title: Rapid MALDI biotyper-based identification and cluster analysis of Streptococcus iniae.
abstract: Streptococcus iniae causes severe mortalities among cultured marine species, especially in the olive flounder (Paralichthys olivaceus), which is economically important in Korea and Japan. Recently, there has been growing concern regarding the emergence of S. iniae as a zoonotic pathogen. Here, 89 S. iniae isolates obtained from diseased olive flounders collected from 2003 to 2008 in Jeju Island, South Korea, were characterized using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The results were aligned both with the available Bruker Daltonics data-base and with a new set of S. iniae data entries developed in our laboratory, and the results were compared. When we used the Bruker Daltonics database, the 89 isolates yielded either "no reliable identification" or were incorrectly identified as Streptococcus pyogenes at the genus level. When we used the new data entries from our laboratory, in contrast, all of the isolates were correctly identified as S. iniae at the genus (100%) and species (96.6%) levels. We performed proteomic analysis, divided the 89 isolates into cluster I (51.7%), cluster II (20.2%), and cluster III (28.1%), and then used the MALDI Biotyper software to identify specific mass peaks that enabled discrimination between clusters and between Streptococcus species. Our results suggest that the use of MALDI TOF MS could outperform the conventional methods, proving easier, faster, cheaper and more efficient in properly identifying S. iniae. This strategy could facilitate the epidemiological and taxonomical study of this important fish pathogen.
authors.affiliation: Laboratory of Aquatic Animal Diseases, Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju, 52828, Republic of Korea.
authors.forename: Si Won
authors.initials: SW
authors.lastname: Kim
authors.affiliation: Division of Microbiology, National Center for Toxicological Research/FDA, Jefferson, Arkansas, USA.
authors.forename: Seong Won
authors.initials: SW
authors.lastname: Nho
authors.affiliation: Laboratory of Aquatic Animal Diseases, Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju, 52828, Republic of Korea.
authors.forename: Se Pyeong
authors.initials: SP
authors.lastname: Im
authors.affiliation: Laboratory of Aquatic Animal Diseases, Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju, 52828, Republic of Korea.
authors.forename: Jung Seok
authors.initials: JS
authors.lastname: Lee
authors.affiliation: Laboratory of Aquatic Animal Diseases, Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju, 52828, Republic of Korea.
authors.forename: Jae Wook
authors.initials: JW
authors.lastname: Jung
authors.affiliation: Laboratory of Aquatic Animal Diseases, Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju, 52828, Republic of Korea.
authors.forename: Jassy Mary S
authors.initials: JM
authors.lastname: Lazarte
authors.affiliation: Laboratory of Aquatic Animal Diseases, Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju, 52828, Republic of Korea.
authors.forename: Jaesung
authors.initials: J
authors.lastname: Kim
authors.affiliation: BluGen Korea, Busan, 48071, Republic of Korea.
authors.forename: Woo-Jai
authors.initials: WJ
authors.lastname: Lee
authors.affiliation: Inland Aquaculture Research Center, NIFS, Changwon, 51695, Republic of Korea.
authors.forename: Jeong-Ho
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Laboratory of Aquatic Animal Diseases, Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju, 52828, Republic of Korea. jungts@gnu.ac.kr.
authors.forename: Tae Sung
authors.initials: TS
authors.lastname: Jung
mesh_terms: D000818:Animals; D001431:Bacteriological Techniques / Q000379:methods*; D016000:Cluster Analysis; D003365:Costs and Cost Analysis; D005393:Fish Diseases / Q000382:microbiology*; D005432:Flounder / Q000382:microbiology*; D007564:Japan; D007723:Korea; D056910:Republic of Korea; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013290:Streptococcal Infections / Q000382:microbiology / Q000662:veterinary*; D000070058:Streptococcus iniae / Q000737:chemistry* / Q000145:classification*; D013997:Time Factors; D014730:Veterinary Medicine / Q000379:methods
keywords: MALDI TOF MS; Paralichthys olivaceus; Streptococcus iniae; database; olive flounder