Characterization of Isolates of Streptococcus agalactiae from Diseased Farmed and Wild Marine Fish from the U.S. Gulf Coast, Latin America, and Thailand

Abstract

We examined Lancefield serogroup B Streptococcus isolates recovered from diseased, cultured hybrid Striped Bass (Striped Bass Morone saxatilis × White Bass M. chrysops) and wild and cultured Gulf Killifish Fundulus grandis from coastal waters of the U.S. Gulf of Mexico (Gulf coast) and compared those isolates to strains from tilapias Oreochromis spp. reared in Mississippi, Thailand, Ecuador, and Honduras and to the original Gulf coast strain identified by Plumb et al. ( 1974 ). The isolates were subjected to phylogenetic, biochemical, and antibiotic susceptibility analyses. Genetic analysis was performed using partial sequence comparison of (1) the 16S ribosomal RNA (rRNA) gene; (2) the sipA gene, which encodes a surface immunogenic protein; (3) the cspA gene, which encodes a cell surface-associated protein; and (4) the secY gene, which encodes components of a general protein secretion pathway. Phylogenies inferred from sipA, secY, and cspA gene sequence comparisons were more discriminating than that inferred from the 16S rRNA gene sequence comparison. The U.S. Gulf coast strains showed a high degree of similarity to strains from South America and Central America and belonged to a unique group that can be distinguished from other group B streptococci. In agreement with the molecular findings, biochemical and antimicrobial resistance analyses demonstrated that the isolates recovered from the U.S. Gulf coast and Latin America were more similar to each other than to isolates from Thailand. Three laboratory challenge methods for inducing streptococcosis in Gulf Killifish were evaluated-intraperitoneal (IP) injection, immersion (IMM), and immersion plus abrasion (IMMA)-using serial dilutions of S. agalactiae isolate LADL 97-151, a representative U.S. Gulf coast strain. The dose that was lethal to 50% of test fish by 14 d postchallenge was approximately 2 CFU/fish via IP injection. In contrast, the fish that were challenged via IMM or IMMA presented cumulative mortality less than 40% by 14 d postchallenge.

Antimicrobial Usage and Antimicrobial Resistance in Animal Production in Southeast Asia: A Review

“…[21,77,78,79,80,81,82,83]. These publications included research related to fish (6) and shrimp farms (2).…”

“…These publications included research related to fish (6) and shrimp farms (2). All publications came from Thailand and Vietnam, even though four investigated aquaculture samples originating from several SEA countries (Thailand, Vietnam, Malaysia, and Indonesia) [78,79,80,82]. One study investigated AMR in isolates from imported aquaculture products from Thailand.…”

Fatal Infection in a Wild Sandbar Shark (Carcharhinus plumbeus), Caused by Streptococcus agalactiae, Type Ia-ST7

“…The S. agalactiae isolate was then serotyped at the National Reference Laboratory (Ministry of Health, Israel) using a molecular serotyping method for epidemiological tracing. A multiplex-PCR for species confirmation and direct identification of S. agalactiae capsular type was performed [9]. Additionally, whole genome sequencing (WGS) was performed.…”

“…Moreover, in 2012 S. agalactiae has also been described as causing deaths of different wild fish species, namely, adult Queensland grouper (Epinephelus lanceolatus), javelin grunter (Pomadasys kaaken), giant sea catfish (Netuma thalassina) and squaretail mullet (Ellochelon vaigensis) in north Queensland, Australia [8]. Another publication revealed an infection caused by S. agalactiae in wild and cultured Gulf Killifish (Fundulus grandis) from coastal waters in the Gulf of Mexico, USA (2015) [9].…”

Galleria mellonellaas an infection model for the multi-host pathogenStreptococcus agalactiaereflects hypervirulence of ST283

“…GBS was initially described in 1887 as an animal pathogen responsible for mastitis in ruminants and although largely eradicated in some countries with a highly developed dairy industry, remains a major cause of bovine mastitis in many countries 1 . In 1966, GBS infection of fish was reported in the USA 2 with subsequent outbreaks described in fish farms in Asia and the Americas 3,4 . GBS infection is often associated with high levels of mortality in fish and with the worldwide growth of aquaculture has significant economic impact 5 .…”