Mutations in gryA but not in parC Reduced Quinolone Susceptibility in Ornithobacterium Rhinotracheale

Translated Titles



范揚棋(Yang-Chi Fan);周崇熙(Chung-Hsi Chou);郭靜蕙(Ching-Hui Kuo);陳秋麟(Chiou-Lin Chen);蔡向榮(Hsiang-Jung Tsai)

Key Words

鳥鼻氣管桿菌 ; 奎諾酮類藥物抗藥性 ; 基因變異 ; 高解析熱熔解分析法 ; Ornithobacterium rhinotracheale ; Quinolone resistance ; Mutation ; High-resolution melting assay



Volume or Term/Year and Month of Publication

39卷2期(2013 / 06 / 01)

Page #

93 - 99

Content Language


Chinese Abstract

針對85株自2004至2006年間於臺灣地區屠宰場及禽鳥養殖場中,自雞、火雞、鴿、鴕鳥、鵪鶉與鳳頭蒼鷹等所分離之鳥鼻氣管桿菌(Ornithobacterium rhinotracheale, ORT)進行奎諾酮類藥物抗藥性之研討。結果顯示本群菌株對nalidixic acid、enrofloxacin與ciprofloxacin產生之抗藥性比率分別為72.9%、24.7%及15.3%。並進一步針對gyrA與parC兩個奎諾酮類藥物抗藥性決定區(quinolone resistant determining regions, QRDRs)進行突變序列探測,其中28.2%之分離株gyrA於基因沒有任何突變點發生;65.9%之分離株在於gyrA基因第83位密碼子發生單點突變,5.9%之分離株在於gyrA基因第83及87位密碼子發生雙點突變,同時此種發生雙點突變之菌株對於enrofloxacin與ciprofloxacin的藥物感受性會比只有第83位密碼子單點突變之菌株更顯著的降低。另一方面,由於發現全部菌株都維持相同的parC基因序列,故而推測parC基因ORT在奎諾酮類藥物抗藥性產生的機制上可能較不重要。本研究同時利用高解析熱熔解(high-resolution melting)法分析gyrA基因之突變,從四種不同熔點曲線可有效區分出不同之gyrA基因序列與抗藥性結果,此技術具有快速偵測ORT分離株對奎諾酮類藥物抗藥性特性之潛在開發能力。

English Abstract

A total of 85 isolates of Ornithobacterium rhinotracheale (ORT) isolated from chicken, turkey, pigeon, ostrich, quail, and Accipiter trivirgatus from 2004 to 2006 in Taiwan were subjected to quinolone resistance analysis. The resistant rates to nalidixic acid, enrofloxacin and ciprofloxacin were 72.9%, 24.7%, and 15.3%, respectively. All isolates were further screened for mutations in the quinolone resistant determining regions (QRDRs) including gyrA and parC genes. In the analysis of gyrA mutation, 28.2% of isolates showed no amino acid change, where 65.9% of isolates were found of one-point mutation at codon 83 and 5.9% of isolates were found of two-point mutations at codon 83 and 87. The results also demonstrated that an additional mutation at codon 87 in gyrA significantly decreased susceptibility than the single mutation at codon 83 did, especially to enrofloxacin and ciprofloxacin. In the analysis of mutation in parC, the finding of all the isolates possessing an identical sequence suggested that parC may not play an important role in the quinolone resistance mechanism in ORT. Four patterns of melting temperature curve were revealed in the high-resolution melting (HRM) analysis. The consistent changes in melting temperatures of different amplicon sequences allow the mutated-gyrA strains to be distinguished from wild-type strains. This rapid detection of gyrA mutations by HRM assay is feasible for extensive quinolone resistance monitoring program.

Topic Category 生物農學 > 動物學
生物農學 > 獸醫