title: Susceptibility testing of Mycobacterium abscessus by isothermal microcalorimetry.
abstract: We evaluated a new method for susceptibility testing of a rapidly growing mycobacterium using real-time measurement of heat (microcalorimetry). MICs of 2 clinical Mycobacterium abscessus isolates were determined by microbroth dilution and E-test. For microcalorimetry, Middlebrook-7H10 agar+10% oleic acid-albumin-dextrose-catalase, containing amikacin, clarithromycin, linezolid, and ciprofloxacin was inoculated with ~10(5)CFU/mL. Heat production was measured at 37°C for 72h. Minimal heat inhibition concentration (MHIC) was defined as the lowest antibiotic concentration inhibiting growth-related heat production. Growth of M. abscessus was detected after a median of 16.5h (range, 8.5-26.9h). Heat detection was proportionally delayed with increasing concentration of antibiotics. MHICs for the tested strains were 16 to >16mg/L for amikacin, >8mg/L for clarithromycin, 4 to >16mg/L for ciprofloxacin, 24 to >32mg/L for linezolid. MHICs were in agreement within two 2-fold dilutions with conventional MICs. Microcalorimetry may accelerate antimicrobial susceptibility testing in mycobacteria and provide additional real-time information on the drug effect.
authors.affiliation: Infectious Diseases Service, Department of Medicine, University Hospital and University of Lausanne, Lausanne, Switzerland. Electronic address: noemie.boillat@chuv.ch.
authors.forename: Noémie
authors.initials: N
authors.lastname: Boillat-Blanco
authors.affiliation: Infectious Diseases Service, Department of Medicine, University Hospital and University of Lausanne, Lausanne, Switzerland; Septic Surgical Unit, Department of Surgery, University Hospital and University of Lausanne, Lausanne, Switzerland. Electronic address: hanna.furustrand@chuv.ch.
authors.forename: Ulrika
authors.initials: U
authors.lastname: Furustrand Tafin
authors.affiliation: Institute of Microbiology, University Hospital and University of Lausanne, Lausanne, Switzerland. Electronic address: katia.jaton-ogay@chuv.ch.
authors.forename: Katia
authors.initials: K
authors.lastname: Jaton
authors.affiliation: Center for Musculoskeletal Surgery, Charité - University Medicine, Free and Humboldt - University of Berlin, Berlin, Germany. Electronic address: andrej.trampuz@charite.de.
authors.forename: Andrej
authors.initials: A
authors.lastname: Trampuz
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002151:Calorimetry / Q000379:methods*; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods*; D009161:Mycobacterium / Q000187:drug effects* / Q000302:isolation & purification; D009165:Mycobacterium Infections, Nontuberculous / Q000382:microbiology; D013696:Temperature; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents
keywords: Antibiotics; Microcalorimetry; Mycobacteria; Mycobacterium abscessus; Susceptibility testing