title: Validation of novel cost-effective antimicrobial gradient strips for the determination of carbapenem susceptibility in Enterobacteriaceae.
abstract: The aim of this study was to validate the use of LML antimicrobial gradient strips for quantitative determination of carbapenem susceptibility in Enterobacteriaceae.
  
  
  
  A total of 95 non-redundant Enterobacteriaceae strains isolated during 2012-2014 were used for this validation study. Initially, LML antimicrobial gradient strips were validated for their performance in comparison with the agar dilution method. The test strip was then validated in comparison with broth microdilution (BMD) and Etest with 24 selected strains using the same inocula and other laboratory parameters.
  
  
  
  The LML strip showed 83%, 68% and 86% essential agreement (within ±1 log2dilution) with the reference methods of agar dilution, BMD and Etest, respectively; furthermore, essential agreement was >90% within ±2 log2dilution. Categorical agreement was ≥87% with all reference methods according to Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints. However, the meropenem strip requires performance improvements to fulfil US Food and Drug Administration (FDA) and International Organization for Standardization (ISO) requirements for an antimicrobial susceptibility test device.
  
  
  
  In LML antimicrobial gradient strip minimum inhibitory concentrations (MICs) were comparable with Etest MICs and it might serve as a reasonable, cost-effective alternative to Etest for quantitative determination of carbapenem susceptibility in Enterobacteriaceae.
authors.affiliation: Department of Microbiology, Faculty of Medicine, Government Theni Medical College, Tamil Nadu Dr M.G.R. Medical University, Theni 625512, India; Department of Microbiology, Faculty of Medicine, Dr A.L.M. Post Graduate Institute of Basic Medical Sciences, University of Madras, Chennai 600113, India. Electronic address: sekaralingam@gmail.com.
authors.forename: Ramalingam
authors.initials: R
authors.lastname: Sekar
authors.affiliation: Department of Microbiology, Faculty of Medicine, Dr A.L.M. Post Graduate Institute of Basic Medical Sciences, University of Madras, Chennai 600113, India.
authors.forename: Seetharaman
authors.initials: S
authors.lastname: Srivani
authors.affiliation: Department of Microbiology, Faculty of Medicine, Government Theni Medical College, Tamil Nadu Dr M.G.R. Medical University, Theni 625512, India.
authors.forename: Sivathanu
authors.initials: S
authors.lastname: Lallitha
authors.affiliation: Department of Microbiology, Faculty of Medicine, Government Theni Medical College, Tamil Nadu Dr M.G.R. Medical University, Theni 625512, India.
authors.forename: Pandiyan
authors.initials: P
authors.lastname: Thenmozhi
authors.affiliation: Department of Microbiology, Faculty of Medicine, Government Theni Medical College, Tamil Nadu Dr M.G.R. Medical University, Theni 625512, India.
authors.forename: Thangam
authors.initials: T
authors.lastname: Devisri
authors.affiliation: Department of Microbiology, Faculty of Medicine, Government Theni Medical College, Tamil Nadu Dr M.G.R. Medical University, Theni 625512, India.
authors.forename: Murugesan
authors.initials: M
authors.lastname: Amudhan
authors.affiliation: Department of Microbiology, Faculty of Medicine, Government Theni Medical College, Tamil Nadu Dr M.G.R. Medical University, Theni 625512, India.
authors.forename: Manoharan
authors.initials: M
authors.lastname: Mythreyee
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D015780:Carbapenems / Q000494:pharmacology*; D052978:Disk Diffusion Antimicrobial Tests / Q000295:instrumentation / Q000379:methods; D024881:Drug Resistance, Bacterial; D004755:Enterobacteriaceae / Q000187:drug effects*; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000295:instrumentation / Q000379:methods*; D010865:Pilot Projects; D012044:Regression Analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000890:Anti-Infective Agents; D015780:Carbapenems
keywords: Antimicrobial gradient strip; Antimicrobial susceptibility testing; Carbapenem resistance; Gradient strip method; Minimum inhibitory concentration