Document Detail


In vitro and in vivo efficacy of florfenicol for treatment of Francisella asiatica infection in tilapia.
MedLine Citation:
PMID:  20713674     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Francisella asiatica is a recently described, Gram-negative, facultative intracellular fish pathogen, known to be the causative agent of francisellosis in warm-water fish. Francisellosis outbreaks have increased in frequency among commercial aquaculture operations and have caused severe economic losses in every case reported. The lack of effective treatments for piscine francisellosis led us to investigate the potential efficacy of florfenicol for inhibition of F. asiatica in vitro and as an oral therapeutic agent in vivo. The MIC of florfenicol for F. asiatica, as determined by the broth dilution method, was 2 μg/ml, which indicates its potential efficacy as a therapeutic agent for treatment of francisellosis. The intracellular susceptibility of the bacterium to florfenicol in tilapia head kidney-derived macrophages (THKDM) was also investigated. Addition of florfenicol to the medium at 10 μg/ml was sufficient to significantly reduce bacterial loads in the THKDM in vitro. Cytotoxicity assays done in infected THKDM also demonstrated drug efficacy in vivo, as determined by lactate dehydrogenase (LDH) release. Levels of LDH released from infected THKDM were significantly lower in macrophages treated with florfenicol (P < 0.001) than in untreated cells. In medicated-feed trials, fish were fed 15 mg of florfenicol/kg of fish body weight for 10 days, and the feeding was initiated at either 1, 3, or 6 days postchallenge. Immersion challenges resulted in 30% mean percent survival in nontreated fish, and fish receiving medicated feed administered at 1 and 3 days postinfection showed higher mean percent survival (100% and 86.7%, respectively). A significant decrease (P < 0.001) in bacterial numbers (number of CFU/g of spleen tissue) was observed in treated groups compared to nontreated infected fish at both 1 and 3 days postchallenge. There were no differences in bacterial burden in the spleens between fish treated 6 days postchallenge and untreated controls. In conclusion, if florfenicol is administered during early stages of infection, it has the potential for effectively treating piscine francisellosis, including the capacity for intracellular penetration and bacterial clearance.
Authors:
Esteban Soto; Richard G Endris; John P Hawke
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-08-16
Journal Detail:
Title:  Antimicrobial agents and chemotherapy     Volume:  54     ISSN:  1098-6596     ISO Abbreviation:  Antimicrob. Agents Chemother.     Publication Date:  2010 Nov 
Date Detail:
Created Date:  2010-10-15     Completed Date:  2011-01-31     Revised Date:  2011-07-28    
Medline Journal Info:
Nlm Unique ID:  0315061     Medline TA:  Antimicrob Agents Chemother     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4664-70     Citation Subset:  IM    
Affiliation:
Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Skip Bertman Drive, Baton Rouge, LA 70803, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Anti-Bacterial Agents / therapeutic use*
Fish Diseases / drug therapy*
Francisella / physiology
Gram-Negative Bacterial Infections / drug therapy*,  microbiology
Thiamphenicol / analogs & derivatives*,  therapeutic use
Tilapia / microbiology,  physiology*
Chemical
Reg. No./Substance:
0/Anti-Bacterial Agents; 15318-45-3/Thiamphenicol; 73231-34-2/florfenicol
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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