A survey of hospitals and clinics in and around Chicago in the US found a 30 per cent rise in reported infections between 2009 and 2010 of a potentially deadly group of bacteria that is resistant to the most commonly used antibiotics.

KPC-producing bacteria were first identified on the east coast of the US in 1999, since when they have been gradually making their way across the country.

Researchers at Rush University Medical Center in Chicago, and the Cook County Department of Public Health who conducted a survey of Chicago-area healthcare facilities said that the incidence of KPC-producing bacteria is rising.

They presented their findings on Friday 22 October at the 48th annual meeting of the Infectious Diseases Society of America in Vancouver.

Although the number of infections is still low, the steep increase is still worrying, considering that Chicago’s first identified case was in December 2007, said the researchers.

KPC stands for Klebsiella pneumoniae carbapenemase, an enzyme produced by variants of the common bacteria Klebsiella pneumoniae that live on the skin and in the mouth and guts of humans and can cause pneumonia and urinary tract infections.

Dr Mary Hayden, director of clinical microbiology and associate professor of infectious diseases and pathology at Rush University Medical Center, told the press that:

“KPC-producing bacteria are a common type of bacterium that has evolved into a dangerous source of infection and a major challenge for infection control.”

“Infections due to these bacteria are difficult to treat because most strains are resistant to the majority of our usual antibiotics,” she added, pointing out the alarming fact that “some strains are resistant to all drugs”, including those used when all other treatments fail.

“Since antibiotics are virtually ineffective against these bacteria, prevention is key,” said Hayden, explaining that infection is often linked to high mortality. She mentioned a study where researchers found patients infected with KPC-positive bacteria were three times more likely to die as patients infected with similar bacteria that did not produce KPC.

In their survey, Hayden and colleagues found that between 2009 and 2010 the number of healthcare facilities in Chicago that reported infections of KPC-producing bacteria went up from 26 out of 54, to 37 out of 57, a rise of 30 per cent, and the average number of patients who tested positive for the superbug at each facility nearly tripled, from 3.8 to 10.2.

They also found that three quarters or more of the patients found with the superbug had been in a nursing home or other long-term care facility.

Hayden said an important way to control the spread of the superbug is coordination between long-term care facilities and acute-care hospitals, since patients infected with it are often transferred between the two. Contact isolation is key to stopping the bacteria spreading.

Once it gains a foothold, the superbug can spread very quickly to other parts of a geographic region. It took only a few years for a major outbreak to occur in Israel after the first case was identified.

According to the US Centers for Disease Control and Prevention (CDC), Klebsiella can spread through person-to-person contact and from patient-to-patient on the hands of healthcare workers: it does not spread through the air.

The bacteria must get into the respiratory system to cause pneumonia, or the blood to cause a bloodstream infection. Hospital patients can become infected when they are on ventilators or have intravenous catheters or wounds (caused by injury or surgery).

Klebsiella rarely infects healthy people.

Sources: Rush University Medical Center, CDC.

Written by: Catharine Paddock, PhD