Healthcare Acquired Infection: Finding Silent Clostridium difficile Carriers

Easy TargetClostridium difficile (C. diff) is a serious healthcare acquired infection often carried by those who don’t present any symptoms.

Universal screening is costly, invasive, and controversial. Thus, identifying likely carriers early is highly desirable.

Similarly, identifying patients at risk of developing an infection can aid in monitoring and diagnosis. Two recent studies indicate the potential for efficient screening and improved infection control by identifying risk factors.

Researchers from the Mayo Clinic studied asymptomatic adults admitted to a tertiary care hospital over a two month period, sampled them for C. diff infections. The study, published in the American Journal of Infection Control, described how the team identified three independent risk factors that were present in 48 percent of their study participants:

  • Recent hospitalization
  • Chronic dialysis
  • Corticosteroid use.

The researchers found that screening only those patients with one of those risk factors would identify 74 percent of the C.diff carriers. The hope is that more efficient screening of carriers at admission can reduce overall incidents of infection.

The journal BMC Medicine contains a study by University of Michigan Medical School researchers that found that adults who suffer from major depression have a 36 percent increased risk of developing a Clostridium difficile infection. Patients who take Remeron® or Prozac®, two common antidepressants, are twice as likely to develop a C. difficile infection.

Most other types of antidepressants did not affect risk of infection. The authors cautioned that patients should not stop taking antidepressants unless they are advised to do so by their physician.

The same study found that widowed adults had a 54 percent higher likelihood of infection than married peers, which the authors posited may have some connection to depression. More research is needed to determine whether the increased risk is caused by intestinal changes during depression or by the medications.

 

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Is that C. diff you sniff? Good dog!

Implementing a canine-based monitoring system for early detection could help control the spread of the infection.It’s no secret that the canine sense of smell is much more sensitive than our own. Now researchers in the Netherlands have shown how that sensitivity can be applied to identification and diagnosis of Clostridium difficile with remarkable accuracy. More importantly, implementing a canine-based monitoring system for early detection could help control the spread of the infection.

The research paper in the British Medical Journal, Using a dog’s superior olfactory sensitivity to identify Clostridium difficile in stools and patients: proof of principle study, describes how a 2-year-old beagle was trained to differentiate known C. diff-infected stool samples from controls. Further, the researchers trained the dog to sit or lie down when C. diff was detected.

The dog’s accuracy was very impressive: sensitivity and specificity were both 100% using samples in the lab. On detection rounds, he correctly identified 25 of the 30 known cases, and 265 of the 270 controls. The paper estimates that most cases of C. diff take 2-7 days to diagnose and start treatment, and suggest that a regular program of canine detection rounds could lead to earlier detection and treatment.

Looking forward to seeing how else you can help, Dr. Dawg.

Vitamin D vs. HAIs

Can something as simple as vitamin D help reduce healthcare-associated infections? A review by Youssef et al.1 published this past spring in the journal Dermato Endocrinology makes a strong case that it could.

Vitamin D can play an antimicrobial role, as it can reduce local and systemic inflammatory responses, and strengthen the body’s immune response. Those mechanisms may be especially important in dealing with antibiotic-resistant bacteria. At the least, vitamin D may be able to reduce inappropriate antibiotic prescriptions, and boost therapeutic response in combination with appropriate antibiotics.

Citing vitamin D’s low cost, especially when compared to the added cost of HAIs, the authors suggest checking vitamin D status when patients are admitted to a hospital and addressing insufficiencies. Many patients have lower than average levels of vitamin D on admission.

According to the studies referenced in the article, vitamin D deficiency is associated with worse outcomes and higher costs for patients with bacteremia, bacterial sepsis, pneumonia, Clostridium difficile, Catheter-associated urinary tract infections, surgical site infections, and virulent organisms like MRSA. Proving causality is obviously a higher benchmark, but this review indicates the value of more research to determine vitamin D’s antimicrobial properties, and whether vitamin D should be a common tool in the multifaceted approach to addressing HAIs.

In the meantime, it looks like Mom was right again: Drink your milk, get some sunshine, and pay attention to your vitamin D levels.

 

1Youssef D, Ranasinghe T, Grant W, Peiris A. Vitamin D’s potential to reduce the risk of hospital-acquired infections. Dermato-Endocrinology 2012; 4:167 – 175; http://dx.doi.org10.4161/derm.20789.

Healthcare Associated Infections in Perspective

To get a sense of the overall scope of the HAI problem, it may help to look at some of the measurable goals and the progress towards those goals. As we consider the size and impact of healthcare associated infections (HAIs) in the only ways those factors can actually be measured, we want to acknowledge that the medical, financial, and emotional cost of HAIs to individuals and families is incalculable.

A quick look at the metrics explain why the effort to prevent HAIs is so compelling on economic as well as moral grounds:

  • 5% (1 in 20) of all hospitalizations in the U.S. result in HAIs 1
  • 1.7 million HAIs result in 100,000 deaths in the U.S. every year
  • Annual U.S. direct medical costs due to HAIs is in excess of $28 billion1
  • 8.7% (~1 in 12) of all hospitalizations worldwide result in HAIs2
  • 30% of intensive care (ICU) patients in high-income countries are affected by HAIs. Low- to middle- income countries could easily see double that rate.2

In other words, in the U.S. HAIs cause more deaths than AIDS3, breast cancer4, and auto accidents5 combined. The extra direct medical costs in the U.S. could pay for about half of the government’s spending for Medicare Part D6 (prescriptions).

It’s worth noting that dollar costs are generally stated as direct medical costs including treatment and resource costs of extended hospital stays due to HAIs. Some economists7 would argue, though, that including the opportunity costs of those resources—the value of their alternative uses—yields a more accurate assessment. The opportunity cost argument would increase the economic burden from HAIs, and would thus justify higher expenditures to prevent infections.

Progress

HAIs are indeed a huge and complex problem, and many groups and government agencies are working on solutions. The U.S. Department of Health and Human Services is shepherding an effort to prevent and ultimately eliminate HAIs. Created in 2009, The National Action Plan to Prevent Healthcare-Associated Infections: Roadmap to Elimination contains five-year targets for reduction of infections or hospitalizations in several areas, and the update reports progress as of October 2011.

A few areas are on track to meet 2013 targets:

  • Central-line associated bloodstream infections should be reduced by 50%
  • Catheter-associated urinary tract infections should be reduced by 25%
  • Surgical site infections should be reduced by 25%
  • MRSA bacteremia data is not yet available, but rates have shown progress towards the 25% reduction goal

But one key area has shown less progress toward the reduction goal:

  • Clostridium difficile infections have leveled off, but not decreased, so a 30% decrease by 2013 seems unlikely.

A quick look at that plan’s executive summary confirms the HAI problem’s complexity and the resulting need for a multifaceted approach:

  • Hand hygiene
  • Equipment sterilization
  • Isolation
  • Environmental service protocols
  • Staff and consumer education
  • Surface sanitation
  • Antimicrobial surfaces

All of the above are important elements of the solution. Hand hygiene is essential, but alone it’s not sufficient to the task of preventing HAIs.

Steady progress towards reduction goals in most of the measures is encouraging. However, such progress is rarely linear or easy to predict: the most easily achieved results come early in the process, and the rest is often slower to realize. Even if and when HAIs are eliminated, constant vigilance and renewed effort will be required to avoid recurrence or new infections from new sources.

 

1 U.S. Centers for Disease Control and Prevention

2 World Health Organization

3 Centers for Disease Control and Prevention, (CDC) (2011 Jun 3). “HIV surveillance–United States, 1981-2008.”. MMWR. Morbidity and mortality weekly report 60 (21): 689-93. PMID 21637182

4 American Cancer Society. Cancer Facts & Figures 2012. Atlanta: American Cancer Society; 2012.

5 ^ “FARS 2010″. National Highway Transportation Safety Administration.

6 Health Care Spending and the Medicare Program – A Data Book – June 2012 Medicare Payment Advisory Commission

7 Graves N. Economics of preventing hospital infection. Emerg Infect Dis [serial online] 2004 Apr [date cited]. Available from: http://wwwnc.cdc.gov/eid/article /10/4/02-0754.htm