Objectives: The aim of this study was to investigate the prevalence and the emergence of plasmid-mediated quinolone resistance among broad-spectrum beta-lactam-resistant Proteus mirabilis and Morganella morganii clinical isolates recovered in the Military Hospital in Tunisia. Methods: Of 200 strains examined, 50 exhibited resistance to quinolones. Quinolone resistance determinants (qnr and aac(6′)-Ib-cr) were characterized by multiplex PCR and sequencing. Chromosomal quinolone resistance mutations in the quinolone resistance-determining region (QRDR) and class 1 integron characterization were analysed by PCR and sequencing. The clonal relationship between the isolates was studied by pulsed-field gel electrophoresis (PFGE). Results: Fourteen isolates harboured qnrA6 and among them 8 (57%) were extended-spectrum beta-lactamase (ESBL) producers, whilst 12 (85%) isolates harboured blaDHA-1. Mutations in the QRDR were detected in gyrA (Ser83Ile, Glu87Lys), gyrB (Ser464Phe), and parC (Ser80Ile). qnrA6 and blaDHA-1 genes were found embedded in complex sul1-type class 1 integrons. A gene cassette carrying aac(6′)-Ib-cr was found located in the class 1 integron upstream of the qacEΔ1 gene. According to the PFGE analysis, the isolates were clonally unrelated. Conclusions: This is the first description in North Africa of class 1 integrons carrying blaDHA-1, qnrA6 gene, and aac(6′)-Ib-cr determinants in clinical strains of Proteus mirabilis and Morganella morganii. © 2013 Informa Healthcare.

Prevalence of quinolone resistance determinant qnrA6 among broad and extended-spectrum beta-lactam-resistant Proteus mirabilis and Morganella Morganii clinical isolates with sul1-type class 1 integron association in a Tunisian hospital

PERILLI, MARIAGRAZIA;AMICOSANTE, Gianfranco;
2013

Abstract

Objectives: The aim of this study was to investigate the prevalence and the emergence of plasmid-mediated quinolone resistance among broad-spectrum beta-lactam-resistant Proteus mirabilis and Morganella morganii clinical isolates recovered in the Military Hospital in Tunisia. Methods: Of 200 strains examined, 50 exhibited resistance to quinolones. Quinolone resistance determinants (qnr and aac(6′)-Ib-cr) were characterized by multiplex PCR and sequencing. Chromosomal quinolone resistance mutations in the quinolone resistance-determining region (QRDR) and class 1 integron characterization were analysed by PCR and sequencing. The clonal relationship between the isolates was studied by pulsed-field gel electrophoresis (PFGE). Results: Fourteen isolates harboured qnrA6 and among them 8 (57%) were extended-spectrum beta-lactamase (ESBL) producers, whilst 12 (85%) isolates harboured blaDHA-1. Mutations in the QRDR were detected in gyrA (Ser83Ile, Glu87Lys), gyrB (Ser464Phe), and parC (Ser80Ile). qnrA6 and blaDHA-1 genes were found embedded in complex sul1-type class 1 integrons. A gene cassette carrying aac(6′)-Ib-cr was found located in the class 1 integron upstream of the qacEΔ1 gene. According to the PFGE analysis, the isolates were clonally unrelated. Conclusions: This is the first description in North Africa of class 1 integrons carrying blaDHA-1, qnrA6 gene, and aac(6′)-Ib-cr determinants in clinical strains of Proteus mirabilis and Morganella morganii. © 2013 Informa Healthcare.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11697/88918
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