Evolution of a Superbug
According to Becky A. Miller, MD, who presented study results at an oral session at the Fifth Decennial International Conference on Healthcare-Associated Infections 2010, hospital-onset, healthcare-associated Clostridium difficile infections (CDI) have increased in frequency. Now, C. difficile has passed methicillin-resistant Staphylococcus aureus (MRSA) infections in the race to be the most prevalent healthcare-acquired infection (HAI) in hospitals.
Since 2007, MRSA infection rates have steadily decreased, whereas rates of CDI have increased. The Duke University study noted the rate of nosocomial CDI as 0.28 cases per 1,000 patient days and the rate of nosocomial MRSA was 0.23 cases per 1,000 patient days. This means nosocomial CDI occurred 25 percent more frequently than nosocomial MRSA.
Since C. difficile spores are shed in stool, these spores can live in the environment for months. The infections are not being prevented by the same methods that are working for MRSA, and the fear is that the above study may only point to the tip of the iceberg since the surveillance did not include CDI cases occurring after discharge.
Changing the Picture
Compounding C. difficile issues in hospitals is the fact that new variants and strains of CDI have increased in virulence, decreased in their response to metronidazole therapy. This is not only happening in hospital settings, but in the community where cases are showing up in nonelderly populations. Even more significant, a number of these cases occurred in patients with no recent hospitalization or antibiotic use, according to a study based on the Rochester Epidemiological Project, released in a presentation for the American College of Gastroenterology 2009 annual scientific meeting. Probable causes for this change may include an older population, broader use of antibiotics and a new, more virulent strain of CDI, according to Darrell S. Pardi at the Mayo Clinic in Rochester, Minn., senior author on the study.
Some cases are proving more difficult to treat with the resistant strains that are emerging and where they’re coming from is not always clear-cut, as it could be overuse of antibiotics or under treatment, where patients aren’t taking their full course of antibiotics or even a novel change of the bacteria that is occurring.
Another study presented at the Decennial described the Mayo Clinic’s targeted strategy to eliminate C. difficile using ultra-germicidal bleach wipes. Before the intervention, the incidence of CDI was 18.4 per 10,000 patient days. After the intervention the incidence decreased to3.76 per 10,000 patient days.
Carlene A. Muto MD, medical director for infection control at the University of Pittsburgh School of Medicine, noted that there is a large undetected reservoir in patients who asymptomatically carry CDI. Many studies have cited non-compliance with patient room cleaning but one key to controlling CDI may lie in the practice of cleaning all surfaces this way rather than only the ones in rooms of patients known to be infected.
Compounding this difficult picture is the fact that common hand-hygiene products are often ineffective at killing CDI as the bacteria is sticky, similar to anthrax. The C.difficile spores have an exosporium that confers a particulate adherence-sticky chains of protein containing substances that stick on hands says Dale Gerding, MD, associate chief of staff, research and development coordinator for Edward Hines Jr. VA Hospital. These results reinforce the need for contact precautions, complete with gloves, for the care of these patients.
In 2010, the Society for Healthcare Epidemiology of America (SHEA) and the Infectious diseases Society of America (IDSA) released new Clinical Practice Guidelines for Clostidium difficile Infection in Adults. The guideline is designed to improve the diagnosis and management of CDI. In addition to diagnosis and management, recommended methods of infection control and environmental management of the pathogen are presented. Recommendations are based on the best available evidence and practices as determined by a joint expert panel appointed by SHEA and the IDSA.
A case definition of CDI should include symptoms (usually diarrhea) and either a stool test result positive for C. difficile toxins or colonoscopic findings demonstrating pseudomembranous colitis.
Clinical manifestations of infection with toxin-producing strains of C. difficile can be as varied as nonsymptomatic carriage, or mild to moderate diarrhea, or a fulminate and sometimes fatal pseudomembraneous colitis. Often, patients will have received antimicrobials within the 14 days before the onset of diarrhea and most will have received an antimicrobial within the previous three months. Fever, cramping, abdominal discomfort and a peripheral leukocytosis are common but found in fewer than half of patients.
The three ways a patient can be exposed to C difficile are:
• Contact with a healthcare worker with transient hand colonization
• Contact with a patient with CDI
• Contact with the contaminated environment
The risk of acquiring the disease during an admission, increases with time and can be as high as 40 percent during hospitalization. Hospitals often must adopt a prevention program that implements more than one method for minimizing exposure to C. difficile.
Infection prevention and control methods might include:
• Hand hygiene
• Contact precautions
• Modification of hospital layout
Hand hygiene is considered to be one of the cornerstones of prevention of nosocomial transmission of C. difficile as it is for many healthcare acquired infections. Studies have confirmed that handwashing will reduce infections, but studies have also revealed that healthcare compliance with hand hygiene is poor. Alcohol-based hand hygiene products have been viewed as a breakthrough for compliance and ease of hand hygiene. Unfortunately, the C. difficile spore is highly resistant to killing by alcohol. Mechanically washing with soap and water is much more effective, but even then only removes around 90 percent of the organism.
Contact precautions, private rooms and co-horting of patients with active CDI are methods that have had varied success. Adding in the use of gloves has also been a viable technique in the control of the spread of the disease due to the difficulty of removing the spores from hands without the use of heavy duty hand cleaners, which can’t be used routinely in healthcare settings.
APIC Releases a Nationwide Progress Poll
On May 19, 2010, the Association for Professionals in Infection Control and Epidemiology (APIC) released a national survey of infection preventionists. Of the hospitals that participated, most are using multiple strategies to address CDI. Other results include:
• 83 percent have hand hygiene initiatives
• 90 percent conduct surveillance or other methods and activities to promptly identify CDI cases
• 94 percent always place these patients on contact precautions, using gowns and gloves when caring for them
• 86 percent have increased their emphasis on environmental cleaning
Some areas of progress are not as evident. Only 30 percent of respondents monitor the number of colectomies at their institutions, which may indicate the more severe strain of CDI. Nearly a quarter of institutions do not monitor environmental cleaning effectiveness. Lack of resources and staff time seems to be the reason some measures have not been implemented.
Four in 10 respondents do not have an antimicrobial stewardship program, which is an important strategy due to the fact that 90 percent of patients with CDI have previously received antibiotics. The variation in some of practices identified in the CDI Pace of Progress Poll point out the need to improve standardization of prevention measures and guide future practices.
With the 2010 update of the SHEA and ADSA Clinical Practice Guidelines for Clostridium difficile Infection in Adults, a step forward has been made toward the standardization of diagnosis as well as preventive methods to control the spread of CDI.
It’s difficult to predict what the future will bring. The past decade has shown us the ability of the disease to become more virulent, as well as beginning to occur among unique populations, such as healthy pari-partum women , who have always been at very low risk for CDI. Consistency in the identification, treatment and prevention measures may be the key to controlling CDI. Constant, diligent surveillance will be essential in the effort to identifying new and changing strains or population demographic changes.
Public awareness of superbugs is at an all time high and affords healthcare the opportunity to extend education to the community outside the hospital setting, including visitors and discharged patients. The more visible the issue, the more opportunities we have to slow the spread of this disease as we have been able to do with MRSA. Any techniques we learn and implement now, will be available to help combat any future contenders for the superbug title.
Carol Shenold, RN, is an infection control practitioner and quality specialist, and works for the Oklahoma Foundation for Medical Quality. She has more than 40 years of acute-care experience, with 20 years in infection control. She had had multiple books and articles published in medical and trade publications, and she has branched out into fiction; her Tali Cates Mystery series is available on Amazon and Kindle.
Association for Professionals in Infection Control and Epidemiology (APIC) “Nationwide Progress Poll Reveals Increased Efforts by Hospitals to Control C. Difficile”: May 19, 2010, www.apic.org Accessed May 24, 2010
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