The Incidence and Timing of S. aureus Bacteremia and Ventilator Associated Pneumonia in Critical Care Units With an Active Surveillance and Decolonization Program

Background: Active surveillance linked to decolonization has been associated with a decrease but not an elimination of invasive Staphylococcus aureus hospital acquired infection (SAHAI) in our critical care patients. We sought to examine the incidence and timing of SA bacteremia (SABSI) and SA ventilator associated pneumonia (SAVAP) in our intensive care units (ICU) to identify further opportunities for attempts at prevention. Objective: To describe the incidence of timing of SABSI and SAVAP in patients admitted to a critical care bed at Cleveland Clinic (CC) between 1/1/09 through 9/30/10. Methods: The cohort was comprised of all patients admitted to one of 6 adult ICUs at CC. Per protocol all patients are assessed for nasal carriage of SA by real time PCR (GenOhm S/R, Becton Dickson, Franklin Lakes, N.J.) at time of admission and then once weekly. Identified carriers receive intranasal mupirocin bid for 5 days and all admitted patients receive a chlorhexidine bath qd. Prospective surveillance for SABSI, both hospital acquired and community onset, and SAVAP is performed by Infection Control (IC) and recorded in a database. Key metrics from the decolonization program, including SABSI and SAVAP, are collected from disparate data sets, automated, and displayed in a web based dashboard using CrystalTM reports. BSI and VAP events were divided into those that occurred 72 hours before and after initial ICU nasal swab and attack rates were calculated. Patient records were reviewed to identify whether they were direct admits to the ICU or if they were transferred from a CC ward or outside facility. Mortality data was gained by chart review and the Social Security Death Index for patients who survived to discharge. Results: During the observation period there were 24,817 admits accounting for 91,374 patient days. There were 50 patients with SAHAI, 38 (76%) SABSI and 12 (24%) SAVAP, for an attack rate of 0.2 per 100 ICU admissions. 90% (45/50) with a SAHAI were nasal carriers of SA. 54% (27/50) were transfers to ICU from a CC ward. 46% (23/50) were directly admitted from outside facilities or the emergency room. A positive nasal swab resulted before 72 hours of the SAHAI in 51% (19/45 less than 24 hours, 20/45 in 24 hours, 22/45 in 48 hours, and 23/45 in 72 hours) and after 72 hours 49% (22/45). Resulting in an attack rate of 0.093% and 0.089% respectively. SAHAI patients has a hospital mortality of 26% (13/50) and 6 month mortality of 46% (23/50). Conclusions: The incidence of SAHAI 72 hours after initial nasal swab in patients admitted to our ICUs is low. Further attempts at an organism specific approach to decreasing SAHAI would require targeting high risk patients on regular nursing floors. SAHAI in this cohort was associated with high short term mortality. 51% of a positive nasal swab in 72 hours upon being admitted suggests surveillance should be performed prior to an ICU admission.