title: Antimicrobial susceptibility among clinical Nocardia species identified by multilocus sequence analysis.
abstract: Antimicrobial susceptibility patterns of 112 clinical isolates, 28 type strains, and 9 reference strains of Nocardia were determined using the Sensititre Rapmyco microdilution panel (Thermo Fisher, Inc.). Isolates were identified by highly discriminatory multilocus sequence analysis and were chosen to represent the diversity of species recovered from clinical specimens in Ontario, Canada. Susceptibility to the most commonly used drug, trimethoprim-sulfamethoxazole, was observed in 97% of isolates. Linezolid and amikacin were also highly effective; 100% and 99% of all isolates demonstrated a susceptible phenotype. For the remaining antimicrobials, resistance was species specific with isolates of Nocardia otitidiscaviarum, N. brasiliensis, N. abscessus complex, N. nova complex, N. transvalensis complex, N. farcinica, and N. cyriacigeorgica displaying the traditional characteristic drug pattern types. In addition, the antimicrobial susceptibility profiles of a variety of rarely encountered species isolated from clinical specimens are reported for the first time and were categorized into four additional drug pattern types. Finally, MICs for the control strains N. nova ATCC BAA-2227, N. asteroides ATCC 19247(T), and N. farcinica ATCC 23826 were robustly determined to demonstrate method reproducibility and suitability of the commercial Sensititre Rapmyco panel for antimicrobial susceptibility testing of Nocardia spp. isolated from clinical specimens. The reported values will facilitate quality control and standardization among laboratories.
authors.affiliation: Mycology Section, Ontario Public Health Laboratories, Public Health Ontario, Toronto, Ontario, Canada lisa.mctaggart@oahpp.ca.
authors.forename: Lisa R
authors.initials: LR
authors.lastname: McTaggart
authors.affiliation: Mycology Section, Ontario Public Health Laboratories, Public Health Ontario, Toronto, Ontario, Canada.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Doucet
authors.affiliation: Mycology Section, Ontario Public Health Laboratories, Public Health Ontario, Toronto, Ontario, Canada.
authors.forename: Maria
authors.initials: M
authors.lastname: Witkowska
authors.affiliation: Mycology Section, Ontario Public Health Laboratories, Public Health Ontario, Toronto, Ontario, Canada Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada Division of Microbiology, Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Richardson
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015373:Bacterial Typing Techniques; D019411:Clinical Laboratory Techniques / Q000379:methods / Q000592:standards; D024881:Drug Resistance, Bacterial / Q000187:drug effects / Q000235:genetics; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods; D058885:Multilocus Sequence Typing; D009615:Nocardia / Q000145:classification / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D009864:Ontario; D011786:Quality Control; D015203:Reproducibility of Results
chemical_list: D000900:Anti-Bacterial Agents