Genetic diversity of geographically distinct Streptococcus dysgalactiae isolates from fish

Abstract

Streptococcus dysgalactiae is an emerging pathogen of fish. Clinically, infection is characterized by the development of necrotic lesions at the caudal peduncle of infected fishes. The pathogen has been recently isolated from different fish species in many countries. Twenty S. dysgalactiae isolates collected from Japan, Taiwan, Malaysia and Indonesia were molecularly characterized by biased sinusoidal field gel electrophoresis (BSFGE) using SmaI enzyme, and tuf gene sequencing analysis. DNA sequencing of ten S. dysgalactiae revealed no genetic variation in the tuf amplicons, except for three strains. The restriction patterns of chromosomal DNA measured by BSFGE were differentiated into six distinct types and one subtype among collected strains. To our knowledge, this report gives the first snapshot of S. dysgalactiae isolates collected from different countries that are localized geographically and differed on a multinational level. This genetic unrelatedness among different isolates might suggest a high recombination rate and low genetic stability.

Rapid identification of pathogenic streptococci isolated from moribund red tilapia (Oreochromis spp.)

“…Hernandez et al (2009) recorded mortalities of similar intensity in the brood-stocks of red tilapia. The first epizootic outbreak caused by S. dysgalactiae was detected in amberjack (Seriola dumerili) and yellowtail (S. quinqueradiata) in Japan (Nomoto et al, 2004), with necrosis in the caudal peduncle area (Abdelsalam et al, 2013(Abdelsalam et al, , 2015. The present study documented heavy losses in large-size red tilapia cultured in a marine aquaculture farm in Egypt.…”

“…The most severe epizootics are caused by S. agalactiae and S. iniae (Chen et al, 2007). Recently, S. dysgalactiae has also been listed as an emerging fish pathogen (Abdelsalam et al, 2009a(Abdelsalam et al, ,b, 2010a(Abdelsalam et al, ,b, 2013(Abdelsalam et al, , 2015. All these Streptococcus spp.…”

Expression, genetic localization and phylogenic analysis of NAPlr in piscine Streptococcus dysgalactiae subspecies dysgalactiae isolates and their patterns of adherence

“…S. dysgalactiae was found in human and porcine β-hemolytic SDSE isolates and in piscine, bovine, and porcine α-hemolytic SDSD isolates [17,37] . Recently, SDSD infection has been observed in farmed fish resulting in severely necrotizing caudal peduncles [23,25] . SDSD caused either an opportunistic infection in immunocompromised patients [12,13,44] , or invasive infection in individuals handling livestock and seafood [10,11] .…”

“…It has been recovered from cobia ( Rachycentron canadum ), basket mullet ( Liza alata ) and grey mullet ( Mugil cephalus ) in Taiwan, hybrid red tilapia ( Oreochromis sp.) in Indonesia, white spotted snapper ( Lutjanus stellatus ) and pompano ( T. blochii ) in Malaysia [9,16,17,23] , and rainbow trout ( Oncorhynchus mykiss ) in Iran [24] . The infected fish revealed systemic pyrogranulomatous inflammation with a severe necrotic lesion in their caudal peduncles [25] .…”

Molecular characterization and pathogenicity of Francisella noatunensis subsp. orientalis isolated from cultured tilapia (Oreochromis sp.) in Taiwan

“…One method that is sensitive and accurate, and enables researchers to detect, identify and classify the bacterial genome is PFGE (Parizad, Parizad, & Valizadeh, 2016). PFGE has been developed to identify species and clinical isolates related to outbreaks of various Gram-positive (Abdelsalam, Eissa, & Chen, 2015;Baseggio, Mansell, Browning, & Browning, 1997;Chen et al, 2012;Nguyen et al, 2017;Sabat et al, 2013;Sandt et al, 2006;Santos-Sanches, Chambel, & Tenreiro, 2015;Tsai, Wang, Yoshida, & Chen, 2015;Yang et al, 2013) and Gram-negative organisms (Sunenshine et al, 2009) including Francisella spp. (Fey et al, 2007;García Del Blanco et al, 2002;Lai et al, 2016).…”