title: Optical Screening for Rapid Antimicrobial Susceptibility Testing and for Observation of Phenotypic Diversity among Strains of the Genetically Clonal Species Bacillus anthracis.
abstract: During high-impact events involvingBacillus anthracis, such as the Amerithrax incident of 2001 or the anthrax outbreaks in Russia and Sweden in 2016, critical decisions to reduce morbidity and mortality include rapid selection and distribution of effective antimicrobial agents for treatment and postexposure prophylaxis. Detection of antimicrobial resistance currently relies on a conventional broth microdilution method that requires a 16- to 20-h incubation time forB. anthracisAdvances in high-resolution optical screening offer a new technology to more rapidly evaluate antimicrobial susceptibility and to simultaneously assess the growth characteristics of an isolate. Herein, we describe a new method developed and evaluated as a rapid antimicrobial susceptibility test forB. anthracisThis method is based on automated digital time-lapse microscopy to observe the growth and morphological effects of relevant antibiotics with an optical screening instrument, the oCelloScope.B. anthracisstrains were monitored over time in the presence or absence of penicillin, ciprofloxacin, or doxycycline. Susceptibility to each antibiotic was determined in ≤4 h, 75 to 80% less than the time required for conventional methods. Time-lapse video imaging compiled from the optical screening images revealed unexpected differences in growth characteristics among strains ofB. anthracis, which is considered to be a clonal organism. This technology provides a new approach for rapidly detecting phenotypic antimicrobial resistance and for documenting growth attributes that may be beneficial in the further characterization of individual strains.
authors.affiliation: Biodefense Research and Development Laboratory, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
authors.forename: Heather P
authors.initials: HP
authors.lastname: McLaughlin
authors.affiliation: Biodefense Research and Development Laboratory, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
authors.forename: Amy S
authors.initials: AS
authors.lastname: Gargis
authors.affiliation: Biodefense Research and Development Laboratory, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
authors.forename: Pierre
authors.initials: P
authors.lastname: Michel
authors.affiliation: Biodefense Research and Development Laboratory, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
authors.forename: David
authors.initials: D
authors.lastname: Sue
authors.affiliation: Biodefense Research and Development Laboratory, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA lweigel4@gmail.com.
authors.forename: Linda M
authors.initials: LM
authors.lastname: Weigel
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D057205:Automation, Laboratory / Q000379:methods; D001408:Bacillus anthracis / Q000145:classification* / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D002939:Ciprofloxacin / Q000494:pharmacology; D004318:Doxycycline / Q000494:pharmacology; D005838:Genotype; D008826:Microbial Sensitivity Tests / Q000379:methods*; D008853:Microscopy / Q000379:methods*; D010406:Penicillins / Q000494:pharmacology; D013997:Time Factors; D059008:Time-Lapse Imaging / Q000379:methods*
chemical_list: D000900:Anti-Bacterial Agents; D010406:Penicillins; D002939:Ciprofloxacin; D004318:Doxycycline
keywords: Bacillus anthracis; morphological differentiation; multidrug resistance; optical screening technology