Central Texas News

A New Tool May Help Reduce The Burden Of Antibiotic Resistant Infections

Antibiotic-resistant infections take a huge toll, with 1.27 million deaths directly attributed to such bacteria (AMR) in 2019. There were 32,000 deaths in the US alone. That’s far higher than the deaths from HIV, for example. In addition to the growing problem of antibiotic resistance, the pipeline of novel antibiotics has drastically shrunken. Antibiotics are simply not as profitable as life-style drugs or those for chronic diseases, so pharmaceutical companies are abandoning the acute infectious disease market.

When a patient has a serious infection, antibiotics are usually started “empirically”—based on the site of infection, what organisms commonly cause infections at those sites, and possible knowledge of bacterial resistance patterns in the community. This approach is a bit better than by guessing blindly, but leaves much to be desired.

Ideally, the patient will have cultures obtained from the infected site to identify the specific organism causing the infection, allowing the best antibiotic to be chosen. This process is time- consuming—it often takes 1-2 days to grow the organism. Isolating it from other bacteria in the specimen can take another 1-2 days. Then add testing the isolated bacteria against an array of antibiotics, which commonly takes 1-2 days.

In the meantime, the patient may not be on an effective antibiotic and is generally on one that is broad-spectrum. That means it will kill a variety of bacteria, often needlessly. It’s like using a shotgun rather than a rifle to kill something, while sometimes missing the culprit. If trying to poison them isn't successful, the survivors have been selected for resistance and “that which doesn't kill me makes me stronger.” This leads to more antibiotic resistance and often to additional side effects for the patient (e.g., C. difficile diarrhea or superinfections, or new infections, which are often more resistant).

Automated systems like Vitek-2, Phoenix, or MicroScan machines, often do the susceptibility testing. Newer strategies are trying to speed up the process. These include flow cytometry, a technique that uses lasers to measure specific types of cells in samples. There are molecular methods, like PCR, that detects genes conferring antimicrobial resistance. Another testing technique is MALDI-TOF MS (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry), which is limited by the need for expensive equipment. (The equipment layout for each is expensive—$5-15,000 for a PCR, to $100-500,000 for a flow cytometer and $270,000 for a MALDI-TOF spectrometer.)

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