Emergence of Escherichia coli isolates producing metallo-lactamase VIM1 in Italy

Abstract number: P1622

D'Andrea M.M., Giani T., Venturelli C., Giacobazzi E., Arena F., Rossolini G.M.

Background: The increasing rate of resistance to oxyimino-cephalosporins and fluoroquinolones in clinical isolates of Enterobacteriaceae prevents the use of these drugs. Given this fact carbapenems are increasingly used in therapy to eradicate infections due to such strains. The appearance of carbapenem resistant isolates of Enterebacteriaceae is worrisome because of the limited therapeutic options that remain for the treatment of infections caused by such strains. In this work we report the appearance and persistence of VIM-positive Escherichia coli strains in an Italian hospital.

Methods: 5 bacterial carbapenem resistant isolates of E. coli were collected during November 2008 – October 2009 from the Modena University Hospital. Identification at the species level and antimicrobial susceptibility tests were performed using the Vitek automated system. MIC for carbapenems were confirmed using Etest and interpreted according to the criteria of CLSI. Genotyping was performed by RAPD and PFGE. b-lactamases content was investigated by PCR using primers specific to blaVIM and blaIMP alleles. Presence of class I integrons was assessed by PCR using primers specific to Int1 integrase gene and the 3'CS sequences. Amplification products were sequenced on double strand using amplification primers.

Results: Analyzed isolates were susceptible only to aminoglicoside, gentamicin and tigecycline. Etest analysis showed a lowering of the MIC values in the presence of EDTA, suggesting the production of a metalllo-b-lactamase. PCR analysis were positive for the blaVIM allele and negative when performed using primers for the blaIMP alleles. Genotyping techniques showed that at least two isolates, obtained from the same ward, were related to each other. PCR investigations showed that the blaVIM-1 allele was part of a class I integron. Sequencing demonstrated that all isolates carried the blaVIM-1 allele.

Conclusions: This study demonstrate the appearance and persistence of VIM-producing clones of E. coli. Such isolates were detected from samples obtained from 2 different wards, suggesting the persistence of such strains in the hospital. Resistance to carbapenems in strains of Enterobacteriaceae is quite uncommon in Italy, and this particular phenotype has mainly to be related to alteration of outer membrane permeability.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
Back to top