The prevalence and mechanism of fluoroquinolone resistance in Escherichia coli isolated from swine farms in China

Abstract

Background It has been demonstrated that swine waste is an important reservoir for resistant genes. Moreover, the bacteria carrying resistant genes and originating from swine feces and wastewater could spread to the external environment. Fluoroquinolones (FQs) are widely used in livestock and poultry for the treatment of bacterial infection. However, resistance to FQs has increased markedly. Results In this study, swine feces and wastewater were sampled from 21 swine farms of seven provinces in China to investigate the prevalence of FQ resistance, including plasmid-mediated fluoroquinolone resistance (PMQR) genes and the occurrence of target mutations. All isolates showed moderate rate of resistance to norfloxacin (43.0%), ciprofloxacin (47.6%), ofloxacin (47.0%) and levofloxacin (38.8%). The percentage of strains resistant to the four FQs antimicrobials was positively correlated with the danofloxacin (DANO) MIC. Among the 74 FQ-resistant isolates, 39 (52.70%) had mutations in gyrA (S83L and D87 to N, Y, G, or H), 21 (28.38%) had mutations in parC (S80I and E84K), 2 (2.70%) had mutations in parE (I355T and L416F), 26 (35.14%) had mutations in marR (D67N and G103S), 1 (1.35%) had mutations in acrR (V29G). While, no mutation was found in gyrB . There were 7 (9.46%) strains carried the qnrS gene, 29 (39.19%) strains carried the oqxAB gene, and 9 (12.16%) strains carried the aac (6′)-Ib-cr gene. In addition, the conjugation assays showed that qnrS , oqxAB and aac (6′)-Ib-cr could be successfully transferred to E. coli J53 from 4 (57.1%), 20 (69.0%) and 5 (55.6%) donor strains, respectively. There were no qnrA , qnrB , qnrC , qnrD and qepA genes detected. Conclusion The present study showed that DANO-resistant E. coli strains isolated from swine farms had significant cross-resistance to other four FQs antimicrobials. Further study revealed that the resistance mechanisms of swine-derived E. coli to FQs may be attributable to the occurrence of chromosomal mutations ( gyrA , parC , parE , marR and acrR genes double-site or single-site mutation) and the presence of PMQR genes ( qnrS, oqxAB and aac (6′)-Ib-cr ). To the best of our knowledge, one novel mutation marR -D67N was found to be associated with FQ resistance, two mutations ...

Danofloxacin Treatment Alters the Diversity and Resistome Profile of Gut Microbiota in Calves

“…Fluoroquinolone (in this case danofloxacin) resistance is primarily conferred through a single mutation in gyrA gene that is involved in DNA supercoiling [66]. The method we employed in the current study does not detect a single nucleotide change, despite the rebound of Campylobacter four days post-treatment, suggesting the emergence of resistant strains, which also complemented by previous trials in our laboratory and in the literature [18,25]. Genes that have been shown to be associated with fluoroquinolone resistance in other bacteria (e.g., qnrA, qnrB, qnrS, etc.)…”

“…It has been suggested that the rise in ciprofloxacin resistance in Campylobacter in humans may, at least in part, be associated with use of danofloxacin and enrofloxacin in other livestock [21,22]. Beyond inducing antibiotic resistance in specific bacterial pathogens, these antibiotics exert selection pressure on gut microbiota that may lead to its alteration and enhance the spread of ARGs within bacterial communities [23][24][25].…”

Prevalence of Antibiotic-Resistant Escherichia coli Isolated from Swine Faeces and Lagoons in Bulgaria

“…Fluoroquinolone-resistant E. coli in China and Korea have been isolated from fecal samples [ 25 , 26 ]. From 171 samples isolated in 2015, from which 52 (30.4%) were from diseased swine and the other 119 (69.6%) were from healthy swine, a total of 59 E. coli isolates (34.5%) were confirmed as fluoroquinolone-resistant (21 (40.4% from diseased swine) and 38 (31.9% from healthy swine)).…”

“…All isolates from China showed the moderate rates of the resistance to norfloxacin (43.0%), ciprofloxacin (47.6%), ofloxacin (47.0%), and levofloxacin (38.8%). They also did not detect the presence of qnr A and qnr B genes [ 26 ]. Hu et al (2017) suggested that the predominant PMQR genes detected in human isolates were qnr A and qnr B, whereas qnr S was detected in swine samples.…”

Molecular Characteristics of Fluoroquinolone-Resistant Escherichia Coli Isolated From Suckling Piglets With Colibacillosis

“…The PMQR genes confer only low-level resistance to FQ; however, they can be spread horizontally among enterobacteria and facilitate the selection of resistant mutants following exposure to FQ [11]. Although studies from several countries have documented the prevalence and characteristics of FQ-resistance in healthy pigs [12][13][14], there is still limited information regarding the molecular characteristics of FQ-resistant and PMQR-positive E. coli isolated from suckling piglets with diarrhea. Therefore, the purpose of this study was to investigate the phenotypic and genotypic characteristics of FQ-resistant E. coli isolates from suckling piglets with colibacillosis.…”