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Yang Y, Zhang AN, Che Y, Liu L, Deng Y, Zhang T. Underrepresented high diversity of class 1 integrons in the environment uncovered by PacBio sequencing using a new primer. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 787:147611. [PMID: 34000537 DOI: 10.1016/j.scitotenv.2021.147611] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 05/01/2021] [Accepted: 05/04/2021] [Indexed: 06/12/2023]
Abstract
Class 1 integrons (CL1s) are one of the major contributors to the horizontal transfer of antibiotic resistance genes (ARGs). However, our knowledge of CL1 in the environment is still very limited due to the limitations of the current PCR primers and the sequencing methods adopted. This study developed a new primer coupled with PacBio sequencing to investigate the underrepresented diversity of CL1s in a mixed environmental sample (i.e. activated sludge from wastewater treatment plant and pig feces from animal farm). The new primer successfully uncovered 20 extra ARGs subtypes and 57% (422/739) more unique integron array structures than the previous primers. Compared to the whole genome database, CL1s revealed in the environment in this study were of much greater diversity, having 93% (900/967) novel array structures. Antibiotic resistance is the predominant function (78.3% genes) carried by CL1, and a vast majority (98.6% genes) of them confer resistance to aminoglycoside, beta-lactam, trimethoprim, or chloramphenicol. Additionally, 78.5% unique CL1 arrays carried more than one ARGs, and 25.9% of them carried ARGs of clinical relevance with high transferability potential posing threat to the general public. Our results indicated the importance of CL1s in the spread of ARGs. Overall, combining PacBio sequencing with the new primer designed in this study largely broadened our knowledge of CL1s in the environment and their significance in the environmental proliferation of ARGs.
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Affiliation(s)
- Yu Yang
- Environmental Microbiome Engineering and Biotechnology Laboratory, Centre for Environmental Engineering Research, Department of Civil Engineering, The University of Hong Kong, Hong Kong
| | - An-Ni Zhang
- Environmental Microbiome Engineering and Biotechnology Laboratory, Centre for Environmental Engineering Research, Department of Civil Engineering, The University of Hong Kong, Hong Kong
| | - You Che
- Environmental Microbiome Engineering and Biotechnology Laboratory, Centre for Environmental Engineering Research, Department of Civil Engineering, The University of Hong Kong, Hong Kong
| | - Lei Liu
- Environmental Microbiome Engineering and Biotechnology Laboratory, Centre for Environmental Engineering Research, Department of Civil Engineering, The University of Hong Kong, Hong Kong
| | - Yu Deng
- Environmental Microbiome Engineering and Biotechnology Laboratory, Centre for Environmental Engineering Research, Department of Civil Engineering, The University of Hong Kong, Hong Kong
| | - Tong Zhang
- Environmental Microbiome Engineering and Biotechnology Laboratory, Centre for Environmental Engineering Research, Department of Civil Engineering, The University of Hong Kong, Hong Kong.
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Chae JB, Kim HC, Kang JG, Choi KS, Chae JS, Yu DH, Park BK, Oh YS, Choi HJ, Park J. The prevalence of causative agents of calf diarrhea in Korean native calves. JOURNAL OF ANIMAL SCIENCE AND TECHNOLOGY 2021; 63:864-871. [PMID: 34447962 PMCID: PMC8367409 DOI: 10.5187/jast.2021.e63] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 03/31/2021] [Accepted: 04/02/2021] [Indexed: 12/04/2022]
Abstract
Infectious calf diarrhea is one of the most significant diseases of neonatal
calves. This study is conducted to identify the prevalence of pathogens in calf
diarrhea for 2 years. A total of 544 feces samples from Korean native beef
calves were obtained to investigate selected seven pathogens causing calf
diarrhea: bovine rotavirus, bovine coronavirus, Cryptosporidium
parvum, bovine viral diarrhea virus, Eimeria
species, Escherichia coli K99, and Salmonella
species. The presence of diarrhea, the number and species of detected pathogens,
and the calves’ ages were analyzed using various statistical methods
depending on the case. Of the 544 calves, 340 calves (62.5%) had normal feces
and 204 calves (37.5%) had diarrhea. The presence of pathogens was significantly
associated with diarrhea (p < 0.01) and fecal scores and
the number of detected pathogens showed a significant linear trend
(p < 0.001). Of the 7 target pathogens, 6 were
detected in samples, but only C. parvum (p =
0.001) and bovine rotavirus (p < 0.001) were found at
significantly higher rates in diarrheic calves than in non-diarrheic calves.
Only Eimeria spp. showed a significant linear trend between the
detection rate of the pathogen and the age groups (p <
0.05).
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Affiliation(s)
- Jeong-Byoung Chae
- Laboratory of Veterinary Internal Medicine, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea
| | - Hyeon-Cheol Kim
- College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University, Chuncheon 24341, Korea
| | - Jun-Gu Kang
- Korea Zoonosis Research Institute, Jeonbuk National University, Iksan 54531, Korea
| | - Kyoung-Seong Choi
- College of Ecology and Environmental Science, Kyungpook National University, Sangju 37224, Korea
| | - Joon-Seok Chae
- Laboratory of Veterinary Internal Medicine, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea
| | - Do-Hyeon Yu
- Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea
| | - Bae-Keun Park
- College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Korea
| | - Yeon-Su Oh
- College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University, Chuncheon 24341, Korea
| | - Hak-Jong Choi
- Microbiology and Functionality Research Group, Research and Development Division, World Institute of Kimchi, Gwangju 61755, Korea
| | - Jinho Park
- Department of Veterinary Internal Medicine, College of Veterinary Medicine, Jeonbuk National University, Iksan 54596, Korea
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Peng Z, Liang W, Hu Z, Li X, Guo R, Hua L, Tang X, Tan C, Chen H, Wang X, Wu B. O-serogroups, virulence genes, antimicrobial susceptibility, and MLST genotypes of Shiga toxin-producing Escherichia coli from swine and cattle in Central China. BMC Vet Res 2019; 15:427. [PMID: 31783837 PMCID: PMC6883634 DOI: 10.1186/s12917-019-2177-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 11/15/2019] [Indexed: 11/12/2022] Open
Abstract
Background Shiga toxin-producing Escherichia coli (STEC) is a leading cause of worldwide food-borne and waterborne infections. Despite an increase in the number of STEC outbreaks, there is a lack of data on prevalence of STEC at the farm level, distribution of serogroups, and virulence factors. Results In the present study, a total of 91 (6.16%) STEC strains were isolated from 1477 samples including pig intestines, pig feces, cattle feces, milk, and water from dairy farms. The isolation rates of STEC strains from pig intestines, pig feces, and cattle feces were 7.41% (32/432), 4.38% (21/480), and 9.57% (38/397), respectively. No STEC was isolated from the fresh milk and water samples. By O-serotyping methods, a total of 30 types of O-antigens were determined, and the main types were O100, O97, O91, O149, O26, O92, O102, O157, and O34. Detection of selected virulence genes (stx1, stx2, eae, ehxA, saa) revealed that over 94.51% (86/91) of the isolates carried more than two types of virulence associated genes, and approximately 71.43% (65/91) of the isolates carried both stx1 and stx2, simultaneously. Antimicrobial susceptibility tests showed that most of the STEC isolates were susceptible to ofloxacin and norfloxacin, but showed resistance to tetracycline, kanamycin, trimethoprim-sulfamethoxazole, streptomycin, amoxicillin, and ampicillin. MLST determined 13 categories of sequence types (STs), and ST297 (31.87%; 29/91) was the most dominant clone. This clone displayed a close relationship to virulent strains STEC ST678 (O104: H4). The prevalence of ST297 clones should receive more attentions. Conclusions Our preliminary data revealed that a heterogeneous group of STEC is present, but the non-O157 serogroups and some ST clones such as ST297 should receive more attentions.
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Affiliation(s)
- Zhong Peng
- State Key Laboratory of Agricultural Microbiology, College of Animal Science and Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.,The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, 430070, China
| | - Wan Liang
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture), Animal Husbandry and Veterinary Institute, Hubei Academy of Agricultural Sciences, Wuhan, China
| | - Zizhe Hu
- State Key Laboratory of Agricultural Microbiology, College of Animal Science and Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.,The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, 430070, China
| | - Xiaosong Li
- State Key Laboratory of Agricultural Microbiology, College of Animal Science and Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.,The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, 430070, China
| | - Rui Guo
- State Key Laboratory of Agricultural Microbiology, College of Animal Science and Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.,The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, 430070, China
| | - Lin Hua
- State Key Laboratory of Agricultural Microbiology, College of Animal Science and Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.,The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, 430070, China
| | - Xibiao Tang
- State Key Laboratory of Agricultural Microbiology, College of Animal Science and Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.,The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, 430070, China
| | - Chen Tan
- State Key Laboratory of Agricultural Microbiology, College of Animal Science and Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.,The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, 430070, China
| | - Huanchun Chen
- State Key Laboratory of Agricultural Microbiology, College of Animal Science and Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.,The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, 430070, China
| | - Xiangru Wang
- State Key Laboratory of Agricultural Microbiology, College of Animal Science and Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China. .,The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, 430070, China.
| | - Bin Wu
- State Key Laboratory of Agricultural Microbiology, College of Animal Science and Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China. .,The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, 430070, China.
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Abstract
Multidrug resistance in Escherichia coli has become a worrying issue that is increasingly observed in human but also in veterinary medicine worldwide. E. coli is intrinsically susceptible to almost all clinically relevant antimicrobial agents, but this bacterial species has a great capacity to accumulate resistance genes, mostly through horizontal gene transfer. The most problematic mechanisms in E. coli correspond to the acquisition of genes coding for extended-spectrum β-lactamases (conferring resistance to broad-spectrum cephalosporins), carbapenemases (conferring resistance to carbapenems), 16S rRNA methylases (conferring pan-resistance to aminoglycosides), plasmid-mediated quinolone resistance (PMQR) genes (conferring resistance to [fluoro]quinolones), and mcr genes (conferring resistance to polymyxins). Although the spread of carbapenemase genes has been mainly recognized in the human sector but poorly recognized in animals, colistin resistance in E. coli seems rather to be related to the use of colistin in veterinary medicine on a global scale. For the other resistance traits, their cross-transfer between the human and animal sectors still remains controversial even though genomic investigations indicate that extended-spectrum β-lactamase producers encountered in animals are distinct from those affecting humans. In addition, E. coli of animal origin often also show resistances to other-mostly older-antimicrobial agents, including tetracyclines, phenicols, sulfonamides, trimethoprim, and fosfomycin. Plasmids, especially multiresistance plasmids, but also other mobile genetic elements, such as transposons and gene cassettes in class 1 and class 2 integrons, seem to play a major role in the dissemination of resistance genes. Of note, coselection and persistence of resistances to critically important antimicrobial agents in human medicine also occurs through the massive use of antimicrobial agents in veterinary medicine, such as tetracyclines or sulfonamides, as long as all those determinants are located on the same genetic elements.
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Belaynehe KM, Shin SW, Yoo HS. Interrelationship between tetracycline resistance determinants, phylogenetic group affiliation and carriage of class 1 integrons in commensal Escherichia coli isolates from cattle farms. BMC Vet Res 2018; 14:340. [PMID: 30419899 PMCID: PMC6233274 DOI: 10.1186/s12917-018-1661-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 10/22/2018] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Carriage of antibiotic-resistant foodborne pathogens by food production animals is one of many contributors to treatment failure in health care settings, and it necessitates an integrated approach to investigate the carriage of resistant pathogens harboring integrons in food-producing animals. METHODS Escherichia coli isolates with reduced susceptibility to tetracycline antibiotics (n = 92) were tested for associations between carriage of class1 integrons, phylogenetic group affiliation and tetracycline resistance determinants using the MIC method, PFGE analysis, PCR and sequencing. RESULTS Phylogroups B1 and A were the most common (58.7 and 19.6%, respectively), followed by groups D (20.7%) and B2 (1.1%). All isolates carried at least one of the tet genes examined. In addition, 88 (95.7%) of all tetracycline-resistant isolates carried tet(A) or tet(B), while 47 (51.1%) and 41 (44.6%) harbored only tet(A) or tet(B), respectively. Likewise, isolates harboring these genes had a higher chance (P < 0.05) of carrying class 1 integrons. Of the tested isolates, 38 (41.3%) carried the intI1 gene. Classical integrons with complete genes (sul1 and qacE∆1) at the 3'-CS were recognized in 27 isolates. PCR screening and subsequent sequencing demonstrated that 84.2% (32/38) of the intI1-positive isolates harbored resistance gene cassettes. Overall, seven gene cassettes were identified, either solely or combined with another gene cassette. The most common gene was aadA1 (10 isolates), followed by a combination of aadA1-dfrA1 (seven isolates), aadA1-dfrA12 (six isolates) and aadA1-aadA2-dfrA12 (three isolates). Genetic typing using PFGE showed minimum clonal relatedness with 28 different clusters and 12-25 discernible DNA fragments. CONCLUSIONS This study brings new insight into the relationships between the presence of integrons, phylogenetic group association and characteristics of tetracycline antibiotic resistance determinants in commensal E. coli strains.
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Affiliation(s)
- Kuastros Mekonnen Belaynehe
- Department of Infectious Diseases, College of Veterinary Medicine, Seoul National University, Seoul, 08826 Republic of Korea
| | - Seung Won Shin
- Department of Infectious Diseases, College of Veterinary Medicine, Seoul National University, Seoul, 08826 Republic of Korea
| | - Han Sang Yoo
- Department of Infectious Diseases, College of Veterinary Medicine, Seoul National University, Seoul, 08826 Republic of Korea
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The genetic background of antibiotic resistance among clinical uropathogenic Escherichia coli strains. Mol Biol Rep 2018; 45:1055-1065. [PMID: 30008141 PMCID: PMC6156760 DOI: 10.1007/s11033-018-4254-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 07/10/2018] [Indexed: 01/07/2023]
Abstract
The spreading mechanisms of antibiotic resistance are related to many bacterial and environment factors. The overuse of antibiotics is leading to an unceasing emergence of new multidrug resistant strains. This problem also concerns uropathogenic Escherichia coli strains, which is the most common pathogen causing urinary tract infections. The aim of this study was the genetic analysis of antibiotic resistance in comparison to the phenotypic background of E. coli strains. The characterized collection of E. coli strains isolated 10 years ago from the urine samples of patients with urinary tract infections was used for antimicrobial susceptibility testing (the disc diffusion method) and analysis of antibiotic resistance genes (PCR reaction, sequencing). Additionally, the presence of ESBL strains was analyzed. Fourteen genes were associated with resistance to beta-lactams, aminoglycosides, sulfonamides and quinolones. The genetic analysis revealed that blaTEM-1 and sul2 were present in almost all of the studied strains. Other drug-resistance genes were very rare or non-existent. Otherwise, the phenotypic resistance to fluoroquinolones was well correlated with the genotypic background of the studied bacteria. The presence of particular genes and specific mutations indicate a high bacterial potential to multidrug resistance. On the other hand, it needs to be emphasized that the standard disk diffusion test for the routine antimicrobial susceptibility analysis is still the best way to estimate the current situation of bacterial drug-resistance.
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Belaynehe KM, Shin SW, Hong-Tae P, Yoo HS. Occurrence of aminoglycoside-modifying enzymes among isolates of Escherichia coli exhibiting high levels of aminoglycoside resistance isolated from Korean cattle farms. FEMS Microbiol Lett 2018. [PMID: 28637330 DOI: 10.1093/femsle/fnx129] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
This study investigated 247 Escherichia coli isolates collected from four cattle farms to characterize aminoglycoside-modifying enzyme (AME) genes, their plasmid replicons and transferability. Out of 247 isolates a high number of isolates (total 202; 81.78%) were found to be resistant to various antibiotics by disc diffusion. Of the 247 strains, 139 (56.3%) were resistant to streptomycin, and other antibiotic resistances followed as tetracycline (12.15%), ampicillin (7%), chloramphenicol (5.7%) and trimethoprim-sulfamethoxazole (0.8%). Among 247 isolates B1 was the predominant phylogenetic group identified comprising 151 isolates (61.1%), followed by groups A (27.9%), D (7%) and B2 (4%). Out of 139 isolates investigated for AME, 130 (93.5%) isolates carried at least one AME gene. aph3″-1a and aph3″-1b (46%) were the principal genes detected, followed by aac3-IVa (34.5%). ant2″-1a was the least detected gene (2.2%). Nine (6.5%) strains carried no AME genes. Twelve (63.2%) among 19 isolates transferred an AME gene to a recipient and aph3΄-1a was the dominant transferred gene. Transferability mainly occurred via the IncFIB replicon type (52.6%). Pulsed-field gel electrophoresis typing demonstrated a higher degree of diversity with 14 distinct cluster types. This result suggests that commensal microflora from food-producing animals has a tremendous ability to harbor and transfer AME genes, and poses a potential risk by dissemination of resistance to humans through the food chain.
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Affiliation(s)
- Kuastros Mekonnen Belaynehe
- Department of infectious diseases, College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea
| | - Seung Won Shin
- Department of infectious diseases, College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea
| | | | - Han Sang Yoo
- Department of infectious diseases, College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea
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Nayakvadi S, Alemao CA, Kumar HC, Rajkumar R, Rajkumar S, Chakurkar EB, Keelara S. Detection and molecular characterization of sorbitol fermenting non-O157 Escherichia coli from goats. Small Rumin Res 2018. [DOI: 10.1016/j.smallrumres.2018.02.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Shin SW, Jung M, Shin MK, Yoo HS. Profiling of antimicrobial resistance and plasmid replicon types in β-lactamase producing Escherichia coli isolated from Korean beef cattle. J Vet Sci 2016; 16:483-9. [PMID: 26119172 PMCID: PMC4701741 DOI: 10.4142/jvs.2015.16.4.483] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 04/28/2015] [Accepted: 04/30/2015] [Indexed: 11/24/2022] Open
Abstract
In this study, 78 isolates of Escherichia coli isolated from Korean beef cattle farms were investigated for the production of extended-spectrum β-lactamase (ESBL) and/or AmpC β-lactamase. In the disc diffusion test with ampicillin, amoxicillin, cephalothin, ceftiofur, cefotaxime, ceftazidime, and cefoxitin, 38.5% of the isolates showed resistance to all of ampicillin, amoxicillin, and cephalothin. The double disc synergy method revealed that none of the isolates produced ESBL or AmpC β-lactamases. DNA sequencing showed that all isolates encoded genes for TEM-1-type β-lactamase. Moreover, 78.2% of the isolates transferred the TEM-1-type β-lactamase gene via conjugation. In plasmid replicon typing of all donors, IncFIB and IncFIA were identified in 71.4% and 41.0% of plasmids, respectively. In transconjugants, IncFIB and IncFIA were the most frequent types detected (61.5% and 41.0%, respectively). Overall, the present study indicates that selection pressures of antimicrobials on β-lactamases in beef cattle may be low relative to other livestock animals in Korea. Moreover, to reduce selection pressure and dissemination of β-lactamase, the long-term surveillance of antimicrobial use in domestic beef cattle should be established.
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Affiliation(s)
- Seung Won Shin
- Department of Infectious Diseases, College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea
| | - Myunghwan Jung
- Department of Infectious Diseases, College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea
| | - Min-Kyung Shin
- Department of Infectious Diseases, College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea
| | - Han Sang Yoo
- Department of Infectious Diseases, College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea.,Institute of Green Bio Science and Technology, Seoul National University, Pyeungchang 25354, Korea
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Prevalence of Antimicrobial Resistance and Transfer of Tetracycline Resistance Genes in Escherichia coli Isolates from Beef Cattle. Appl Environ Microbiol 2015; 81:5560-6. [PMID: 26048929 DOI: 10.1128/aem.01511-15] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 06/02/2015] [Indexed: 01/22/2023] Open
Abstract
The aim of this study was to investigate the prevalence and transferability of resistance in tetracycline-resistant Escherichia coli isolates recovered from beef cattle in South Korea. A total of 155 E. coli isolates were collected from feces in South Korea, and 146 were confirmed to be resistant to tetracycline. The tetracycline resistance gene tet(A) (46.5%) was the most prevalent, followed by tet(B) (45.1%) and tet(C) (5.8%). Strains carrying tet(A) plus tet(B) and tet(B) plus tet(C) were detected in two isolates each. In terms of phylogenetic grouping, 101 (65.2%) isolates were classified as phylogenetic group B1, followed in decreasing order by D (17.4%), A (14.2%), and B2 (3.2%). Ninety-one (62.3%) isolates were determined to be multidrug resistant by the disk diffusion method. MIC testing using the principal tetracyclines, namely, tetracycline, chlortetracycline, oxytetracycline, doxycycline, and minocycline, revealed that isolates carrying tet(B) had higher MIC values than isolates carrying tet(A). Conjugation assays showed that 121 (82.9%) isolates could transfer a tetracycline resistance gene to a recipient via the IncFIB replicon (65.1%). This study suggests that the high prevalence of tetracycline-resistant E. coli isolates in beef cattle is due to the transferability of tetracycline resistance genes between E. coli populations which have survived the selective pressure caused by the use of antimicrobial agents.
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