Determination of extended-spectrum β-lactamase-producing Klebsiella pneumoniae isolated from horses with respiratory manifestation.

BACKGROUND AND AIM: The World Health Organization considers multidrug-resistant (MDR) Klebsiella pneumoniae a major global threat. Horses harbor commensal isolates of this bacterial species and potentially serve as reservoirs for human MDR bacteria. This study investigated antimicrobial resistance in horses caused by extended-spectrum β-lactamase (ESBL)-producing K. pneumoniae.

MATERIALS AND

METHODS

One hundred fifty-nine nasal swab samples were collected from horses with respiratory distress not treated with cefotaxime and erythromycin. Biochemical and serological identification was performed on all samples. Polymerase chain reaction (PCR) was used to detect 16S-23S ITS, mucoviscosity-associated gene (magA), uridine diphosphate galacturonate 4-epimerase gene (uge), and iron uptake system gene (kfu), bla TEM, bla SHV, and bla CTX genes. Sequence analysis and phylogenetic relatedness of randomly selected K. pneumoniae isolates carrying the bla TEM gene were performed.

RESULTS

Ten isolates of Klebsiella spp. were obtained from 159 samples, with an incidence of 6.28% (10 of 159). Based on biochemical and serological identification, K. pneumoniae was detected in 4.4% (7 of 159) of the samples. Using PCR, all tested K. pneumoniae isolates (n=7) carried the 16S-23S ITS gene. By contrast, no isolates carried magA, uge, and kfu genes. The bla TEM gene was detected in all test isolates. Moreover, all isolates did not harbor the bla SHV or bla CTX gene. Sequence analysis and phylogenetic relatedness reported that the maximum likelihood unrooted tree generated indicated the clustering of the test isolate with the other Gram-negative isolate bla TEM. Finally, the sequence distance of the bla TEM gene of the test isolate (generated by Lasergene) showed an identity range of 98.4-100% with the bla TEM gene of the different test isolates.

CONCLUSION

The misuse of antimicrobials and insufficient veterinary services might help generate a population of ESBL-producing K. pneumoniae in equines and humans, representing a public health risk.