Identification of Sites of Acinetobacter Colonization through Surveillance Cultures in Hospitalized Patients

Background: Acinetobacter spp are ubiquitous, gram-negative coccobacilli and important opportunistic pathogens, capable of causing serious nosocomial infections. An outbreak of ventilator associated pneumonia secondary to these organisms was identified in the Intensive Care Unit at our institution. We devised a program of active surveillance to allow identification and subsequent isolation in colonized patients. However, unlike other significant nosocomial pathogens, there are few studies analyzing the sites of colonization and role of surveillance cultures in patients with Acinetobacter carriage. Objective: To identify the main reservoir sites of Acinetobacter carriage through surveillance cultures and thus improve infection control strategies to help prevent outbreaks in hospitalized patients. Methods: Design: We obtained surveillance cultures for Acinetobacter carriage between July and December 2008. Study Population: All patients admitted to Saint Agnes Hospital who fulfilled one or more of the following screening criteria: Admitted from a nursing, assisted living or rehabilitation facility Having artificial airway, tracheostomy or endotracheal tube Having a grade III or IV decubitus ulcer Having draining wounds of any kind Admitted to the critical care units Data Collection: Acinetobacter surveillance cultures were obtained from four primary sites: axilla, groin, respiratory and wound (if any). Results: A total of 1432 patients (4568 cultures) were screened over the 6 month period. The rate of Acinetobacter colonization was 4.9% with 110 positive cultures in 70 unique patients. Of positive cultures 17.2% (19 total) were from the axilla, 32.7% (36) the groin, 30.9% (34) respiratory sites, & 19.1% (21) wounds. In patients with positive axilla cultures only 5.7% did not have another site positive whereas 28.5% of patients with a positive culture had only a groin culture positive. Conclusions: Recovery of Acinetobacter colonization is highest in respiratory and groin cultures. When wounds are present they also have high rates of recovery. The axillary cultures had a lower yield and did not substantially enhance detection of colonization when added to the other culture sites. Respiratory, groin and wound surveillance cultures are useful in detecting colonized patients and allowing the implementation of isolation strategies to minimize nosocomial transmission of Acinetobacter.