Originally published in September 2019 by researchers at the University of California, San Francisco. Updated in October 2024 by PSNet’s editorial team. PSNet primers are regularly reviewed and updated by the PSNet Editorial Team to ensure that they reflect current research and practice in the patient safety field. 

Background

Healthcare–associated infections (HAIs) are among the most common complications of hospital care. More than one million HAIs occur across the United States healthcare system every year. According to a study by the Centers for Disease Control and Prevention (CDC), at any given time, approximately 1 of every 31 hospitalized patients in the United States has an HAI, meaning that approximately 633,300 patients contract one of these infections annually. In 2023, the Pennsylvania Patient Safety Reporting System received 23,970 HAI reports from long-term care facilities in Pennsylvania. These infections can lead to significant morbidity and mortality, with tens of thousands of lives lost each year. HAIs are estimated to cost billions of dollars annually. Such infections were long accepted by clinicians as an inevitable hazard of hospitalization and in-patient care. However, it is now understood that relatively straightforward approaches can prevent many common HAIs. As a result, hospitals, nursing homes, and clinicians are prioritizing efforts to reduce the burden of these infections. Fortunately, considerable progress has been made in preventing specific HAIs through federally sponsored programs from AHRQ, CDC, and the Centers for Medicare and Medicaid Services (CMS).

Surgical site infections (SSIs) and infections associated with indwelling devices—ventilator-associated pneumonia (VAP), central line–associated bloodstream infections (CLABSIs), and catheter-associated urinary tract infections (CAUTIs)—have historically accounted for a large proportion of HAIs, but recent data indicates that the epidemiology of HAIs is evolving. The CDC's 2011 data indicate that infections associated with specific indwelling devices (CLABSI, CAUTI, and VAP) and SSIs account for approximately half of all HAIs. Infections caused by the bacterium Clostridium difficile have rapidly become more common in hospitals, and C. difficile is now responsible for more than 12% of all HAIs. Preventing transmission of C. difficile and antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) is therefore an increasing focus of attention.

The COVID-19 pandemic introduced new, urgent HAI concerns. Personal protective equipment shortages, the built environment, and rapidly changing evidence surrounding transmission of the disease contributed to early nosocomial spread of COVID-19. Older adults living in long-term care facilities were hit especially hard, with CMS reporting 172,753 nursing home resident deaths as of September 2024. 

In addition to healthcare-acquired COVID-19, the pandemic challenged existing HAI-prevention efforts. In a 2021 survey, infection prevention professionals in US hospitals reported CLABSI and VAE prevention practices increased or remained the same during the pandemic, but use of CAUTI prevention practices decreased. According to data reported to the National Healthcare Safety Network, the incidence of healthcare-associated infections increased from 2019 to 2020, the first year of the pandemic.

Prevention of HAIs

A cornerstone of HAI prevention is appropriate hand hygiene. Although the effectiveness of simple hand washing in preventing infection transmission has been known for decades, until recently hand hygiene rates among all clinicians were low. Strategies to improve hand hygiene that rely on traditional educational approaches as well as enhanced monitoring of hand hygiene, feedback on hand hygiene practice in a facility, and sociocultural approaches have resulted in improved hand hygiene at many hospitals and other healthcare facilities. What's more, strong evidence links higher hand hygiene rates to lower overall HAI rates.

The CDC has evidence-based guidelines that detail methods to prevent specific HAIs in the inpatient and outpatient setting. The challenge has been making it easy for clinicians and healthcare executives to establish and adopt the recommended methods as standard practice in healthcare delivery organizations. Organizations that successfully overcome this obstacle represent some of the major successes of the patient safety movement. For example, the development and implementation of the AHRQ-supported Comprehensive Unit-based Safety Program (CUSP) has brought about significant advances in HAI prevention. CUSP combines improvement in safety culture, teamwork, and communications, together with a checklist that incorporates a manageable set of evidence-based measures to prevent a particular HAI. The implementation of CUSP to prevent CLABSI has resulted in dramatic nationwide reductions in these serious infections, thanks in part to AHRQ-funded research and dissemination programs that fostered the use of CUSP in intensive care units across the country. Conceptually similar approaches have also been successful in reducing rates of SSIs, and AHRQ funded a large nationwide effort to promote the use of CUSP to reduce rates of CAUTI. The combination of improvement in organizational culture and use of the checklist has powered the reductions in CLABSI that have been achieved. In-depth analysis of the project has identified other important components of the program, such as rigorous data measurement and feedback and reframing of CLABSI as a social problem in a clinical environment.

The increasing threat posed by infections such as C. difficile is also stimulating efforts to address this issue. Strategies to prevent C. difficile infections primarily involve limiting antibiotic use (a major cause of these infections), particularly through antibiotic stewardship programs, preventing patient-to-patient transmission of the bacteria through isolation procedures and hand hygiene, and increased and improved cleaning of the environment of care including patient rooms. Toolkits to help hospitals establish antibiotic stewardship programs directed to C. difficile have been developed and disseminated. Prevention of transmission of antibiotic-resistant bacteria follows similar principles.

Current Context

The large burden of disease posed by HAIs has resulted in considerable regulatory attention. CMS has put limits on reimbursement for the costs of care associated with certain HAIs since 2008. Reducing the risk of HAIs is a Joint Commission National Patient Safety Goal (NPSG). The NPSG specifically requires adherence to hand hygiene practices and also considers death or serious disability due to an HAI to be a sentinel event (not primarily related to the natural course of the patient's illness or underlying condition). Appropriate hand hygiene, influenza vaccination for healthcare workers, and prevention of VAP, CLABSI, and SSI are among the National Quality Forum's 30 Safe Practices for Better Healthcare.

Publicly reported hospital-specific HAI rates are also being more widely utilized to monitor hospital quality of care. CMS publicly reports certain HAI rates on its Hospital Compare website. The effect of these policies, as well as the CMS nonpayment policy for HAIs, remains unclear. A 2013 study found that statewide mandatory reporting of CLABSIs did not appear to have any effect on infection rates. Another study found that the CMS "no pay for errors" policy had no measurable effect on rates of CLABSIs and CAUTIs in hospitals, and another found that few hospitals were actually denied payment due to CAUTI.

One important challenge in using public reporting and payment policies to catalyze efforts to decrease HAIs is that the definitions are complex and may be subject to interpretation by healthcare providers. The CDC's National Healthcare Safety Network (NHSN) has developed standard, auditable definitions for common HAIs in order to standardize reporting of infection rates and allow for more accurate comparison of infection rates between hospitals and tracking of infection rates over time.

As standardized measurement strategies and quality and safety interventions are adopted by more providers and systems, there is now evidence that shows more patients are being protected from HAIs. The most recent data from the Partnership for Patients Initiative indicates that the overall rate of Hospital-Acquired Conditions (HACs) decreased by 8% between 2014 and 2016, representing more than 220,000 adverse events prevented in adult patients during that time period. This includes reductions in several types of HAIs, including central line–associated bloodstream infections, Clostridium difficile diarrhea, and ventilator-associated pneumonia.