Study: What’s Behind Antibiotic Resistance in the U.S.?

As antibiotic resistance becomes more widespread in the United States, researchers are trying to answer the question of why. And according to a new study, antibiotic resistance may be more closely linked to how extensively a specific antibiotic is used, rather than how often individuals take antibiotics.

For the study, researchers queried two nationwide pharmacy prescription claims databases, Truven Health MarketScan Research Database and Medicare. They collected data on antibiotic use for about 60 million Americans (one-fifth of the population) between 2011 and 2014. This data were evaluated in conjunction with an antibiotic resistance database, ResistanceOpen, for information from 2012 to 2015. The study authors focused on 72 pairs of antibiotics and bacteria.

In 2011, 34% of the study cohort received antibiotics, and 10% of the population used 57% of the antibiotics. Rates were similar for all the years studied. The researchers discovered that the more a particular antibiotic was used by the population, the more likely people were to become resistant to it.

According to the study authors, “we found that intense use had a weaker association with resistance than extensive use. If the use-resistance relationship is causal, these results suggest that reducing total use and selection intensity will require reducing broadly-distributed, low-intensity use.”

Senior study author Yonatan Grad, of the department of immunology and infectious diseases, Harvard TH Chan School of Public Health, Boston, said of the findings, “Our results show that most antibiotic use is occasional—by people taking just one antibiotic course in a year—and that this occasional use is more closely linked with antibiotic resistance than intense, repeated use.”

Lead study author Scott Olesen, a postdoctoral fellow also from Harvard’s immunology and infectious diseases department, said the results “suggest that combatting inappropriate antibiotic use among people who don’t take many antibiotics may be just as important, or more important, to fighting resistance than focusing on high-intensity users.”

“More antibiotic use generally means more antibiotic resistance, but it seems like the number of people taking antibiotics might matter more than the amount they’re taking,” said Olesen.

The Search for ‘Evolution-Proof’ Antibiotics

Not Just Antibiotics: Is Cancer Chemotherapy Driving Antimicrobial Resistance?

Study Finds Antibiotic Use Linked to Kidney Stone Risk

Antibiotics May Be Able to Treat Appendicitis Without Surgery

Sources: eLife, Harvard TH Chan School of Public Health