308 Control of a Cluster of Multidrug Resistant Acinetobacter baumanii (MDR-Ab) in a Neurosurgical Critical Care Unit (NCCU)

Friday, March 19, 2010
Grand Hall (Hyatt Regency Atlanta)
Donna Fellerman, RN, BA, CIC , The Johns Hopkins Hospital, Baltimore, MD
Trish Perl, MD, MSc , The Johns Hopkins Hospital, Baltimore, MD
Gail Biba, BSN, RN, CNRN , The Johns Hopkins Hospital, Baltimore, MD
Pamela Zimmerman, RRT , The Johns Hopkins Hospital, Baltimore, MD
Tracy Ross, BS, MT, (ASCP) , The Johns Hopkins Hospital, Baltimore, MD
Karen C. Carroll, MD , The Johns Hopkins Hospital, Baltimore, MD
Lisa L. Maragakis, MD , Johns Hopkins University, Baltimore, MD

Control of a Cluster of Multidrug Resistant Acinetobacter baumanii (MDR-Ab) in a Neurosurgical Critical Care Unit (NCCU)

Background:   MDR-Ab is difficult to eradicate in hospitals because of its predilection to contaminate the environment.  Mitigation of outbreaks often includes enforcement of hand hygiene and cleaning.  In 2/08 and 5/08, 2 sporadic cases of hospital-acquired MDR-Ab occurred in the NCCU, a 22 bed unit in a 1,000 bed urban teaching hospital. Four additional cases occurred in 8/08 9/08.

Objective:   Identify the source of Acinetobacter transmission in NCCU.

Methods:  The hospital data base (Theradoc, Salt Lake City) was queried to identify cases.  Respiratory therapy and isolation practices were observed.  Respiratory equipment, shared equipment and potential environmental sources, including rooms inhabited by current or past isolated patients, were cultured.  Hydrogen peroxide vapor (HPV) is routinely used to decontaminate isolation rooms after discharge and records were reviewed.  Surveillance cultures of patients (axilla, groin and wounds) on admission and weekly were initiated.  Organisms were compared using pulsed-field gel electrophoresis (PFGE). Education on the occurrence of the cluster and severity of the infections was provided to all staff. Prospectively collected hand hygiene compliance (by unidentified surveyors) was analyzed.  Intensive environmental cleaning and disinfection was performed and all rooms were treated with HPV.

Results:  In addition to the initial 6 patients, two more patients acquired MDR-Ab in10/08 and 11/08.  All 8 had cultures that grew MDR-Ab from the sputum; one also grew the organism in blood; and one in blood and CSF.  None of 15 composite environmental cultures, including ventilators and sinks, grew MDR-Ab.  Of over 300 patient surveillance cultures, only one (0.3%) grew MDR-Ab.  All isolation rooms were decontaminated with HPV and somewere missed in the previous months.  Five of the MDR-Ab isolates were strain typed by PFGE revealing 3 strains.  Two patients in adjacent rooms had strain 1; one with pneumonia and one with  meningitis and bacteremia.  Two other patients had strain 2, although they were not housed on the unit concurrently.  One patient expired due to sepsis.  The fifth patient had a unique strain. Hand hygiene ranged from 16% to 81% in 2008, and was noted to be lowest at the times of MDR-Ab transmission. In 10/08, hand hygiene increased to 68% after intensive observations and reinforcement of best practices. Only 1 additional case was identified 12/08-10/09.  

Conclusions: In this cluster, several MDR-Ab strains were present, indicating multiple sources of the organism rather than a point source such as contaminated equipment.  We found that aggressive cleaning of the environment with HPV and improving hand hygiene compliance aborted transmission of MDR-Ab in this ICU.