'Superbug' infects eight patients at Phila. hospital

A Philadelphia hospital was struck last year by an outbreak of drug-resistant bacteria associated with the use of a special kind of hard-to-clean endoscope, according to city data.

Eight people examined with the scopes became infected with bacteria resistant to a class of last-resort antibiotics called carbapenems, and two died, the city Department of Public Health said. These "superbug" bacteria have an estimated mortality rate ranging from 25 percent to 50 percent in those infected. But both of the Philadelphia patients who died had serious underlying conditions, so their deaths were deemed "not clearly related" to the infection, department spokesman Jeff Moran said.

Such bacteria also can be spread through contact with the skin and other surfaces in health-care settings, and evidence suggests they are becoming more common.

In a December 2012 Health Department survey, 11 hospitals reported that in the previous year, they had at least one case - meaning a patient who was either infected with carbapenem-resistant bacteria or was "colonized" with them but did not get sick. Five of the 11 reported more than 20 cases.

"It is a more prevalent problem than most people realize," said Caroline Johnson, director of the department's division of disease control.

The survey did not ask whether the infections were acquired at the hospital, whether via an unclean endoscope or other means. But the scopes - complex instruments called duodenoscopes that are used to diagnose and treat problems in the bile ducts and pancreatic ducts - are coming under increasing scrutiny. They have been linked to outbreaks elsewhere in recent years, including in Seattle, Pittsburgh, and the Chicago suburb of Park Ridge.

"This is a real public-health problem," said biomedical engineer Lawrence Muscarella, a Montgomeryville infection-control consultant who has been urging the Food and Drug Administration to toughen recommendations on device design and cleaning.

The FDA has not issued any official alert about the devices but said it was working with manufacturers to come up with ways to minimize risk.

"The design of the duodenoscope can increase the difficulty in cleaning," the agency said in a statement.

Among other steps, instructions call for the scopes, which typically cost about $40,000, to be thoroughly brushed and rinsed, followed by treatment with a liquid chemical germicide. In its statement, the FDA said strict adherence to these steps should reduce the infection risk.

Yet some hospitals have decided to go beyond what is recommended with a more time-consuming method called gas sterilization, said Chris Lavanchy, engineering director at the ECRI Institute, a Plymouth Meeting nonprofit organization that evaluates medical devices.

"The thinking is that the gas may permeate areas where the liquid can't get to," Lavanchy said.

Among the devices' tough-to-clean features are their narrow channels and intricate mechanisms, which can develop cracks or imperfections over time, Lavanchy said.

He cautioned that the need for gas sterilization had not been established, and that the institute was reviewing evidence and coming up with guidelines for hospitals. A query sent to Philadelphia-area hospitals through the Hospital Association of Pennsylvania did not turn up any local facilities that use the gas technique.

Duodenoscopes are used in 500,000 procedures a year in the United States, according to a coalition of professional societies whose members have expertise in endoscopes. The groups, which include the American Society for Gastrointestinal Endoscopy, said they were aware of fewer than 100 cases in which carbapenem-resistant bacteria had been transmitted by the scopes in the last few years.

Johnson declined to identify the Philadelphia hospital with infections linked to the scopes, saying the city did not want to discourage facilities from reporting cases.

She warned that the number of cases was likely higher than reported, in part because some hospital labs lack the sophistication to identify the bacteria in question.

"A place who tells you they have no cases may or may not really have no cases," Johnson said.

Manufacturers of the devices include Fujifilm, Pentax Medical, and Olympus, all of which have said they are working with the FDA.

During an examination, the patient is typically sedated and the scope is inserted in the mouth, down the throat, and into the stomach and duodenum.

The Pennsylvania Health Department does not require reporting of carbapenem-resistant infections. New Jersey does, but no outbreaks have been reported there in the last three years, said Donna Leusner, spokeswoman for the state Health Department.

Philadelphia health officials say five other clusters of cases were reported at city nursing homes in the last three years, not linked to any identifiable source.

The bacteria are resistant because they have evolved the ability to make an enzyme that destroys carbapenem antibiotics, said Henry Chambers, director of clinical research services at the University of California, San Francisco. They include certain strains of E. coli and another microbe, Klebsiella.

A healthy person is likely to be able to ward off the bacteria, even if it enters the gastrointestinal tract. That is because the microbe expends extra energy to make the enzymes that confer drug resistance, and therefore grows more slowly than most gut bacteria and is "outcompeted," said Chambers, chair of the antimicrobial resistance committee for the Infectious Diseases Society of America.

But in a hospital patient who gets antibiotics, regular gut bacteria are largely wiped out, giving the drug-resistant variety a clear shot at proliferating.

"These guys are the ones left standing," Chambers said, calling them "the cockroaches of the microbial world."

Then, he said, if the patient has a catheter inserted, gets a break in the skin, or is put on a ventilator, the suddenly dominant bacterium can invade the lungs or bloodstream, with dire consequences.

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Inquirer staff writer Tom Torok contributed to this article.