Intervention to reduce transmission of resistant bacteria in intensive care

Abstract

Background: Intensive care units (ICUs) are high-risk settings for the transmission of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus (VRE).

Methods: In a cluster-randomized trial, we evaluated the effect of surveillance for MRSA and VRE colonization and of the expanded use of barrier precautions (intervention) as compared with existing practice (control) on the incidence of MRSA or VRE colonization or infection in adult ICUs. Surveillance cultures were obtained from patients in all participating ICUs; the results were reported only to ICUs assigned to the intervention. In intervention ICUs, patients who were colonized or infected with MRSA or VRE were assigned to care with contact precautions; all the other patients were assigned to care with universal gloving until their discharge or until surveillance cultures obtained at admission were reported to be negative.

Results: During a 6-month intervention period, there were 5434 admissions to 10 intervention ICUs, and 3705 admissions to 8 control ICUs. Patients who were colonized or infected with MRSA or VRE were assigned to barrier precautions more frequently in intervention ICUs than in control ICUs (a median of 92% of ICU days with either contact precautions or universal gloving [51% with contact precautions and 43% with universal gloving] in intervention ICUs vs. a median of 38% of ICU days with contact precautions in control ICUs, P<0.001). In intervention ICUs, health care providers used clean gloves, gowns, and hand hygiene less frequently than required for contacts with patients assigned to barrier precautions; when contact precautions were specified, gloves were used for a median of 82% of contacts, gowns for 77% of contacts, and hand hygiene after 69% of contacts, and when universal gloving was specified, gloves were used for a median of 72% of contacts and hand hygiene after 62% of contacts. The mean (±SE) ICU-level incidence of events of colonization or infection with MRSA or VRE per 1000 patient-days at risk, adjusted for baseline incidence, did not differ significantly between the intervention and control ICUs (40.4±3.3 and 35.6±3.7 in the two groups, respectively; P=0.35).

Conclusions: The intervention was not effective in reducing the transmission of MRSA or VRE, although the use of barrier precautions by providers was less than what was required. (Funded by the National Institute of Allergy and Infectious Diseases and others; STAR*ICU ClinicalTrials.gov number, NCT00100386.).

Figure 1. Randomization of Intensive Care Units (ICUs) and Follow-up of Patients

The ICU-level percentage of patients with multiple admissions was 7.6% among all ICU stays and 6.1% among ICU stays of 3 days or more; therefore, each admission was treated as an independent event. A total of 20 ICUs were eligible for the study, of which 19 participated. In addition, 1 medical ICU assigned to the control group was withdrawn from the study owing to a failure to collect surveillance cultures according to the study protocol. Data from this ICU were excluded from all analyses. During the intervention period, there were 24,484 total ICU patient-days in the intervention ICUs and 16,579 total ICU patient-days in the control ICUs. A total of 18,136 ICU patient-days at risk (74% of total ICU patient-days) in the intervention group and 11,827 ICU patient-days at risk (71% of total ICU patient-days) in the control group were included in the primary analysis. ICU stays could have multiple reasons for not being eligible for the primary analysis.

Figure 2. Use of Hand Hygiene, Gloves, and Gowns by Health Care Providers in Intensive Care Units (ICUs) during Contacts with Patients or Their Immediate Environment

The box plot diagram shows the distribution of ICU-level percentages for the use of component measures for all contacts (white boxes) and according to type of contact (colored boxes). The box represents the interquartile range and the horizontal line inside the box the median; vertical lines represent the maximum and minimum percentages. Contaminated refers to actual or potential contact with secretions, excretions, mucous membranes, non-intact skin, or items or surfaces that are likely to be contaminated with body secretions or excretions. Data regarding sterile contacts in both ICU groups and the use of standard precautions in intervention ICUs are not presented because of the small number of observed contacts. The distributions of types of contacts across all precaution categories were as follows: in intervention ICUs, contaminated, 15%; blood or body fluid, 8%; invasive device, 6%; any other patient, 34%; and environment only, 37%; in control ICUs, contaminated, 15%; blood or body fluid, 8%; invasive device, 8%; any other patient, 32%; and environment only, 37%. Data for individual ICUs are provided in Tables 6 through 11 in the Supplementary Appendix.

Figure 3. Monthly Incidence of Colonization or Infection with Methicillin-Resistant Staphylococcus aureus (MRSA) or Vancomycin-Resistant Enterococcus (VRE) among Patients in Intensive Care Units (ICUs)

The box plot diagram shows the distribution of ICU-level incidences of colonization or infection with MRSA or VRE. The box represents the interquartile range, and the horizontal line inside the box the median; vertical lines represent the maximum and minimum percentages. The median number of incidences of colonization or infection according to period were as follows: in intervention ICUs during the baseline period, 30.1 (range, 14.5 to 76.1) for MRSA or VRE, 11.9 (range, 6.8 to 19.6) for MRSA, and 25.7 (range, 9.7 to 78.2) for VRE, and in intervention ICUs during the intervention period, 40.3 (range, 20.8 to 54.9) for MRSA or VRE, 14.6 (range, 6.8 to 21.8) for MRSA, and 36.8 (range, 6.6 to 87.0) for VRE; in control ICUs during the baseline period, 32.5 (range, 12.3 to 58.4) for MRSA or VRE, 13.2 (range, 3.8 to 39.4) for MRSA, and 27.1 (range 9.9 to 53.4) for VRE, and in control ICUs during the intervention period, 32.6 (range, 15.8 to 60.7) for MRSA or VRE, 11.1 (range, 6.6 to 48.9) for MRSA, and 29.9 (range, 11.1 to 71.1) for VRE. Individual ICU data are provided in the figure and Table 2 in the Supplementary Appendix.