Mapping C. difficile Exposures and Infections in the Hospital

Mitigating Clostridium difficile (C. difficile) infections are a challenging aspect of health care infection control. Prevention efforts cover an array of services and include strategies ranging from environmental services to laboratory guidance to antimicrobial stewardship, and more. New studies continue to highlight emerging preventive measures, such as the importance of patient involvement in hand hygiene efforts; however, the truth is that there are many pieces to the prevention of C. difficile infections and we continue to struggle to get a handle on this nuisance.

Hand hygiene, pathogen exposure, isolation technique, exposure to antibiotics, cleaning and disinfecting practices, and many other factors impact the spread of C. difficile throughout a health care facility. It would be valuable to learn exactly how this spore-forming organism moves through a health care facility. For example, if a patient with a C. difficile infection is in the emergency department and a non-infected patient comes in a few hours later, are they at risk?

Investigators on a new study sought to answer these questions through the use of spatial and temporal mapping of C. difficile to identify nosocomial transmission. During an evaluation of a large university hospital during one month in 2013 and 2015, investigators considered the space (emergency department, operating room, cardiology, ultrasound, etc) that was contaminated for 24 hours following a patient with C. difficile being in the space. Patients that were exposed (ie, passed through that space while it was considered contaminated) were followed for 60 days. If a patient developed C. difficile within 24 hours of their exposure, it was not considered related to the exposure (as the incubation period would be too short). The investigators used the hospital’s electronic medical records system and excluded patients who already had a C. difficile infection within the past year.

After reviewing 86,648 adult hospitalizations and a whopping 434,745 patient location changes during the study periods, the investigators found 1152 laboratory-confirmed cases of C. difficile. Those patients who were positive had moved through a mean of 4.2 hospital spaces (which also means they likely contaminated the spaces they moved through).

The investigators found that both exposure and risk of developing C. difficile infection following exposure tended to vary but being exposed in the emergency department computed tomography scanner (CT) area was significantly associated with developing C. difficile. Although not statistically significant, the incidence of C. difficile among exposed patients was also higher in nuclear medicine, and bone marrow transplant (BMT) and magnetic resonance imaging (MRI) suites.

All told, this means that those patients who visit a hospital emergency room CT after a patient with C. difficile has been in the space (within the last 24 hours), are at an increased risk of becoming infected themselves. This study is fascinating in that it addresses the role of environmental contamination and frequent patient movement within health care. Although I think the exposure window of 24 hours after the space was “contaminated” may be a bit short, given how tough disinfecting is and the inconsistencies in cleaning, this research gives new insight into higher risk areas for C. difficile transmission.