To characterize bla_CTX-M IncFII plasmids and clones of Escherichia coli from cats and dogs and to compare them with bla_CTX-M IncFII plasmids reported in humans. From December 2006 to April 2010, 518 E. coli isolates from clinical infections in cats and dogs were screened for extended-spectrum β-lactamase (ESBL) production. Antimicrobial susceptibility was performed by disc diffusion and resistance genes were identified by PCR and sequencing. Plasmids were characterized using PCR-based replicon typing and sub-typing schemes, restriction fragment length polymorphism analysis, S1-PFGE and Southern hybridization. Isolates were characterized by PFGE, phylogenetic grouping, O25b typing and multilocus sequence typing. Nineteen E. coli isolates (3.7%) produced ESBLs, of which 14 (74%) carried bla_CTX-M IncFII plasmids. The bla_CTX-M-15 gene was predominant and located on F31:A4:B1, F36:A4:B1 or F36:A1:B20 plasmids, abundantly reported in humans. The bla_CTX-M-15 F22:A1:B20 or F2:A2:B20 plasmids were also found. Different sequence types (STs) were identified, such as ST10, ST410, ST359, ST617 and ST224. Only one E. coli isolate belonged to the ST131 E. coli clone and carried a bla_CTX-M-14 F2:A2:B20 plasmid. 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-15 IncFII plasmids suggests exchanges of these plasmids with the human reservoir.

Pseudomonas aeruginosa is a major human pathogen, which also affects animals. It is thought that P. aeruginosa has a non-clonal epidemic population structure, with distinct isolates found in humans, animals or the environment. However, very little is known about the structure of the P. aeruginosa population from diseased animals. Data on antimicrobial resistance are also scarce. Thirty-four already registered and 19 new MLST profiles were identified. Interestingly, a few clones were more prevalent, and clones associated to human outbreaks were also detected. Multidrug resistance phenotypes were overall rare. We highlight the non clonal structure of the population and show a higher prevalence of specific clones, possibly correlating with higher pathogenicity. The low proportion of antimicrobial resistance contrasts with the high resistance rate of human isolates.

To characterize bla_CTX-M-15-carrying plasmids and lineages of nine strains of Escherichia coli from cattle. Plasmid DNA was analysed using PCR-based replicon typing and plasmid sub-typing schemes, restriction fragment length polymorphism, S1 nuclease-PFGE and Southern hybridization. Strains were characterized by PFGE, multilocus sequence typing, phylogenetic grouping and B2-O25b:H4-ST131 (where ST stands for sequence type) clone screening. Susceptibilities to antimicrobials were determined by agar diffusion and resistance genes were characterized by PCR and sequencing. The bla_CTX-M-15 gene was found on F31:A4:B1/IncFII and F2:A–:B–/IncFII plasmids, which have been reported abundantly in humans. On F31:A4:B1/IncFII plasmids, the bla_CTX-M-15 gene was associated with the bla_TEM-1, bla_OXA-1 and aac(6′)-Ib-cr resistance genes. The bla_CTX-M-15 gene was also found on IncI1 plasmids of the CC31 clonal complex, recently identified in the human epidemic and virulent E. coli clone O104:H4. None of the cattle isolates belonged to the human and widespread clone B2-O25b:H4/ST131, but were mostly of new STs and of the phylogenetic groups A (n = 4), B1 (n = 3) or D (n = 2). The E. coli isolates harbouring the bla_CTX-M-15-carrying plasmids were genetically diverse, and were recovered from different geographical locations and farms and at different times. This study demonstrates that bla_CTX-M-15-carrying plasmids from cattle-derived non-ST131 E. coli isolates were highly similar to those found in ST131 E. coli isolates commonly reported in humans. It also exemplifies the key role of plasmids versus clonal dissemination in the spread of the bla_CTX-M-15 gene among cattle, and possibly between E. coli isolates detected in humans and cattle.