Efficacy of florfenicol for control of mortality associated with Francisella noatunensis subsp. orientalis in Nile tilapia, Oreochromis niloticus (L.)

Esteban Soto Martinez, S. Kidd, P. S. Gaunt, R. Endris

Research output: Contribution to journalArticle

13 Scopus citations


Francisella noatunensis subsp. orientalis (Fno) (syn. F. asiatica) is an emergent Gram-negative facultative intracellular bacterium. Although it is considered one of the most pathogenic bacteria in fish, there are no commercially available treatments or vaccines. The objective of this project was to determine the most efficacious concentration of florfenicol (FFC) [10, 15 or 20 mg FFC kg-1 body weight (bw) per days for 10 days] administered in feed to control experimentally induced infections of Fno in Nile tilapia, Oreochromis niloticus (L.), reared in a recirculating aquaculture system. The cumulative mortality of fish that received 0, 10, 15 or 20 mg FFC kg-1 bw per day was 60, 37, 14 and 16%, respectively. Francisella noatunensis subsp. orientalis genome equivalents were detected in water from all challenged groups with slight reduction in the concentration in the florfenicol-treated groups 4 days after treatment. The mean LOG of CFU Fno mg-1 spleen was 3-5 and was present in all challenged groups at necropsy 11 days after treatment (21 days after challenge). Results show that florfenicol administered at doses of 15 and 20 mg FFC kg-1 bw per days for 10 days significantly reduced mortality associated with francisellosis in Nile tilapia.

Original languageEnglish (US)
Pages (from-to)411-418
Number of pages8
JournalJournal of Fish Diseases
Issue number4
StatePublished - Apr 2013
Externally publishedYes



  • Florfenicol
  • Francisella noatunensis subsp. orientalis
  • Nile tilapia

ASJC Scopus subject areas

  • Aquatic Science
  • veterinary (miscalleneous)

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