A 60-year-old man is admitted overnight for chronic obstructive pulmonary disease (COPD) exacerbation. While awaiting disposition on hospital day 10, the nurse reports that the patient is having copious amounts of loose stools that smell like C. diff. You order both the toxin A/B assay and glutamate dehydrogenase antigen, but only the toxin assay is positive. You then order a polymerase chain reaction (PCR) that ends up being positive, and you treat the patient with oral vancomycin for a C. difficile infection. Unfortunately, this scenario of a patient acquiring a new infection while hospitalized is exceedingly common and one that every clinical practitioner has encountered.
In this week’s issue of the NEJM, Magill and colleagues at the Centers for Disease Control and Prevention (CDC) present data on just how common health care–associated infections (HAIs) are in U.S. hospitals. They report that HAIs affected 3.2% of hospitalized patients in 2015, representing a 20% reduction from a similar 2011 survey. The investigators conducted point-prevalence surveys of HAIs in nearly 200 diverse U.S. hospitals and compared the 2015 and 2011 survey results. To capture a snapshot of the HAI burden, the data in these surveys represented one day of randomly selected admitted patients from the morning census. HAIs were defined as infections that were not present on admission and required antimicrobial therapy on that survey day. The authors acknowledged that the criterion of antibiotic therapy as a specific indicator of HAIs missed a portion of infections.
The reduction in the prevalence of HAIs was driven largely by reductions in surgical-site and urinary tract infections. In 2011, surgical-site infection was the most common HAI, but fell by 42% in 2015 to the third most common HAI. In 2015, the most common HAIs were pneumonia, followed by gastrointestinal infections, surgical-site infections, device-associated infections (e.g., central line–associated bloodstream infections), and urinary tract infections. The prevalence of C. difficile infections and hospital-acquired pneumonia (referred to as non–ventilator-associated pneumonia in this study) did not change significantly between the two surveys. (Of note, the Infectious Diseases Society of American eliminated the concept of health care-associated pneumonia (HCAP) in 2016 and despite the use of the term in this paper, the term hospital-acquired pneumonia (HAP) is now used to refer to pneumonia after 2 days of hospital admission.)
The lower prevalence of HAIs is encouraging and indicates that national attention and hospital initiatives to prevent nosocomial infections are succeeding. However, which initiatives (provider practice or hospital directives) caused the change are unknown due to the study design.
NEJM Deputy Editor, Dr. Lindsey R. Baden comments, “These data are quite provocative, suggesting improvements in some areas but not in others. A challenge in interpretation is the evolving definitions and clinical diagnostic approach for these HAIs such as new testing for C. difficile. The authors have tried to minimize these concerns but careful evaluation of temporal trends is required to enable the best approaches to further the improvements noted.”
Despite no reduction in the prevalence of HAP and our knowledge of the significant associated morbidity and mortality even with treatment, no clear guidelines currently exist to prevent HAP. How the medical community might be galvanized to preemptively reduce the risk for HAP in inpatients and whether effective methods even exist beyond patient positioning will remain of interest.
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Tenzing T. Lama, MD, MScRes, is a resident physician in the department of Anesthesiology and Pain Medicine at the University of Washington and a Fellow at the Ethics and Transformative Values Center at the Massachusetts Institute of Technology. He graduated from Harvard Medical School and Oxford. He is ultimately interested in an academic career in cardiac critical care with a research interest in mechanical circulatory support devices and nitric oxide.