Veterinary hospital-acquired infections in pets with a ciprofloxacin-resistant CTX-M-15-producing Klebsiella pneumoniae ST15 clone.

Sir, CTX-M-15 is an extended-spectrum b-lactamase (ESBL) extensively reported in humans, and in particular in Escherichia coli clones of sequence types (STs) ST131 and ST405. The blaCTX-M-15 gene has also become prevalent in Klebsiella pneumoniae, causing outbreaks in hospitals worldwide. – 4 In animals, a highly prevalent ESBL gene is the blaCTX-M-1 gene, with the blaCTX-M-15 gene also being found in E. coli isolated from food-producing animals and pets. From 2008 to 2010, 24 K. pneumoniae isolates were recovered from urine samples of unrelated dogs (n1⁄418) and cats (n1⁄46), 17 of which were collected in the same referral veterinary hospital specialized for surgery in the near suburbs of Paris, France. The other seven isolates were from pets attending surrounding regular veterinary clinics. Susceptibility testing to 32 antimicrobials was performed by agar diffusion and interpreted according to approved clinical breakpoints (http://www.sfm-microbiologie. fr). All isolates were resistant to ceftiofur, cefotaxime, ceftazidime and aztreonam, resistant or of intermediate susceptibility to cefepime, and susceptible to cefoxitin and imipenem. ESBL production was systematically confirmed by a positive synergy test between ceftazidime and clavulanate. All isolates were resistant to ciprofloxacin, streptomycin, sulphonamides and trimethoprim, and 19 isolates were also resistant to kanamycin, gentamicin, tobramycin and netilmicin; only 2 isolates were resistant to tetracycline. Patterns of PFGE performed on XbaIdigested genomic DNA were indistinguishable or differed by no more than two bands (data not shown), strongly suggesting that the same clone was responsible for all infections. Furthermore, all isolates belonged to ST15. The blaCTX-M, blaTEM, blaSHV and blaOXA b-lactamase genes and the aac(6′)-Ib-cr, qnrA, qnrB and qnrS genes were determined by PCR and sequenced when detected (Beckman Coulter, London, UK). The blaCTX-M-15 gene, preceded by the ISEcp1 element, and the blaOXA-1, blaTEM-1 and aac(6′)-Ib-cr genes were identified in all 24 K. pneumoniae isolates. None of the qnr genes was detected, including the qnrS1 gene that has been reported in association with the blaCTX-M-15 and aac(6′)-Ib-cr genes. 6 rep typing revealed the IncR and IncF (but not IncFIIk and IncX) replicons in all isolates, as determined using the PCR-based replicon typing scheme. Considering the clonality of the strains, only a randomly chosen subset of them (9/24) was further investigated. The transformation of plasmid DNA into E. coli K12 was performed with selection on cefotaxime-supplemented plates. All transformants displayed the ESBL phenotype along with most co-resistances (Table 1). They also harboured all b-lactam genes detected in the donor, together with the aac(6′)-Ib-cr gene. In the nine donors, S1-PFGE plasmid profiling demonstrated two plasmids, one of 120 kb and the other ranging from 40 to 70 kb, depending on the isolate. In the nine