Resistance of Acinetobacter baumannii clinical isolates to carbapenems is on the rise worldwide mainly in association with the production of OXA-23. Until recently, however, OXA-23 was absent in Spain. In this work, we report the molecular characterization of a hospital outbreak of OXA-23-producing A. baumannii in Barcelona caused by a multidrug-resistant (MDR) clone belonging to international clone IC-II/sequence type ST85 between October 2010 and May 2011. bla OXA-23 was carried in a plasmid of 90 kb and located within the composite transposon Tn2006.
Acinetobacter baumannii is considered an important opportunistic pathogen causing pneumonia, bacteremia, and other respiratory and urinary tract infections (1, 2), and it is also responsible for nosocomial outbreaks worldwide, especially in intensive care units (ICUs) (3). Eradication of nosocomial infections caused by A. baumannii is particularly troublesome due to the ability of this bacterium to rapidly acquire antimicrobial resistance (4) and persist in the environment for long periods of time (5). Increased resistance to carbapenems in A. baumannii has raised special concerns during the last decade, especially since it is associated mostly with the production of acquired carbapenemases belonging to either class B metallo--lactamases or carbapenem-hydrolyzing OXA-type class D -lactamases (2).Outbreak multidrug-resistant (MDR) isolates causing hospital infections across Europe usually belong to one of the three main international clones or lineages (IC-I, IC-II, and IC-III) (6), with recent studies reporting the spread of genetically related epidemic clones of A. baumannii producing OXA-23 and belonging to IC-II within the Mediterranean region (7-11). Until very recently, however, OXA-23-producing A. baumannii was absent in Spain (12). In this work, we report the molecular characterization of an OXA-23-producing A. baumannii strain causing a hospital outbreak in Barcelona between October 2010 and May 2011.(Some of this work was presented at the 23rd European Congress of Clinical Microbiology and Infectious Diseases [ECCMID], 27 to 30 April 2013, Berlin, Germany.)In October 2010, the first carbapenem-resistant A. baumannii isolate associated with this outbreak was identified by Vitek (bioMérieux, Marcy l'Etoile, France) and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) (Bruker Daltonics GmbH, Leipzig, Germany) (13) from a bronchial aspirate from a 36-year-old male patient admitted to the ICU of the Hospital del Mar, Barcelona, Spain, because of cardiac arrest due to cocaine overdose. The patient had a record of multiple psychiatric stays during the previous 2 years and was already colonized upon ICU admission. Until May 2011, subsequent screenings recovered carbapenem-resistant A. baumannii isolates from 17 different patients and 3 environmental dry surfaces within the ICU. In 10 of the 17 patients (59%), A. baumannii was recovered from rectal samples and its presence was considered colonization, whereas in the re...
