Klebsiella pneumoniae are important nosocomial pathogens that are increasingly reported as multidrug resistant (MDR). Companion animals (CA) with urinary tract infections (UTI) may become infected with MDR and virulent K. pneumoniae and thus act as reservoir to humans. This study aimed to characterize and compare the clonal relatedness of K. pneumoniae isolated from companion animals and humans with UTI. K. pneumoniae isolated from CA (n=26) and from community and hospital-acquired human UTIs (n=76) were tested by disk diffusion for susceptibility (AST) against 28 antimicrobials according to CLSI. Resistant isolates were screened for sixteen resistance genes and seven virulence genes by PCR. All CA isolates and third-generation cephalosporin-resistant (3GCr) human isolates were typed by MLST. Population structure of CA and human isolates were further characterized by PFGE-XbaI macro-restriction using Dice/UPGMA clustering analysis with a 1.5% tolerance.

The high-risk clonal K. pneumoniae lineage ST15 predominated in CA isolates (61,5%, n=16/26) and clustered together with a similarity index (SI)=69%. Most CA ST15 isolates belonged to two clusters (ST15a, ST15b) with SI>80%. Interestingly, all CA ST15 showed resistance to fluoroquinolones and 75% (n=12/16) were 3GCr mainly due to CTX-M-15. Two human ST15-CTX-M-15 K. pneumoniae were detected, one of which belonged to ST15b cluster. CA and human ST15-CTX-M-15 K. pneumoniae shared fimH-mrkD-kfu-ycfM virulence profile with few (n=4) also harboring yersiniabactin. Additionally, 3GC-susceptible human K. pneumoniae (unknown ST) also clustered with ST15a (n=2) and ST15b (n=1). All CA/human ST15a and ST15b strains were fluoroquinolone-resistant.

The hospital adapted ST11 K. pneumoniae clonal lineage was detected in CA (n=1) and humans (n=1) showing the same MDR AST profile. On PFGE analysis, both ST11 were closely related (SI=81.1%) and shared several virulence (fimH-mrkD-kpn-ycfM-yersiniabactin) and resistance (DHA/aphAI-IA/aac(6')-Ib/tet(A)/sul1) genes. CA ST11 strain also harbored CTX-M-15 and qnrB.

3GCr ST348 from CA (n=1) and humans (n=1) showed a cluster SI=86.7%. Although similar in PFGE analysis, the AST varied between the strains with CA and human ST348 harboring CMY-2 and CTX-M-15, respectively.

This study shows that CA and humans can become infected with clonal-related K. pneumoniae some of which belong to high-risk clonal lineages. These results reveal the potential zoonotic nature of K. pneumoniae UTIs in CA, and therefore infection control measures should be advised to owners to avoid the spread of resistant and virulent K. pneumoniae.

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, respectively.