title: First characterization of a Providencia stuartii clinical isolate from a Tunisian intensive care unit coproducing VEB-1-a, OXA-2, qnrA6 and aac(6')-Ib-cr determinants.
abstract: A clinical Providencia stuartii isolate SM662 was recovered from a patient hospitalized in the intensive care unit at the Military hospital, Tunisia. This isolate was resistant to penicillins, cephalosporins, aminoglycosides and fluoroquinolones. A marked in vitro synergy between ceftazidime or cefotaxime and amoxicillin-clavulanic acid on Mueller-Hinton agar plates suggested the presence of an extended-spectrum-β-lactamase. In addition, an unusual synergy was found between cefepime or aztreonam, and cefoxitin or imipenem on a double disk synergy test suggesting a VEB-type extended-spectrum-β-lactamase. The characterization of β-lactamases and associated resistance genes was performed by isoelectric focusing, polymerase chain reaction and nucleotide sequencing. Two β-lactamases bands with pI values of 5.4 and 7.7, which were matched to TEM-1, VEB-1-a and OXA-2-like β-lactamases were detected. The blaVEB-1-a gene was found to be associated with complex genetic structures, including Re elements. These β-lactamases were not transferred by electroporation or conjugation experiments to the transconjugants and electroporants. Hybridization methods showed that the extended-spectrum-β-lactamase encoding gene may have a chromosomal localization. The isolate SM662 produced the quinolone resistance determinants qnrA6 and aac(6')-Ib-cr which were successfully transferred. The detection of an associated chromosomal quinolone resistance revealed the presence of a gyrA mutation at codon 83 (Ser83Ile). This is the first report of the linkage VEB-1-a/OXA-2-like in P. stuartii associated with the description of qnrA6 and aac(6')-Ib-cr genes in this isolate.
authors.affiliation: Laboratory of Biochemistry and Biotechnology, Department of Biology, Faculty of Sciences of Tunis, Campus Universitaire, 2092 El-Manar II, Tunis, Tunisia. Electronic address: sihemmahrouki@yahoo.fr.
authors.forename: Sihem
authors.initials: S
authors.lastname: Mahrouki
authors.affiliation: Laboratory of Biochemistry and Biotechnology, Department of Biology, Faculty of Sciences of Tunis, Campus Universitaire, 2092 El-Manar II, Tunis, Tunisia.
authors.forename: Hela
authors.initials: H
authors.lastname: Chihi
authors.affiliation: Laboratory of Biochemistry and Biotechnology, Department of Biology, Faculty of Sciences of Tunis, Campus Universitaire, 2092 El-Manar II, Tunis, Tunisia.
authors.forename: Amel
authors.initials: A
authors.lastname: Bourouis
authors.affiliation: Laboratory of Microbiology, Military Hospital of Tunis, 1089 Monfleury, Tunis, Tunisia.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Ben Moussa
authors.affiliation: Laboratory of Biochemistry and Biotechnology, Department of Biology, Faculty of Sciences of Tunis, Campus Universitaire, 2092 El-Manar II, Tunis, Tunisia.
authors.forename: Omrane
authors.initials: O
authors.lastname: Belhadj
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D029968:Escherichia coli Proteins; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D011532:Providencia / Q000145:classification / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D014416:Tunisia; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; C039404:beta-lactamase OXA-2; C119424:beta-lactamase VEB-1, E coli; D001618:beta-Lactamases
keywords: ESBL; Providencia stuartii; aac(6′)-Ib-cr; qnrA6