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

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-ß-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 >32 mg/L, and 15 isolates exhibited high-level colistin resistance (MICs >32 mg/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.

Nosocomial infections in heart surgery patients: active surveillance in two Italian hospitals.

In Italy no nosocomial infection surveillance database has been established despite the fact that a decrease of nosocomial infection rates was one of the priorities of the Italian National Health Plan 1998--2000. Heart surgery operations are the most frequent high risk procedures in western countries. Active surveillance was performed at the heart surgery wards of two Italian hospitals (Rome and Catania, Southern Italy) in accordance with the methods described for the National Nosocomial Infections Surveillance (NNIS) System of the USA. In both hospitals surgical site infections (SSIs) were the most frequently encountered type of nosocomial infections, accounting for 57.2% in Rome and 50% in Catania, and SSI rates in coronary artery bypass grafts with both chest and donor site incisions, calculated by risk index equal to 1, were above the 90th percentile for the NNIS System. The urinary catheter-associated urinary tract infection (UTI) rate (5.8%) in Catania exceeded the 90th percentile for the NNIS System, while the device-associated UTI (1.6%), bloodstream (4.1%) and pneumonia (8.0%) rates, from the hospital in Rome, did not. All device utilization ratios were lower than the 10th percentile for the NNIS System. Our study demonstrated that the NNIS methodology is applicable to Italian hospitals, although with some limitations mainly regarding the minimal surveillance duration required for significant interhospital comparison, and highlighted the need of a national comparison of surveillance data as benchmark.