Drug-resistant superbug bacterial infections strike one in five nursing home residents with advanced dementia and more than 10 percent of the cases are not cleared by four or more types of antibiotics.

That’s the troubling conclusion of new research was published online in Infection Control & Hospital Epidemiology, the journal of the Society for Healthcare Epidemiology of America.

The findings, by researchers from Rhode Island Hospital, suggest life-threatening drug bacteria — such as carbapenem-resistant Enterobacteriaceae (CRE) and Klebsiella pneumoniae carbapenemase (KPC) — are more common than previously believed.

"Nursing home residents with advanced dementia usually have an increased need for healthcare worker assistance, as well as frequent exposure to antibiotics. This combination may be leading to a subset of vulnerable long-term care residents at high risk of both acquiring and spreading these dangerous bugs," said lead researcher Erika D'Agata, M.D., an infectious disease physician.

"Frequent hospitalization among these residents also provides a constant influx of drug-resistant bacteria into the hospital setting, further fostering the spread throughout the healthcare delivery system."

For the study, researchers followed 152 nursing home residents with advanced dementia in 22 Boston-area facilities for a year. The results showed nearly 20 percent of the residents were infected with more than one multi-drug resistant germ, and bacteria were present in patients 82 percent of the 22 nursing homes.

Drug-resistant E. coli and Proteus mirabilis were the most common bacteria found in the patients and nearly 90 percent of the germs were resistant to three types of antibiotics, most notably ciprofloxacin, gentamicin, and extended-spectrum penicillins.

"Ongoing efforts to curb the acquisition and spread of this bacteria among nursing homes residents is crucial since this is an issue that goes beyond just one realm of care," said Dr. D'Agata.

"Healthcare institutions must work together to help curb the transmission of these emerging, dangerous pathogens."