Characterisation of qnr plasmid-mediated quinolone resistance in Enterobacteriaceae from Italy: association of the qnrB19 allele with the integron element ISCR1 in Escherichia coli

Richter, Sara N.; Frasson, Ilaria; Bergo, Cristina; Manganelli, Riccardo; Cavallaro, Antonietta; Palù, Giorgio

doi:10.1016/j.ijantimicag.2010.02.015

« Previous Next »International Journal of Antimicrobial Agents
Volume 35, Issue 6 , Pages 578-583, June 2010

Characterisation of qnr plasmid-mediated quinolone resistance in Enterobacteriaceae from Italy: association of the qnrB19 allele with the integron element ISCR1 in Escherichia coli

Sara N. Richter
- Department of Histology, Microbiology and Medical Biotechnologies, University of Padua, via Gabelli 63, 35121 Padua, Italy
- Azienda Ospedaliera of Padua, Microbiology and Virology Unit, via Giustiniani 2, 35121 Padua, Italy
- Corresponding author. Tel.: +39 049 827 2346; fax: +39 049 827 2355.
Ilaria Frasson
- Department of Histology, Microbiology and Medical Biotechnologies, University of Padua, via Gabelli 63, 35121 Padua, Italy
Cristina Bergo
- Azienda Ospedaliera of Padua, Microbiology and Virology Unit, via Giustiniani 2, 35121 Padua, Italy
Riccardo Manganelli
- Department of Histology, Microbiology and Medical Biotechnologies, University of Padua, via Gabelli 63, 35121 Padua, Italy
- Azienda Ospedaliera of Padua, Microbiology and Virology Unit, via Giustiniani 2, 35121 Padua, Italy
Antonietta Cavallaro
- Azienda Ospedaliera of Padua, Microbiology and Virology Unit, via Giustiniani 2, 35121 Padua, Italy
Giorgio Palù
- Department of Histology, Microbiology and Medical Biotechnologies, University of Padua, via Gabelli 63, 35121 Padua, Italy
- Azienda Ospedaliera of Padua, Microbiology and Virology Unit, via Giustiniani 2, 35121 Padua, Italy

Received 14 January 2010; accepted 10 February 2010. published online 01 April 2010.

Abstract

The spread of plasmid-mediated quinolone resistance determinants (qnr-like determinants) was evaluated in a collection of 232 ciprofloxacin-resistant or extended-spectrum β-lactamase (ESBL)-producing enterobacterial isolates recovered between November 2007 and May 2008 at Padua University Hospital, Italy. qnr genes were mainly found in Klebsiella pneumoniae (68%) and to a lesser extent in Escherichia coli (5.1%). Among the qnrA1, qnrS1 and qnrB19 alleles found, the latter was by far the most frequent. Genetic environment analysis revealed that one qnrB19 gene in E. coli was embedded in an ISCR1 complex class 1 integron. All other qnrB19 genes were flanked by an ISEcp1C region as part of the Tn2012 transposon. qnrA1- and qnrS1-containing strains were not clonally related. Both topoisomerase II mutations and ESBL (mainly SHV-12, TEM-1 and TEM-150 types) were present in most of the qnr-positive strains. qnrB19 is extremely frequent in K. pneumoniae isolates from Italy. In addition, association of qnrB19 with the ISCR1 mobile element in E. coli suggests a broad distribution of this resistance gene in the near future.