More on CDIs

If there is a pathogenic face to antibiotic resistance, it's MRSA, or methicillin-resistant Staphylococcus aureus. It can be gross and gory, affects both the elderly in nursing homes and children on athletic teams, and causes more deaths in the U.S. each year than AIDS. But is it the infection you should be most worried about during a hospital stay?

New research suggests that Clostridium difficile infections (CDIs) may be overtaking MRSA as the most threatening of the antibiotic-resistant infections the American healthcare system faces. Scientists affiliated with Duke's Infection Control Outreach Network (DICON) presented a study at last weekend's Fifth Decennial International Conference on Healthcare- Associated Infections that found CDI rates in excess of MRSA infections in community hospitals in the Southeast United States. In this group of 30 hospitals, which were monitored from January 2008 through June 2009, C. difficle was the leading healthcare-associated infection (HAI). C. difficile beat out MRSA, 612 cases (0.26 per 1,000 patient-days) to 505 cases (0.22 per 1,000 patient-days).

Previous studies also suggest that the mortality rate for CDI is higher than MRSA. But it's also possible that CDI is more preventable, because it is so closely linked to previous antibiotic usage in each individual patient, and largely confined to healthcare settings (except in pediatrics - see "CDIs Increasing in Children" below). This is one case where effective infection control and prevention strategies, as well as public education, could go a long way. You can learn more about C. difficile from the CDC and the Mayo Clinic.

CDIs Increasing in Children

New research published in Emerging Infections Diseases suggests a more than 80 percent increase in the number of childhood hospitalizations due to Clostridium difficile between 1997 and 2006. The study (ahead of print, see pdf here), led by Marya Zilberberg, drew statistics from multiple databases of pediatric hospitalizations. In the ten years examined, the number of children hospitalized for C. difficile infection (CDI) increased from 7.24 per 10,000 hospitalizations to 12.80. In 1997, there were 4,626 pediatric hospitalizations for CDI, compared to 8,417 in 2006 – an average increase of 9 percent each year.

In that time, practitioners have also recognized the spread of a more virulent form of C. difficile that causes more hospitalizations and has elevated case-fatality rates. CDIs are almost exclusively hospital-acquired; they do not affect healthy people in the community. C. difficile is a common, generally harmless commensal bacteria. But in patients taking long-term, low doses of antibiotics, changes in bacterial communities can offset the microbial balance and allow C. difficile to run rampant in the system. And the symptoms of CDI – diarrhea and a range of intestinal conditions – make it especially dangerous in a hospital setting, where it can be unwittingly transferred by patients and practitioners or through contamination in the environment. CDI is costly for both patients and hospitals – an IDSA/SHEA report cites a $3.2 billion annual price tag for U.S. hospitals for CDI management, and a 16.7% one-year mortality rate for patients. It’s also complicated to eliminate from the environment because as a spore-forming bacteria it can withstand treatment with alcohol-based cleaning products.

But while CDI in adults consistently shows up in healthcare settings following antibiotic treatment, its epidemiology appears to be different in children. Many cases of pediatric CDI, Zilberberg and her colleagues explain, are community-based in origin with no recent history of antibiotic treatment. In addition, many neonates are colonized with C. difficile but do not get sick, whereas cases of CDI jump to 32.01 per 10,000 hospitalizations for non-newborns less than one year old and peak in children aged one to four. In light of their observed increases in CDI and as a more virulent strain predominates, the authors call for more research on C. difficile, especially targeted at this non-newborn infant population.