C W Li

Publications (2)3.53 Total impact

• Article: Streptococcus agalactiae, an Emerging Pathogen for Cultured Ya-Fish, Schizothorax prenanti, in China.

  Y Geng, K Y Wang, X L Huang, D F Chen, C W Li, S Y Ren, Y T Liao, Z Y Zhou, Q F Liu, Z J Du, W M Lai
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  ABSTRACT: Streptococcus agalactiae (Group B streptococcus) has emerged as an important pathogen that affects humans and animals, including aquatic species. S. agalactiae infections are becoming an increasing problem in aquaculture and have been reported worldwide in a variety of fish species, especially those living in warm water. Recently, a very serious infectious disease of unknown aetiology broke out in ya-fish (Schizothorax prenanti) farms in Sichuan Province. A Gram-positive, chain-forming coccus was isolated from moribund cultured ya-fish. The goals of this study were to identify the bacterial strains isolated from diseased fish between 2009 and 2011 in Sichuan Province, China, to evaluate the pathogenicity of the pathogen in ya-fish, crucian carp (Carassius carassius) and the Nile tilapia (Oreochromis niloticus); and to determine the susceptibility of the pathogen strains to many currently available anti-microbial agents. The virulence tests were conducted by intraperitoneal injection of bacterial suspensions. In this study, four strains of a Gram-positive, chain-forming coccus were isolated from moribund cultured ya-fish (S. prenanti). The coccoid microorganism was identified as S. agalactiae using a commercial streptococcal grouping kit and 16S rDNA sequencing analysis. Susceptibility of the isolates to 22 antibiotics was tested using the disc diffusion method. All isolates showed a similar antibiotic susceptibility, which were sensitive to amoxicillin, ciprofloxacin, lomefloxacin, chloramphenicol, rifampin, vancomycin, azithromycin, florfenicol, cefalexin, cefradine and deoxycycline and resistant to gentamicin, sinomin (SMZ/TMP), penicillin, tenemycin, fradiomycin and streptomycin. Furthermore, the virulence tests were conducted by intraperitoneal injection of the isolated strain GY101 in ya-fish, crucian carp and the Nile tilapia. This coccus was lethal to ya-fish, Nile tilapia and crucian carp. The mortality rates of infected ya-fish were 100%, 100%, 60% and 20% at doses of 1.0 × 10⁷, 1.0 × 10⁶, 1.0 × 10⁵ and 1.0 × 10⁴ CFU/fish, respectively. The values were 100%, 80%, 60% and 30% for Nile tilapia and 100%, 60%, 10% and 0% for crucian carp. To our knowledge, this is the first report of S. agalactiae as a pathogen of ya-fish.
  Transboundary and Emerging Diseases 12/2011; 59(4):369-75. · 1.81 Impact Factor
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  Available from: utk.edu

  Article: First report of a ranavirus associated with morbidity and mortality in farmed Chinese giant salamanders (Andrias davidianus).

  Y Geng, K Y Wang, Z Y Zhou, C W Li, J Wang, M He, Z Q Yin, W M Lai
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  ABSTRACT: From February to May 2010, an outbreak of disease occurred amongst farmed Chinese giant salamanders (Andrias davidianus) in Hanzhong County, Shanxi Province, China. Clinical signs included anorexia, lethargy, ecchymoses and swollen areas on the head and limbs, and skin ulceration. The aim of this study was to determine the cause of this disease. Necropsy examination revealed subcutaneous and intramuscular oedema, swollen and pale livers with multifocal haemorrhage, swollen kidneys with multifocal haemorrhage and distended fluid-filled intestines with areas of haemorrhage. Light microscopy revealed intracytoplasmic inclusions suggestive of a viral infection in a variety of organs, as well as degeneration and necrosis of these organs. Electron microscopy of ultrathin sections of the same tissues revealed iridovirus-like particles within the inclusions. Of the six specimens tested, all were positive for ranavirus major capsid protein (MCP) gene. Sequence alignments of the ranavirus MCP gene from these specimens showed 95-98% similarity with published ranavirus data. The virus, provisionally designated as Chinese giant salamander virus (CGSV), was isolated from tissue homogenates of diseased salamanders following inoculation of epithelioma papilloma cyprini cells. Sequence analysis of the MCP genes showed that the isolated virus was a ranavirus with marked sequence identity to other members of the genus Ranavirus. Koch's postulates were fulfilled by infecting healthy Chinese giant salamanders with the CGSV. These salamanders all died within 6-8 days. This is the first report of ranavirus infection associated with mass mortality in Chinese giant salamanders.
  Journal of comparative pathology 01/2011; 145(1):95-102. · 1.73 Impact Factor