Phenotypic and Genotypic Heterogeneity among Streptococcus iniae Isolates Recovered from Cultured and Wild Fish in North America, Central America and the Caribbean Islands

Abstract

Streptococcus iniae, the etiological agent of streptococcosis in fish, is an important pathogen of cultured and wild fish worldwide. During the last decade outbreaks of streptococcosis have occurred in a wide range of cultured and wild fish in the Americas and Caribbean islands. To gain a better understanding of the epizootiology of S. iniae in the western hemisphere, over 30 S. iniae isolates recovered from different fish species and geographic locations were characterized phenotypically and genetically. Species identities were determined biochemically and confirmed by amplification and sequencing of the 16S rRNA gene. Repetitive-element palindromic PCR fingerprinting as well as biochemical and antimicrobial susceptibility profiles suggest that a single strain of S. iniae was responsible for two different disease outbreaks among reef fishes in the Caribbean, one in 1999 and another in 2008. Interestingly, a majority of the isolates recovered from cultured fish in the Americas were genetically distinct from the Caribbean isolates and exhibited a trend toward higher minimal inhibitory concentration with respect to several antibiotics as well as greater genetic variability. The biological significance of this genetic variability is unclear, but it could have implications for future vaccine development and treatment.

Comparative Phenotypic and Genotypic Analysis of Edwardsiella Isolates from Different Hosts and Geographic Origins, with Emphasis on Isolates Formerly Classified as E. tarda, and Evaluation of Diagnostic Methods

“…Genetic fingerprinting. Repetitive extragenic palindromic PCR (rep-PCR) fingerprinting was performed on isolates using previously published primer sets (Table 10) and modifications to existing protocols (31,38,59,60,88). Briefly, 50-l reaction mixtures comprised 25 l of IQ Supermix (Bio-Rad; Hercules, CA), 20 pmol (ERIC I and II) or 40 pmol (ERIC II, BOX, and GTG 5 ) of primer, 10 ng of DNA template, and nuclease-free water to volume.…”

Examining the interplay between Streptococcus agalactiae, the biopolymer chitin and its derivative

“…Streptococcosis is caused by gram‐positive, globally distributed bacteria capable of infecting more than 27 species of fish inhabiting fresh, brackish, and marine waters (Bowater et al, ; Chou et al, ; Keirstead et al, ; Klesius, Shoemaker, & Evans, ; Sheehan et al, ). Streptococcus agalactiae in particular not only causes invasive disease in fish but also poses a zoonotic hazard.…”

Genotyping and pathogenicity of Streptococcus iniae strains recovered from cultured Oreochromis niloticus at Kafr El-Shiekh Governorate, Egypt.

“…The results obtained from susceptibility assays showed that S. iniae isolates can be mainly controlled by antibiotics especially oxytetracycline and florfenicol. Oxytetracycline and florfenicol were recommended to the fisheries in USA, resulting in the powerful control of the bacterial fish outbreaks (Chou et al 2014).…”

“…In a Korean study, S. iniae strains had been clustered into two genotypes in the flounder using BoxA primer and virulence (Kim et al, 2014). While, other works demonstrated the limited utility of using the Box primer to discriminate between S. iniae isolates recovered from different host's species from either fish or mammals in North America (Dodson et al 1999) or recovered from different geographic locations in the Americas and Caribbean islands (Chou et al 2014) which generated one homogenous group using the Box primers. By contrast, S. iniae isolates formed three distinct clusters using the GTG5 primer (Chou et al 2014).…”

“…Typing of S. iniae bacteria into known groups is essential to understand the epizootiology and better control of these problematic organisms. Many molecular techniques have been used to study genotypic diversity of S. iniae (Dodson et al, 1999 andChou et al, 2014). Therefore, this study describes isolation, pathogenicity and genotypic heterogeneity of S. iniae isolated from cultured tilapia (O. niloticus) at Kafr El-Shiekh Governorate.…”