Characterization of Multidrug-Resistant Escherichia coli Isolates from Animals Presenting at a University Veterinary Hospital

Abstract

In this study, we examined molecular mechanisms associated with multidrug resistance (MDR) in a collection of Escherichia coli isolates recovered from hospitalized animals in Ireland. PCR and DNA sequencing were used to identify genes associated with resistance. Class 1 integrons were prevalent (94.6%) and contained gene cassettes recognized previously and implicated mainly in resistance to aminoglycosides, ␤-lactams, and trimethoprim (aadA1, dfrA1-aadA1, dfrA17-aadA5, dfrA12-orfF-aadA2, bla OXA-30 -aadA1, aacC1-orf1-orf2-aadA1, dfr7). Class 2 integrons (13.5%) contained the dfrA1-sat1-aadA1 gene array. The most frequently occurring phenotypes included resistance to ampicillin (97.3%), chloramphenicol (75.4%), florfenicol (40.5%), gentamicin (54%), neomycin (43.2%), streptomycin (97.3%), sulfonamide (98.6%), and tetracycline (100%). The associated resistance determinants detected included bla TEM , cat, floR, aadB, aphA1, strA-strB, sul2, and tet(B), respectively. The bla CTX-M-2 gene, encoding an extended-spectrum ␤-lactamase (ES␤L), and bla CMY-2 , encoding an AmpC-like enzyme, were identified in 8 and 18 isolates, respectively. The mobility of the resistance genes was demonstrated using conjugation assays with a representative selection of isolates. High-molecular-weight plasmids were found to be responsible for resistance to multiple antimicrobial compounds. The study demonstrated that animal-associated commensal E. coli isolates possess a diverse repertoire of transferable genetic determinants. Emergence of ES␤Ls and AmpC-like enzymes is particularly significant. To our knowledge, the bla CTX-M-2 gene has not previously been reported in Ireland.

Antimicrobial Susceptibility Patterns and Conjugation Characteristics of Escherichia Coli Isolates From Broiler and Indigenous Chicken in Kericho County, Kenya

“…These results (Table 2) are in agreement with the earlier studies which revealed that plasmids with large molecular size are responsible for high resistance in E. coli to antibiotics; there is direct correlation between the rate of resistance and the size of plasmid [Karczmarczyk et al, 2011]. There was no correlation ( Table 2) between rate of resistance and number of plasmids, which is in agreement with earlier studies [González and Blanco, 1985].…”

Antibiotic Resistance: How Much Do We Know and Where Do We Go from Here?

“…These findings highlight the importance of the commensal microfloras of food-producing animals as reservoirs of transferable MDR. The same group also characterized MDR E. coli isolates from hospitalized animals, further illustrating that animal-associated commensal E. coli strains possess a wide array of transferable genetic determinants (11). A similar conclusion was also derived by Schink et al (21) through the study of bla CTX-M-1 genes from E. coli.…”

Changes of resistome, mobilome and potential hosts of antibiotic resistance genes during the transformation of anaerobic digestion from mesophilic to thermophilic

“…S3), and significant correlations existed between the eight aminoglycoside resistance genes themselves (Fig. 4, Table S9), which might be attributed to the coexistence of aminoglycoside resistance genes in bacterial genomes (Karczmarczyk et al, 2011;Cain and Hall, 2012). Thus, co-selection might play an important role in their dissemination during the transition period.…”