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671 Utility of Surveillance Cultures for Control of Multi-Drug Resistant (MDR) Acinetobacter

Saturday, March 20, 2010: 2:45 PM
Centennial I-II (Hyatt Regency Atlanta)
Emily Sickbert-Bennett, MS , University of North Carolina Health Care, Chapel Hill, NC
Vickie M. Brown, RN, MPH , University of North Carolina Health Care, Chapel Hill, NC
William A. Rutala, PhD , University of North Carolina Health Care, Chapel Hill, NC
Rebecca H. Brooks, RN, BSN , University of North Carolina Health Care, Chapel Hill, NC
Melissa B. Miller, PhD , University of North Carolina Health Care, Chapel Hill, NC
Melissa C. Jones, MT(ASCP) , University of North Carolina Health Care, Chapel Hill, NC
David J. Weber, MD, MPH , University of North Carolina Health Care, Chapel Hill, NC
Background:

The CDC recommends the use of surveillance cultures as part of enhanced precautions.  Limited data are available on the utility of surveillance cultures for identifying patients with MDR Acinetobacter sp.  

Objective:

Estimate the incidence of Acinetobacter infections/colonizations identified by surveillance cultures, compare the sensitivity of wounds and respiratory sites for recovery of Acinetobacter sp., and describe the costs associated with surveillance screening.

Methods:

An outbreak of MDR Acinetobacter baumanni occurred from August 2007 to June 2008 in two intensive care units (ICUs).  Beginning January 2008, enhanced control measures included patient/staff cohorting and weekly surveillance cultures of patients not known to be colonized.    Acinetobacter screening cultures were conducted using CHROMagar Acinetobacter media with 96.8% sensitivity and 88.9% specificity.  Data from 2 time periods were analyzed, 1 January 2008 to 30 June 2008 when the outbreak was ongoing and 1 July 2008 to 31 July 2009, an endemic period when colonized/infected patients remained in the ICUs and transmission was controlled.

Results:

During the entire time period of 1 January 2008 to 31 July 2009, 16 of 1508 patients (1.1%) were identified as positive by screen in the absence of (N=9) or prior to a clinical culture (N=7) identifying MDR Acinetobacter.  During the outbreak period, 1.9% of screened patients (7/367) compared to 0.8% (9/1141) in the non-outbreak period were identified.   Four patients developed healthcare associated infections on average 17 days after a positive screen (range of 3-47 days).

Among the 32 patients identified as positive by either a positive screen (N=16) or positive clinical culture first (N=16), 50% of subsequent wound and 64% of subsequent respiratory cultures (tracheal aspirate or if not intubated, throat swab) were found to be positive for Acinetobacter.

2961 Acinetobacter cultures were obtained from 1508 patients and were analyzed at a cost of $50,514.

Conclusions:

 MDR-Acinetobacter surveillance cultures detected few newly colonized patients especially in a non-outbreak setting despite using a culture technique with relatively high sensitivity and specificity.  These data suggest that acquisition of MDR-Acinetobacter colonization in an outbreak or non-outbreak setting is low.  In addition, our findings suggest that a respiratory tract specimen offers higher sensitivity for detecting the organism if present.