Spread of a carbapenem- and colistin-resistant Acinetobacter baumannii ST2 clonal strain causing outbreaks in two Sicilian hospitals

A. Agodi, E. Voulgari, M. Barchitta, A. Quattrocchi, P. Bellocchi, A. Poulou, C. Santangelo, G. Castiglione, L. Giaquinta, M. A. Romeo, G. Vrioni, A. Tsakris

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54 Citations (Scopus)


Background: Infections caused by multidrug-resistant (MDR) Acinetobacter baumannii have become an important healthcare-associated problem, particularly in intensive care units (ICUs). Aim: To investigate the emergence of carbapenem- and colistin-resistant A.baumannii infections in two Sicilian hospitals. Methods: From October 2008 to May 2011, a period which included two Italian Nosocomial Infections Surveillance in ICUs network (SPIN-UTI) project surveys, all carbapenem-resistant A.baumannii isolates from the ICUs of two hospitals in Catania, Italy, were prospectively collected. Minimum inhibitory concentrations (MICs) were measured by agar dilution, and phenotypic testing for metallo-β-lactamase (MBL) production was performed. Carbapenem resistance genes and their genetic elements were identified by polymerase chain reaction and sequencing. Genotypic relatedness was assessed by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing. Patient-based surveillance was conducted using the SPIN-UTI protocol and previous antibiotic consumption was recorded. Findings: Twenty-six carbapenem-resistant A.baumannii were identified. Imipenem and meropenem MICs ranged from 4 to >32mg/L, and 15 isolates exhibited high-level colistin resistance (MICs >32mg/L). PFGE demonstrated that all isolates belonged to a unique clonal type and were assigned to ST2 of the international clone II. They harboured an intrinsic blaOxA-51-like carbapenemase gene, blaOxA-82, which was flanked upstream by ISAba1. Conclusions: The dissemination of clonally related isolates of carbapenem-resistant A.baumannii in two hospitals is described. Simultaneous resistance to colistin in more than half of the isolates is a problem for effective antibiotic treatment. Prior carbapenem and colistin consumption may have acted as triggering factors.

Original languageEnglish
Pages (from-to)260-266
Number of pages7
JournalJournal of Hospital Infection
Issue number4
Publication statusPublished - Apr 2014
Externally publishedYes


  • Acinetobacter
  • Carbapenemase
  • Colistin resistance


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