Predominance of international clone 2 OXA-23-producing-Acinetobacter baumannii clinical isolates in Greece, 2015: results of a nationwide study★
Introduction
Acinetobacter baumannii isolates are increasingly causing severe infections among debilitated patients, particularly in intensive care units (ICUs) [1]. Carbapenem resistance is currently widespread among A. baumannii, with rates reaching or exceeding 90% in Southern and Eastern European countries [2]. Carbapenem-resistant A. baumannii (CRAB) are commonly resistant to most available antimicrobials except colistin, tigecycline and minocycline [3], [4]. Tracking the evolution and clonal composition of CRAB isolates is important to support the implementation of control strategies. Molecular epidemiological studies usually reveal clonality of CRAB, with outbreak strains usually belonging to international clones (IC) 1 and 2 and a few additional clonal lineages [5].
In Greek hospitals, during the last few years the vast majority of A. baumannii isolates are CRAB [2], which currently represent the most frequent infection pathogen in the ICU (http://www.mednet.gr/whonet/). Regarding their clonal nature and carbapenemase gene content, we showed previously in a Greek nationwide study conducted from 2000 to 2009 that CRAB were harbouring only the OXA-58 carbapenemase gene; IC1 was the most common lineage until 2004, with IC2 prevailing during 2005–2009 [6].
Studies in several European countries have shown that OXA-23 tends to gradually replace OXA-58 among CRAB [7], [8]. Also, a preliminary study from a single Greek hospital in 2011 reported that OXA-23 was more common than OXA-58 [9]. Given the increased frequency and importance of CRAB, the present follow-up nationwide study was conducted to analyse the resistance phenotypes, carbapenemase gene content, genetic relatedness and evolution of clonal lineages among CRAB recovered from Greek patients during 2015.
Section snippets
Bacterial strains
During 2015, as many as 2500 A. baumannii isolates were identified in 11 tertiary hospitals located in eight cities in Northern (Thessaloniki, Serres, Alexandroupolis), Western (Ioannina), Central (Athens, Piraeus, Larissa) and Southern (Heraklion) Greece. The rate of CRAB in these hospitals during 2015 was 95%, with virtually all clinically important A. baumannii being CRAB. The present study included 194 randomly selected non-repetitive CRAB isolates recovered during 2015 from clinical
Patient data, susceptibility testing and carbapenemase genes
Of the patients that yielded CRAB, 70.1% were male and 29.9% female; most of them were hospitalised in ICUs (56.2%), 20.6% in medical wards, 17% in surgical wards, 2.1% in long-term care facilities and 4.1% were outpatients. Isolates were obtained from blood (45.9%), the respiratory tract (21.6%), skin and soft tissue (11.3%), urine (9.3%) and various other clinical samples (11.9%).
The 194 CRAB isolates showed imipenem and meropenem MICs ≥ 32 µg/mL and were non-susceptible to all
Discussion
Acinetobacter baumannii exhibits particularly high carbapenem resistance rates in several regions worldwide [22]. Of note, during 2015 essentially no clinically important carbapenem-susceptible A. baumannii isolate has been recovered in the study Greek hospitals. The almost universal resistance to carbapenems and SAM precludes the use of β-lactams and considerably limits effective treatment options. Carbapenem resistance in A. baumannii is regularly due to the production of oxacillinases, the
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2020, Journal of Global Antimicrobial ResistanceCitation Excerpt :International clone VI (IC-6) belongs to the carbapenem-resistant A. baumannii ST944Oxf/78Pas [Oxford/Pasteur multilocus sequence typing (MLST) scheme] [1,2] and presents high biofilm-forming ability, increased resistance to desiccation and an enhanced capacity for host cell adhesion/invasion, favouring its diffusion and persistence [3]. Since 2006, IC-6 has been identified in European countries (Italy, Russia, Greece and Germany), Asia (Kuwait) and North and South America (the USA and French Guiana) [1,4–9]. In the context of surveillance of carbapenem-resistant A. baumannii infections in a hospital from the Brazilian Amazon region, we verified the occurrence of the pandemic IC-6/ST944Oxf/78Pas lineage and revealed particular genomic features considering its mobilome and resistome.
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Part of this work was presented at the 26th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID), Amsterdam, The Netherlands, 9–12 April 2016.
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Collaborators of the Greek Study Group on Acinetobacter Antimicrobial Resistance are listed in the Appendix.