The Occurrence and Characterization of Extended-Spectrum-Beta-Lactamase-Producing Escherichia coli Isolated from Clinical Diagnostic Specimens of Equine Origin

Abstract

Simple Summary: The spread and development of extended spectrum beta-lactamase (ESBL)-mediated antimicrobial resistance is a significant concern in healthcare with impacts to animal and public health alike. While the occurrence of the ESBL phenotype in Escherichia coli has been investigated in depth by numerous studies, there is still a lack of information regarding ESBL-producing bacterial isolates from clinical specimens of equine origin. In this study, we investigated the incidence of ESBL-producing E. coli in hospitalized horses. Overall, 207 E. coli isolates were analyzed for their antimicrobial susceptibility and 13 ESBL-producing E. coli isolates were genotypically characterized. Seven out of the 13 E. coli isolates were found to harbor the resistance genes bla CTX-M-1 or bla SHV-1 and a novel beta-lactamase TEM gene variant, bla TEM-233 was discovered. Furthermore, despite being phenotypically susceptible to tested carbapenems, 1 out of 13 E. coli isolates was PCR-positive for the carbapenemase gene, bla IMP-1 . The latter is an alarming finding because the presence of carbapenemase resistance genes in equine pathogens is extremely rare. In conclusion, equines can be reservoirs for ESBL-producing Enterobacteriaceae, and further investigation into this species group is necessary to understand their impact in the spread and development of antibiotic resistance genes.Abstract: Escherichia coli isolates were recovered from clinical specimens of equine patients admitted to the Texas A&M Veterinary Medical Teaching Hospital over a five-year period. Ceftiofur resistance was used as a marker for potential extended-spectrum beta-lactamase (ESBL)-activity, and of the 48 ceftiofur-resistant E. coli isolates, 27.08% (n = 13) were phenotypically ESBL-positive. Conventional PCR analysis followed by the large-scale bla Finder multiplex PCR detected the ESBL genes, CTX-M-1 and SHV, in seven out of the 13 isolates. Moreover, beta-lactamase genes of TEM-1-type, BER-type (AmpC), and OXA-type were also identified. Sequencing of these genes resulted in identification of a novel TEM-1-type gene, called bla TEM-233 , and a study is currently underway to determine if this gene confers the ESBL phenotype. Furthermore, this report is the first to have found E. coli ST1308 in horses. This subtype, which has been reported in other herbivores, harbored the SHV-type ESBL gene. Finally, one out of 13 E. coli isolates was PCR-positive for the carbapenemase gene, bla IMP-1 despite the lack of phenotypically proven resistance to imipenem. With the identification of novel ESBL gene variant and the demonstrated expansion of E. coli sequence types in equine patients, this study underscores the need for more investigation of equines as reservoirs for ESBL-producing pathogens. ]. The wide application of beta-lactam antibiotics has been considered as a driving factor in the development and spread of extended-spectrum beta-lactamase (ESBL)-conferred resistance in Gram-negative bacterial pathogens such as Escherichia coli, Klebsiella spp., and Sa...

Molecular characterization and antimicrobial resistance of potentially human‐pathogenic Escherichia coli strains isolated from riding horses

“…In the current study, phylogenetic assessment of the equine isolates showed no relationship among virulence, resistance and phylogenetic background; resistant/non-resistant and virulent/non-virulent E. coli strains frequently belonged to B1 phylo-group. In agreement with our results, many studies around the world have reported B1 as the predominant phylo-type in equine E. coli isolates [ 34 , 39 , 40 ]. Conversely, Sukmawinata et al (2019), reported B2 as the most common phylogenetic group among extended-spectrum β-lactamase-producing E. coli isolates from healthy thoroughbred race horses in Japan [ 41 ].…”

Characterizing the antimicrobial resistance profile of Escherichia coli found in sport animals (fighting cocks, fighting bulls, and sport horses) and soils from their environment

“…Regarding samples from horses, there appears to be no previous report of the AMR pattern in equine E. coli isolates in Thailand. Antimicrobial resistance occurrence in E. coli isolates in Thai horses in this study seems lower than that reported in Turkey [48] and South Korea [49], but was similar to that reported in Japan [26]. The highest level of resistance in the equine E. coli isolates was against AM (15.2%), CF (12.1%), TE (12.1%), and SXT (9.1%).…”

Equine Gram-Negative Oral Microbiota: An Antimicrobial Resistances Watcher?

“…As mentioned by de Lagarde et al and Argudín et al [ 16 , 27 ], it is possible that mobile genetic elements, such as plasmids, transmit resistance genes from commensal to pathogenic strains that could infect the horse leading to complications during treatments. Although the bacteria founded in the present study are commensals in the horses’ mouth, 89% have high zoonotic potential (e.g., Klebsiella pneumoniae , Escherichia coli ) [ 28 , 29 , 30 ]. Due to the close contact between humans and horses, it is highly possible that humans will be infected with multidrug-resistant strains.…”