause disease easier.

The emergence of antibiotic-resistant bacteria that cause disease has been one of humanity's biggest problems. The abuse and overuse of antibiotics have contributed to their rise.

According to the World Health Organization, some bacteria, such as Staphylococcus aureus and E. coli, have been linked to over a million deaths. These numbers are expected to increase in the years to come. Treatment effectiveness can be improved with a prompt diagnosis.

Generally, the doctor diagnoses the patient and gives them medicines. The patient then takes it for 2-3 days before realizing that the medicine is not working and goes back to the doctor. Even diagnosing that the bacteria is antibiotic-resistant from blood or urine tests takes time. We wanted to reduce that time-to-diagnosis.

Uday Maitra, Professor, Department of Organic Chemistry, Indian Institute of Science

Maitra’s lab and associates have tackled this problem in a paper published in ACS Sensors. They have created a quick diagnosis method that looks for the presence of bacteria resistant to antibiotics using a platform made of glowing paper.

A bacterium can develop antibiotic resistance in a number of ways. For example, the bacteria could grow to the point where it can identify the medication and expel it from its cell. In a different instance, the bacteria generate an enzyme known as β-lactamase, which breaks down the β-lactam ring, a crucial structural element of popular antibiotics such as carbapenem and penicillin, making the drug inactive.

The method created by the teams at JNCASR and IISc includes adding biphenyl-4-carboxylic acid (BCA) to a supramolecular hydrogel matrix that also contains terbium cholate (TbCh). When exposed to UV light, this hydrogel typically releases green fluorescence.

In the lab, we synthesized an enzyme substrate by tethering BCA to the cyclic [β-lactam] ring that is a part of the antibiotic. When you mix this with TbCh hydrogel, there is no green emission as the sensitizer is ‘masked.’ In the presence of β-lactamase enzyme, the gel will produce green emission. β-lactamase enzyme in the bacteria is the one that cuts open the drug, destroys, and unmasks the sensitizer BCA. So, the presence of β-lactamase is signaled by green emission.

Arnab Dutta, PhD Student and Study Lead Author, Department of Organic Chemistry, Indian Institute of Science

The luminescence signals the presence of antibiotic-resistant bacteria, and the luminescence intensity indicates the bacterial load. The green intensity was found to be extremely low for non-resistant bacteria, making it easier to distinguish them from resistant bacteria.

The next task was to figure out how to reduce the cost of the technology. The cost of the current diagnostic tools increases the cost of testing.

The group worked with Adiuvo Diagnostics, a company based in Tamil Nadu, to design the Illuminate Fluorescence Reader, a portable, tiny imaging device specially made for the team. A sheet of paper infused with hydrogel was used as the medium, significantly reducing the cost.

Several LEDs installed in the instrument shine UV light when needed. An integrated camera records the green fluorescence emitted by the enzyme, and a specialized software program quantifies the intensity, thereby aiding in the determination of the bacterial load.

The team from IISc tied up with Jayanta Haldar’s research group from JNCASR to check their approach to urine samples.

We used samples from healthy volunteers and added pathogenic bacteria to mimic Urinary Tract Infections. It successfully produced the outcome within two hours.

Uday Maitra, Professor, Department of Organic Chemistry, Indian Institute of Science

The researchers’ next move is to collaborate with hospitals to test this technology using patient samples.

Journal Reference:

Dutta, A., et al. (2024) Augmenting Antimicrobial Resistance Surveillance: Rapid Detection of β-Lactamase-Expressing Drug-Resistant Bacteria through Sensitized Luminescence on a Paper-Supported Hydrogel. ACS Sensors. doi.org/10.1021/acssensors.3c02065.