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Antimicrob Agents Chemother. 2015 Oct 19;60(1):215-21. doi: 10.1128/AAC.01559-15. Print 2016 Jan.

Molecular Characterization of Carbapenem-Nonsusceptible Enterobacterial Isolates Collected during a Prospective Interregional Survey in France and Susceptibility to the Novel Ceftazidime-Avibactam and Aztreonam-Avibactam Combinations.

Author information

1
Département d'Anesthésie-Réanimation, CHU Amiens-Picardie, Amiens, France, and INSERM U1088, Université de Picardie Jules Verne, Amiens, France.
2
Service de Bactériologie, Pôle de Biologie Pathologie Génétique du CHU de Lille, Lille, France.
3
Laboratoire de Biologie Médicale, Hôpital d'Abbeville, Abbeville, France.
4
Département de Biologie Médicale, Centre Hospitalier de Beauvais, Beauvais, France.
5
Laboratoire de Biologie Médicale, Hôpital de Compiègne, Compiègne, France.
6
Service de Bactériologie, Centre Hospitalo-Universitaire d'Amiens, Hôpital Sud, Amiens, France.
7
CHU de Caen, Service de Microbiologie, Caen, France, and Université de Caen Basse Normandie, EA 4655 (Équipe Antibio-Résistance), Caen, France.
8
Service de Bactériologie, Centre Hospitalo-Universitaire d'Amiens, Hôpital Sud, Amiens, France INSERM, IAME, UMR 1137, Paris, France hedi.mammeri@wanadoo.fr.

Abstract

An interregional surveillance program was conducted in the northwestern part of France to determine the prevalence of carbapenem-nonsusceptible Enterobacteriaceae (CNSE) isolates and their susceptibility to ceftazidime-avibactam and aztreonam-avibactam combinations. Nonduplicate CNSE clinical isolates were prospectively collected from six hospitals between June 2012 and November 2013. MICs of ceftazidime and aztreonam, alone or combined with a fixed concentration of avibactam (4 μg/ml), and those of carbapenems (comparator agents) were determined. MICs of ertapenem in combination with phenylalanine arginine-naphthylamide dihydrochloride (PAβN) were also determined to assess active efflux. Genes encoding carbapenemases, plasmid-mediated AmpC enzymes, extended-spectrum β-lactamases (ESBLs), and major outer membrane proteins (OMPs) were amplified and sequenced. OMPs were also extracted for SDS-PAGE analysis. Among the 139 CNSE isolates, mainly Enterobacter spp. and Klebsiella pneumoniae, 123 (88.4%) were ertapenem nonsusceptible, 12 (8.6%) exhibited reduced susceptibility to all carbapenems, and 4 Proteeae isolates (2.9%) were resistant to imipenem. Carbapenemase production was detected in only two isolates (producing OXA-48 and IMI-3). In contrast, OMP deficiency, in association with AmpCs and/or ESBLs (mainly CTX-M-9, SHV-12, and CTX-M-15), was largely identified among CNSE isolates. The ceftazidime-avibactam and aztreonam-avibactam combinations exhibited potent activity against CNSE isolates (MIC50/MIC90, 1/1 μg/ml and 0.5/0.5 μg/ml, respectively) compared to that of ceftazidime and aztreonam alone (MIC50/MIC90, 512/512 μg/ml and 128/512 μg/ml, respectively). This study reveals the in vitro activity of ceftazidime-avibactam and aztreonam-avibactam combinations against a large collection of porin-deficient enterobacterial isolates that are representative of the CNSE recovered in the northern part of France.

PMID:
26482307
PMCID:
PMC4704208
DOI:
10.1128/AAC.01559-15
[Indexed for MEDLINE]
Free PMC Article

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