title: Carbapenem and multidrug resistance in Gram-negative bacteria in a single centre in Italy: considerations on in vitro assay of active drugs.
abstract: In intensive care units (ICUs), the most important causes of nosocomial bacterial infections are mainly multidrug-resistant (MDR) and extensively drug-resistant (XDR) Acinetobacter baumannii and Klebsiella pneumoniae strains. Mortality related to these infections is very high due to lack of effective therapy and the severity of patient conditions. This study aimed to assess the prevalence of carbapenem resistance genes in 77 carbapenem-resistant Gram-negative bacteria isolated from severe infections (bloodstream, pulmonary and urinary tract) during the period 1 January to 31 July 2013 in a general ICU in Catania, Italy, and to examine their susceptibility to tigecycline and colistin using two different methods. In total, 52 A. baumannii belonging to the same sequence type (ST) 2 clone and carrying the bla(OXA-23) gene as well as 25 K. pneumoniae carrying bla(KPC-3) were isolated. Four distinct pulsotypes were identified in K. pneumoniae, which correlated with four distinct STs: ST258 and ST512, spread worldwide, and ST147 and ST395 detected for the first time in Italy. A. baumannii isolates showed an XDR profile and were fully susceptible only to colistin; all KPC-producing K. pneumoniae isolates were MDR, whilst colistin was active against 19 of 25 strains. These results show that broth microdilution (BMD) is a reliable in vitro susceptibility test for colistin, above all K. pneumoniae, whilst both the gradient test and BMD are suitable for tigecycline susceptibility testing of A. baumannii.
authors: Department of Bio-Medical Sciences, Section of Microbiology, University of Catania, Via Androne 81, 95124 Catania, Italy. Electronic address: mezzate@unict.it.
authors: Maria Lina
authors: ML
authors: Mezzatesta
authors: Department of Bio-Medical Sciences, Section of Microbiology, University of Catania, Via Androne 81, 95124 Catania, Italy.
authors: Carla
authors: C
authors: Caio
authors: Department of Laboratory Medicine and Advanced Biotechnologies, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy.
authors: Floriana
authors: F
authors: Gona
authors: Department of Bio-Medical Sciences, Section of Microbiology, University of Catania, Via Androne 81, 95124 Catania, Italy.
authors: Roberta
authors: R
authors: Cormaci
authors: Department of Bio-Medical Sciences, Section of Microbiology, University of Catania, Via Androne 81, 95124 Catania, Italy.
authors: Iasmine
authors: I
authors: Salerno
authors: Department of Bio-Medical Sciences, Section of Microbiology, University of Catania, Via Androne 81, 95124 Catania, Italy.
authors: Tiziana
authors: T
authors: Zingali
authors: Intensive Care Unit 1, Cannizzaro Hospital, Catania, Italy.
authors: Carmelo
authors: C
authors: Denaro
authors: Intensive Care Unit 1, Cannizzaro Hospital, Catania, Italy.
authors: Mauro
authors: M
authors: Gennaro
authors: Intensive Care Unit 1, Cannizzaro Hospital, Catania, Italy.
authors: Cristiana
authors: C
authors: Quattrone
authors: Department of Bio-Medical Sciences, Section of Microbiology, University of Catania, Via Androne 81, 95124 Catania, Italy.
authors: Stefania
authors: S
authors: Stefani
mesh_terms: D040981:Acinetobacter baumannii / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015780:Carbapenems / Q000494:pharmacology; D003091:Colistin / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005838:Genotype; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology*; D006801:Humans; D007362:Intensive Care Units; D007558:Italy; D007711:Klebsiella pneumoniae / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D008911:Minocycline / Q000031:analogs & derivatives* / Q000494:pharmacology; D058885:Multilocus Sequence Typing; D000078304:Tigecycline; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems; D000078304:Tigecycline; D001618:beta-Lactamases; D008911:Minocycline; D003091:Colistin
keywords: Acinetobacter baumannii; Carbapenemase; Colistin; Klebsiella pneumoniae; Tigecycline