The fluoroquinolone-resistant (FQ^R) O25b-H30 subclone of E. coli sequence type 131 (ST131-O25b-H30), with its nested ESBL (CTX-M-15)-associated H30Rx subset, is the most global disseminated virulent B2 group E. coli multidrug-resistant lineage causing infection in humans. Within phylogenetic group D, the sequence type 648 complex (STc648) is another human increasingly resistance-associated E. coli lineage. This study aimed to detect and evaluate the prevalence of human pandemic clones among E. coli strains causing urinary tract infection in companion animals and to characterize their virulence and antimicrobial resistance.

For this study 298 E. coli (1999–2014) isolated from companion animals with urinary tract infection were studied regarding clonal background, virulence and antimicrobial resistance. Susceptibility towards sixteen antimicrobial agents was done by the disk diffusion. PCR-based assays were used to detect the phylogroup (A, B1, B2 and D), Pathogenicity associated-islands (PAIs) (n=8), urovirulence genes (n=8), antimicrobial resistance genes (n=13), the human pandemic E. coli ST131-O25b, O25b-H30, O25b-H30Rx and O16 lineages. Furthermore, all third-generation cephalosporin (3GC) resistant E. coli were typed for MLST in order to detect E. coli sequence type 648 complex. Regarding phylogenetic background the isolates were predominantly from group-B2 (55.4%, n=165/298), followed by group-A (16.1%, n=48/298), group-B1 (14.8%, n=44/298) and group-D (13.8%, n=41/298).

The group-B2 ST131-O25b and O16 lineages represented 10% (n=30/298) of all the uropathogenic strains and ST131-O25b-H30 was the most common 25.0% (n=7/28), all were MDR and FQ^R. The ST131-O25b-H30 most common pathogenicity and virulence-associated genes profiles were PAI I_CFT073-PAI IV₅₃₆-PAI II_CFT073 (28.6%, n=2/7), ecp-papEF-iucD (27.3%, n=3/7). About 43% of ST131-O25b-H30 strains (n=3/7) were the FQ^R H30Rx–bla_CTX-M-15 producer subclone. Among the 3GC-resistant E. coli phylogroup D, the most represented lineage was the ST648 71.4% (n=10/14), followed by ST405, ST1775, ST57 and ST354 (7.1%, n=1/14 each). All ST648 isolates were MDR, bla_CMY-2 producers and one had also bla_CTX-M-9. ST648 PAIs and virulence genes profiles belonged mostly to PAI I_CFT073PAI IV₅₃₆ (40.0%, n=4/10), PAI II₅₃₆-PAI I_CFT073-PAI IV₅₃₆ (30.0%, n=3/10), and ecpA-papEF (70%, n=7/10), respectively.

In this study we report for the first time the detection of the worldwide-disseminated ST131-O25b-H30 virulent, MDR and FQ^R human clone and its CTX-M-15-H30Rx subclone in companion animals. The detection of human high-risk pandemic E. coli lineages causing UTI in companion animals besides the animal health problem is a great public-health concern.

Acknowledgements: With financial support of CIISA and FCT through Project UID/CVT/00276/2013. AB and CM hold FCT PhD grants SFRH/BD/113142/2015 and SFRH/BD/77886/2011.

Disclosures

Disclosures to report:

With financial support of CIISA and FCT through Project UID/CVT/00276/2013. AB and CM hold FCT PhD grants SFRH/BD/113142/2015 and SFRH/BD/77886/2011.