A huge new study finds that about half of all patients in intensive care wards around the world are battling some kind of infection.

The study looked 1,265 intensive care units in hospitals in 75 countries, including Canada. In one 24-hour period in 2007, the researchers found that 51 per cent of the over 14,000 patients in ICUs that day had infections. Of those infected:

  • 60 per cent had pneumonias
  • 20 per cent were infections inside the abdomen
  • 15 per cent were infections of the urinary tract

The most common bacterial infection was caused by Staphylococcus aureus, including MRSA (Methicillin-resistant Staphylococcus aureus). E. coli and Pseudomonas were also common.

Countries in Central and South America had the highest infection rates while more developed countries such as Australia and New Zealand had the lowest rates.

The longer the patients stayed in intensive care, the bigger their risk of becoming infected, the findings suggest. The infection rate increased from 32 per cent for patients with an ICU stay of one day or less, to more than 70 per cent for patients with an ICU stay of more than seven days.

Not surprisingly, infected patients had longer ICU and hospital lengths of stay than those not infected, found the study, published in JAMA, the Journal of the American Medical Association.

Patients in ICUs who were battling infections were more than twice as likely to die than non-infected patients (25 per cent vs. 11 per cent). Their in-hospital death rate overall was also higher than non-infected patients (33 per cent vs. 15 per cent).

"Importantly, the incidence of sepsis is increasing, as is the number of consequent infection-related deaths," Dr. Jean-Louis Vincent of Erasme University Hospital in Brussels, Belgium and colleagues write.

It's been well-documented that infections can increase the risk of death in hospital. But the authors estimate they also account for about 40 per cent of total ICU health care costs.

Dr. John Marshall of St. Michael's Hospital in Toronto, one of the authors of the study, says the research gives a good picture of the scope of the problem worldwide.

"One of the things that this study actually allows us to do, is to begin to get a sense as to how much of the burden of infection is an added burden on a patient who is already at risk of dying because of the underlying diseases that led them to be in the intensive care unit," he said in a statement.

In an accompanying editorial, Dr. Steven M. Opal, of Warren Alpert Medical School of Brown University in Providence, R.I., and Dr. Thierry Calandra, of Centre Hospitalier Universitaire Vaudois and University of Lausanne in Switzerland, write that a number of the infections appearing in hospitals are cause for worry.

A form of bacteria known as gram-negative now account for 63 per cent of infections, they note, which is worrying since such infections were once on the wane.

"This is not a favorable trend, because resistance among gram-negative bacteria is increasing and the number of therapeutic alternatives to treat these infections is diminishing," they write.

There are a number of things doctors could do to limit infections in hospital, they write. Firstly, doctors should work to combat antibiotic resistance by limiting the use of antibiotics to patients who clearly have bacterial infections and then discontinue their use when their possible benefits have been obtained.

What's also needed are new, faster tests that can determine if a patient is really infected with bacteria.

"With few alternatives available, it is understandable why intensivists opt for liberal antibiotic use and rely heavily on these therapeutic agents to carry patients through critical illness to recovery," Opal and Calandra wrote.

But even more important, new drugs need to be developed to replace the increasingly obsolete classes of antibiotics that currently exist, they insist.

"Development of novel classes of antimicrobial agents is sadly lacking and needs to be a major research priority. New drugs are needed to replace the increasingly obsolete classes of antibiotics that currently exist," they write.

"A 'post-antibiotic era' is difficult to contemplate but might become a reality unless the threat of progressive antibiotic resistance is taken seriously."