title: Diversity of genetic lineages among CTX-M-15 and CTX-M-14 producing Escherichia coli strains in a Tunisian hospital.
abstract: Fourteen broad-spectrum-cephalosporin-resistant Escherichia coli isolates were recovered between June and December 2007 in a Tunisian hospital. Genes encoding extended-spectrum-beta-lactamases (ESBL) and other resistance genes were characterized by PCR and sequencing. The following ESBL genes were identified: bla (CTX-M-15) (12 isolates), bla (CTX-M-14a) (one isolate), and bla (CTX-M-14b) (one isolate). The bla (OXA-1) gene was detected in 13 bla (CTX-M)-producing strains and a bla (TEM-1) gene in 6 of them. The ISEcp1 sequence was found upstream of bla (CTX-M) genes in 8 of 14 strains, and orf477 or IS903 downstream of this gene in 13 strains. Nine of the strains carried class 1 integrons and five different gene cassette arrangements were detected, dfrA17-aadA5 being the most common. One of the strains (bla (CTX-M-14a)-positive) harbored three class 1 integrons, and one of them was non-previously described containing as gene cassettes new variants of aac(6')-Ib and cmlA1 genes and it was linked to the bla (CTX-M-14a) gene flanked by a truncated ISEcp1 sequence (included in GenBank with accession number JF701188). CTX-M-15-producing strains were ascribed to phylogroup B2 (six isolates) and D (six isolates). Multilocus-sequence-typing revealed ten different sequence-types (STs) among ESBL-positive E. coli strains with prevalence of ST405 (four strains of phylogroup D) and ST131 types (two strains of phylogroup B2 and serogroup O25b). A high clonal diversity was also observed among studied strains by pulsed-field-gel-electrophoresis (11 unrelated profiles). CTX-M-15 is an emergent mechanism of resistance in the studied hospital and the world-disseminated 0:25b-ST131-B2 and ST405-D clones have been identified among CTX-M-15-producing isolates.
authors.affiliation: Faculté des Sciences de Tunis, Laboratoire Microorganismes et Biomolécules Actives, Université Tunis-El Manar, 2092, Tunis, Tunisia.
authors.forename: Karim
authors.initials: K
authors.lastname: Ben Slama
authors.forename: Rym
authors.initials: R
authors.lastname: Ben Sallem
authors.forename: Ahlem
authors.initials: A
authors.lastname: Jouini
authors.forename: Salwa
authors.initials: S
authors.lastname: Rachid
authors.forename: Laurence
authors.initials: L
authors.lastname: Moussa
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Sáenz
authors.forename: Vanesa
authors.initials: V
authors.lastname: Estepa
authors.forename: Sergio
authors.initials: S
authors.lastname: Somalo
authors.forename: Abdellatif
authors.initials: A
authors.lastname: Boudabous
authors.forename: Carmen
authors.initials: C
authors.lastname: Torres
mesh_terms: D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000145:classification / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D014644:Genetic Variation; D006761:Hospitals; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D014416:Tunisia; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D001618:beta-Lactamases