Extended-spectrum β-lactamase-producing Escherichia coli isolated from healthy Thoroughbred racehorses in Japan

Comparison of approaches for source attribution of ESBL-producing Escherichia coli in Germany

Extended-spectrum beta-lactamase (ESBL)-producing Escherichia (E.) coli have been widely described as the cause of treatment failures in humans around the world. The origin of human infections with these microorganisms is discussed controversially and in most cases hard to identify. Since they pose a relevant risk to human health, it becomes crucial to understand their sources and the transmission pathways. In this study, we analyzed data from different studies in Germany and grouped ESBL-producing E. coli from different sources and human cases into subtypes based on their phenotypic and genotypic characteristics (ESBL-genotype, E. coli phylogenetic group and phenotypic antimicrobial resistance pattern). Then, a source attribution model was developed in order to attribute the human cases to the considered sources. The sources were from different animal species (cattle, pig, chicken, dog and horse) and also from patients with nosocomial infections. The human isolates were gathered from community cases which showed to be colonized with ESBL-producing E. coli. We used the attribution model first with only the animal sources (Approach A) and then additionally with the nosocomial infections (Approach B). We observed that all sources contributed to the human cases, nevertheless, isolates from nosocomial infections were more related to those from human cases than any of the other sources. We identified subtypes that were only detected in the considered animal species and others that were observed only in the human population. Some subtypes from the human cases could not be allocated to any of the sources from this study and were attributed to an unknown source. Our study emphasizes the importance of human-to-human transmission of ESBL-producing E. coli and the different role that pets, livestock and healthcare facilities may play in the transmission of these resistant bacteria. The developed source attribution model can be further used to monitor future trends. A One Health approach is necessary to develop source attribution models further to integrate also wildlife, environmental as well as food sources in addition to human and animal data.

Evaluation of quercetin as a potential β-lactamase CTX-M-15 inhibitor via the molecular docking, dynamics simulations, and MMGBSA

Antimicrobial resistance (AMR) threatens millions of people around the world and has been declared a global risk by the World Economic Forum. One of the important AMR mechanisms in Enterobacteriaceae is the production of extended-spectrum β-lactamases. The most common ESBL, CTX-M β-lactamases, is spread to the world by CTX-M-15 and CTX-M-14. Sulbactam, clavulanic acid, and tazobactam are first-generation β-lactamase inhibitors and avibactam is a new non-β-lactam β-lactamase inhibitor. We studied that avibactam, sulbactam, clavulanic acid, tazobactam, and quercetin natural flavonoids were docked to target protein CTXM-15. Subsequently, the complexes were simulated using the molecular dynamics simulations method during 100 ns for determining the final binding positions of ligands. Clavulanic acid left CTX-M-15 and other ligands remained in the binding site after the simulation. The estimated binding energies were calculated during 100 ns simulation by the MMGBSA-MMPBSA method. The estimated free binding energies of avibactam, sulbactam, quercetin, tazobactam, and clavulanic acid were sorted as –33.61 kcal/mol, –16.04 kcal/mol, –14 kcal/mol, –12.68 kcal/mol, and –2.95 kcal/mol. As a result of both final binding positions and free binding energy calculations, Quercetin may be evaluated an alternative candidate and a more potent β-lactamases inhibitor for new antimicrobial combinations to CTX-M-15. The results obtained in silico studies are predicted to be a preliminary study for in vitro studies for quercetin and similar bioactive natural compounds. These studies are notable for the discovery of natural compounds that can be used in the treatment of infections caused by β-lactamase-producing pathogens.

Duplication of blaCTX-M-1 and a class 1 integron on the chromosome enhances antimicrobial resistance in Escherichia coli isolated from racehorses in Japan

OBJECTIVES

Extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae have become a cause for great concern. Although some studies have reported the prevalence of ESBL-producing bacteria and ESBL-encoding genes in horses worldwide, the genetic structure surrounding the ESBL gene has not been analysed in detail. In the present study, we isolated two ESBL-producing Escherichia coli strains from diseased racehorses in Japan and demonstrated the mechanisms underlying the acquisition of their antimicrobial resistance (AMR) genes.

METHODS

Two ESBL-producing E. coli strains (E148 and E189) were isolated from the heart and liver of horses with endocarditis and sepsis in 2014 and 2016, respectively, in Japan. Complete genomic sequences of the two strains were analysed using a PacBio RSII sequencer. Antimicrobial susceptibility testing was performed by the agar dilution method.

RESULTS

The two isolates possessed a chromosomal AMR gene cluster containing bla_CTX-M-1 that was similar to the pEQ1 plasmid found in E. coli isolated from a racehorse in the Czech Republic. In one of the two strains, tandem duplication of the 16-kb region containing bla_CTX-M-1 and a class 1 integron, which occurred via IS26-mediated recombination, increased minimum inhibitory concentrations (MICs) associated with the duplicated AMR genes.

CONCLUSION

Chromosomal bla_CTX-M-1 possibly derived from the pEQ1 or pEQ1-like plasmid was found in Japanese equine E. coli isolates. In Japanese strains, many AMR genes containing bla_CTX-M-1 and the class 1 integron are highly accumulated in one region on the chromosome, and the AMR of E. coli was enhanced via the IS26-mediated duplication of the AMR gene cluster.

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

Background

Transmission of antimicrobial resistant and virulent Escherichia coli (E. coli) from animal to human has been considered as a public health concern. This study aimed to determine the phylogenetic background and prevalence of diarrheagenic E. coli and antimicrobial resistance in healthy riding-horses in Iran. In this research, the genes related to six main pathotypes of E. coli were screened. Also, genotypic and phenotypic antimicrobial resistance against commonly used antibiotics were studied, then phylo-grouping was performed on all the isolates.

Results

Out of 65 analyzed isolates, 29.23 % (n = 19) were determined as STEC and 6.15 % (n = 4) as potential EPEC. The most prevalent antimicrobial resistance phenotypes were against amoxicillin/clavulanic acid (46.2 %) and ceftriaxone (38.5 %). bla_TEM was the most detected resistance gene (98.4 %) among the isolates and 26.15 % of the E. coli isolates were determined as multi-drug resistant (MDR). Three phylo-types including B1 (76.92 %), A (13.85 %) and D (3.08 %) were detected among the isolates.

Conclusions

Due to the close interaction of horses and humans, these findings would place emphasis on the pathogenic and zoonotic potential of the equine strains and may help to design antimicrobial resistance stewardship programs to control the dissemination of virulent and multi-drug resistant E. coli strains in the community.

Third Generation Cephalosporin Resistant Enterobacterales Infections in Hospitalized Horses and Donkeys: A Case-Case-Control Analysis

In human medicine, infections caused by third-generation cephalosporin-resistant Enterobacterales (3GCRE) are associated with detrimental outcomes. In veterinary medicine, controlled epidemiological analyses are lacking. A matched case–case–control investigation (1:1:1 ratio) was conducted in a large veterinary hospital (2017–2019). In total, 29 infected horses and donkeys were matched to 29 animals with third-generation cephalosporin-susceptible Enterobacterales (3GCSE) infections, and 29 uninfected controls (overall n = 87). Despite multiple significant associations per bivariable analyses, the only independent predictor for 3GCRE infection was recent exposure to antibiotics (adjusted odds ratio (aOR) = 104, p < 0.001), but this was also an independent predictor for 3GCSE infection (aOR = 22, p < 0.001), though the correlation with 3GCRE was significantly stronger (aOR = 9.3, p = 0.04). In separated multivariable outcome models, 3GCRE infections were independently associated with reduced clinical cure rates (aOR = 6.84, p = 0.003) and with 90 days mortality (aOR = 3.6, p = 0.003). Klebsiella spp. were the most common 3GCRE (36%), and bla_CTX-M-1 was the major β-lactamase (79%). Polyclonality and multiple sequence types were evident among all Enterobacterales (e.g., Klebsiella pneumoniae, Escherichia coli, Enterobacter cloacae). The study substantiates the significance of 3GCRE infections in equine medicine, and their independent detrimental impact on cure rates and mortality. Multiple Enterobacterales genera, subtypes, clones and mechanisms of resistance are prevalent among horses and donkeys with 3GCRE infections.

Antimicrobial resistance profiles and phylogenetic groups of Escherichia coli isolated from healthy Thoroughbred racehorses in Japan

In this study, we investigated the occurrence of antimicrobial resistance in commensal Escherichia coli isolated from healthy Thoroughbred (TB) racehorses in Japan. A total of 212 fecal samples were individually collected from TB racehorses from March 2017 to August 2018 at Japan Racing Association training centers. E. coli was isolated by using selective agar media, deoxycholate-hydrogen sulfide-lactose (DHL) and eosin methylene blue (EMB). A total of 417 E. coli isolates were examined against 10 antimicrobial agents by using the broth microdilution method. The 417 E. coli isolates were phylogenetically grouped using a multiplex polymerase chain reaction. The highest proportion of resistance was observed for streptomycin (30.9%, 129/417) followed by ampicillin (19.4%, 81/417), trimethoprim (15.8%, 66/417), tetracycline (8.4%, 35/417), chloramphenicol (2.6%, 11/417), kanamycin (1.2%, 5/417), nalidixic acid (0.5%, 2/417), cefazolin (0.2%, 1/417), colistin (0.2%, 1/417), and gentamycin (0%). Multidrug-resistant (MDR) E. coli was detected in 7.9% (33/417) of isolates. The proportions of resistance against ampicillin, streptomycin, kanamycin, and chloramphenicol and of multidrug-resistant phenotypes in E. coli belonging to phylogenetic group B2 were significantly higher than those of other groups. This study clarified the distribution of antimicrobial-resistant (AMR) E. coli in Japanese racehorses. A continuous monitoring program for antimicrobial resistance is required to control the spread of AMR bacteria in racehorses.

Extended spectrum β lactamase-producing Enterobacteriaceae shedding by race horses in Ontario, Canada

Background

We aimed to investigate the prevalence, molecular epidemiology and prevalence factors for Extended Spectrum β-Lactamase-producing Enterobacteriaceae (ESBL-E) shedding by race horses. A cross-sectional study was performed involving fecal samples collected from 169 Thoroughbred horses that were housed at a large racing facility in Ontario, Canada. Samples were enriched, plated on selective plates, sub-cultured to obtain pure cultures and ESBL production was confirmed. Bacterial species were identified and antibiotic susceptibility profiles were assessed. E. coli sequence types (ST) and ESBL genes were determined using multilocus sequence type (MLST) and sequencing. Whole genome sequencing was performed to isolates harboring CTX-M-1 gene. Medical records were reviewed and associations were investigated.

Results

Adult horses (n = 169), originating from 16 different barns, were sampled. ESBL-E shedding rate was 12% (n = 21/169, 95% CI 8–18%); 22 ESBL-E isolates were molecularly studied (one horse had two isolates). The main species was E. coli (91%) and the major ESBL gene was CTX-M-1 (54.5%). Ten different E. coli STs were identified. Sixty-four percent of total isolates were defined as multi-drug resistant. ESBL-E shedding horses originated from 8/16 different barns; whereas 48% (10/21) of them originated from one specific barn. Overall, antibiotic treatment in the previous month was found as a prevalence factor for ESBL-E shedding (p = 0.016, prevalence OR = 27.72, 95% CI 1.845–416.555).

Conclusions

Our findings demonstrate the potential diverse reservoir of ESBL-E in Thoroughbred race horses. Multi-drug resistant bacteria should be further investigated to improve antibiotic treatment regimens and equine welfare.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-020-02701-z.

Multidrug-Resistant ESBL/AmpC-Producing Klebsiella pneumoniae Isolated from Healthy Thoroughbred Racehorses in Japan

Simple Summary

Extended-spectrum β-lactamases (ESBLs) and AmpC β-lactamases (AmpCs) have been recognized as an emerging global problem in humans and animals. These enzymes provide a mechanism of resistance by inactivating β-lactam antibiotics and are mostly encoded on plasmids, which can be easily transmitted to other bacteria in humans, animals, and the environment. Several clinical diseases caused by Klebsiella spp. infection have been confirmed in the horse community. The emergence of antimicrobial resistance in Klebsiella spp. increases the risk of treatment failure in infected horses. In this study, we investigated the presence of ESBL/AmpC-producing Klebsiella spp. isolated from healthy Thoroughbred racehorses in Japan. The results showed that ESBL/AmpC-producing Klebsiella pneumoniae (ESBL/AmpC-KP) isolated from horses have co-resistance to other β-lactam antibiotics as multidrug-resistant (MDR) bacteria. Genetic relatedness analysis suggested that plasmid-mediated AmpC-KP clones may spread between horses. This is the first study to show K. pneumoniae carrying MDR plasmid-mediated AmpC isolated from racehorses. Continuous monitoring antimicrobial resistance to this species is required in order to control the spread of MDR ESBL/AmpC-KP in the racehorse community.

Abstract

Extended-spectrum β-lactamase (ESBL)- and AmpC β-lactamase (AmpC)-producing Klebsiella spp. have become a major health problem, leading to treatment failure in humans and animals. This study aimed to evaluate the presence of ESBL/AmpC-producing Klebsiella spp. isolated from racehorses in Japan. Feces samples from 212 healthy Thoroughbred racehorses were collected from the Japan Racing Association Training Centers between March 2017 and August 2018. ESBL/AmpC-producing Klebsiella spp. were isolated using selective medium containing 1 µg/mL cefotaxime. All isolates were subjected to bacterial species identification (MALDI-TOF MS), antimicrobial susceptibility test (disk diffusion test), characterization of resistance genes (PCR), conjugation assay, and genetic relatedness (multilocus sequence typing/MLST). Twelve ESBL/AmpC-producing Klebsiella pneumoniae (ESBL/AmpC-KP) were isolated from 3.3% of horse samples. Antimicrobial resistance profiling for 17 antimicrobials showed all ESBL/AmpC-KP were multidrug-resistant (MDR). Only 1 isolate was confirmed as an ESBL producer (bla_CTX-M-2-positive), whereas the other 11 isolates were plasmid-mediated AmpC (pAmpC) producers (bla_CMY positive). On the basis of MLST analysis, the ESBL-KP isolate was identified as sequence type (ST)-133 and four different STs among AmpC-KP isolates, ST-145, ST-4830, ST-4831, and ST-4832, were found to share six of the seven loci constituting a single-locus variant. This is the first study to show K. pneumoniae carrying MDR pAmpC isolated from a racehorse.

IncI1 Plasmid Associated with blaCTX-M-2 Transmission in ESBL-Producing Escherichia coli Isolated from Healthy Thoroughbred Racehorse, Japan

In our previous study, extended spectrum β-lactamase (ESBL)-producing Escherichia coli (ESBLEC) were isolated from healthy Thoroughbred racehorse feces samples in Japan. Some ESBL genes were predicted to be located on the conjugative plasmid. PCR-based replicon typing (PBRT) is a useful method to monitor and detect the association of replicons with specific plasmid-borne resistant genes. This study aimed to evaluate the plasmid replicon associated with ESBLEC isolated from healthy Thoroughbred racehorses at Japan Racing Association Training Centers in Japan. A total of 24 ESBLECs isolated from 23 (10.8%) individual Thoroughbred racehorse feces samples were used in this study. ESBL gene transfer was performed using a conjugation assay. Then, replicon types of ESBLEC isolates and their transconjugants were determined using PBRT. Pulsed-field gel electrophoresis (PFGE) was performed to look at the clonality of the ESBLECs isolates. ESBLECs were detected from 10.8% of healthy Thoroughbred racehorses. The bla_CTX-M-2 was identified as the dominant type of ESBL gene, followed by bla_CTX-M-1 and bla_TEM-116. In this study, only the bla_CTX-M-2 and the IncI1 plasmid were transferred to transconjugants. The PFGE results showed that ESBL genes were distributed in diversity of ESBLECs. This finding suggested that the IncI1 plasmid was associated with the dissemination of bla_CTX-M-2 in Thoroughbred racehorses in Japan.