title: Creation of an In-House Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Corynebacterineae Database Overcomes Difficulties in Identification of Nocardia farcinica Clinical Isolates.
abstract: Nocardiosis is a rare disease that is caused by Gram-positive actinobacteria of the Nocardia genus and affects predominantly immunocompromised patients. In its disseminated form, it has a predilection for the central nervous system and is associated with high mortality rates. Therefore, prompt identification of the pathogen is critical. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry is a relatively novel technique used for identification of microorganisms. In this work, an upgraded MALDI-TOF Biotyper database containing Corynebacterineae representatives of strains deposited in the Polish Collection of Microorganisms was created and used for identification of the strain isolated from a nocardial brain abscess, mimicking a brain tumor, in an immunocompetent patient. Testing with the API Coryne system initially incorrectly identified Rhodococcus sp., while chemotaxonomic tests, especially mycolic acid analysis, enabled correct Nocardia identification only at the genus level. Subsequent sequence analysis of 16S rRNA and secA1 genes confirmed the identification. To improve the accuracy of the results, an in-house database was constructed using optimized parameters; with the use of the database, the strain was eventually identified as Nocardia farcinica. Clinical laboratories processing various clinical strains can upgrade a commercial database to improve and to accelerate the results obtained. This is especially important in the case of Nocardia, for which valid microbial diagnosis remains challenging; reference laboratories are often required to identify and to survey these rare actinobacteria.
authors.affiliation: Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland pasciak@iitd.pan.wroc.pl.
authors.forename: Mariola
authors.initials: M
authors.lastname: Paściak
authors.affiliation: Department of Neurosurgery, Regional Specialist Hospital, Legnica, Poland Department of Neurosurgery, Specialist Medical Center, Polanica-Zdrój, Poland.
authors.forename: Władysław
authors.initials: W
authors.lastname: Dacko
authors.affiliation: Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Sikora
authors.affiliation: Department of Microbial Diagnostics, Regional Specialist Hospital, Legnica, Poland.
authors.forename: Danuta
authors.initials: D
authors.lastname: Gurlaga
authors.affiliation: Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Pawlik
authors.affiliation: Department of Neurosurgery, Specialist Medical Center, Polanica-Zdrój, Poland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Miękisiak
authors.affiliation: Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland Wrocław Research Center EIT+, Wrocław, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Gamian
mesh_terms: D001922:Brain Abscess / Q000175:diagnosis* / Q000382:microbiology; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D005260:Female; D006801:Humans; D008875:Middle Aged; D008969:Molecular Sequence Data; D009615:Nocardia / Q000737:chemistry / Q000302:isolation & purification*; D009617:Nocardia Infections / Q000175:diagnosis* / Q000382:microbiology; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S