Despite growing concerns over antibiotic resistance worldwide, a large share of patients in U.S. hospitals may be receiving antibiotics when they are no longer necessary, or are not warranted in the first place, according to a new study published in The Lancet Infectious Diseases.
The study, co-authored by researchers at the Center for Disease Dynamics, Economics & Policy (CDDEP) and The University of Maryland School of Medicine, examined courses of antibiotic therapy in six US hospitals treating over 6000 patients during the study period, nearly 2/3rd of whom received antibiotics.
 "When first treating infections, we usually do not know what organism is causing the infection and start patients on one or more broad-spectrum antibiotics to maximize our odds of success." explained Dr. Daniel J Morgan, an infectious disease physician at the University of Maryland School of Medicine and one of the study's co-authors. "However, once lab results become available, it is essential to narrow therapy accordingly, or stop antibiotics altogether if there is no evidence of infection."
To see how often this practice was followed, the authors analyzed the medical records of 1200 randomly chosen patients that had received antibiotics during their stay, and recorded whether they were escalated, narrowed or discontinued, or remained unchanged after five days of taking antibiotics.
One key finding of the study was that even when clinical signs of infection were absent, in some cases broad-spectrum antibiotics were still prescribed - and continued even after five days of therapy. This kind of overprescription of antimicrobials contributes to antibiotic resistance, which has grown across the country in recent years.
"Wherever you live in the US, antibiotic resistance has increased in the last two decades," said Ramanan Laxminarayan, one of the study's authors and director of Washington, DC-based research organization CDDEP.
Antibiotic stewardship is one of the main strategies used to curb antibiotic resistance; stewardship programs involve review of patient responses to antibiotics, such as those that were examined in the study, to decide what course of therapy should be continued, as well as stricter oversight on who is started on antibiotics in the first place.
Findings from this study shed light on another issue regarding antibiotic misuse - the availability of accurate rapid diagnostic tools. Without the ability to quickly and easily determine what pathogens are causing the infection and how they would respond to antibiotics, doctors are more likely to overprescribe in hopes that antibiotics may cure whatever ails the patient.
However, such tests need to be utilized correctly in order to assure appropriate antibiotic use. Though physicians took diagnostic images and collected cultures from more than half of patients at the start of therapy, when those initial results came back negative, antimicrobials were still continued in more than half of patients.
Antibiotic resistance remains a persistent and growing health concern in America. According to a 2013 study done by the Centers for Disease Control and Prevention, up to 2 million Americans are infected with antibiotic-resistant bacteria each year. In September 2014, President Obama announced a White House executive order on combating antibiotic-resistant bacteria, along with a national strategy for attacking the problem countrywide.
The key message of this study is a straightforward one, according to Laxminarayan. "Even in high-quality US facilities, there is a lot of inappropriate and unnecessary antibiotic use," he said.