Abstract
We report the genetic characterization of 15 Klebsiella pneumoniae (KP) and 4 isolates of K. oxytoca (KO) from clinical cases in dogs and cats and showing extended-spectrum cephalosporin (ESC) resistance. Extended spectrum beta-lactamase (ESBL) and AmpC genes, plasmid-mediated quinolone resistance (PMQR) and co-resistances were investigated. Among KP isolates, ST101 clone was predominant (8/15, 53%), followed by ST15 (4/15, 27%). ST11 and ST340, belonging to Clonal Complex (CC)11, were detected in 2012 (3/15, 20%). MLST on KP isolates corresponded well with PFGE results, with 11 different PFGE patterns observed, including two clusters of two (ST340) and four (ST101) indistinguishable isolates, respectively. All isolates harbored at least one ESBL or AmpC gene, all carried on transferable plasmids (IncR, IncFII, IncI1, IncN), and 16/19 were positive for PMQR genes (qnr family or aac(6′)-Ib-cr). The most frequent ESBL was CTX-M-15 (11/19, 58%), detected in all KP ST101, in one KP ST15 and in both KP ST340. bla CTX-M-15 was carried on IncR plasmids in all but one KP isolate. All KP ST15 isolates harbored different ESC resistance genes and different plasmids, and presented the non-transferable bla SHV-28 gene, in association with bla CTX-M-15, bla CTX-M-1 (on IncR, or on IncN), bla SHV-2a (on IncR) or bla CMY-2 genes (on IncI1). KO isolates were positive for bla CTX-M-9 gene (on IncHI2), or for the bla SHV-12 and bla DHA-1 genes (on IncL/M). They were all positive for qnr genes, and one also for the aac(6′)-Ib-cr gene. All Klebsiella isolates showed multiresistance towards aminoglycosides, sulfonamides, tetracyclines, trimethoprim and amphenicols, mediated by strA/B, aadA2, aadB, ant (2")-Ia, aac(6′)-Ib, sul, tet, dfr and cat genes in various combinations. The emergence in pets of multidrug-resistant Klebsiella with ESBL, AmpC and PMQR determinants, poses further and serious challenges in companion animal therapy and raise concerns for possible bi-directional transmission between pets and humans, especially at household level.
Highlights
Klebsiella are bacterial pathogens that can cause a variety of severe infections in humans, mainly due to K. pneumoniae (KP) [1], [2] and to a lesser degree to K. oxytoca (KO) [3], [4]
Genetic relatedness The 15 Klebsiella pneumoniae (KP) isolates investigated by Multilocus Sequence Typing (MLST) were assigned to four different Sequence Types (ST): ST11 (n = 1), ST340 (n = 2), ST101 (n = 8), and ST15 (n = 4) (Figure 1)
To the best of our knowledge, all the extended-spectrum cephalosporin (ESC) resistant Klebsiella investigated were from sporadic clinical cases, two clusters of KO (n = 2) and KP ST101 (n = 4) showed 100% similarity
Summary
Klebsiella are bacterial pathogens that can cause a variety of severe infections in humans, mainly due to K. pneumoniae (KP) [1], [2] and to a lesser degree to K. oxytoca (KO) [3], [4]. Increasing antimicrobial resistance, especially towards aminoglycosides, (fluoro)quinolones, third and fourth generation cephalosporins, cephamycins, and carbapenems have been reported in the last decade [8], [9], [10], and poses serious therapeutic problems when treating Klebsiella infections in humans. Scarce information is reported on the occurrence of extended spectrum beta-lactamases (ESBLs), AmpC beta-lactamases and plasmid mediated quinolone resistance (PMQR) in Klebsiella isolates from companion animals [11], [12]. The aim of the study was to provide molecular characterization of extended-spectrum cephalosporin (ESC) resistance and PMQR in Klebsiella isolates from clinical cases or lesions in necropsied animals of canine and feline origin in Italy. A further aim was to determine phenotype and genotype of co-resistances, and to provide plasmid identification and genetic relatedness by Multilocus Sequence Typing (MLST) and Pulsed Field Gel Electrophoresis (PFGE) among the isolates, to evaluate potential clustering of ESC, PMQR, and other resistance genes among clones
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