Genetic and phenotypic comparison of Nocardia seriolae isolated from fish in Japan

Abstract

The phenotypic and genetic characterizations of 58 isolates of the fish pathogen Nocardia seriolae, from amberjack, Seriolae dumerili, yellowtail, Seriola quinqueradiata, Japanese flounder, Paralichthys olivaceus, and chub mackerel, Scomber japonicus, in Japan from 1970-2005, were examined to investigate the epidemiological relationship between isolates. The phenotypic and genetic characterizations were determined by alpha-glucosidase activity and biased sinusoidal field gel electrophoresis (BSFGE) analysis, respectively. There was no alpha-glucosidase activity in strains isolated from 2000-05 (n = 50) with a few exceptions (n = 3), while all strains isolated from 1970-90 (n = 8) were positive. In BSFGE analysis, digestions with restriction enzymes Xba I and Ase I produced 15 and 16 restriction patterns, respectively. All restriction patterns obtained from 50 strains isolated during 2000-05 were unrelated to those obtained from eight strains isolated during 1970-90, with the exception of two strains isolated during recent outbreaks. Based on the phenotypic and genetic characterizations, recent outbreaks of nocardiosis in Japan are suggested to be epidemiologically unrelated to earlier outbreaks in Japan. Although a low genetic relationship was observed in the restriction pattern between recent and earlier isolates, identity was confirmed between these groups of isolates because five representative strains showed 99.9% homology with N. seriolae ATCC43993(T) in the 16S rRNA sequence.

Application of α-glucosidase activity and drug susceptibility tests to epidemiological studies on the fish pathogen Nocardia seriolae

“…Examination of the a-glu activity by API ZYM revealed that 95 out of 110 strains (86.4%) were negative for the a-glu activity, while 15 out of 110 strains (13.6%) were positive for the activity. These data are consistent with those of a previous study [11], which reported that most of the N. seriolae strains isolated in Japan in 2000-2005 were negative for a-glu activity, while the a-glu-positive strains were only isolated from amberjack. In the present study, a-glu-positive strains were isolated from both amberjack and yellowtail.…”

“…Our previous studies [11,12] have suggested that the aglucosidase (a-glu) activity test is useful to indicate the epidemiological aspects of N. seriolae, because positive aglu activity was common in the Taiwanese strains, while negative a-glu activity was common in the Japanese strains. Furthermore, genetic variations were observed between the a-glu-positive and -negative strains.…”

Epidemiological study on Lactococcus garvieae isolates from fish in Japan

“…garvieae infection, in addition to Nocardia seriolae [10] and Lancefield group C Streptococcus dysgalactiae [11] infections, is a well-known bacterial disease in the Japanese aquaculture industry; however, only a few epidemiological studies have been conducted on L. garvieae [12,13]. This study aimed to investigate the epidemiology of L. garvieae strains isolated from diseased fish collected between 1980 and 2007 in Japan by using biased sinusoidal field gel electrophoretic (BSFGE) analysis, phage typing, and drug susceptibility tests.…”

Nocardia seriolae, a causative agent of systematic granuloma in spotted butterfish, Scatophagus argus, Linn

“…Elkesh et al (2013) reported systemic nocardiosis in cultured meagre, Argyrosomus regius Asso with a low to variable morbidity and 1-4% total mortality. Recently, Japanese sea-perch, Lateolabrax japonicum, striped mullet, Mugil cephalus, large yellow croaker, Larimichthys crocea (Richardson), three striped tigerfish, Terapon jarbua, weakfish, Cynoscion regalis (Bloch and Schneider) and yellowtail have all been infected with N. seriolae (Chen et al, 2000;Wang et al, 2005;Shimahara et al, 2006;Shimahara et al, 2008;Wang et al, 2009;Cornwell et al, 2011). Although isolation and bacteriological analysis are complex and time-consuming, N. seriolae has been identified as one of the major nocardial pathogens in fish.…”