Use of MALDI-TOF Mass Spectrometry for the Fast Identification of Gram-Positive Fish Pathogens

Abstract

Gram-positive cocci, such as Streptococcus agalactiae, Lactococcus garvieae, Streptococcus iniae, and Streptococcus dysgalactiae subsp. dysgalactiae, are found throughout the world, particularly in outbreaks in farmed fish, and are thus associated with high economic losses, especially in the cultivation of Nile Tilapia. The aim of this study was to evaluate the efficacy of matrix-assisted laser desorption ionization (MALDI)-time of flight (TOF) mass spectrometry (MS) as an alternative for the diagnosis of these pathogens. One hundred and thirty-one isolates from Brazilian outbreaks assisted by the national authority were identified using a MALDI Biotyper from Bruker Daltonics. The results showed an agreement with respect to identification (Kappa = 1) between this technique and 16S ribosomal RNA gene sequencing for S. agalactiae and L. garvieae. However, for S. iniae and S. dysgalactiae subsp. dysgalactiae, perfect agreement was only achieved after the creation of a custom main spectra profile, as well as further comparisons with 16S ribosomal RNA and multilocus sequence analysis. MALDI-TOF MS was shown to be an efficient technology for the identification of these Gram-positive pathogens, yielding a quick and precise diagnosis.

Identification and typing of Vagococcus salmoninarum using genomic and proteomic techniques

“…MALDI‐TOF‐MS has proven to be a useful method for differentiation of closely related bacteria affecting fish (Assis et al, ; Fernández‐Álvarez et al, ; Kim et al, ; Topić Popović et al, ), but the ability of this technique for identification and typing of V. salmoninarum strains has not been evaluated. As reported for other bacteria isolated from veterinary and environmental samples (Assis et al, ; Fernández‐Álvarez et al, ; Kim et al, ), the results of the present study confirm the need to expand the databases with bacteria isolated from fish, since the species V. salmoninarum or R. salmoninarum , pathogens of importance to the aquaculture industry, could not be identified even at the genus level. Other aquatic Gram‐positive bacteria such as S. parauberis NCIMB 703043, S. iniae CECT 7363 and L. garvieae CECT 5274 were only identified at the genus level, probably due to the low number of proteomic profiles of these bacteria in the Bruker Biotyper database (V. 3.1).…”

“…This is because this method mainly detects the most abundant and conserved ribosomal protein fractions of bacteria, which can be used for classification of bacteria at the level of genus, species (Assis et al, 2017;Fernández-Álvarez, Torres-Corral, Saltos-Rosero, & Santos, 2017;Kim et al, 2015Kim et al, , 2017, subspecies (Kudirkiene, Welker, Knudsen, & Bojesen, 2015) or serotype (Dieckmann, Helmuth, Erhard, & Malorny, 2008;Fernández-Álvarez et al, 2018a;Torres-Corral, Fernández-Álvarez, & Santos, 2019). Unfortunately, most of the databases available so far concentrate on bacteria relevant to the medical field, requiring the creation of in-house databases to achieve high levels of identification and typing in aquatic bacteria (Assis et al, 2017;Fernández-Álvarez et al, 2018a;Fernández-Álvarez, Torres-Corral, & Santos, 2018b;Kim et al, 2017;Topić Popović et al, 2017). The aim of the present study was to evaluate the capacity of immunological, proteomic and molecular techniques for the diagnosis of vagococcosis, as well as for typing V. salmoninarum strains.…”

Atypical Multibacterial Granulomatous Myositis in a Horse: First Report in Italy

“…The preparation was allowed to dry at room temperature. Spectra using the FlexControl MicroFlex LT mass spectrometer (Bruker Daltonics) were acquired in accordance with Assis et al [25]. Previous calibration of the mass spectrometer was performed using a bacterial standard test [26].…”

Haemato-immunological responses and effectiveness of feed-based bivalent vaccine against Streptococcus iniae and Aeromonas hydrophila infections in hybrid red tilapia (Oreochromis spp.)

“…Amongst the advantages of culturing tilapia is its general hardiness, farming in high stocking densities, adaptability to different production systems, easier reproduction, owing to its higher growth rate, with advances in easily genetic improvement of brood fish for target breeding having further developed these characteristics [8,9]. Nevertheless, tilapia sector in globally has been facing currently different health risk for 18], S. agalactiae and F. noatunensis [19], A. veronii and F. columnare [20] and F. noatunensis subsp. orientalis and Shewanella putrefaciens [21].…”

“…Nevertheless, there is still complexity to understand the mechanisms of oral vaccination that are involved in the uptake of antigens [32,33]. Although, results from oral immunization in fish are contradictory but few researches showed satisfactory results [19,34,35].…”