scholarly journals Transfer Potential of Plasmids Conferring Extended-Spectrum-Cephalosporin Resistance in Escherichia coli from Poultry

2017 ◽  
Vol 83 (12) ◽  
Author(s):  
Solveig Sølverød Mo ◽  
Marianne Sunde ◽  
Hanna Karin Ilag ◽  
Solveig Langsrud ◽  
Even Heir
Keyword(s):  
Escherichia Coli ◽  
Plasmid Transfer ◽  
Conjugative Plasmid ◽  
High Survival ◽  
Content Type ◽  
E Coli ◽  
Broiler Production ◽  
Extended Spectrum ◽  
Resistance Plasmids ◽  
Environmental Bacteria

ABSTRACT Escherichia coli strains resistant to extended-spectrum cephalosporins (ESC) are widely distributed in Norwegian broiler production, and the majority harbor transferable IncK or IncI1 plasmids carrying bla CMY-2 . Persistent occurrence in broiler farms may occur through the survival of ESC-resistant E. coli strains in the farm environment, or by transfer and maintenance of resistance plasmids within a population of environmental bacteria with high survival abilities. The aim of this study was to determine the transferability of two successful bla CMY-2 -carrying plasmids belonging to the incompatibility groups IncK and IncI1 into E. coli and Serratia species recipients. Initially, conjugative plasmid transfer from two E. coli donors to potential recipients was tested in an agar assay. Conjugation was further investigated for selected mating pairs in surface and planktonic assays at temperatures from 12°C to 37°C. Transfer of plasmids was observed on agar, in broth, and in biofilm at temperatures down to 25°C. The IncK plasmid was able to transfer into Serratia marcescens , and transconjugants were able to act as secondary plasmid donors to different E. coli and Serratia species recipients. All transconjugants displayed an AmpC phenotype corresponding to the acquisition of bla CMY-2 . In summary, the results indicate that the IncK plasmid may transfer between E. coli and Serratia spp. under conditions relevant for broiler production. IMPORTANCE Certain bla CMY-2 -carrying plasmids are successful and disseminated in European broiler production. Traditionally, plasmid transferability has been studied under conditions that are optimal for bacterial growth. Plasmid transfer has previously been reported between E. coli bacteria in biofilms at 37°C and in broth at temperatures ranging from 8 to 37°C. However, intergenus transfer of bla CMY-2 -carrying plasmids from E. coli to environmental bacteria in the food-processing chain has not been previously studied. We demonstrate that bla CMY-2 -carrying plasmids are capable of conjugative transfer between different poultry-associated bacterial genera under conditions relevant for broiler production. Transfer to Serratia spp. and to hosts with good biofilm-forming abilities and with the potential to act as secondary plasmid donors to new hosts might contribute to the persistence of these resistance plasmids. These results contribute to increased knowledge of factors affecting the persistence of ESC resistance in broiler production and can provide a basis for improvement of routines and preventive measures.

scholarly journals Molecular Characterization of Resistance to Extended-Spectrum Cephalosporins in Clinical Escherichia coli Isolates from Companion Animals in the United States

2011 ◽  
Vol 55 (12) ◽  
pp. 5666-5675 ◽  
Author(s):  
Bashar W. Shaheen ◽  
Rajesh Nayak ◽  
Steven L. Foley ◽  
Ohgew Kweon ◽  
Joanna Deck ◽  
...  
Keyword(s):  
United States ◽  
Escherichia Coli ◽  
Regulatory Region ◽  
Companion Animals ◽  
The United States ◽  
Conjugative Plasmid ◽  
Chromosomal Gene ◽  
Content Type ◽  
E Coli ◽  
Extended Spectrum

ABSTRACTResistance to extended-spectrum cephalosporins (ESC) among members of the familyEnterobacteriaceaeoccurs worldwide; however, little is known about ESC resistance inEscherichia colistrains from companion animals. Clinical isolates ofE. coliwere collected from veterinary diagnostic laboratories throughout the United States from 2008 to 2009.E. coliisolates (n= 54) with reduced susceptibility to ceftazidime or cefotaxime (MIC ≥ 16 μg/ml) and extended-spectrum-β-lactamase (ESBL) phenotypes were analyzed. PCR and sequencing were used to detect mutations in ESBL-encoding genes and the regulatory region of the chromosomal geneampC. Conjugation experiments and plasmid identification were conducted to examine the transferability of resistance to ESCs. All isolates carried theblaCTX-M-1-group β-lactamase genes in addition to one or more of the following β-lactamase genes:blaTEM,blaSHV-3,blaCMY-2,blaCTX-M-14-like, andblaOXA-1.DifferentblaTEMsequence variants were detected in some isolates (n= 40). Three isolates harbored ablaTEM-181gene with a novel mutation resulting in an Ala184Val substitution. Approximately 78% of the isolates had mutations in promoter/attenuator regions of the chromosomal geneampC, one of which was a novel insertion of adenine between bases −28 and −29. Plasmids ranging in size from 11 to 233 kbp were detected in the isolates, with a common plasmid size of 93 kbp identified in 60% of isolates. Plasmid-mediated transfer of β-lactamase genes increased the MICs (≥16-fold) of ESCs for transconjugants. Replicon typing among isolates revealed the predominance of IncI and IncFIA plasmids, followed by IncFIB plasmids. This study shows the emergence of conjugative plasmid-borne ESBLs amongE. colistrains from companion animals in the United States, which may compromise the effective therapeutic use of ESCs in veterinary medicine.

scholarly journals Novel Conjugative Plasmid from Escherichia coli of Swine Origin That Coharbors the Multiresistance Genecfrand the Extended-Spectrum-β-Lactamase GeneblaCTX-M-14b

2014 ◽  
Vol 59 (2) ◽  
pp. 1337-1340 ◽  
Author(s):  
Wan-Jiang Zhang ◽  
Xiu-Mei Wang ◽  
Lei Dai ◽  
Xin Hua ◽  
Zhimin Dong ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Conjugative Plasmid ◽  
Content Type ◽  
Conjugative Plasmids ◽  
Extended Spectrum ◽  
Lactamase Gene

ABSTRACTTwo porcineEscherichia coliisolates harbored thecfrgene on conjugative plasmids of 38,405 bp (pGXEC6) and 41,646 bp (pGXEC3). In these two plasmids, thecfrgene was located within a 4,612-bp region containing atnpA-IS26-cfr-IS26-Δhypelement. Plasmid pGXEC3 was almost identical to pGXEC6 except for a 3,235-bp ISEcp1-blaCTX-M-14binsertion. The colocation of the multiresistancecfrgene with an extended-spectrum-β-lactamase gene on a conjugative plasmid may support the dissemination of these genes by coselection.

scholarly journals Phylogenetic Grouping and Virulence Potential of Extended-Spectrum-β-Lactamase-Producing Escherichia coli Strains in Cattle

2012 ◽  
Vol 78 (13) ◽  
pp. 4677-4682 ◽  
Author(s):  
Charlotte Valat ◽  
Frédéric Auvray ◽  
Karine Forest ◽  
Véronique Métayer ◽  
Emilie Gay ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Virulence Determinants ◽  
Phylogenetic Groups ◽  
Content Type ◽  
E Coli ◽  
Extended Spectrum ◽  
Specific Distribution ◽  
Extended Spectrum Beta Lactamases ◽  
Phylogenetic Grouping ◽  
Almost All

ABSTRACTIn line with recent reports of extended-spectrum beta-lactamases (ESBLs) inEscherichia coliisolates of highly virulent serotypes, such as O104:H4, we investigated the distribution of phylogroups (A, B1, B2, D) and virulence factor (VF)-encoding genes in 204 ESBL-producingE. coliisolates from diarrheic cattle. ESBL genes, VFs, and phylogroups were identified by PCR and a commercial DNA array (Alere, France). ESBL genes belonged mostly to the CTX-M-1 (65.7%) and CTX-M-9 (27.0%) groups, whereas those of the CTX-M-2 and TEM groups were much less represented (3.9% and 3.4%, respectively). One ESBL isolate wasstx1andeaepositive and belonged to a major enterohemorrhagicE. coli(EHEC) serotype (O111:H8). Two other isolates wereeaepositive butstxnegative; one of these had serotype O26:H11. ESBL isolates belonged mainly to phylogroup A (55.4%) and, to lesser extents, to phylogroups D (25.5%) and B1 (15.6%), whereas B2 strains were quasi-absent (1/204). The number of VFs was significantly higher in phylogroup B1 than in phylogroups A (P= 0.04) and D (P= 0.02). Almost all of the VFs detected were found in CTX-M-1 isolates, whereas only 64.3% and 33.3% of them were found in CTX-M-9 and CTX-M-2 isolates, respectively. These results indicated that the widespread dissemination of theblaCTX-Mgenes within theE. colipopulation from cattle still spared the subpopulation of EHEC/Shiga-toxigenicE. coli(STEC) isolates. In contrast to other reports on non-ESBL-producing isolates from domestic animals, B1 was not the main phylogroup identified. However, B1 was found to be the most virulent phylogroup, suggesting host-specific distribution of virulence determinants among phylogenetic groups.

scholarly journals Competitive Exclusion Reduces Transmission and Excretion of Extended-Spectrum-β-Lactamase-Producing Escherichia coli in Broilers

2017 ◽  
Vol 83 (11) ◽  
Author(s):  
Daniela Ceccarelli ◽  
Alieda van Essen-Zandbergen ◽  
Bregtje Smid ◽  
Kees T. Veldman ◽  
Gert Jan Boender ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Competitive Exclusion ◽  
Intervention Strategy ◽  
Substantial Reduction ◽  
Poultry Production ◽  
Broiler Meat ◽  
Content Type ◽  
E Coli ◽  
Extended Spectrum ◽  
Probiotic Product

ABSTRACT Extended-spectrum β-lactamases (ESBLs) and plasmid-mediated AmpC β-lactamases (pAmpC) are enzymes able to hydrolyze a large variety of β-lactam antibiotics, including third-generation cephalosporins and monobactams. Broilers and broiler meat products can be highly contaminated with ESBL- and pAmpC-producing Escherichia coli strains, also known as extended-spectrum cephalosporin (ESC)-resistant E. coli strains, and can be a source for human infections. As few data on interventions to reduce the presence of ESC-resistant E. coli in broilers are available, we used transmission experiments to examine the role of competitive exclusion (CE) on reducing transmission and excretion in broilers. A broiler model to study the transmission of ESC-resistant E. coli was set up. Day-old chickens were challenged with an ESBL-producing E. coli strain isolated from healthy broilers in the Netherlands. Challenged and not challenged chicks were housed together in pairs or in groups, and ESBL-producing E. coli transmission was monitored via selective culturing of cloacal swab specimens. We observed a statistically significant reduction in both the transmission and excretion of ESBL-producing E. coli in chicks treated with the probiotic flora before E. coli challenge compared to the transmission and excretion in untreated controls. In conclusion, our results support the use of competitive exclusion as an intervention strategy to control ESC-resistant E. coli in the field. IMPORTANCE Extended-spectrum β-lactamases (ESBLs) and plasmid-mediated AmpC β-lactamases are a primary cause of resistance to β-lactam antibiotics among members of the family Enterobacteriaceae in humans, animals, and the environment. Food-producing animals are not exempt from this, with a high prevalence being seen in broilers, and there is evidence pointing to a possible foodborne source for human contamination. We investigated the effect of administration of a commercial probiotic product as an intervention to reduce the amount of ESBL-producing Escherichia coli in broilers. Our results showed a substantial reduction in the level of colonization of broiler intestines by ESBL-producing E. coli after administration of commercial probiotic product. The protective effect provided by these probiotics could be implemented on a larger scale in poultry production. Reductions in the levels of ESBL-producing Enterobacteriaceae in the food chain would considerably benefit public health.

scholarly journals Impact of Extended-Spectrum β-Lactamase Production on Treatment Outcomes of Acute Pyelonephritis Caused by Escherichia coli in Patients without Health Care-Associated Risk Factors

2015 ◽  
Vol 59 (4) ◽  
pp. 1962-1968 ◽  
Author(s):  
Sun Hee Park ◽  
Su-Mi Choi ◽  
Dong-Gun Lee ◽  
Sung-Yeon Cho ◽  
Hyo-Jin Lee ◽  
...  
Keyword(s):  
Risk Factors ◽  
Escherichia Coli ◽  
Health Care ◽  
Treatment Outcomes ◽  
Acute Pyelonephritis ◽  
Esbl Production ◽  
Content Type ◽  
E Coli ◽  
Extended Spectrum ◽  
The Impact

ABSTRACTExtended-spectrum β-lactamase-producingEscherichia coli(ESBL-EC) is increasingly identified as a cause of acute pyelonephritis (APN) among patients without recent health care contact, i.e., community-associated APN. This case-control study compared 75 cases of community-associated ESBL-EC APN (CA-ESBL) to 225 controls of community-associated non-ESBL-EC APN (CA-non-ESBL) to identify the risk factors for ESBL-EC acquisition and investigate the impact of ESBL on the treatment outcomes of community-associated APN (CA-APN) caused byE. coliat a Korean hospital during 2007 to 2013. The baseline characteristics were similar between the cases and controls; the risk factors for ESBL-EC were age (>55 years), antibiotic use within the previous year, and diabetes with recurrent APN. The severity of illness did not differ between CA-ESBL and CA-non-ESBL (Acute Physiology and Chronic Health Evaluation [APACHE] II scores [mean ± standard deviation], 7.7 ± 5.9 versus 6.4 ± 5.3;P= 0.071). The proportions of clinical (odds ratio [OR], 1.76; 95% confidence interval [CI], 0.57 to 5.38;P= 0.323) and microbiological (OR, 1.16; 95% CI, 0.51 to 2.65;P= 0.730) cures were similar, although the CA-ESBL APN patients were less likely to receive appropriate antibiotics within 48 h. A multivariable Cox proportional hazards analysis of the prognostic factors for CA-APN caused byE. colishowed that ESBL production was not a significant factor for clinical (hazard ratio [HR], 0.39; 95% CI, 0.12 to 1.30;P= 0.126) or microbiological (HR, 0.49; 95% CI, 0.21 to 1.12;P= 0.091) failure. The estimates did not change after incorporating weights calculated using propensity scores for acquiring ESBL-EC. Therefore, ESBL production did not negatively affect treatment outcomes among patients with community-associatedE. coliAPN.

scholarly journals Relative Fecal Abundance of Extended-Spectrum-β-Lactamase-Producing Escherichia coli Strains and Their Occurrence in Urinary Tract Infections in Women

2013 ◽  
Vol 57 (9) ◽  
pp. 4512-4517 ◽  
Author(s):  
Etienne Ruppé ◽  
Brandusa Lixandru ◽  
Radu Cojocaru ◽  
Çağrı Büke ◽  
Elisabeth Paramythiotou ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Virulence Factors ◽  
Urinary Tract Infections ◽  
Predictive Values ◽  
Content Type ◽  
Extended Spectrum Beta Lactamase ◽  
E Coli ◽  
Extended Spectrum ◽  
Tract Infections

ABSTRACTExtended-spectrum-beta-lactamase (ESBL)-producingEscherichia coli(ESBLE. coli) strains are of major concern because few antibiotics remain active against these bacteria. We investigated the association between the fecal relative abundance (RA) of ESBL-producingE. coli(ESBL-RA) and the occurrence of ESBLE. coliurinary tract infections (UTIs). The first stool samples passed after suspicion of UTI from 310 women with subsequently confirmedE. coliUTIs were sampled and tested for ESBL-RA by culture on selective agar. Predictive values of ESBL-RA for ESBLE. coliUTI were analyzed for women who were not exposed to antibiotics when the stool was passed. ESBLE. coliisolates were characterized for ESBL type, phylogroup, relatedness, and virulence factors. The prevalence of ESBLE. colifecal carriage was 20.3%, with ESBLE. coliUTIs being present in 12.3% of the women. The mean ESBL-RA (95% confidence interval [CI]) was 13-fold higher in women exposed to antibiotics at the time of sampling than in those not exposed (14.3% [range, 5.6% to 36.9%] versus 1.1% [range, 0.32% to 3.6%], respectively;P< 0.001) and 18-fold higher in women with ESBLE. coliUTI than in those with anotherE. coliUTI (10.0% [range, 0.54% to 100%] versus 0.56% [range, 0.15% to 2.1%[, respectively;P< 0.05). An ESBL-RA of <0.1% was 100% predictive of a non-ESBLE. coliUTI. ESBL type, phylogroup, relatedness, and virulence factors were not found to be associated with ESBL-RA. In conclusion, ESBL-RA was linked to the occurrence of ESBLE. coliUTI in women who were not exposed to antibiotics and who had the same clone ofE. coliin urine samples and fecal samples. Especially, a low ESBL-RA appeared to be associated with a low risk of ESBLE. coliinfection.

scholarly journals Carbapenem Therapy for Bacteremia Due to Extended-Spectrum-β-Lactamase-Producing Escherichia coli or Klebsiella pneumoniae: Implications of Ertapenem Susceptibility

2012 ◽  
Vol 56 (6) ◽  
pp. 2888-2893 ◽  
Author(s):  
Nan-Yao Lee ◽  
Ching-Chi Lee ◽  
Wei-Han Huang ◽  
Ko-Chung Tsui ◽  
Po-Ren Hsueh ◽  
...  
Keyword(s):  
Risk Factors ◽  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
Content Type ◽  
Extended Spectrum Beta Lactamase ◽  
E Coli ◽  
Medical Centers ◽  
Extended Spectrum ◽  
Appropriate Therapy ◽  
Related Mortality

ABSTRACTA retrospective study was conducted at two medical centers in Taiwan to evaluate the clinical characteristics, outcomes, and risk factors for mortality among patients treated with a carbapenem for bacteremia caused by extended-spectrum-beta-lactamase (ESBL)-producing organisms. A total of 251 patients with bacteremia caused by ESBL-producingEscherichia coliandKlebsiella pneumoniaeisolates treated by a carbapenem were identified. Among these ESBL-producing isolates, rates of susceptibility to ertapenem (MICs ≤ 0.25 μg/ml) were 83.8% and 76.4%, respectively; those to meropenem were 100% and 99.3%, respectively; and those to imipenem were 100% and 97.9%, respectively. There were no significant differences in the critical illness rate (P= 0.1) or sepsis-related mortality rate (P= 0.2) for patients with bacteremia caused by ESBL-producingK. pneumoniae(140 isolates, 55.8%) andE. coli(111 isolates, 44.2%). Multivariate analysis of variables related to sepsis-related mortality revealed that the presence of severe sepsis (odds ratio [OR], 15.9; 95% confidence interval [CI], 5.84 to 43.34;P< 0.001), hospital-onset bacteremia (OR, 4.65; 95% CI, 1.42 to 15.24;P= 0.01), and ertapenem-nonsusceptible isolates (OR, 5.12; 95% CI, 2.04 to 12.88;P= 0.001) were independent risk factors. The patients receiving inappropriate therapy had a higher sepsis-related mortality than those with appropriate therapy (P= 0.002), irrespective of ertapenem, imipenem, or meropenem therapy. Infections due to the ertapenem-susceptible isolates (MICs ≤ 0.25 μg/ml) were associated with a more favorable outcome than those due to ertapenem-nonsusceptible isolates (MICs > 0.25 μg/ml), if treated by a carbapenem. However, the mortality for patients with bacteremic episodes due to isolates with MICs of ≤0.5 μg/ml was similar to the mortality for those whose isolates had MICs of >0.5 μg/ml (P= 0.8). Such a finding supports the rationale of the current CLSI 2011 criteria for carbapenems forEnterobacteriaceae.

scholarly journals Risk Factors for Infection or Colonization with CTX-M Extended-Spectrum-β-Lactamase-Positive Escherichia coli

2012 ◽  
Vol 56 (11) ◽  
pp. 5575-5580 ◽  
Author(s):  
Jennifer H. Han ◽  
Kei Kasahara ◽  
Paul H. Edelstein ◽  
Warren B. Bilker ◽  
Ebbing Lautenbach
Keyword(s):  
Risk Factors ◽  
Escherichia Coli ◽  
Control Strategies ◽  
Content Type ◽  
E Coli ◽  
Extended Spectrum ◽  
Increased Risk ◽  
Urinary Culture ◽  
Multivariable Analyses ◽  
And Control

ABSTRACTThere has been a significant increase in the prevalence ofEnterobacteriaceaethat produce CTX-M-type extended-spectrum β-lactamases. The objective of this study was to evaluate risk factors for infection or colonization with CTX-M-positiveEscherichia coli. A case-control study was conducted within a university system from 1 January 2007 to 31 December 2008. All patients with clinical cultures withE. colidemonstrating resistance to extended-spectrum cephalosporins were included. Case patients were designated as those with cultures positive for CTX-M-positiveE. coli, and control patients were designated as those with non-CTX-M-producingE. coli. Multivariable logistic regression analyses were performed to evaluate risk factors for CTX-M-positive isolates. A total of 83 (56.8%) of a total of 146 patients had cultures with CTX-M-positiveE. coli. On multivariable analyses, there was a significant association between infection or colonization with CTX-M-type β-lactamase-positiveE. coliand receipt of piperacillin-tazobactam in the 30 days prior to the culture date (odds ratio [OR], 7.36; 95% confidence interval [CI], 1.61 to 33.8;P= 0.01) and a urinary culture source (OR, 0.36; 95% CI, 0.17 to 0.77;P= 0.008). The rates of resistance to fluoroquinolones were significantly higher in isolates from case patients than in isolates from control patients (90.4 and 50.8%, respectively;P< 0.001). We found that nonurinary sources of clinical cultures and the recent use of piperacillin-tazobactam conferred an increased risk of colonization or infection with CTX-M-positiveE. coli. Future studies will need to focus on outcomes associated with infections due to CTX-M-positiveE. coli, as well as infection control strategies to limit the spread of these increasingly common organisms.

scholarly journals Impact of Ceftiofur Injection on Gut Microbiota and Escherichia coli Resistance in Pigs

2015 ◽  
Vol 59 (9) ◽  
pp. 5171-5180 ◽  
Author(s):  
M. A. Fleury ◽  
G. Mourand ◽  
E. Jouy ◽  
F. Touzain ◽  
L. Le Devendec ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gut Microbiota ◽  
Treated Group ◽  
Conjugative Plasmid ◽  
Health Concern ◽  
Pcr Analysis ◽  
Contamination Level ◽  
Content Type ◽  
E Coli ◽  
The Impact

ABSTRACTResistance to extended-spectrum cephalosporins (ESCs) is an important health concern. Here, we studied the impact of the administration of a long-acting form of ceftiofur on the pig gut microbiota and ESC resistance inEscherichia coli. Pigs were orally inoculated with an ESC-resistantE. coliM63 strain harboring a conjugative plasmid carrying a gene conferring resistance,blaCTX-M-1. On the same day, they were given or not a unique injection of ceftiofur. Fecal microbiota were studied using quantitative PCR analysis of the main bacterial groups and quantification of short-chain fatty acids.E. coliand ESC-resistantE. coliwere determined by culture methods, and the ESC-resistantE. coliisolates were characterized. The copies of theblaCTX-M-1gene were quantified. After ceftiofur injection, the main change in gut microbiota was the significant but transitory decrease in theE. colipopulation. Acetate and butyrate levels were significantly lower in the treated group. In all inoculated groups,E. coliM63 persisted in most pigs, and theblaCTX-M-1gene was transferred to otherE. coli. Culture and PCR results showed that the ceftiofur-treated group shed significantly more resistant strains 1 and 3 days after ESC injection. Thereafter, on most dates, there were no differences between the groups, but notably, one pig in the nontreated group regularly excreted very high numbers of ESC-resistantE. coli, probably leading to a higher contamination level in its pen. In conclusion, the use of ESCs, and also the presence of high-shedding animals, are important features in the spread of ESC resistance.

scholarly journals Genetic Determinants of Resistance to Extended-Spectrum Cephalosporin and Fluoroquinolone in Escherichia coli Isolated from Diseased Pigs in the United States

mSphere ◽  
2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Shivdeep Singh Hayer ◽  
Seunghyun Lim ◽  
Samuel Hong ◽  
Ehud Elnekave ◽  
Timothy Johnson ◽  
...  
Keyword(s):  
United States ◽  
Escherichia Coli ◽  
High Risk ◽  
The United States ◽  
Genetic Determinants ◽  
Content Type ◽  
E Coli ◽  
Extended Spectrum ◽  
Animal Populations ◽  
Swine Population

ABSTRACT Fluoroquinolones and cephalosporins are critically important antimicrobial classes for both human and veterinary medicine. We previously found a drastic increase in enrofloxacin resistance in clinical Escherichia coli isolates collected from diseased pigs from the United States over 10 years (2006 to 2016). However, the genetic determinants responsible for this increase have yet to be determined. The aim of the present study was to identify and characterize the genetic basis of resistance against fluoroquinolones (enrofloxacin) and extended-spectrum cephalosporins (ceftiofur) in swine E. coli isolates using whole-genome sequencing (WGS). blaCMY-2 (carried by IncA/C2, IncI1, and IncI2 plasmids), blaCTX-M (carried by IncF, IncHI2, and IncN plasmids), and blaSHV-12 (carried by IncHI2 plasmids) genes were present in 87 (82.1%), 19 (17.9%), and 3 (2.83%) of the 106 ceftiofur-resistant isolates, respectively. Of the 110 enrofloxacin-resistant isolates, 90 (81.8%) had chromosomal mutations in gyrA, gyrB, parA, and parC genes. Plasmid-mediated quinolone resistance genes [qnrB77, qnrB2, qnrS1, qnrS2, and aac-(6)-lb′-cr] borne on ColE, IncQ2, IncN, IncF, and IncHI2 plasmids were present in 24 (21.8%) of the enrofloxacin-resistant isolates. Virulent IncF plasmids present in swine E. coli isolates were highly similar to epidemic plasmids identified globally. High-risk E. coli clones, such as ST744, ST457, ST131, ST69, ST10, ST73, ST410, ST12, ST127, ST167, ST58, ST88, ST617, ST23, etc., were also found in the U.S. swine population. Additionally, the colistin resistance gene (mcr-9) was present in several isolates. This study adds valuable information regarding resistance to critical antimicrobials with implications for both animal and human health. IMPORTANCE Understanding the genetic mechanisms conferring resistance is critical to design informed control and preventive measures, particularly when involving critically important antimicrobial classes such as extended-spectrum cephalosporins and fluoroquinolones. The genetic determinants of extended-spectrum cephalosporin and fluoroquinolone resistance were highly diverse, with multiple plasmids, insertion sequences, and genes playing key roles in mediating resistance in swine Escherichia coli. Plasmids assembled in this study are known to be disseminated globally in both human and animal populations and environmental samples, and E. coli in pigs might be part of a global reservoir of key antimicrobial resistance (AMR) elements. Virulent plasmids found in this study have been shown to confer fitness advantages to pathogenic E. coli strains. The presence of international, high-risk zoonotic clones provides worrisome evidence that resistance in swine isolates may have indirect public health implications, and the swine population as a reservoir for these high-risk clones should be continuously monitored.

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