Isolation and Pathogenicity ofStreptococcus iniaein Cultured Red Hybrid Tilapia in Malaysia

Abstract

This study describes the isolation and pathogenicity of Streptococcus iniae in cultured red hybrid tilapia (Nile Tilapia Oreochromis niloticus × Mozambique Tilapia O. mossambicus) in Malaysia. The isolated gram-positive S. iniae appeared punctiform, transparently white, catalase and oxidase negative and produced complete β-hemolysis on blood agar, while a PCR assay resulted in the amplification of the 16 S rRNA gene and lactate oxidase encoded genes. The isolate was sensitive to tetracycline, vancomycin, and bacitracin but was resistant to streptomycin, ampicillin, penicillin, and erythromycin. Pathogenicity trials conducted in local red hybrid tilapia (mean ± SE = 20.00 ± 0.45 g) showed 90.0, 96.7, and 100.0% mortality within 14 d postinfection following intraperitoneal exposure to 10, 10, and 10 CFU/mL of the pathogen, respectively. The clinical signs included erratic swimming, lethargy, and inappetance at 6 h postinfection, while mortality was recorded at less than 24 h postinfection in all infected groups. The LD of S. iniae against the red hybrid tilapia was 10 CFU/mL. The post mortem examinations revealed congested livers, kidneys, and spleens of the infected fish. This is the first report of S. iniae experimental infection in cultured red hybrid tilapia in Malaysia. Received January 20, 2017; accepted July 16, 2017.

Effects of Infertility by Cabergoline on Serum Sex Hormones and the Inter- and Intra-Sexual Social Behaviors of Female Rattus losea

“…Likewise, its capability to grow optimally in a medium with salt concentrations from 0% to 3.0% gave it an ability to be lethal to both freshwater and marine fish species (Kia and Mehrabi, 2013). Biochemical profiles of S. iniae HNM-1 differs with most of the previously reported strains, for instance, it exhibits great variations in ɑ-galactosidase, β-glucuronidase and trehalose reactions compared with the strains reported by (Rahmatullah et al, 2017;El Aamri et al, 2010;Jantrakajorn et al, 2014;Dodson et al, 1999), but comparable with the dolphin isolate which was the first isolated strain of S. iniae (Pier and Madin, 1976). Inconsistency in biochemical profiles is common among different strains of the bacteria, which can lead to frequent miss-identification of S. iniae using the biochemical method (Lau et al, 2003).…”

“…S. iniae HNM-1 was found to be resistant to many important antibiotics that include Amoxicillin, gentamycin, Penicillin G and spectinomycin. This signifies an emergence of multidrug resistance strain unlike previously reported strains that were susceptible to most of the antibiotics (Rahmatullah et al, 2017;El Aamri et al, 2010;Kayansamruaj et al, 2017). The cumulative mortalities and LD 50 of HNM-1 strain in A. sinensis indicated the high vulnerability of A. sinensis to its infection.…”

Phenotypic and genotypic characterization of Streptococcus spp. isolated from tilapia (Oreochromis spp.) cultured in river‐based cage and earthen ponds in Northern Thailand

“…Several researchers have demonstrated that the transmission of Streptococcus spp. in tilapia is horizontal (Iregui, Comas, Vasquez, & Verjan, ; Rahmatullah et al, ). Present studies have found high mortality and rates of bacterial infection with high stocking density (over 78 fish/m 3 ).…”

Streptolysin Encoding Genes sagC and sagD as Biomarkers of Fish Pathogen Streptococcus iniae: An In Silico Study

“…The isolated Gram-positive S. iniae appeared punctiform, transparently white, catalase and oxidase negative and produced complete b-hemolysis on blood agar. The isolate was sensitive to tetracycline, vancomycin, and bacitracin but was resistant to streptomycin, ampicillin, penicillin, and erythromycin (Ortega et al, 2018;Rahmatullah et al, 2017;Rajoo et al, 2015).…”