Use of oxytetracycline for the treatment of tremor disease in the Chinese mitten crab Eriocheir sinensis

Abstract

The causative agent of tremor disease (TD) in the Chinese mitten crab Eriocheir sinensis has been shown to be a member of the genus Spiroplasma. In the present study, a susceptibility test indicated that oxytetracycline (OTC) has both a high degree of efficacy in the inhibition of Spiroplasma and a broad range of safe concentrations. Treatment experiments showed that the best concentration of OTC for use against TD was 40 mg OTC kg -1 crab weight. Acute toxicity experiments demonstrated that the 24 and 48 h median lethal dosages (LD 50 ) of OTC for this species of crab were 366 and 340 mg OTC kg -1 crab body weight, respectively, while the safe concentration was 82.5 mg OTC kg -1 crab weight. We suggest that OTC has potential as a highly effective inhibitor of Spiroplasma pathogens in aquatic animals and has been proven to be a potent, safe and low cost cure for TD. This represents a novel use of OTC in the therapeutic treatment of an aquacultural disease caused by a Spiroplasma pathogen.KEY WORDS: Oxytetracycline · Spiroplasma · Tremor disease · Acute toxicity · Chinese mitten crab · Eriocheir sinensis Resale or republication not permitted without written consent of the publisherDis Aquat Org 84: [243][244][245][246][247][248][249][250] 2009 experiments . Similar results were obtained in subsequent studies (Zhang et al. 2002, Wang et al. 2003a. Subsequent isolation and analysis of the 16S rRNA gene, which was the 'gold standard' of microbiological classification, confirmed the agent to be a spiroplasma (Wang et al. 2003b(Wang et al. , 2004a. This was the first spiroplasma to be found in aquatic crustaceans and it began to change our understanding of the host range of these organisms (Christensen et al. 2005, Regassa & Gasparich 2006). Koch's postulates were later fulfilled for the spiroplasma, providing definitive proof that this agent was the cause of TD (Wang et al. 2004a).As mentioned above, many scholars have studied TD since it became epidemic in the Chinese mitten crab (Pan 1998, Yang & Cai 1998, Wei 1999, Huang 2000, Shen et al. 2000. Although the TD pathogen had not been accurately characterized, different medical compounds were administered as therapies, but no efficient disease controls were found. In the present study we examined the susceptibility of spiroplasma to 8 different chemical compounds used in aquaculture: calcium oxide, niclosamide, deltamethrin, cupric sulfate pentahydrate, potassium permanganate, bromochlorodimethylhydantoin, Benzylpenicillin and oxytetracycline (OTC). Many antibacterial compounds have been tested in aquaculture systems, including calcium oxide and potassium permanganate for their chemotherapeutic control of ectoparasites (Saprolegnia, Trichodina, Myxobolus, Hemiclepsis, Argulus, and Posthodiplostomum) attached to cultured fish (Singhal et al. 1986). Niclosamide belongs to the anthelminthic family of medicines and has been used to treat broad or fish tapeworm, dwarf tapeworm and beef tapeworm infections (WHO 1984). The anthelminthic efficacy of niclosamid...

Spiroplasma eriocheiris Enters Drosophila Schneider 2 Cells and Relies on Clathrin-Mediated Endocytosis and Macropinocytosis

“…Spiroplasma eriocheiris, as the first Spiroplasma pathogen found in crustaceans (5,6), was previously identified as a causative agent of Eriocheir sinensis tremor disease (TD). The biochemical and biological properties (7), evolutionary analysis (8), taxonomic identification (9,10), and antibacterial testing (11) of S. eriocheiris have been previously documented.…”

Kinetic analysis of oxytetracycline residues in Chinese mitten crab, Eriocheir sinensis, muscle following intramuscular administration

“…2009). Appropriate OTC concentrations for treatment of spiroplasma infection in E. sinensis can be theoretically obtained with a single intramuscular administration dose of 36.37 mg kg −1 , providing equal therapeutic effectiveness as the dose of 40 mg kg −1 recommended in a previous study (Liang et al. 2009), and a treatment period of 432.01 h.…”

“…A practical use of the pharmacokinetic data is the possibility to design dosage regimens in which levels of a specific drug can be maintained above the MIC and below toxic effects. The 24 and 48 h median lethal dosages (LD50) of OTC in E. sinensis (366 and 340 mg kg −1 body weight, respectively) were fairly high and offered a wide potential dose range (Liang et al. 2009).…”

“…Prior to injection, crabs were surface disinfected with 75% ethanol and weighed individually. To investigate the muscle concentrations following intramuscular dosing, three doses were chosen between the recommended treatment level (40 mg kg −1 body weight) and the minimum inhibitory concentration (MIC, 2 mg kg −1 body weight) as determined by in vitro test (Liang, Feng, Wu, Gu & Wang 2009). OTC solutions were prepared by dissolving the desired dosages of the drug in sterile 0.9% sodium chloride.…”

Bacterial diseases of crabs: A review

“…Diagnoses and prevention of spiroplasma disease of freshwater culture crustaceans in China have been established recently Liang et al, 2009). ELISA for the rapid field diagnoses of the spiroplasma pathogen was developed and the whole test procedure was rapid, being completed within 3 h without any equipment.…”