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Emergence of metallo-b-lactamase-producing Proteus mirabilis in the community setting

Abstract number: 1733_850

Poulou A., Markou F., Kolliou V., Iliopoulou H., Tsakris A., Rozi P.

Objectives: Metallo-b-lactamases (MBLs) constitute a growing class of b-lactamases that readily hydrolyse most b-lactams including carbapenems. Acquired MBLs have emerged among nosocomial Pseudomonas aeruginosa isolates and more recently among other Gram-negative pathogens such as Acinetobacter baumannii and several enterobacterial species. However, their dissemination in the community setting has not been described. In the present study we report the emergence of MBL-producing Proteus mirabilis recovered from outpatients in a rural area.

Methods: A total of 202 P. mirabilis isolates were consecutively recovered from patients with community-onset clinical infections (87% from urinary tract infections) in a rural Greek region. Identification and susceptibility testing was performed with the Microscan system (Dade Behring). Among isolates with reduced susceptibility to imipenem (MIC > 4 mg/L), phenotypic detection of MBL production was performed using the E-test MBL (AB Biodisk). The genes encoding the MBLs were characterised by PCR and sequencing analysis.

Results: Nine (4.5%) P. mirabilis isolates exhibited reduced susceptibility to imipenem (MICs ranged from 32 to >256 mg/L). All but one of the isolates, were susceptible to aminoglycosides and aztreonam but resistant to the other b-lactams, quinolones and trimethoprim; the remaining isolate was pandrug-resistant. Production of MBL was detected in all 9 isolates with E-test MBL. Furthermore, genetic analysis identified a blaVIM-1 gene cassette in a class 1 integron in all cases. The majority of the isolates (8/9) were recovered from urine specimens of outpatients who had a history of hospitalisation in the previous three months. They had treated during their hospitalisation with aminoglycosides, ticarcillin/clavulanic and fluoroquinolones. Aztreonam was used for the treatment of MBL-positive infections with successful results.

Conclusions: We detected a high prevalence of infections associated with MBL-producing P. mirabilis in the community setting of our region. Previous hospitalisation and exposure to antimicrobials were predictive of MBL-producing P. mirabilis community-onset infection. Continuous surveillance is essential for the early recognition and for the preventation of dissemination of such strains by indicating the proper treatment.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Subject:
Location: ICC, Munich, Germany
Presentation type:
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