TORONTO — A Montreal hospital has been battling for the last year to extinguish an outbreak with a worrisome and highly drug-resistant bacteria.
The outbreak at the Jewish General is the first in Canada caused by this strain of the bacteria, a bug that has sparked serious concern because of how easily it spreads and its ability to transfer resistance to other bacteria.
A report on the outbreak was presented in Chicago on Sunday to the Interscience Conference on Antimicrobial Agents and Chemotherapy, a major annual gathering of infectious diseases specialists.
Dr. Mark Miller, head of infection control at the Jewish General, said the outbreak has been brought under control, but a few patients with the bacteria are still being treated in the hospital.
The outbreak was caused by Klebsiella pneumoniae, which is normally found in the human intestine. In healthy people, these bacteria can live in the intestine without causing illness. In hospitals, however, they can cause a range of infections, including pneumonia, bloodstream infections and urinary tract infections.
Klebsiella pneumoniae traditionally have been treated with antibiotics called carbepenems. But in the last decade or so, a strain of the bacteria has developed that is resistant to this class of drugs. To make matters worse, the genetic component that gives Klebsiella pneumoniae this resistance has the capacity to transfer into other bacteria, making them resistant to these drugs as well.
The strain with this component is called KPC-producing Klebsiella pneumoniae, and it has even more tricks in its arsenal. The gene that makes it resistant to carbepenems is packaged in a cassette of genes that confer resistance to a number of other antibiotics.
Miller said the version that slipped into his hospital could only be treated with two antibiotics — an old drug with serious side-effects and a newer drug. He and others worry about the day they will find KPC that responds to no drugs at all.
That has happened. In fact, the Ottawa Hospital had three cases of KPC-producing Klebsiella pneumoniae in 2008, one of which was resistant to all antibiotics.
Microbiologist Marc Desjardins said the Ottawa Hospital was lucky — the three cases didn’t spark an outbreak. (One patient caught the bacteria from one of the other two, but there was no sustained spread in the hospital.) But the patients were hard to treat and for one, nothing worked.
“The bug was resistant to everything. There was absolutely not a single antibiotic we could give that patient,” Desjardins said. The woman, who had other grave health problems, eventually died.
Battling bacteria that are not susceptible to any antibiotics is a nightmare scenario, he admitted.
“At least in serious infections, there is hope to actually treat the infection. With KPCs, if your organism is resistant to everything, we currently in our baggage of antibiotics have nothing available to treat them,” Desjardins said.
“The only thing to do is to use combinations (of antibiotics) and hope.”
KPC was first spotted in North Carolina in 1998. Since then, bacteria with this factor have spread widely. Hospitals in Israel and Greece have battled the problem. In the United States, New York state has experienced a lot of KPC outbreaks.
Canada first started to look for KPC in 2009, said Dr. Michael Mulvey, head of the division of antimicrobial resistance and nosocomial (hospital-acquired) infections at the Public Health Agency of Canada. Since then, surveillance has spotted 80 cases, a figure Mulvey thinks is probably an underestimate.
Most have been isolated cases, though another Quebec hospital has battled an outbreak, Mulvey said. He would not disclose the location or the name of the facility.
“The risk to Canadians right now is very low,” Mulvey insisted.
“But in the hospitals, we’re always concerned about antimicrobial resistance, especially in the very ill patients that are immunocompromised. And the fact that these are multi-drug resistant and the odd one is now pan-resistant, it certainly is a concern in the hospitals.”
At the Jewish General, the first KPC case was discovered in August of last year. Since then, 27 patients have tested positive for it. Some died, though Miller said it was a judgment call as to whether the bacteria caused their deaths or merely contributed to their decline. He would not say how many KPC patients had died.
“We’ve been truly impressed,” Miller said of the bacteria’s ability to spread from person to person and the facility with which it shares its resistance capabilities with other bacteria in its general class.