736. Multi-drug Resistant Providencia stuartii Isolates from Greece: Co-carriage of Cephalosporin (SHV-5, VEB-1), Carbapenem (VIM-1) and Aminoglycoside (RmtB) Resistance Determinants
Session: Poster Abstract Session: Antimicrobials: Resistance Mechanisms
Friday, October 4, 2013
Room: The Moscone Center: Poster Hall C
Background: Carbapenem resistant enterobacteria (CRE) producing class A (KPC) and metallo-β-lactamases (VIM) have frequently been reported from hospitals in Greece. Treatment options are limited, although some strains of certain species are susceptible to aminoglycosides or polymyxins. In this study we investigated the mechanisms of multi-drug resistance in six Providencia stuartii isolates recovered during a 4 month period (12/2012-03/2013) from six different patients in a hospital in Athens. 

Methods: Isolates were identified by MALDI-ToF mass spectrometry. Antimicrobial susceptibility was conducted by disc diffusion and MICs were determined by Etest. Phenotypic screens for ESBL and MBL production was undertaken using cephalosporin / carbapenem / inhibitor combined discs. Molecular detection of antimicrobial resistance genes was undertaken using DNA microarrays, PCR amplification, nucleotide sequencing and PCR mapping of resistance islands. Isolate relatedness was determined by Random Amplified Polymorphic DNA (RAPD). 

Results: All isolates were resistant to ceftazidime, imipenem, ciprofloxacin, amikacin, tigecycline, colistin and fosfomycin but susceptible to meropenem and temocillin. Combination disc testing suggested co-production of ESBL and MBL enzymes. A commercial microarray assay  identified blaSHV and blaVIM. Multiplex PCR and sequencing identified blaVEB-1 and confirmed the presence of genes encoding blaSHV-5 and blaVIM-1. All isolates contained the 16S RNA methylase gene rmtB as well as dfraA12 and aadA2 within a class 1 integron structure. RAPD typing identified three distinct strains. 

Conclusion:  The combination of high level amikacin resistance in a CRE species with intrinsic resistance to polymyxins and tigecycline has important implications for treatment. Co-carriage of blaSHV-5, blaVIM-1, dfraA12 and aadA2 has recently been reported localized to a 180Kb multireplicon plasmid in P. stuartii. To our knowledge, this is the first report of isolates of this species also carrying blaVEB-1 and rmtB. 

Olga Oikonomou, MD1,2, Michael Hornsey, PhD2, Lynette Phee, MD2, Jonathan Betts, PhD2 and David W. Wareham, MD, PhD2, (1)Microbiology, 'Sotiria' Chest Diseases Hospital, Athens, Greece, (2)Blizard Institute, Queen Mary University London, London, United Kingdom

Disclosures:

O. Oikonomou, None

M. Hornsey, None

L. Phee, None

J. Betts, None

D. W. Wareham, None

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