A highly resistant form of a common bacterium recently popped up in two Rhode Island patients, only the 12th and 13th times it has been spotted in this country.
And while the Centers for Disease Control and Prevention cites Rhode Island Hospital for fast work in stamping it out, federal officials are worried the next time might not go as well. They’re asking U.S. hospitals to be alert to the threat this strain of drug-resistant germs poses.
“The cat’s out of the bag,” says Dr. Leonard Mermel of Brown University Medical School. “It’s spreading,” he tells Shots. “But we need to do what we can — nationally, globally and locally — to curtail its spread as much as possible.”
The bacteria are called carbapenem-resistant Enterobacteriaceae or CRE. They’re black sheep in a big herd of mostly harmless germs that includes common organisms inhabiting everybody’s gut, such as the familiar E. coli. In the Rhode Island case, the germ was Klebsiella, which can cause pneumonia and a variety of other infections.
The particular trait of these bugs causing most concern is a set of genes, originally seen in New Delhi, that confer resistance to practically all antibiotics. Even more alarming, these New Delhi genes reside on a circular piece of DNA called a plasmid that can be transferred easily to many other kinds of bacteria, rendering them “extensively drug resistant,” or XDR.
The CDC says only one antibiotic, called colistin, can treat the New Delhi strain.
While other forms of CRE have been seen in U.S. hospitals and nursing homes with increasing frequency over the past decade, the New Delhi variant is only beginning to show up.
“As these organisms become increasingly prevalent, treatment of health care-associated infections most likely will become more difficult or even impossible,” write Israeli physicians Mitchell Schwaber and Yehuda Carmeli in JAMA, the Journal of the American Medical Association..
If they become widespread, extensively resistant enterobacteriaceae “could make the hospital environment unsafe even to the general population undergoing simple and elective procedures,” Schwaber and Carmeli warn.
The recent case shows how these bad bug are spreading far from their Indian origins. A Cambodian woman who lives in Rhode Island visited her homeland last May. She became sick with what was eventually diagnosed as lymphoma. Last December, she was hospitalized in Ho Chi Minh City before flying home, where she was admitted to Rhode Island Hospital for a three-month stay.
In February, the woman suffered a bladder infection caused by a different drug-resistant bacterium. That turned out to be a lucky break — for the hospital if not for her — because it resulted in her being placed on special infection control precautions.
In March, an infectious disease doctor noticed the woman’s urine was cloudy – a sign of possible infection, even though she had no fever or other symptoms. Laboratory testing indicated a possible case of carbapenem-resistant Klebsiella, so the hospital sent a specimen to the CDC, which confirmed the diagnosis.
Fortunately, the woman’s immune system cleared the infection after the urinary catheter was removed. In other hospital outbreaks of the New Delhi bug, some involving hundreds of cases, up to 40 percent of patients have died. That’s a higher mortality rate than the notorious MRSA, or resistant staph.
The hospital did bacterial cultures on all the other patients on the cancer ward and found only one who had picked up the same strain of resistant Klebsiella, and that patient didn’t suffer obvious symptoms.
Mermel says there’s no sign that caregivers got infected. The hospital decontaminated the entire ward, since these germs can live on surfaces such as handrails as well as medical equipment.
Mermel says it’s been an upsetting experience. “I’m concerned, but with the large numbers of patients on that ward, we have not found it anywhere else,” he says.
This week the CDC updated recommendations to hospitals and nursing homes on how to deal with carbapenem-resistant Enterobacteriaceae. “Not only are these organisms associated with high mortality rates, but they have the potential to spread quickly,” the CDC warns.