Contributed Commentary by Brian Harrel
March 5, 2019 | It is no secret that Clostridium difficile infections (CDI) are a serious threat to public health. This often-deadly pathogen is the leading cause of healthcare-associated infections in the United States, representing nearly 500,000 cases annually. It is imperative that we find effective ways to curb its transmission, particularly within hospitals and other healthcare facilities, in order to improve patient outcomes and overall human health.
Existing guidelines for testing possible CDI cases restrict the use of molecular diagnostics to very specific patient profiles. However, new studies have begun to demonstrate that a broader approach to C. difficile testing—comprehensive screening of patients admitted to hospitals—could offer significant progress toward reducing the incidence of nosocomial transmission.
Modifying the way molecular diagnostics are used for this pathogen could dramatically reduce the number of people infected with C. difficile by allowing earlier identification and mitigation steps that can limit its ability to spread. Since these infections often lead to chronic health problems or even death, any reduction in incidence would provide a major improvement to human health.
Current Guidelines
In recent years, the guidelines for C. difficile testing have changed. The guidance issued last year by the Infectious Diseases Society of America and the Society for Healthcare Epidemiology of America recommends using molecular diagnostics in a fairly narrow way. The primary driver behind this decision is that molecular tests cannot differentiate between cases where C. difficile is the causal pathogen and where it is a harmless member of the patient’s intestinal microbiome.
To avoid overdiagnosis of CDI, these guidelines suggest using molecular diagnostics only when healthcare professionals have reason to believe the patient is suffering from an active CDI. This is typically when a patient has recently undergone antibiotic treatment or has experienced the onset of symptoms after being admitted to the hospital for a number of days. In these cases, the rapid turnaround time for a molecular assay is a great advantage for guiding isolation and treatment.
Screening Studies
While clinical guidelines focus on verifying detection of active C. difficile infections, they fail to offer guidance about how to use molecular testing to rein in the spread of this pathogen within healthcare facilities.
To address nosocomial infections, many clinical research teams have formulated testing algorithms to screen for, rather than diagnose, potentially infected patients. Some studies indicate that nearly 30% of people may be asymptomatic carriers of C. difficile. These carriers represent a tremendous reservoir of infection potential when admitted to a hospital, and some reports indicate that these people increase the risk of CDI for those patients who come into close contact with them.
In two recent studies that looked at thousands of patients, clinical researchers tested the hypothesis that isolation of asymptomatic C. difficile carriers from the rest of the hospital population would reduce the transmission of this pathogen. Molecular diagnostics were used to identify carriers upon admission to a healthcare facility, and in both cases, the results demonstrated that universal screening paired with isolation protocols resulted in significantly reduced C. difficile transmission.
In one of those studies, conducted at an acute-care facility in Canada, results showed that rates of healthcare-associated C. difficile infections dropped by more than half after the implementation of screening and isolation protocols. The team determined that the new approach prevented more than 60% of nosocomial CDI, which translated into a savings of as much as $627,000 in patient care costs during the course of the study.
A similar study conducted at two university hospitals in Denmark also showed a decrease in nosocomial transmission of C. difficile from carriers once screening and isolation protocols were in use. In this study, the overall rate of CDI dropped from 4.6% to 2.6%, a 43% decrease.
Looking Ahead
Based on the data in these studies and others, the case for screening patients for CDI continues to gain strength. The potential opportunity to positively affect patient health through reductions in the nosocomial transmission of C. difficile is an exciting development that should be weighed carefully when considering the use of molecular testing in a clinical setting. As antimicrobial stewardship continues to drive clinical practice, it is likely that C. difficile screening will have an important role to play as hospitals strive to achieve their patient outcome and economic goals with regard to nosocomial infections.
While the decision to screen for C. difficile must ultimately rest with hospital leaders who understand their unique patient populations, molecular screening for this pathogen appears to offer a real opportunity to decrease the overall burden of nosocomial infections in many healthcare settings.
Brian Harrel, MS, serves as Global Product Marketing Manager at Luminex. He can be reached at bharrel@luminexcorp.com.