Molecular epidemiology of Acinetobacter baumannii spread in an adult intensive care unit under an endemic setting

Acinetobacter baumannii (Ab) clones I, III, and IV were recovered in several Buenos Aires City hospitals. We investigated the prevalence of these clones with epidemic behavior (EB) in our intensive care unit (ICU) under an endemic setting and its spread.

A 10-week prospective cohort study including surveillance cultures of newly admitted patients was conducted. Air, environment, and staff hands were weekly screened. In the seventh week, a new environmental cleaning protocol and a staff hand hygiene reeducation program were implemented.

Almost 15% of all screening samples (159/1042) were Ab positive. Up to the seventh week, carbapenem-resistant clone If was the main one recovered from patients, environmental frequently touched surfaces (EFTS), and staff hands screening samples. Few air samples were Ab positive. Clone I was also isolated from patients at admission. After the seventh week, a significant reduction of EFTS contamination and of clone If isolation was observed. During the last 3 weeks, clone I was no longer isolated from patients. Instead, the newly identified clone IVb was mainly cross transmitted. It was also recovered from staff hands and from EFTS. In the last week, clone If was again isolated from 1 bed rail.

Patients with EB clones-positive culture at admission provide verification that interhospital patient transfers play a role in these clones spread. However, subtypes such as clone If seem to be endemic in our ICU. EFTS showed to have potential for EB clones transmission via transient staff hand carriage. Transmission did not involve airborne route.