The discovery of antibiotics in the early part of the 20th century changed modern medicine. Simple infections that previously killed people became easy to treat. Antibiotics ability to stave off infections made possible routine surgeries, organ transplants, and chemotherapy for the treatment of cancer.
A new test developed at Caltech that identifies antibiotic-resistant bacteria in as little as 30 minutes could help to better choose which antibiotics to treat an infection.
When doctors treat patients with bacterial infections, they often skip over first-line antibiotics like methicillin or amoxicillin drugs those bacteria more likely to be resistant to and go straight for stronger second-line antibiotics, like ciprofloxacin. This practice increases the chance that the treatment will be effective, but it is not ideal.
“Right now, we’re over prescribing, so we’re seeing resistance much sooner than we have to for a lot of the antibiotics that we would otherwise want to preserve for more serious situations,” says Nathan Schoepp, a Caltech graduate student.
urinary tract infections
Researchers aimed to develop a test that could complete during a single visit to the doctor’s office. They focused on one of the most common types of infections in humans, urinary tract infections (UTIs), which 50 percent of women contract during their lifetimes.
For tests, the researchers collected from a patient with a UTI are divided into two parts. One part exposed to an antibiotic for 15 minutes, while the other part incubates without antibiotics. The bacteria from each sample broken open to release their cellular contents, which run through a process that combines a detection chemistry technique called digital real-time loop-mediated isothermal amplification with a device SlipChip.
This combination replicates specific DNA markers so they can image and individually counted as discrete fluorescent spots.
The test operates on the principle that typical bacteria will replicate their DNA less well in an antibiotic solution, resulting in the presence of fewer DNA markers. However, if the bacteria resistant to the antibiotic, their DNA replication will not hamper and the test will reveal similar numbers of DNA markers in both the treated and untreated solutions.
When used on 54 samples of urine from patients with UTIs caused by the bacteria Escherischia coli. The test results had a 95% match with those obtained using the standard two-day test, which considers the gold standard for accuracy.
Blood infections are more difficult to test, because the bacteria present in much lower numbers than they are in urine. But, such a test could help reduce mortality from blood-borne infections, which can turn fatal if not treated quickly.
More information: [Science Translational Medicine]