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This is the first known extensive study on ESBL-producing E. coli isolates from pets in France. The ST131 clone was rare. However, the predominance of human-like bla(CTX-M) IncFII plasmids suggests exchanges of these plasmids with the human reservoir.

Most ESBL-producing E. cloacae from animals studied here (69.4%) belonged to potentially high-risk clones in humans, in particular ST114 (44.4%). These data raise questions and potential concerns about the transfer of E. cloacae between animals and humans.

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The spread of plasmid-mediated quinolone resistance determinants (qnr-like determinants, aac(6')-Ib-cr and qepA genes) was evaluated in a collection of 281 nalidixic acid-resistant enterobacterial isolates recovered between September 2005 and December 2007 at the Sahloul Hospital, Sousse, Tunisia. Sixteen percent of those isolates carried qnr genes encoding the QnrB1, QnrB2, QnrA6 or QnrS1 determinants. Most qnr-positive isolates were extended-spectrum ß-lactamase (ESBL) producers, being predominantly of the CTX-M-15 type, but also of the SHV-28 and SHV-12 types. The qnr genes were located on plasmids with a size in the range 55-150 kb. The qnrB2 gene was associated with sul1-type integron structures and the qnrB1 gene was associated with orf1005, whereas the genetic environment of qnrA6 was unknown. In two isolates, the qnrS1 gene was located downstream of an ISEcl2 element on plasmids that often carried the narrow-spectrum ß-lactamase gene bla(LAP-2); qepA and aac(6')-Ib-cr were not detected. The present study highlights the wide spread of Qnr-like determinants in Tunisia, with an association with the ESBL CTX-M-15 in human clinical isolates.

One hundred extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae were recovered from the intensive care unit and the urology ward of the University Hospital of Sahloul in Tunisia between May 2005 and May 2006. The majority of strains showed a high level of resistance to cefotaxime and ceftazidime. Double-disk synergy test and E-test strips were used to confirm production of ESBLs. The molecular analysis revealed that the majority of strains (91%) carried genes encoding CTX-M-15. SHV-12 and SHV-2a were produced, respectively, by 9% and 3% of the strains. Pulsed-field gel electrophoresis of ESBL-producing Klebsiella pneumoniae isolates revealed four different clonal groups and three for Escherichia coli, showing the absence of spread of any epidemic clone. The CTX-M-15 ESBL-producing E. coli of the major clonal group belong to the B2 phylogenetic group, to the sequence type 131, and has a high virulence potential. In conclusion, CTX-M-15 ESBLs accounted for the overwhelming majority of ESBL types among Enterobacteriaceae from our hospital. This study confirms the high rate of ESBLs in Tunisia and further demonstrates the worldwide spread of genes coding for CTX-M-15 enzymes in clinical isolates.

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