Los Angeles—Treating pyelonephritis once was fairly routine, with clinicians generally prescribing a fluoroquinolone for the potentially serious kidney infection.
A new study published in the journal Emerging Infectious Diseases notes that now, however, antibiotic-resistant bacteria are making it more difficult to treat the common but severe kidney infection when patients present to an emergency department.
Pyelonephritis, an infection of the kidney usually caused by E coli bacteria and which can start as a urinary tract infection, causes fever, back pain and vomiting, according to background information in the article. About half of people infected require hospitalization, and, it not treated with effective antibiotics, the infection can cause sepsis and death.
The new study, conducted by UCLA researchers, was based on data from 10 large hospital emergency departments around the country. Nearly 12% of patients diagnosed with pyelonephritis had infections resistant to the standard class of antibiotic used in treatment. Researchers point out that, in the past, ciprofloxacin was often the agent of choice.
While the resistance rate was just 4% a decade ago, according to the report, risk factors such as international travel, recent hospitalization or treatment with an antibiotic can drive fluoroquinolone resistance rates past 20% in certain cases.
The study also documents the emergence of infections caused by a specific strain of E coli—extended-spectrum beta-lactamases (ESBL)—that is resistant to additional types of antibiotics, severely limiting treatment options. The enzymes, which were first detected in 1979 and are most often found in developing nations, were not cited in previous studies on this topic, according to the researchers.
“This is a very real example of the threat posed by the emergence of new antibiotic-resistant strains of bacteria, which greatly complicates treatment of infection,” explained lead author David Talan, MD.
For the study, researchers focused on 453 patients diagnosed with kidney infection between July 2013 and December 2014, with the rates of ESBL-related infections varying from 0% to more than 20%, depending on the location of the ED and patient risk factors.
Because about one in three people infected with ESBL-producing E coli had no traditional risk factors for antibiotic resistance, study authors warn, the bacterial strain likely is now endemic in the United States. They also emphasize that three of every four patients infected with ESBL-producing E coli were initially treated with antibiotics ineffective against that particular strain of bacteria, which placed them at risk of poor outcomes, the report notes.
The study calls for the development of new medications as well as revised guidelines calling for treatment with different types and combinations of antibiotics.
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