Concerns about antibiotic-resistant bacteria have been growing in recent years, and researchers at the Yerkes National Primate Research Center (YNPRC) have added another to the list. Klebsiella pneumoniae, a bacterium that causes blood, soft tissue and urinary tract infections, has been found resistant to colistin, a powerful last resort antibiotic. In 2013, the Centers for Disease Control and Prevention (CDC) listed Carbapenem-resistant Enterobacteriaceae (CRE), which include Klebsiella, as one of the top three urgent antibiotic resistant threats.

According to the CDC, healthy people usually don’t contract this type of infection. It usually affects patients in hospitals, nursing homes and other health-care settings. Patients whose care requires devices such as ventilators, urinary catheters or intravenous catheters, and patients who are taking antibiotics for a long period of time are most at risk for CRE infections. Various types of Klebsiella are estimated to be responsible for 10 percent of infections acquired in health-care facilities.

“This is concerning because Klebsiella is a more common cause of infection than Enterobacter,” said David Weiss, a researcher at the Yerkes National Primate Research Center and the director of the Emory Antibiotic Resistance Center. “To our knowledge, this type of [antibiotic-resistant] Klebsiella has not been observed in the United States before.”

Despite the extra time required, Dr. Weiss and his colleagues recommend clinical laboratories consider testing for heteroresistance to colistin if this last line antibiotic is required for CRE treatment.