Abstract
The phenotypic detection of plasmid-acquired AmpC (pAmpC) in Escherichia coli is challenging, and molecular methods are required for confirmation. In addition to cefoxitin resistance, multiresistance and high-level resistance to cephalosporins have both been suggested as criteria for targeting isolates with pAmpC, but data to support these proposed criteria are lacking. A Swedish collection of 378 isolates with either putative chromosomal hyperproduction of AmpC (cAmpC) or pAmpC were subjected to disk diffusion and minimum inhibitory concentration (MIC) determination with the Etest. The frequency of resistance to gentamicin, ciprofloxacin, and trimethoprim among cAmpC and pAmpC was compared to elucidate the issue of multidrug resistance. Lastly, methods for the phenotypic confirmation of pAmpC were compared. One in-house disk diffusion method, one method employing NeoSensitabs (Rosco), and one Etest method (bioMérieux) were compared. The analysis of histograms based on both disk diffusion and the Etest showed that resistance [according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST)] to cefotaxime and/or ceftazidime occurred in almost all isolates. By coining resistance instead of non-susceptibility, the number of isolates required to subject to phenotypic testing/genotypic confirmation dropped by more than 40 %, without compromising the sensitivity substantially. Further, almost 70 % of isolates with pAmpC were non-multidrug resistant, clearly indicating that this is an inappropriate criterion for further investigation. The phenotypic tests all had more than 90 % sensitivity, and the best sensitivities were obtained with the in-house method and with the ceftazidime ± cloxacillin NeoSensitab. In conclusion, clinical resistance to cefotaxime and/or ceftazidime seems to be an appropriate criterion for pAmpC screening, and several phenotypic methods perform well for the phenotypic confirmation of AmpC production prior to genotypic confirmation.
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References
Giske CG, Sundsfjord AS, Kahlmeter G, Woodford N, Nordmann P, Paterson DL et al (2009) Redefining extended-spectrum β-lactamases: balancing science and clinical need. J Antimicrob Chemother 63(1):1–4
Park YS, Adams-Haduch JM, Shutt KA, Yarabinec DM 3rd, Johnson LE, Hingwe A et al (2012) Clinical and microbiologic characteristics of cephalosporin-resistant Escherichia coli at three centers in the United States. Antimicrob Agents Chemother 56(4):1870–1876
Brolund A, Wisell KT, Edquist PJ, Elfström L, Walder M, Giske CG (2010) Development of a real-time SYBRGreen PCR assay for rapid detection of acquired AmpC in Enterobacteriaceae. J Microbiol Methods 82(3):229–233
Polsfuss S, Bloemberg GV, Giger J, Meyer V, Böttger EC, Hombach M (2011) Practical approach for reliable detection of AmpC β-lactamase-producing Enterobacteriaceae. J Clin Microbiol 49(8):2798–2803
Nadjar D, Rouveau M, Verdet C, Donay L, Herrmann J, Lagrange PH et al (2000) Outbreak of Klebsiella pneumoniae producing transferable AmpC-type β-lactamase (ACC-1) originating from Hafnia alvei. FEMS Microbiol Lett 187(1):35–40
Tan TY, Ng LS, He J, Koh TH, Hsu LY (2009) Evaluation of screening methods to detect plasmid-mediated AmpC in Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis. Antimicrob Agents Chemother 53(1):146–149
Giske CG, Gezelius L, Samuelsen Ø, Warner M, Sundsfjord A, Woodford N (2011) A sensitive and specific phenotypic assay for detection of metallo-β-lactamases and KPC in Klebsiella pneumoniae with the use of meropenem disks supplemented with aminophenylboronic acid, dipicolinic acid and cloxacillin. Clin Microbiol Infect 17(4):552–556
European Committee on Antimicrobial Susceptibility Testing (2013) Breakpoint tables for interpretation of MICs and zone diameters. Available online at: http://www.eucast.org/clinical_breakpoints/. Accessed 10 January 2013
Birkett CI, Ludlam HA, Woodford N, Brown DF, Brown NM, Roberts MT et al (2007) Real-time TaqMan PCR for rapid detection and typing of genes encoding CTX-M extended-spectrum β-lactamases. J Med Microbiol 56(Pt 1):52–55
Rasheed JK, Jay C, Metchock B, Berkowitz F, Weigel L, Crellin J et al (1997) Evolution of extended-spectrum β-lactam resistance (SHV-8) in a strain of Escherichia coli during multiple episodes of bacteremia. Antimicrob Agents Chemother 41(3):647–653
Robberts FJ, Kohner PC, Patel R (2009) Unreliable extended-spectrum β-lactamase detection in the presence of plasmid-mediated AmpC in Escherichia coli clinical isolates. J Clin Microbiol 47(2):358–361
Dierikx C, van der Goot J, Fabri T, van Essen-Zandbergen A, Smith H, Mevius D (2013) Extended-spectrum-β-lactamase- and AmpC-β-lactamase-producing Escherichia coli in Dutch broilers and broiler farmers. J Antimicrob Chemother 68(1):60–67
Matsumura Y, Yamamoto M, Higuchi T, Komori T, Tsuboi F, Hayashi A et al (2012) Prevalence of plasmid-mediated AmpC β-lactamase-producing Escherichia coli and spread of the ST131 clone among extended-spectrum β-lactamase-producing E. coli in Japan. Int J Antimicrob Agents 40(2):158–162
Rodríguez-Baño J, Miró E, Villar M, Coelho A, Gozalo M, Borrell N et al (2012) Colonisation and infection due to Enterobacteriaceae producing plasmid-mediated AmpC β-lactamases. J Infect 64(2):176–183
Hansen F, Hammerum AM, Skov RL, Giske CG, Sundsfjord A, Samuelsen O (2012) Evaluation of ROSCO Neo-Sensitabs for phenotypic detection and subgrouping of ESBL-, AmpC- and carbapenemase-producing Enterobacteriaceae. APMIS 120(9):724–732
Halstead FD, Vanstone GL, Balakrishnan I (2012) An evaluation of the Mast D69C AmpC Detection Disc Set for the detection of inducible and derepressed AmpC β-lactamases. J Antimicrob Chemother 67(9):2303–2304
Peter-Getzlaff S, Polsfuss S, Poledica M, Hombach M, Giger J, Böttger EC et al (2011) Detection of AmpC β-lactamase in Escherichia coli: comparison of three phenotypic confirmation assays and genetic analysis. J Clin Microbiol 49(8):2924–2932
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C.G.G.: member of the EUCAST Steering Committee. Other authors: no conflicts of interest to declare.
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Edquist, P., Ringman, M., Liljequist, B.O. et al. Phenotypic detection of plasmid-acquired AmpC in Escherichia coli—evaluation of screening criteria and performance of two commercial methods for the phenotypic confirmation of AmpC production. Eur J Clin Microbiol Infect Dis 32, 1205–1210 (2013). https://doi.org/10.1007/s10096-013-1869-x
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DOI: https://doi.org/10.1007/s10096-013-1869-x