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Randall LP, Horton RH, Chanter JI, Lemma F, Evans SJ. A decline in the occurrence of extended-spectrum β-lactamase-producing Escherichia coli in retail chicken meat in the UK between 2013 and 2018. J Appl Microbiol 2020; 130:247-257. [PMID: 32364269 DOI: 10.1111/jam.14687] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 04/08/2020] [Accepted: 04/27/2020] [Indexed: 11/29/2022]
Abstract
AIMS The aim of this study was to report on the occurrence of antimicrobial resistant (AMR) Escherichia coli from retail chicken meat samples in the UK, with particular focus on AmpC and extended spectrum beta-lactamase (ESBL) production and carbapenem resistance. METHODS AND RESULTS Methods from EU protocols were used for selective isolation of AmpC-/ESBL-producing E. coli, carbapenem-resistant E. coli and for performing minimum inhibitory concentrations. Additional work not part of EU protocols included viable counts, detection by PCR of blaCTX-M , blaOXA, blaSHV and blaTEM genes in ESBL-phenotype E. coli and screening for mcr plasmid-mediated colistin resistance. From the 313/309 retail chicken meat samples tested in 2016/2018, carbapenem or mcr plasmid-mediated colistin-resistant E. coli were not detected. For 2016/2018 chicken samples, 141/42 (45·0%/13·6%), 90/23 (28·8%/7·4%), 48/16 (15·3%/5·2%) and 3/3 (1·0%/1·0%) were positive for ESBL- and/or AmpC-, ESBL- alone AmpC- alone and AmpC+ESBL-phenotype E. coli respectively. ESBL-producing E. coli were predominantly blaCTX-M-1 . All AmpC and/or ESBL-phenotype E. coli were sensitive to colistin, ertapenem, imipenem, meropenem, temocillin and tigecycline, applying epidemiological cut-off values. CONCLUSIONS A previous study in 2013/14 showed that 65·4% of retail chicken meat samples tested in the UK were positive for ESBL-producing (mainly CTX-M) E. coli. Since then the proportion of samples positive in the UK has dropped significantly to 7·4% in 2018. SIGNIFICANCE AND IMPACT OF THE STUDY Significant reductions in antimicrobials used in the UK poultry meat sector between 2012 and 2016 may be linked to significant reductions in AmpC/ESBL-phenotype E. coli in retail chicken between 2013/14 and 2018.
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Affiliation(s)
- L P Randall
- Animal and Plant Health Agency (Weybridge), New Haw Addlestone, Surrey, UK
| | - R H Horton
- Animal and Plant Health Agency (Weybridge), New Haw Addlestone, Surrey, UK
| | - J I Chanter
- Animal and Plant Health Agency (Starcross), Starcross, Exeter, UK
| | - F Lemma
- Animal and Plant Health Agency (Weybridge), New Haw Addlestone, Surrey, UK
| | - S J Evans
- Animal and Plant Health Agency (Weybridge), New Haw Addlestone, Surrey, UK
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Velasova M, Smith RP, Lemma F, Horton RA, Duggett NA, Evans J, Tongue SC, Anjum MF, Randall LP. Detection of extended-spectrum β-lactam, AmpC and carbapenem resistance in Enterobacteriaceae in beef cattle in Great Britain in 2015. J Appl Microbiol 2019; 126:1081-1095. [PMID: 30693606 DOI: 10.1111/jam.14211] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 01/02/2019] [Accepted: 01/21/2019] [Indexed: 02/06/2023]
Abstract
AIMS This study investigated the occurrence and genetic diversity of Enterobacteriaceae with extended-spectrum β-lactamase (ESBL)-, AmpC- and carbapenemase-mediated resistance in British beef cattle, and related risk factors. METHODS AND RESULTS Faecal samples (n = 776) were obtained from farms in England and Wales (n = 20) and Scotland (n = 20) in 2015. Isolates from selective agars were identified by MALDI ToF mass spectrometry. Selected isolates were characterized by multiplex PCR (blaCTX -M, blaOXA , blaSHV and blaTEM genes), whole-genome sequencing (WGS), minimum inhibitory concentrations and pulsed-field gel electrophoresis. None of the faecal samples yielded carbapenem-resistant Escherichia coli. Ten (25%) of the farms tested positive for ESBL-producing CTX-M Enterobacteriaceae, 15 (37·5%) of the farms were positive for AmpC phenotype E. coli and none were positive for carbapenem-resistant E. coli. WGS showed a total of 30 different resistance genes associated with E. coli, Citrobacter and Serratia from ESBL agars, and colocation of resistance genes with blaCTX -M1 . Buying bulls and bringing in fattening cattle from another farm were identified as significant risk factors for positive samples harbouring CTX-M Enterobacteriaceae or AmpC phenotype E. coli respectively. CONCLUSIONS Beef cattle on a proportion of farms in GB carry ESBL-producing Enterobacteriaceae. Factors, such as operating as a closed herd, may have an important role in reducing introduction and transmission of resistant Enterobacteriaceae. The results indicate management factors may play an important role in impacting ESBL prevalence. In particular, further study would be valuable to understand the impact of maintaining a closed herd on reducing the introduction of resistant Enterobacteriaceae. SIGNIFICANCE AND IMPACT OF THE STUDY This is the first study showing the presence of ESBL-producing Enterobacteriaceae in British beef cattle.
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Affiliation(s)
- M Velasova
- Animal and Plant Health Agency (Weybridge), Addlestone, UK
| | - R P Smith
- Animal and Plant Health Agency (Weybridge), Addlestone, UK
| | - F Lemma
- Animal and Plant Health Agency (Weybridge), Addlestone, UK
| | - R A Horton
- Animal and Plant Health Agency (Weybridge), Addlestone, UK
| | - N A Duggett
- Animal and Plant Health Agency (Weybridge), Addlestone, UK
| | - J Evans
- SRUC (Inverness Campus), Edinburgh, UK
| | | | - M F Anjum
- Animal and Plant Health Agency (Weybridge), Addlestone, UK
| | - L P Randall
- Animal and Plant Health Agency (Weybridge), Addlestone, UK
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Duggett NA, Randall LP, Horton RA, Lemma F, Kirchner M, Nunez-Garcia J, Brena C, Williamson SM, Teale C, Anjum MF. Molecular epidemiology of isolates with multiple mcr plasmids from a pig farm in Great Britain: the effects of colistin withdrawal in the short and long term. J Antimicrob Chemother 2018; 73:3025-3033. [DOI: 10.1093/jac/dky292] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 06/25/2018] [Indexed: 12/22/2022] Open
Affiliation(s)
- Nicholas A Duggett
- Animal and Plant Health Agency, Weybridge, New Haw, Addlestone, Surrey, UK
| | - Luke P Randall
- Animal and Plant Health Agency, Weybridge, New Haw, Addlestone, Surrey, UK
| | - Robert A Horton
- Animal and Plant Health Agency, Weybridge, New Haw, Addlestone, Surrey, UK
| | - Fabrizio Lemma
- Animal and Plant Health Agency, Weybridge, New Haw, Addlestone, Surrey, UK
| | - Miranda Kirchner
- Animal and Plant Health Agency, Weybridge, New Haw, Addlestone, Surrey, UK
| | | | - Camilla Brena
- Animal and Plant Health Agency (Thirsk), West House, Station Road, Thirsk, North Yorkshire, UK
| | - Susanna M Williamson
- Animal and Plant Health Agency (Bury St Edmunds), Rougham Hill, Bury St Edmunds, Suffolk, UK
| | - Christopher Teale
- Animal and Plant Health Agency (Shrewsbury), Kendal Road, Shrewsbury, UK
| | - Muna F Anjum
- Animal and Plant Health Agency, Weybridge, New Haw, Addlestone, Surrey, UK
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AbuOun M, Stubberfield EJ, Duggett NA, Kirchner M, Dormer L, Nunez-Garcia J, Randall LP, Lemma F, Crook DW, Teale C, Smith RP, Anjum MF. mcr-1 and mcr-2 (mcr-6.1) variant genes identified in Moraxella species isolated from pigs in Great Britain from 2014 to 2015. J Antimicrob Chemother 2018; 73:2904. [PMID: 30053008 DOI: 10.1093/jac/dky272] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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AbuOun M, Stubberfield EJ, Duggett NA, Kirchner M, Dormer L, Nunez-Garcia J, Randall LP, Lemma F, Crook DW, Teale C, Smith RP, Anjum MF. mcr-1 and mcr-2 variant genes identified in Moraxella species isolated from pigs in Great Britain from 2014 to 2015. J Antimicrob Chemother 2018; 72:2745-2749. [PMID: 29091227 DOI: 10.1093/jac/dkx286] [Citation(s) in RCA: 167] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Accepted: 07/13/2017] [Indexed: 11/14/2022] Open
Abstract
Objectives To determine the occurrence of mcr-1 and mcr-2 genes in Gram-negative bacteria isolated from healthy pigs in Great Britain. Methods Gram-negative bacteria (n = 657) isolated from pigs between 2014 and 2015 were examined by WGS. Results Variants of mcr-1 and mcr-2 were identified in Moraxella spp. isolated from pooled caecal contents of healthy pigs at slaughter collected from six farms in Great Britain. Other bacteria, including Escherichia coli from the same farms, were not detected harbouring mcr-1 or mcr-2. A Moraxella porci-like isolate, MSG13-C03, harboured MCR-1.10 with 98.7% identity to MCR-1, and a Moraxella pluranimalium-like isolate, MSG47-C17, harboured an MCR-2.2 variant with 87.9% identity to MCR-2, from E. coli; the isolates had colistin MICs of 1-2 mg/L. No intact insertion elements were identified in either MSG13-C03 or MSG47-C17, although MSG13-C03 harboured the conserved nucleotides abutting the ISApl1 composite transposon found in E. coli plasmids and the intervening ∼2.6 kb fragment showed 97% identity. Six Moraxella osloensis isolates were positive for phosphoethanolamine transferase (EptA). They shared 62%-64.5% identity to MCR-1 and MCR-2, with colistin MICs from 2 to 4 mg/L. Phylogenetic analysis indicated that MCR and EptA have evolved from a common ancestor. In addition to mcr, the β-lactamase gene, blaBRO-1, was found in both isolates, whilst the tetracycline resistance gene, tetL, was found in MSG47-C17. Conclusions Our results add further evidence for the mobilization of the mcr-pap2 unit from Moraxella via composite transposons leading to its global dissemination. The presence of mcr-pap2 from recent Moraxella isolates indicates they may comprise a reservoir for mcr.
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Affiliation(s)
- Manal AbuOun
- Department of Bacteriology, Animal and Plant Health Agency, Weybridge, Surrey KT153NB, UK.,National Institute for Health Research Health Protection Research Unit, University of Oxford in partnership with PHE, Oxford, UK
| | - Emma J Stubberfield
- Department of Bacteriology, Animal and Plant Health Agency, Weybridge, Surrey KT153NB, UK
| | - Nick A Duggett
- Department of Bacteriology, Animal and Plant Health Agency, Weybridge, Surrey KT153NB, UK
| | - Miranda Kirchner
- Department of Bacteriology, Animal and Plant Health Agency, Weybridge, Surrey KT153NB, UK
| | - Luisa Dormer
- Department of Bacteriology, Animal and Plant Health Agency, Weybridge, Surrey KT153NB, UK
| | - Javier Nunez-Garcia
- Department of Bacteriology, Animal and Plant Health Agency, Weybridge, Surrey KT153NB, UK
| | - Luke P Randall
- Department of Bacteriology, Animal and Plant Health Agency, Weybridge, Surrey KT153NB, UK
| | - Fabrizio Lemma
- Department of Bacteriology, Animal and Plant Health Agency, Weybridge, Surrey KT153NB, UK
| | - Derrick W Crook
- National Institute for Health Research Health Protection Research Unit, University of Oxford in partnership with PHE, Oxford, UK.,Modernising Medical Microbiology Consortium, Nuffield Department of Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Christopher Teale
- Department of Bacteriology, Animal and Plant Health Agency, Weybridge, Surrey KT153NB, UK
| | - Richard P Smith
- Department of Bacteriology, Animal and Plant Health Agency, Weybridge, Surrey KT153NB, UK
| | - Muna F Anjum
- Department of Bacteriology, Animal and Plant Health Agency, Weybridge, Surrey KT153NB, UK.,Modernising Medical Microbiology Consortium, Nuffield Department of Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
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Randall LP, Horton RA, Lemma F, Martelli F, Duggett NAD, Smith RP, Kirchner MJ, Ellis RJ, Rogers JP, Williamson SM, Simons RRL, Brena CM, Evans SJ, Anjum MF, Teale CJ. Longitudinal study on the occurrence in pigs of colistin-resistant Escherichia coli carrying mcr-1 following the cessation of use of colistin. J Appl Microbiol 2018; 125:596-608. [PMID: 29741287 DOI: 10.1111/jam.13907] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 04/09/2018] [Accepted: 04/12/2018] [Indexed: 11/27/2022]
Abstract
AIMS In 2015, colistin-resistant Escherichia coli and Salmonella with the mcr-1 gene were isolated from a pig farm in Great Britain. Pigs were subsequently monitored over a ~20-month period for the occurrence of mcr-1-mediated colistin resistance and the risk of mcr-1 E. coli entering the food chain was assessed. METHODS AND RESULTS Pig faeces and slurry were cultured for colistin-resistant E. coli and Salmonella, tested for the mcr-1 gene by PCR and selected isolates were further analysed. Seventy-eight per cent of faecal samples (n = 275) from pigs yielded mcr-1 E. coli after selective culture, but in positive samples only 0·2-1·3% of the total E. coli carried mcr-1. Twenty months after the initial sampling, faecal samples (n = 59) were negative for E. coli carrying mcr-1. CONCLUSIONS The risk to public health from porcine E. coli carrying mcr-1 was assessed as very low. Twenty months after cessation of colistin use, E. coli carrying mcr-1 was not detected in pig faeces on a farm where it was previously present. SIGNIFICANCE AND IMPACT OF THE STUDY The results suggest that cessation of colistin use may help over time to reduce or possibly eliminate mcr-1 E. coli on pig farms where it occurs.
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Affiliation(s)
- L P Randall
- Animal and Plant Health Agency (Weybridge), New Haw, Addlestone, Surrey, UK
| | - R A Horton
- Animal and Plant Health Agency (Weybridge), New Haw, Addlestone, Surrey, UK
| | - F Lemma
- Animal and Plant Health Agency (Weybridge), New Haw, Addlestone, Surrey, UK
| | - F Martelli
- Animal and Plant Health Agency (Weybridge), New Haw, Addlestone, Surrey, UK
| | - N A D Duggett
- Animal and Plant Health Agency (Weybridge), New Haw, Addlestone, Surrey, UK
| | - R P Smith
- Animal and Plant Health Agency (Weybridge), New Haw, Addlestone, Surrey, UK
| | - M J Kirchner
- Animal and Plant Health Agency (Weybridge), New Haw, Addlestone, Surrey, UK
| | - R J Ellis
- Animal and Plant Health Agency (Weybridge), New Haw, Addlestone, Surrey, UK
| | - J P Rogers
- Animal and Plant Health Agency (Bury St Edmunds), Bury St Edmunds, Suffolk, UK
| | - S M Williamson
- Animal and Plant Health Agency (Bury St Edmunds), Bury St Edmunds, Suffolk, UK
| | - R R L Simons
- Animal and Plant Health Agency (Weybridge), New Haw, Addlestone, Surrey, UK
| | - C M Brena
- Animal and Plant Health Agency (Thirsk), Thirsk, North Yorkshire, UK
| | - S J Evans
- Animal and Plant Health Agency (Weybridge), New Haw, Addlestone, Surrey, UK
| | - M F Anjum
- Animal and Plant Health Agency (Weybridge), New Haw, Addlestone, Surrey, UK
| | - C J Teale
- Animal and Plant Health Agency (Shrewsbury), Shrewsbury, UK
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Horton RA, Duncan D, Randall LP, Chappell S, Brunton LA, Warner R, Coldham NG, Teale CJ. Longitudinal study of CTX-M ESBL-producing E. coli strains on a UK dairy farm. Res Vet Sci 2016; 109:107-113. [PMID: 27892858 DOI: 10.1016/j.rvsc.2016.09.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 08/17/2016] [Accepted: 09/29/2016] [Indexed: 11/29/2022]
Abstract
The aim of this study was to investigate the bacterial strains and farm environment that may contribute to the persistence of ESBL-producing E. coli on a single UK dairy farm. A longitudinal study was conducted comprising 6 visits, between August and October 2010, followed by a further visit at approximately 69weeks after the initial visit. Faecal and environmental samples were collected from different parts of the farm. The persistence and extent of faecal shedding of ESBL E. coli by individual calves was also determined. Twenty two different PFGE types were identified. Four of these were persistent during the study period and were associated with serotypes: O98, O55, O141 and O33. The counts suggest that shedding in calf faeces was an important factor for the persistence of strains, and the data will be useful for parameterising mathematical models of the spread and persistence of ESBL strains within a dairy farm.
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Affiliation(s)
- R A Horton
- Animal and Plant Health Agency (APHA) Weybridge, New Haw, Addlestone, Surrey KT15 3NB, United Kingdom.
| | - D Duncan
- Animal and Plant Health Agency (APHA) Weybridge, New Haw, Addlestone, Surrey KT15 3NB, United Kingdom
| | - L P Randall
- Animal and Plant Health Agency (APHA) Weybridge, New Haw, Addlestone, Surrey KT15 3NB, United Kingdom
| | - S Chappell
- Animal and Plant Health Agency (APHA) Weybridge, New Haw, Addlestone, Surrey KT15 3NB, United Kingdom
| | - L A Brunton
- Animal and Plant Health Agency (APHA) Weybridge, New Haw, Addlestone, Surrey KT15 3NB, United Kingdom
| | - R Warner
- Animal and Plant Health Agency (APHA) Weybridge, New Haw, Addlestone, Surrey KT15 3NB, United Kingdom
| | - N G Coldham
- Animal and Plant Health Agency (APHA) Weybridge, New Haw, Addlestone, Surrey KT15 3NB, United Kingdom
| | - C J Teale
- Animal and Plant Health Agency (APHA) Weybridge, New Haw, Addlestone, Surrey KT15 3NB, United Kingdom
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Randall LP, Mueller-Doblies D, Lemma FL, Horton RA, Teale CJ, Davies RH. Characteristics of ciprofloxacin and cephalosporin resistant Escherichia coli isolated from turkeys in Great Britain. Br Poult Sci 2013; 54:96-105. [PMID: 23444859 DOI: 10.1080/00071668.2013.763902] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
1. A field study was performed to investigate the presence and characteristics of ciprofloxacin-resistant, extended spectrum β-lactamase (ESBL) and AmpC Escherichia coli from turkeys in Great Britain. E. coli were isolated from ~9000 boot swab samples from 27 different farms owned by four different companies. Between 1 and 14 visits were made to each farm (mean 3) at between 0 and 15 m intervals (mean ~5 m). 2. CHROMagar ECC with and without ciprofloxacin or cephalosporin antibiotics was used as selective isolation media. Representative isolates with different phenotypes were tested for mutations in gyrA and for: qnrA, B, S, qepA and aac(6')-Ib genes, for ESBL phenotype, the presence of bla genes and plasmid type, and for ampC genes Representative ciprofloxacin-resistant and CTX-M isolates were further tested for serotype and PFGE type. On ciprofloxacin selective media 55% of samples yielded ciprofloxacin resistant E. coli and of those further analysed, most had ciprofloxacin MICs >4 mg/l and mutations in gyrA. 3. For the different companies, the mean number of samples per farm with cefoxitin- or cefotaxime-resistant isolates ranged from 1·0% to 61·9% and 4·7% to 31·7% respectively. Cefotaxime-resistance was most commonly associated with an ESBL phenotype, a CTX-M-1 or CTX-M-14 sequence type and an I1-γ or K plasmid inc type. The mechanism of cefoxitin resistance was not determined for most isolates, but where determined it was bla . 4. PFGE and serotyping showed clonally-related isolates persisting over multiple visits suggesting both more prudent use of antibiotics and improved farm hygiene are needed to address the issue of antimicrobial resistance in isolates from turkeys.
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Affiliation(s)
- L P Randall
- Animal Health and Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey, United Kingdom.
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Reeves HE, Lotz SB, Kennedy E, Randall LP, Coldham NG, La Ragione RM. Evaluation of an autogenous vaccine in cattle against Escherichia coli bearing the CTX-M-14 plasmid. Res Vet Sci 2013; 94:419-24. [PMID: 23360687 DOI: 10.1016/j.rvsc.2013.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 12/11/2012] [Accepted: 01/01/2013] [Indexed: 10/27/2022]
Abstract
Enteric bacteria with resistance to third and fourth generation cephalosporin antibiotics, especially Escherichia coli bearing the blaCTX-M gene, have been detected in a wide range of food producing animals. However, commercial vaccines for these organisms are not currently available. An autogenous vaccine was prepared from E. coli bearing the blaCTX-M-14 gene and evaluated as a potential control measure to reduce shedding and dissemination of these organisms in cattle. Calves (n=30) received either an autogenous vaccine prepared from E. coli serotype O33 bearing the blaCTX-M-14 gene or a placebo by intramuscular injection on three separate occasions. Two weeks after the final vaccination, all calves were challenged by oral gavage with the O33 CTX-M-14 strain of E. coli (1×10(10) CFU). Faeces, intestinal mucosa and blood samples were taken for enumeration of total and CTX-M-14 E. coli and for assessment of the humoral immune response. The cumulative number of total E. coli excreted at 7 days post-challenge was significantly (p=0.006) lower in the vaccinated group than the placebo group. However, there was no significant difference in the shedding of either CTX-M-14 E. coli or total E. coli between vaccinated and placebo calves throughout the study period. The systemic immune response to E. coli O33 antigen was tested by ELISA and was significantly higher (p<0.001) in vaccinated than placebo calves. However, there was no significant difference in the mucosal immune response. These findings do not support the use of autogenous vaccination for the control of CTX-M-14 E. coli in calves.
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Affiliation(s)
- H E Reeves
- Department of Bacteriology and Food Safety, Animal Health and Veterinary Laboratories Agency (AHVLA) Weybridge, New Haw, Addlestone, Surrey, KT15 3NB, United Kingdom.
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Stokes MO, Cottell JL, Piddock LJV, Wu G, Wootton M, Mevius DJ, Randall LP, Teale CJ, Fielder MD, Coldham NG. Detection and characterization of pCT-like plasmid vectors for blaCTX-M-14 in Escherichia coli isolates from humans, turkeys and cattle in England and Wales. J Antimicrob Chemother 2012; 67:1639-44. [PMID: 22514265 DOI: 10.1093/jac/dks126] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVES To detect and characterize Escherichia coli strains and pCT-like plasmids implicated in the dissemination of the CTX-M-14 gene in animals and humans, in England and Wales. METHODS UK CTX-M-14-producing E. coli (n=70) from cattle (n=33), turkeys (n=9), sheep (n=2) and humans (n=26) were screened using multiplex PCR for the detection of a previously characterized plasmid, pCT. Isolates found to be carrying two or more pCT genetic markers were further analysed using PFGE. Their antimicrobial-resistance genes and virulence genes were also determined. These plasmids were transferred to Salmonella enterica serotype Typhimurium 26R and further examined for incompatibility type, genetic environment of the bla(CTX-M-14) gene, size, restriction fragment length polymorphism (RFLP) and nikB sequence. RESULTS The 25 E. coli isolates carrying pCT genetic markers generated 19 different PFGE profiles, and 23 isolates had different virulence and antimicrobial-resistance gene patterns. One isolate from cattle was a verotoxigenic E. coli ('VTEC'); the rest were commensal or extra-intestinal pathogenic E. coli. pCT-like plasmids with similar molecular characteristics (size, replicon type, RFLP pattern, pCT markers and genetic environment of the bla(CTX-M-14) gene) were detected in 21/25 of the field isolates, which comprised those from cattle (n=9), turkeys (n=8) and humans (n=4). All pCT-like plasmids were conjugative, and most were IncK (n=21) and had the same local genetic environment flanking the bla(CTX-M-14) gene (n=23). RFLP analysis demonstrated ≥ 75% similarity among most plasmids (n=22). CONCLUSIONS pCT-like plasmids were common vectors for horizontal dissemination of 30% of the bla(CTX-M-14) genes to different E. coli isolates from humans, cattle and turkeys.
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Affiliation(s)
- M O Stokes
- Department of Bacteriology, Animal Health and Veterinary Laboratories Agency, Addlestone, UK.
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Delsol AA, Halfhide DE, Bagnall MC, Randall LP, Enne VI, Woodward MJ, Roe JM. Persistence of a wild type Escherichia coli and its multiple antibiotic-resistant (MAR) derivatives in the abattoir and on chilled pig carcasses. Int J Food Microbiol 2010; 140:249-53. [DOI: 10.1016/j.ijfoodmicro.2010.03.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Revised: 03/12/2010] [Accepted: 03/14/2010] [Indexed: 11/25/2022]
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Randall LP, Kirchner M, Teale CJ, Coldham NG, Liebana E, Clifton-Hadley F. Evaluation of CHROMagar CTX, a novel medium for isolating CTX-M-ESBL-positive Enterobacteriaceae while inhibiting AmpC-producing strains. J Antimicrob Chemother 2008; 63:302-8. [PMID: 19043079 DOI: 10.1093/jac/dkn485] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES The aim of this study was to evaluate CHROMagar CTX (CHROMagar France), a novel agar for the selective isolation of Enterobacteriaceae expressing the bla(CTX-M) gene in the presence of enteric bacteria expressing AmpC enzymes. METHODS A panel of 150 Gram-negative bacteria (mainly Escherichia coli, Enterobacter, Klebsiella, Pseudomonas and Salmonella) isolated from humans and animals were assembled for the purpose of evaluating CHROMagar CTX and comparing it with CHROMagar ECC with the addition of 1, 2, 4 and 8 mg/L cefotaxime or ceftazidime and with bioMérieux extended-spectrum beta-lactamase (ESBL)-Bx agar. CHROMagar CTX was also assessed for its ability to isolate bla(CTX-M) strains from farm animal faeces (n = 342). RESULTS The panel contained CTX-M-positive (n = 70) strains (CTX-M types 1, 9, 14 and 15), ESBLs (n = 31) belonging to other families (OXA, PER, SHV, TEM, VEB), strains positive for ampC genes (n = 31), strains that overexpressed ampC (n = 6), non-ESBL/AmpC strains (n = 11) and Klebsiella oxytoca (n = 1). CHROMagar CTX was superior to other agars tested for selective isolation of Enterobacteriaceae expressing the bla(CTX-M) gene with 100% sensitivity and 64.2% specificity for CTX-M strains in the panel and 90.1% of the colonies from animal faeces plated on CHROMagar CTX were CTX-M strains. CONCLUSIONS CHROMagar CTX is a valuable agar in situations where it is important to isolate bla(CTX-M) strains in the presence of AmpC strains. The agar may be particularly useful in veterinary studies, where AmpC-producing commensal E. coli can be encountered reasonably frequently in the enteric flora of some animal species and may also be useful, following further evaluation, for samples from humans.
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Affiliation(s)
- L P Randall
- Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey KT15 3NB, UK.
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Randall LP, Bagnall MC, Karatzas KA, Coldham NC, Piddock LJV, Woodward MJ. Fitness and dissemination of disinfectant-selected multiple-antibiotic-resistant (MAR) strains of Salmonella enterica serovar Typhimurium in chickens. J Antimicrob Chemother 2007; 61:156-62. [PMID: 17999979 DOI: 10.1093/jac/dkm415] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES The aims of this study were to determine whether strains of Salmonella enterica serovar Typhimurium which had acquired low-level multiple antibiotic resistance (MAR) through repeated exposure to farm disinfectants were able to colonize and transmit between chicks as easily as the parent strain and, if such strains were less susceptible to fluoroquinolones, would high-level resistance be selected after fluoroquinolone treatment. METHODS Two mutants were compared with the isogenic parent. In the first experiment, day-old chicks were co-infected with both the parent and a mutant to determine their relative fitness. In the second experiment, parent and mutant strains (in separate groups of chicks) were assessed for their ability to transmit from infected (contact) to non-infected (naive) birds and with respect to their susceptibility to fluoroquinolone treatment. Birds were regularly monitored for the presence of Salmonella in caecal contents. Replica plating was used to monitor for the selection of antibiotic-resistant strains. RESULTS The parent strain was shown to be significantly fitter than the two mutants and was more rapidly disseminated to naive birds. Antibiotic treatment did not preferentially select for the two mutants or for resistant strains. CONCLUSIONS The disinfectant-exposed strains, although MAR, were less fit, less able to disseminate than the parent strain and were not preferentially selected by therapeutic antibiotic treatment. As such, these strains are unlikely to present a greater problem than other salmonellae in chickens.
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Affiliation(s)
- Luke P Randall
- Department of Food and Environmental Safety, Veterinary Laboratories Agency, New Haw, Surrey KT15 3NB, UK.
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14
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Randall LP, Cooles SW, Coldham NG, Penuela EG, Mott AC, Woodward MJ, Piddock LJV, Webber MA. Commonly used farm disinfectants can select for mutant Salmonella enterica serovar Typhimurium with decreased susceptibility to biocides and antibiotics without compromising virulence. J Antimicrob Chemother 2007; 60:1273-80. [PMID: 17897935 DOI: 10.1093/jac/dkm359] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES To determine if one passage of Salmonella enterica serovar Typhimurium in the presence of farm disinfectants selected for mutants with decreased susceptibility to disinfectants and/or antibiotics. METHODS Eight Salmonella Typhimurium strains including field isolates and laboratory mutants were exposed to either a tar oil phenol (PFD) disinfectant, an oxidizing compound disinfectant (OXC), an aldehyde based disinfectant (ABD) or a dairy sterilizer disinfectant (based on quaternary ammonium biocide) in agar. The susceptibility of mutants obtained after disinfectant exposure to antibiotics and disinfectants was determined as was the accumulation of norfloxacin. The proteome of SL1344 after exposure to PFD and OXC was analysed using two-dimensional liquid chromatography mass spectrometry. RESULTS Strains with either acrB or tolC inactivated were more susceptible to most disinfectants than other strains. The majority (3/5) of mutants recovered after disinfectant exposure required statistically significantly longer exposure times to disinfectants than their parent strains to generate a 5 log kill. Small decreases in antibiotic susceptibility were observed but no mutants were multiply antibiotic-resistant (MAR). Notably exposure to ABD decreased susceptibility to ciprofloxacin in some strains. Mutants with increased disinfectant tolerance were able to survive and persist in chicks as well as in parent strains. Analysis of proteomes revealed significantly increased expression of the AcrAB-TolC efflux system after PFD exposure. CONCLUSIONS Data presented demonstrate that efflux pumps are required for intrinsic resistance to some disinfectants and that exposure to disinfectants can induce expression of the AcrAB-TolC efflux system, but that single exposure was insufficient to select for MAR strains.
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Affiliation(s)
- L P Randall
- Department of Food and Environmental Safety, Veterinary Laboratories Agency, New Haw, Surrey KT15 3NB, UK
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Randall LP, Cooles SW, Coldham NC, Stapleton KS, Piddock LJV, Woodward MJ. Modification of enrofloxacin treatment regimens for poultry experimentally infected with Salmonella enterica serovar Typhimurium DT104 to minimize selection of resistance. Antimicrob Agents Chemother 2006; 50:4030-7. [PMID: 17030564 PMCID: PMC1694010 DOI: 10.1128/aac.00525-06] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Revised: 07/02/2006] [Accepted: 09/19/2006] [Indexed: 11/20/2022] Open
Abstract
We hypothesized that higher doses of fluoroquinolones for a shorter duration could maintain efficacy (as measured by reduction in bacterial count) while reducing selection in chickens of bacteria with reduced susceptibility. Chicks were infected with Salmonella enterica serovar Typhimurium DT104 and treated 1 week later with enrofloxacin at the recommended dose for 5 days (water dose adjusted to give 10 mg/kg of body weight of birds or equivalence, i.e., water at 50 ppm) or at 2.5 or 5 times the recommended dose for 2 days or 1 day, respectively. The dose was delivered continuously (ppm) or pulsed in the water (mg/kg) or by gavage (mg/kg). In vitro in sera, increasing concentrations of 0.5 to 8 microg/ml enrofloxacin correlated with increased activity. In vivo, the efficacy of the 1-day treatment was significantly less than that of the 2- and 5-day treatments. The 2-day treatments showed efficacy similar to that of the 5-day treatment in all but one repeat treatment group and significantly (P < 0.01) reduced the Salmonella counts. Dosing at 2.5x the recommended dose and pulsed dosing both increased the peak antibiotic concentrations in cecal contents, liver, lung, and sera as determined by high-pressure liquid chromatography. There was limited evidence that shorter treatment regimens (in particular the 1-day regimen) selected for fewer strains with reduced susceptibility. In conclusion, the 2-day treatment would overall require a shorter withholding time than the 5-day treatment and, in view of the increased peak antibiotic concentrations, may give rise to improved efficacy, in particular for treating respiratory and systemic infections. However, it would be necessary to validate the 2-day regimen in a field situation and in particular against respiratory and systemic infections to validate or refute this hypothesis.
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Affiliation(s)
- Luke P Randall
- Department of Food and Environmental Safety, Veterinary Laboratories Agency, New Haw, Surrey, KT15 3NB, United Kingdom.
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Coldham NG, Randall LP, Piddock LJV, Woodward MJ. Effect of fluoroquinolone exposure on the proteome of Salmonella enterica serovar Typhimurium. J Antimicrob Chemother 2006; 58:1145-53. [PMID: 17062612 DOI: 10.1093/jac/dkl413] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES The physiological response of Salmonella enterica serovar Typhimurium to fluoroquinolone antibiotics was investigated using proteomic methods. METHODS Proteomes were prepared from strain SL1344 following treatment of broth cultures with ciprofloxacin (0.03 and 0.008 mg/L; 2x and 0.5x MIC) and enrofloxacin (0.03 mg/L) and from a multiple antibiotic resistant (MAR) mutant. Protein expression was determined by two-dimensional HPLC-MS(n) and also after exposure to ciprofloxacin by two-dimensional gel electrophoresis (2D-GE). RESULTS The number of proteins (mean +/- SD) detected by 2D-GE derived from control cultures of the wild-type strain was significantly (P < 0.05) reduced from 296 +/- 77 to 153 +/- 36 following treatment with ciprofloxacin (0.03 mg/L). Raised expression (P < 0.05) of 17 proteins was also detected, and increases of up to 8-fold (P < 0.0001) were observed for subunits of F1F0-ATP synthase, TolC and Imp. Analysis by two-dimensional HPLC-MS(n) provided higher proteome coverage with 787 +/- 50 proteins detected, which was reduced (P < 0.005) to 560 +/- 14 by ciprofloxacin (0.03 mg/L). Increased expression of 43 proteins was observed which included those detected by 2D-GE and additionally the efflux pump protein AcrB. The basal expression of the AcrAB/TolC efflux pump was elevated in the MAR mutant compared with the untreated wild-type and augmented following treatment with ciprofloxacin (0.03 mg/L). F1F0-ATP synthase and Imp were only elevated in the mutant when treated with ciprofloxacin. CONCLUSIONS These studies suggest that increased expression of AcrAB/TolC was associated with resistance while other increases, such as in F1F0-ATP synthase and Imp, were a response to fluoroquinolone.
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Affiliation(s)
- Nick G Coldham
- Department of Food and Environmental Safety, Veterinary Laboratories Agency, Addlestone, Surrey, KT15 3NB, UK.
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Buckley AM, Webber MA, Cooles S, Randall LP, La Ragione RM, Woodward MJ, Piddock LJV. The AcrAB-TolC efflux system of Salmonella enterica serovar Typhimurium plays a role in pathogenesis. Cell Microbiol 2006; 8:847-56. [PMID: 16611233 DOI: 10.1111/j.1462-5822.2005.00671.x] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The ability of an isogenic set of mutants of Salmonella enterica serovar Typhimurium L354 (SL1344) with defined deletions in genes encoding components of tripartite efflux pumps, including acrB, acrD, acrF and tolC, to colonize chickens was determined in competition with L354. In addition, the ability of L354 and each mutant to adhere to, and invade, human embryonic intestine cells and mouse monocyte macrophages was determined in vitro. The tolC and acrB knockout mutants were hyper-susceptible to a range of antibiotics, dyes and detergents; the tolC mutant was also more susceptible to acid pH and bile and grew more slowly than L354. Complementation of either gene ablated the phenotype. The tolC mutant poorly adhered to both cell types in vitro and was unable to invade macrophages. The acrB mutant adhered, but did not invade macrophages. In vivo, both the acrB mutant and the tolC mutant colonized poorly and did not persist in the avian gut, whereas the acrD and acrF mutant colonized and persisted as well as L354. These data indicate that the AcrAB-TolC system is important for the colonization of chickens by S. Typhimurium and that this system has a role in mediating adherence and uptake into target host cells.
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Affiliation(s)
- Anthony M Buckley
- Antimicrobial Agents Research Group, Division of Immunity and Infection, University of Birmingham, Birmingham B15 2TT, UK
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Webber M, Buckley AM, Randall LP, Woodward MJ, Piddock LJV. Overexpression of marA, soxS and acrB in veterinary isolates of Salmonella enterica rarely correlates with cyclohexane tolerance. J Antimicrob Chemother 2006; 57:673-9. [PMID: 16492722 DOI: 10.1093/jac/dkl025] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES To determine the contribution of the AcrAB efflux system to cyclohexane tolerance in Salmonella enterica. METHODS The expression of the efflux pump gene, acrB, and regulators marA and soxS from 46 isolates of S. enterica of 14 different serovars was determined by comparative RT-PCR and denaturing HPLC analysis. RESULTS Twenty-one of the 46 isolates were cyclohexane tolerant, a phenotype associated with multiple antibiotic resistance (MAR) and overexpression of efflux pumps. Of the cyclohexane-tolerant isolates 81% were MAR, whereas only 44% of the cyclohexane-susceptible isolates were MAR, confirming the association between cyclohexane tolerance and MAR. However, there was no correlation between cyclohexane tolerance or MAR and overexpression of acrB, soxS or marA. CONCLUSIONS These data suggest that cyclohexane tolerance in S. enterica can be mediated by an acrB-independent mechanism.
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Affiliation(s)
- Mark Webber
- Antimicrobial Agents Research Group, Division of Immunity and Infection, University of Birmingham, UK
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Randall LP, Coldham NG, Woodward MJ. Detection of mutations in Salmonella enterica gyrA, gyrB, parC and parE genes by denaturing high performance liquid chromatography (DHPLC) using standard HPLC instrumentation. J Antimicrob Chemother 2005; 56:619-23. [PMID: 16141278 DOI: 10.1093/jac/dki293] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
AIMS Quinolone antibiotics are the agents of choice for treating systemic Salmonella infections. Resistance to quinolones is usually mediated by mutations in the DNA gyrase gene gyrA. Here we report the evaluation of standard HPLC equipment for the detection of mutations (single nucleotide polymorphisms; SNPs) in gyrA, gyrB, parC and parE by denaturing high performance liquid chromatography (DHPLC). METHODS A panel of Salmonella strains was assembled which comprised those with known different mutations in gyrA (n = 8) and fluoroquinolone-susceptible and -resistant strains (n = 50) that had not been tested for mutations in gyrA. Additionally, antibiotic-susceptible strains of serotypes other than Salmonella enterica serovar Typhimurium strains were examined for serotype-specific mutations in gyrB (n = 4), parC (n = 6) and parE (n = 1). Wild-type (WT) control DNA was prepared from Salmonella Typhimurium NCTC 74. The DNA of respective strains was amplified by PCR using Optimase proofreading DNA polymerase. Duplex DNA samples were analysed using an Agilent A1100 HPLC system with a Varian Helix DNA column. Sequencing was used to validate mutations detected by DHPLC in the strains with unknown mutations. RESULTS Using this HPLC system, mutations in gyrA, gyrB, parC and parE were readily detected by comparison with control chromatograms. Sequencing confirmed the gyrA predicted mutations as detected by DHPLC in the unknown strains and also confirmed serotype-associated sequence changes in non-Typhimurium serotypes. CONCLUSIONS The results demonstrated that a non-specialist standard HPLC machine fitted with a generally available column can be used to detect SNPs in gyrA, gyrB, parC and parE genes by DHPLC. Wider applications should be possible.
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Affiliation(s)
- L P Randall
- Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey KT15 3NB, UK.
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Randall LP, Clouting CS, Gradel KO, Clifton-Hadley FA, Davies RD, Woodward MJ. Farm disinfectants select for cyclohexane resistance, a marker of multiple antibiotic resistance, in Escherichia coli. J Appl Microbiol 2005; 98:556-63. [PMID: 15715857 DOI: 10.1111/j.1365-2672.2004.02488.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AIMS The aim of this study was to determine if three classes of farm disinfectants were able to select for ciprofloxacin or cyclohexane tolerant [indicative of a multiple antibiotic resistance (MAR) phenotype] Escherichia coli and if cyclohexane-tolerant E. coli could be isolated from farms. METHODS AND RESULTS Chicken slurry containing ca 1 : 99 ratio ciprofloxacin resistant : susceptible E. coli (10 different resistant strains examined) was treated for 24 h with each of the disinfectants and examined for survival of resistant : susceptible strains. Ciprofloxacin-sensitive (n=5) and -resistant (n=5) E. coli were grown with sublethal concentrations of the disinfectants and then plated to agar containing ciprofloxacin or overlaid with cyclohexane. Escherichia coli (n=389) isolated from farms were tested for cyclohexane tolerance. Minimum inhibitory concentrations (MIC) were determined against representative isolates and mutants. The disinfectants did not select for the ciprofloxacin-resistant E. coli in poultry slurry but following growth with each of the three disinfectants, higher numbers (P < or = 0.023) of cyclohexane-tolerant E. coli were isolated and these had a MAR phenotype. Of the 389 farm E. coli tested, only one was cyclohexane tolerant. CONCLUSIONS It is possible that in a farm environment, E. coli could be exposed to similar concentrations of the disinfectants that are selected for MAR type organisms under these laboratory conditions. SIGNIFICANCE AND IMPACT OF THE STUDY Data from this study suggest that cyclohexane-resistant E. coli are not common on farms, but in view of the ease of isolating them in the laboratory with farm disinfectants, further investigations on farms are warranted.
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Affiliation(s)
- L P Randall
- Department of Food and Environmental Safety, Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey, UK.
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Randall LP, Eaves DJ, Cooles SW, Ricci V, Buckley A, Woodward MJ, Piddock LJV. Fluoroquinolone treatment of experimental Salmonella enterica serovar Typhimurium DT104 infections in chickens selects for both gyrA mutations and changes in efflux pump gene expression. J Antimicrob Chemother 2005; 56:297-306. [PMID: 15956100 DOI: 10.1093/jac/dki189] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES To determine the efficacy of enrofloxacin (Baytril) in chickens in eradicating three different resistance phenotypes of Salmonella enterica and to examine the resistance mechanisms of resulting mutants. METHODS In two separate replicate experiments (I and II), three strains of Salmonella enterica serovar Typhimurium DT104 [strain A, fully antibiotic-sensitive strain; strain B, isogenic multiple antibiotic-resistant (MAR) derivative of A; strain C, veterinary penta-resistant phenotype strain containing GyrA Phe-83], were inoculated into day-old chicks at approximately 10(3) cfu/bird. At day 10, groups of chicks (n =10) were given either enrofloxacin at 50 ppm in their drinking water for 5 days or water alone (control). Caecal contents were monitored for presence of Salmonella and colonies were replica plated to media containing antibiotics or overlaid with cyclohexane to determine the proportion of isolates with reduced susceptibility. The MICs of antibiotics and cyclohexane tolerance were determined for selected isolates from the chicks. Mutations in topoisomerase genes were examined by DHPLC and expression of marA, soxS, acrB, acrD and acrF by RT-PCR. RESULTS In experiment I, but not II, enrofloxacin significantly reduced the numbers of strain A compared with the untreated control group. In experiment II, but not I, enrofloxacin significantly reduced the numbers of strain B. Shedding of strain C was unaffected by enrofloxacin treatment. Birds infected with strains A and B gave rise to isolates with decreased fluoroquinolone susceptibility. Isolates derived from strain A or B requiring >128 mg/L nalidixic acid for inhibition contained GyrA Asn-82 or Phe-83. Isolates inhibited by 16 mg/L nalidixic acid were also less susceptible to antibiotics of other chemical classes and became cyclohexane-tolerant (e.g. MAR). CONCLUSIONS These studies demonstrate that recommended enrofloxacin treatment of chicks rapidly selects for strains with reduced fluoroquinolone susceptibility from fully sensitive and MAR strains. It can also select for MAR isolates.
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Affiliation(s)
- Luke P Randall
- Department of Food and Environmental Safety, Veterinary Laboratories Agency, New Haw, Surrey KT15 3NB, UK.
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Pumbwe L, Randall LP, Woodward MJ, Piddock LJV. Evidence for multiple-antibiotic resistance in Campylobacter jejuni not mediated by CmeB or CmeF. Antimicrob Agents Chemother 2005; 49:1289-93. [PMID: 15793099 PMCID: PMC1068584 DOI: 10.1128/aac.49.4.1289-1293.2005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An efflux system, CmeABC, in Campylobacter jejuni was previously described, and a second efflux system, CmeDEF, has now been identified. The substrates of CmeDEF include ampicillin, ethidium bromide, acridine, sodium dodecyl sulfate (SDS), deoxycholate, triclosan, and cetrimide, but not ciprofloxacin or erythromycin. C. jejuni NCTC11168 and two efflux pump knockout strains, cmeB::Kan(r) and cmeF::Kan(r), were exposed to 0.5 to 1 microg of ciprofloxacin/ml in agar plates. All mutants arising from NCTC11168 were resistant to ciprofloxacin but not to other agents and contained a mutation resulting in the replacement of threonine 86 with isoleucine in the quinolone resistance-determining region of GyrA. Mutants with two distinct phenotypes were selected from the efflux pump knockout strains. Mutants with the first phenotype were resistant to ciprofloxacin only and had the same substitution within GyrA as the NCTC11168-derived mutants. Irrespective of the parent strain, mutants with the second phenotype were resistant to ciprofloxacin, chloramphenicol, tetracycline, ethidium bromide, acridine orange, and SDS and had no mutation in gyrA. These mutants expressed levels of the efflux pump genes cmeB and cmeF and the major outer membrane protein gene porA similar to those expressed by the respective parent strains. No mutations were detected in cmeF or cmeB. Accumulation assays revealed that the mutants accumulated lower concentrations of drug. These data suggest the involvement of a non-CmeB or -CmeF efflux pump or reduced uptake conferring multiple-antibiotic resistance, which can be selected after exposure to a fluoroquinolone.
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Affiliation(s)
- Lilian Pumbwe
- Antimicrobial Agents Research Group, Division of Infection and Immunity, University of Birmingham, Birmingham, B15 2TT, United Kingdom
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Randall LP, Cooles SW, Piddock LJV, Woodward MJ. Mutant prevention concentrations of ciprofloxacin and enrofloxacin for Salmonella enterica. J Antimicrob Chemother 2004; 54:688-91. [PMID: 15243029 DOI: 10.1093/jac/dkh360] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
OBJECTIVES To determine the mutant prevention concentrations (MPCs) of ciprofloxacin and enrofloxacin against four strains of Salmonella enterica serovar Enteritidis and four strains of S. Typhimurium including one fully susceptible, one multiply resistant (MAR), one GyrA mutant and one GyrA/MAR mutant. Further, to examine mutants arising after exposure to sub-MPC concentrations of the antibiotics for susceptibility to ciprofloxacin and enrofloxacin, and cyclohexane tolerance. METHODS MICs were determined using the agar dilution method of the BSAC. The MPC was recorded as the lowest concentration of antibiotic to inhibit growth from an inoculum of 10(10) cfu. RESULTS The MPCs and resulting MPC/MIC ratios of enrofloxacin were generally two- to four-fold higher than for ciprofloxacin. At 24 h for both antibiotics, MPCs were lowest for the fully susceptible strains (0.25-0.5 mg/L), similar for the MAR (1-4 mg/L) and GyrA (2-4 mg/L) mutants and highest for the GyrA/MAR mutants (1-8 mg/L). MPC/MIC ratios at 24 h were 2-16 for all strains except those for the MAR strains without mutation in gyrA where the ratios were 8-64. CONCLUSIONS The ability to eradicate Salmonella in vivo depends on many factors such as antibiotic susceptibility of the strain, dose and route of administration. It is suggested that these MPC values will be useful when considering dosing strategies. In view of the high MPC/MIC ratio, MAR strains with wild-type gyrA, although susceptible to ciprofloxacin (MICs 0.06-0.13 mg/L), may give rise to treatment failures.
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Affiliation(s)
- L P Randall
- Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey, UK.
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Randall LP, Cooles SW, Piddock LJV, Woodward MJ. Effect of triclosan or a phenolic farm disinfectant on the selection of antibiotic-resistant Salmonella enterica. J Antimicrob Chemother 2004; 54:621-7. [PMID: 15269199 DOI: 10.1093/jac/dkh376] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVE To determine the effect of growth of five strains of Salmonella enterica and their isogenic multiply antibiotic-resistant (MAR) derivatives with a phenolic farm disinfectant or triclosan (biocides) upon the frequency of mutation to resistance to antibiotics or cyclohexane. METHODS Strains were grown in broth with or without the biocides and then spread on to agar containing ampicillin, ciprofloxacin or tetracycline each at 4x MIC or agar overlaid with cyclohexane. Incubation was for 24 and 48 h and the frequency of mutation to resistance was calculated for strains with and without prior growth with the biocides. MICs were determined and the presence of mutations in the acrR and marR regions was determined by sequencing and the presence of mutations in gyrA by light-cycler analysis, for a selection of the mutants that arose. RESULTS The mean frequency of mutation to antibiotic or cyclohexane resistance was increased approximately 10- to 100-fold by prior growth with the phenolic disinfectant or triclosan. The increases were statistically significant for all antibiotics and cyclohexane following exposure to the phenolic disinfectant (P </= 0.013), and for ampicillin and cyclohexane following exposure to triclosan (P </= 0.009). Mutants inhibited by >1 mg/L ciprofloxacin arose only from strains that were MAR. Reduced susceptibility to ciprofloxacin (at 4x MIC for parent strains) alone was associated with mutations in gyrA. MAR mutants did not contain mutations in the acrR or marR region. CONCLUSIONS These data renew fears that the use of biocides may lead to an increased selective pressure towards antibiotic resistance.
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Affiliation(s)
- L P Randall
- Department of Food and Environmental Safety, Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey, UK.
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Pumbwe L, Randall LP, Woodward MJ, Piddock LJV. Expression of the efflux pump genes cmeB, cmeF and the porin gene porA in multiple-antibiotic-resistant Campylobacter jejuni. J Antimicrob Chemother 2004; 54:341-7. [PMID: 15201231 DOI: 10.1093/jac/dkh331] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS In Escherichia coli, increased expression of efflux pumps and/or decreased expression of porins can confer multiple antibiotic resistance (MAR), causing resistance to at least three unrelated classes of antibiotics, detergents and dyes. It was hypothesized that in Campylobacter jejuni, the efflux systems CmeABC, CmeDEF and the major outer membrane porin protein, MOMP (encoded by porA) could confer MAR. METHODS The expression of cmeB, cmeF and porA in 32 MAR C. jejuni isolated from humans or poultry was determined by comparative (C)-reverse transcriptase (RT)-PCR and denaturing DHPLC. A further 13 ethidium bromide-resistant isolates and three control strains were also investigated. Accumulation of ciprofloxacin+/-carbonyl cyanide-m-chlorophenyl hydrazone (CCCP) was also determined for all strains. RESULTS Although resistance to ethidium bromide has been associated with MAR, expression of all three genes was similar in the ethidium bromide-resistant isolates. These data indicate that CmeB, CmeF and MOMP play no role in resistance to this agent in C. jejuni. Six MAR isolates over-expressed cmeB, 3/32 over-expressed cmeB and cmeF. No isolates over-expressed cmeF alone. Expression of porA was similar in all isolates. All nine isolates that over-expressed cmeB contained a mutation in cmeR, substituting glycine 86 with alanine. All cmeB over-expressing isolates also accumulated low concentrations of ciprofloxacin, which were restored to wild-type levels in the presence of CCCP. CONCLUSIONS These data indicate that over-expression of cmeB is associated with MAR in isolates of C. jejuni. However, as cmeB was over-expressed by only one-third (9/32) of MAR isolates, these data also indicate other mechanisms of MAR in C. jejuni.
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Affiliation(s)
- Lilian Pumbwe
- Antimicrobial Agents Research Group, Division of Immunity and Infection, University of Birmingham, Birmingham B15 2TT, UK
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Randall LP, Cooles SW, Osborn MK, Piddock LJV, Woodward MJ. Antibiotic resistance genes, integrons and multiple antibiotic resistance in thirty-five serotypes of Salmonella enterica isolated from humans and animals in the UK. J Antimicrob Chemother 2004; 53:208-16. [PMID: 14729766 DOI: 10.1093/jac/dkh070] [Citation(s) in RCA: 213] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES To examine 397 strains of Salmonella enterica of human and animal origin comprising 35 serotypes for the presence of aadB, aphAI-IAB, aadA1, aadA2, bla(Carb(2)) or pse1, bla(Tem), cat1, cat2, dhfr1, floR, strA, sul1, sul2, tetA(A), tetA(B) and tetA(G) genes, the presence of class 1 integrons and the relationship of resistance genes to integrons and antibiotic resistance. RESULTS Some strains were resistant to ampicillin (91), chloramphenicol (85), gentamicin (2), kanamycin (14), spectinomycin (81), streptomycin (119), sulfadiazine (127), tetracycline (108) and trimethoprim (45); 219 strains were susceptible to all antibiotics. bla(Carb(2)), floR and tetA(G) genes were found in S. Typhimurium isolates and one strain of S. Emek only. Class 1 integrons were found in S. Emek, Haifa, Heidelberg, Mbandaka, Newport, Ohio, Stanley, Virchow and in Typhimurium, mainly phage types DT104 and U302. These strains were generally multi-resistant to up to seven antibiotics. Resistance to between three and six antibiotics was also associated with class 1 integron-negative strains of S. Binza, Dublin, Enteritidis, Hadar, Manhattan, Mbandaka, Montevideo, Newport, Typhimurium DT193 and Virchow. CONCLUSION The results illustrate specificity of some resistance genes to S. Typhimurium or non- S. Typhimurium serotypes and the involvement of both class 1 integron and non-class 1 integron associated multi-resistance in several serotypes. These data also indicate that the bla(Carb(2)), floR and tetA(G) genes reported in the SG1 region of S. Typhimurium DT104, U302 and some other serotypes are still predominantly limited to S. Typhimurium strains.
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Affiliation(s)
- L P Randall
- Food and Environmental Safety Department, Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey KT15 3NB.
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Randall LP, Ridley AM, Cooles SW, Sharma M, Sayers AR, Pumbwe L, Newell DG, Piddock LJV, Woodward MJ. Prevalence of multiple antibiotic resistance in 443 Campylobacter spp. isolated from humans and animals. J Antimicrob Chemother 2003; 52:507-10. [PMID: 12917241 DOI: 10.1093/jac/dkg379] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
AIMS In view of recent findings that a multidrug efflux pump CmeABC exists in Campylobacter jejuni, 391 C. jejuni and 52 Campylobacter coli of human and animal origin were examined for a multidrug resistance phenotype. MATERIALS AND METHODS The MICs of ampicillin, chloramphenicol, ciprofloxacin, erythromycin, kanamycin, tetracycline, cetrimide, triclosan, acridine orange, paraquat and ethidium bromide were determined. Resistance to organic solvents and the effect of salicylate (known inducer of the marRAB operon in Escherichia coli and Salmonella) were also examined. RESULTS Two C. coli and 13 C. jejuni isolates, mainly from pigs or poultry, were resistant to three or more antibiotics and 12 of these strains had reduced susceptibility to acridine orange and/or ethidium bromide. Strains (n = 20) that were less susceptible to acridine orange, ethidium bromide and triclosan were significantly more resistant (P < 0.05) to ampicillin, chloramphenicol, ciprofloxacin, erythromycin, nalidixic acid and tetracycline, with two- to four-fold increases in MIC values compared with strains (n = 20) most susceptible to acridine orange, ethidium bromide and triclosan. Growth of strains with 1 mM salicylate caused a small (up to two-fold) but statistically significant (P < or = 0.005) increase in the MICs of chloramphenicol, ciprofloxacin, erythromycin and tetracycline. CONCLUSIONS These data indicate that multiple antibiotic resistant (MAR)-like Campylobacter strains occur and it may be postulated that these may overexpress cmeABC or another efflux system.
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Affiliation(s)
- L P Randall
- Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey KT15 3NB, UK.
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Abstract
Chromosomally encoded systems involved in low level resistance of bacteria to different classes of antibiotics (mainly beta-lactams, chloramphenicol, quinolones and tetracycline), disinfectants and in resistance to organic solvents have been the focus of considerable interest in recent years. The multiple antibiotic resistance (mar) locus of Escherichia coli and Salmonella is perhaps the best described system involved in this type of resistance which is induced by MarA, the activator protein encoded by the marRAB locus. The mar -locus is reported to mediate resistance primarily by up-regulating efflux of some antibiotics, disinfectants and organic solvents via the AcrAB-TolC efflux pump and down regulating influx through Outer Membrane Protein F (OmpF). Whilst the level of antibiotic resistance conferred by marRAB is only low level, there are increasing data to suggest that marRAB and related systems are important in clinical antibiotic resistance, possibly as a 'stepping stone' to higher levels of resistance. Other related systems include up-regulation of RobA, SoxS and AcrAB which give rise to a similar resistance phenotype to that conferred by up-regulation of MarA. The aim of this paper is to review the function and significance of the mar -locus and related systems with a particular focus on its implications in veterinary medicine.
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Affiliation(s)
- L P Randall
- Department of Bacterial Disease, Veterinary Laboratories Agency (Weybridge) New Haw, Addlestone, Surrey, KT15 3NB, United Kingdom
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Liebana E, Clouting C, Cassar CA, Randall LP, Walker RA, Threlfall EJ, Clifton-Hadley FA, Ridley AM, Davies RH. Comparison of gyrA mutations, cyclohexane resistance, and the presence of class I integrons in Salmonella enterica from farm animals in England and Wales. J Clin Microbiol 2002; 40:1481-6. [PMID: 11923377 PMCID: PMC140356 DOI: 10.1128/jcm.40.4.1481-1486.2002] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This study is focused on real-time detection of gyrA mutations and of the presence of class I integrons in a panel of 100 veterinary isolates of Salmonella enterica from farm animals. The isolates were selected on the basis of resistance to nalidixic acid, representing a variety of the most prevalent serotypes in England and Wales. In addition, organic solvent (cyclohexane) resistance in these isolates was investigated in an attempt to elucidate the presence of efflux pump mechanisms. The most prevalent mutation among the isolates studied was Asp87-Asn (n = 42), followed by Ser83-Phe (n = 38), Ser83-Tyr (n = 12), Asp87-Tyr (n = 4), and Asp87-Gly (n = 3). Two distinct subpopulations were identified, separated at the 1-mg/liter breakpoint for ciprofloxacin: 86% of isolates with mutations in codon 83 showed MICs of >or=1 mg/liter, while 89.8% of isolates with mutations in codon 87 presented MICs of <or=0.5 mg/liter. Cyclohexane resistance was more prevalent among Ser83 mutants than among Asp87 mutants (34.7 and 4%, respectively), and in 79% of isolates that presented both gyrA mutations and cyclohexane resistance, the level of ciprofloxacin resistance was >or=2.0 mg/liter. Thirty-four isolates contained class I integrons, with 71% of the S. enterica serovar Typhimurium isolates and 6.9% of isolates belonging to other serotypes containing such elements. The methods used represent sensitive ways of investigating the presence of gyrA mutations and of detecting class-I integrons in Salmonella isolates. The results can be obtained in less than 1 h from single colonies without the need for purifying DNA.
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Affiliation(s)
- Ernesto Liebana
- Department of Bacterial Diseases, Veterinary Laboratories Agency-Weybridge, Addlestone, Surrey KT15 3NB, UK.
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Randall LP, Cooles SW, Sayers AR, Woodward MJ. Association between cyclohexane resistance in Salmonella of different serovars and increased resistance to multiple antibiotics, disinfectants and dyes. J Med Microbiol 2001; 50:919-924. [PMID: 11599743 DOI: 10.1099/0022-1317-50-10-919] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A panel of 388 salmonellas of animal and human origin, comprising 35 serotypes, was tested for resistance to cyclohexane and to a range of antibiotics, disinfectants and dyes. Cyclohexane resistance was detected in 41 isolates (10.6%): these comprised members of the serovars Binza (1 of 15), Dublin (1 of 24), Enteritidis (1 of 61), Fischerkietz (4 of 5), Livingstone (9 of 11), Montevideo (1 of 32), Newport (4 of 23), Saint-paul (1 of 3), Senftenberg (10 of 24) and Typhimurium (9 of 93). Most (39 of 41) of the cyclohexane-resistant isolates were from poultry. Statistical analysis showed that the cyclohexane-resistant strains were significantly more resistant than the cyclohexane-susceptible strains to ampicillin, chloramphenicol, ciprofloxacin, erythromycin, nalidixic acid, tetracycline, trimethoprim, cetrimide and triclosan. The multiresistance patterns seen were typical of those caused by efflux pumps, such as AcrAB. The emergence of such resistance may play an important role in the overall antibiotic resistance picture of Salmonella, with particular effect on ciprofloxacin.
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Affiliation(s)
- Luke P Randall
- Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey KT15 3NB
| | - Sue W Cooles
- Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey KT15 3NB
| | - Antony R Sayers
- Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey KT15 3NB
| | - Martin J Woodward
- Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey KT15 3NB
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Abstract
The virulence of a Salmonella enterica serovar Typhimurium DT014 strain in which marA was insertionally inactivated was compared to its isogenic parent in vitro and in vivo. In vitro, the numbers of the marA mutant phagocytosed by porcine lung macrophages were significantly increased, while survival at 24 h inside macrophages and adherence to human gut cells were significantly reduced in comparison with the parent strain. In vivo, the marA inactivated strain, in competition with its parent strain, persisted for a shorter period in chickens, was present in the caeca at significantly lower levels and invaded the deeper organs to a significantly lesser extent. Therapeutic antibiotic treatment of one group of chickens with oxytetracycline favoured the persistence of both the parent strain and, to a lesser extent, the marA inactivated strain; but interestingly, increased tetracycline resistance of Salmonella isolates after treatment of birds with antibiotic was seen only for the parent strain. Further work is needed to elucidate how mar is involved in virulence and if its inactivation can minimise the ability of bacteria to become antibiotic-resistant in vivo.
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Affiliation(s)
- L P Randall
- Department of Bacteriological Diseases, Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey KT15 3NB
| | - M J Woodward
- Department of Bacteriological Diseases, Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey KT15 3NB
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Abstract
In order to understand the role of the mar locus in Salmonella with regard to multiple antibiotic resistance, cyclohexane resistance, and outer membrane protein F (OmpF) regulation, a marA::gfp reporter mutant was constructed in an antibiotic-sensitive Salmonella enterica serovar Typhimurium DT104 background. Salicylate induced marA, whereas a number of antibiotics, disinfectants, and various growth conditions did not. Increased antibiotic resistance was observed upon salicylate induction, although this was shown to be by both mar-dependent and mar-independent pathways. Cyclohexane resistance, however, was induced by salicylate by a mar-dependent pathway. Complementation studies with a plasmid that constitutively expressed marA confirmed the involvement of mar in Salmonella with low-level antibiotic resistance and cyclohexane resistance, although the involvement of mar in down regulation of OmpF was unclear. However, marA overexpression did increase the expression of a ca. 50-kDa protein, but its identity remains to be elucidated. Passage of the marA::gfp reporter mutant with increasing levels of tetracycline, a method reported to select for mar mutants in Escherichia coli, led to both multiple-antibiotic and cyclohexane resistance. Collectively, these data indicate that low-level antibiotic resistance, cyclohexane resistance, and modulation of OMPs in Salmonella, as in E. coli, can occur in both a mar-dependent and mar-independent manner.
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Affiliation(s)
- L P Randall
- Department of Bacterial Disease, Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey KT15 3NB, United Kingdom
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Abstract
The objective of the study was to determine the effects of inoculating cattle orally with a strain of Escherichia coli O157:H7 (A84/92). However, before they were challenged two of the six calves were found to be infected naturally with a wild-type strain of E coli O157 and two more of them became infected later. The number of daily faeces samples from which the wild-type E coli O157 was isolated ranged from one to 10. After they were inoculated, A84/92 was detected in all the calves' faeces on one to six of the next 14 days, and later from the faeces samples of three calves on two, three, and 11 occasions, the last occasion being between 19 and 51 days after inoculation. Two calves were redosed with A84/92, and the organism was isolated on a further five and 15 occasions, the last being after 20 and 58 days. In three dry cows, A84/92 was isolated from the faeces on three to 11 of the 14 days after they were inoculated. Two of the cows were redosed and from one of them it was isolated on 15 occasions, the last being 44 days after the initial infection; in the other cow no further isolation was made. In three lactating cows, it was detected on three to four of the 14 days after they were inoculated, and similar results were obtained after they were reinoculated. None of the animals showed clinical signs and no lesions were detected in the intestines of the calves. Three calves had a serological response to E coli O157 but, with the exception of one cow which had a slight increase to IgM levels, no serological changes were observed in the adult cattle.
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Affiliation(s)
- C Wray
- Veterinary Laboratories Agency-Weybridge, New Haw, Addlestone, UK
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Affiliation(s)
- L P Randall
- Central Veterinary Laboratory, New Haw, Addlestone, Surrey
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Randall LP, Wray C, McLaren IM. Studies on the development and use of a monoclonal sandwich ELISA for the detection of verotoxic Escherichia coli in animal faeces. Vet Rec 1997; 140:112-5. [PMID: 9042694 DOI: 10.1136/vr.140.5.112] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A sandwich ELISA using monoclonal antibodies to Escherichia coli verocytotoxins 1 and 2 for capture and detection was developed for detection of verocytotoxin-producing Escherichia coli (VTEC) in animal faeces. For optimal toxin detection, the faeces were cultured in MacConkey broth before subculture on to trypticase soy agar containing mitomycin C. It was possible to detect between 10 and 10(3) VTI-producing and 1 to 10 VT2-producing E coli/g faeces, and overall the sensitivity and specificity of the ELISA for VTEC in faeces were 80.5 per cent and 91.2 per cent, respectively, when compared with a verocell assay. A limited survey of faeces from healthy animals (89 cattle, 16 sheep, 22 pigs, 11 goats and six domestic fowl) and faeces from 144 cattle with enteric disease detected VTEC in 64 per cent, 63 per cent, 5 per cent, 45 per cent, none and 16 per cent of the samples, respectively.
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Affiliation(s)
- L P Randall
- Bacteriology Department, Central Veterinary Laboratory, New Haw, Addlestone, Surrey
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