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Seminar 811  

Seminar:  811 

1

Speaker(s)

Yen-Ping Chen

Topic

Analysis of gyrase of Riemerella anatipestifer isolates with reduced susceptibility to quinolones

Abstract

Riemerella anatipestifer is an etiological agent that can cause serious disease especially in waterfowl. Quinolones (quinolones and fluoroquinolones) interact with the bacterial topoisomerases (DNA gyrase and topoisomerase IV). They are broad-spectrum and effective antimicrobials in the treatment of a wide variety of human and veterinary infections, including R. anatipestifer infection. This study investigated the mutations of topoisomerases associated with quinolone resistance in clinical and laboratory-generated R. anatipestifer. Most clinical isolates with reduced susceptibility to quinolones possessed amino acid alterations at Ser83 to Arg or Ile in GyrA. In laboratory mutants, all of the mutations were found in GyrA and GyrB but none in ParC and ParE. The most frequent mutation in GyrA was alterations at Ser83 to Ile or Asn which was concurred with aforementioned clinical strains, followed by alterations at Asp87 to Ala, Gly or Tyr and alterations at Ser84 to Pro. Most mutants induced by higher concentration of quinolones and with more mutation points showed higher minimal inhibitory concentration (MIC) values, although some mutants with identical mutation type showed different MIC profiles, suggesting that overexpression of the efflux system or other potential mechanisms might have also been existed.

 

2

Speaker(s)

Li-Hsuan Chen

Topic

Serological survey of Q fever in goat in Taiwan between 2008 and 2010

Abstract

Coxiella burnetii, the pathogen of Q fever, is a commonly existed zoonotic disease all over the world except New Zealand. Q fever was already in Taiwan since 1989, and steadily existed till now. Q fever becomes one cause of the abortion in ruminant and causes economic loss in Taiwan, especially in goat farms. To realize serological distribution and change of Q fever in goat, all sera collected from all over Taiwan were tested by ELISA. The overall seropositive rate of goat in 2008, 2009, and 2010 were 17.9% (384/2142), 23.4% (685/2923), and 28.8% (530/1841), respectively. The positive rate by farms showed 55.9% (38/68), 69.3% (79/114), and 71.8% (51/71).To prevent and control this disease, the goat farmers should be well informed and educated about characteristics of Q fever. Also, they should keep pregnant livestock separate from other animals, and know how to treat excretion after animal delivery to limit spread of C. burnetii.

3

Speaker(s)

Chien-Chih Wu

Topic

Evaluation of a Foreign Streptococcus iniae Vaccine in Giant Seaperch and Giant Grouper

Abstract

The objective of the present study was to evaluate safety and efficacy of commercial inactivated Streptococcus iniae vaccine produced by foreign company in the cultured giant seaperch Lates calcariferand giant grouper Epinephelus lanceolatus juveniles under laboratory and field conditions. The laboratory safety test was performed by intraperitoneal injection with double doses of vaccine into 27 giant seaperch and 20 giant grouper; there was no death or adverse effect observed during 14 days after vaccination. The laboratory efficacy test showed the mortality of single dose-vaccinated group was significantly lower than that of non-vaccinated group while challenge with Streptococcus iniae 3 weeks after vaccination with  relative percent survival (RPS) values ranged from 81% to 86% for giant seaperch and 86% to 100% for giant grouper, respectively. The mortality were 41.6% (208/500) and 0% (0/500) on giant seaperch and giant grouper injected with one dose of vaccine in field trial farm, respectively. The high mortality due to Oodinium spp. and Trichodina spp. infestation was confirmed in giant seaperch. In field efficacy test, vaccinated and controlled fish were challenged with Streptococcus iniae 3 weeks after vaccination, and the RPS values ranged from 66% to 76% for giant seaperch and 100% for giant grouper. Our results indicated good safety of the tested vaccine when injected on healthy fish and it can meet the requirement of efficacy for vaccine inspection (RPS ≥ 60%).