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EDs Are Struggling with More Antibiotic-Resistant Pyelonephritis Cases

LOS ANGELES – Remember when treating pyelonephritis in the emergency department was usually as straightforward as prescribing a fluoroquinolone?

Those days are long gone, according to a new study published in the journal Emerging Infectious Diseases. The UCLA-led research shows how antibiotic-resistant bacteria are making it more difficult to treat the common but severe kidney infection.

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, if not treated with effective antibiotics, the infection can cause sepsis and death.

The new study was based on data from 10 large hospital emergency departments around the country, where nearly 12% of patients diagnosed with pyelonephritis had infections resistant to the standard class of antibiotic used in treatment — fluoroquinolones, often ciprofloxacin.

A decade ago, research suggested the resistance rate was just 4%, study authors report. Yet, in certain cases now, risk factors such as international travel, recent hospitalization, or treatment with an antibiotic can drive fluoroquinolone resistance rates past 20%, they write.

The study also documents the emergence of infections caused by a specific strain of E. coli — extended-spectrum beta-lactamase (ESBL)-producing — that is resistant to additional types of antibiotics, severely limiting treatment options. The enzymes, which first were detected in 1979 and are found most often 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.

The study involved 453 patients diagnosed with kidney infection between July 2013 and December 2014. Results indicate that the rates of ESBL-related infections varied from 0% to more than 20%, depending on the location of the ED and patient risk factors.

Study authors warn that, because about one in three people infected with ESBL-producing E. coli had no traditional risk factors for antibiotic resistance, the bacterial strain likely is now endemic in the United States. Furthermore, three of every four patients infected with ESBL-producing E. coli were treated initially with antibiotics ineffective against that particular strain of bacteria, which placed them at risk of poor outcomes, the report notes.

Study authors call for the development of new medications as well as revised guidelines calling for treatment with different types and combinations of antibiotics. In addition, they suggest that emergency physicians evaluating treatment options should be aware of antibiotic resistance rates in their regions and quickly test bacteria samples to determine specific strains.