Characterisation of blaDIM1, a novel integron-located metallo-beta-lactamase gene from a Pseudomonas stutzeri clinical isolate in the Netherlands
Abstract number: O309
Poirel L., Rodriguez-Martinez J., Al Naiemi N., Debets-Ossenkopp Y., Nordmann P.
Objectives: Characterisation of the mechanism involved in the uncommon resistance to carbapenems observed from a Pseudomonas stutzeri isolate recovered from a patient hospitalised in the Netherlands with a chronic tibia osteomyelitis. That strain was resistant to ticarcillin, piperacillin-tazobactam, imipenem and meropenem, of intermediate susceptibility to ceftazidime and cefepime, and susceptible to aztreonam.
Methods: Screening for metallo-beta-lactamase (MBL) production was performed using the E-test method with a strip combining imipenem and EDTA. Shotgun cloning was performed with XbaI-digested DNA of P. stutzeri and pBK-CMV cloning vector. Selection was performed on amoxicillin and kanamycin-containing plates.
Results:E. coli TOP10 (pDIM-1) recombinant strains were obtained, displaying resistance to penicillins and ceftazidime, reduced susceptibility to cefepime, imipenem and meropenem, and full susceptibility to aztreonam. Sequence analysis identified a novel Ambler class B beta-lactamase DIM-1 for "Dutch IMipenemase" (pI 6.1) weakly related to all other MBLs. DIM-1 shared 52% amino acid identity with the most closely related MBL GIM-1, and 45 and 30% identity with the IMP and VIM subgroups, respectively. DIM-1 hydrolyzes very efficiently imipenem and meropenem, expanded-spectrum cephalosporins, but spares aztreonam. The blaDIM-1 gene was as a form of a gene cassette located at the first position in a class 1 integron, but the 59be of that gene cassette was truncated giving rise to a fusion with an aadB gene cassette encoding an aminoglycoside adenylyltransferase. The third and last gene cassette corresponded to the qacH cassette encoding resistance to disinfectants.
Conclusion: A novel MBL gene was identified in P. stutzeri further underlining (i) the diversity of acquired MBL genes, especially among non-fermenters, (ii) that Pseudomonas sp. may be a reservoir of these genes and (iii) the possibility of spread of important resistance determinants in Northern part of Europe.
|Session name:||19th European Congress of Clinical Microbiology and Infectious Diseases|
|Location:||Helsinki, Finland, 16 - 19 May 2009|
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