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Technical Information — HAI and Antibiotic Use Prevalence Survey


Healthcare-associated infections (HAIs) are major causes of morbidity and mortality in the United States. A growing proportion of these infections are due to resistant pathogens such as methicillin–resistant Staphylococcus aureus and multidrug-resistant Gram-negative bacilli. To continue to develop effective strategies to prevent HAIs, reduce the prevalence of resistant pathogens, and support appropriate use of antimicrobial agents, it is essential to understand the burden of HAIs infections in U.S. hospitals and the types of HAIs and causative organisms, and to know the prevalence of antimicrobial use, the types of agents being used, and the rationale for their use.

Most hospitals participating in the CDC’s National Healthcare Safety Network (NHSN) focus on surveillance of device– and procedure–associated HAIs. This prevalence survey, which is the CDC’s first large–scale HAI prevalence survey in more than 30 years, will complement NHSN data by addressing all HAIs (including those that are not associated with a medical device or procedure) across all acute care inpatients, to inform local and/or national policies and help target HAI surveillance efforts.

This is also CDC’s first–ever, large–scale antimicrobial use prevalence survey among U.S. acute care inpatients. This information will help inform and target antimicrobial stewardship efforts.

Project Summary

This point prevalence (i.e., one day) survey project has been conducted in three phases.

  1. Phase 1 was a pilot survey conducted in 2009 in nine acute care hospitals in Jacksonville, FL. A major objective of Phase 1 was to test the survey design and data collection adequacy through a validation assessment. This phase is complete; results were presented at the Fifth Decennial International Conference on Healthcare–Associated Infections. Final results will be published in early 2012 in Infection Control and Hospital Epidemiology.
  2. Phase 2 was a limited roll–out survey conducted in 2010 in 22 acute care hospitals within the catchment areas of the 10 Emerging Infections Program (EIP) sites . This limited roll-out effort informed the design and conduct of the full–scale prevalence survey (Phase 3). Phase 2 is complete; preliminary results were presented at the 2011 Society for Healthcare Epidemiology of America annual meeting.
  3. Phase 3 is a full–scale survey conducted in 2011 in more than 180 acute care hospitals across the 10 EIP sites. Data collection for the Phase 3 survey is anticipated to be complete by December 31, 2011. Preliminary results are anticipated to be available in 2012.

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Surveillance Objectives

The objectives for the Phase 3 survey are as follows:

  • Estimate HAI prevalence in a large sample of U.S. acute care inpatients;
  • Determine the distribution of HAIs by pathogen (including antimicrobial-resistant pathogens) and major infection site across the spectrum of hospital locations; and
  • Estimate the prevalence and describe the rationale for antimicrobial use in a large sample of U.S. acute care inpatients.

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Phase 3 survey hospitals:

Each EIP site attempted to engage up to 25 randomly-selected hospitals within its catchment area. Healthcare facilities that were excluded were: specialty care hospitals , long term acute care facilities, rehabilitation and skilled nursing facilities, psychiatric hospitals, acute care units of other institutions (for example, acute care hospital units in prisons, universities or residential institutions), and federal healthcare facilities.

Phase 3 survey patient population:

A random sample of acute care inpatients in each participating hospital on the hospital survey date was included in the survey. Patients housed in the following locations were excluded: psychiatric units, rehabilitation units, skilled nursing or long-term care units, same–day treatment or surgery units, outpatient clinics, and emergency departments. Observation-status patients housed on an acute care inpatient unit were excluded if length of stay at the time of the survey was less than 24 hours.

Hospital participation was voluntary. A Primary Team (PT) consisting of infection prevention and other staff members in each facility participated in survey training activities conducted by CDC and the EIP sites. The PTs conducted the survey on a single day in their own facilities and collected a limited amount of demographic and clinical information on surveyed patients, including whether they were on antimicrobial agents at the time of the survey.

Records of patients who were identified by PT members as having been on antimicrobials at the time of the survey were reviewed in detail retrospectively by EIP surveillance officers to assess antimicrobial use and identify HAIs. HAIs were defined according to existing NHSN criteria (available at:

Data will be aggregated across participating facilities for analysis. Three measures of prevalence rates will be calculated:

  • prevalence of HAI, defined as the ratio of the number of HAIs to the total number of patients included in the survey sample;
  • the prevalence of patients with HAI, defined as the ratio of the number of patients with one or more HAI to the total number of patients included in the survey sample; and
  • prevalence of patients receiving antimicrobial agents, defined as the ratio of the number of patients receiving an agent to the total number of patients included in the survey sample.

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