广西卵形鲳鲹海豚链球菌基因分型、耐药谱型以及毒力基因检测

为了解近年来广西卵形鲳鲹海豚链球菌流行菌株的基因型信息以及菌株间的差异,对2015—2016年从广西地区7个养殖场的患病卵形鲳鲹体内分离得到的17株海豚链球菌菌株分别进行了基因型分析、耐药谱测定以及毒力基因检测。采用随机扩增多态性DNA标记技术(RAPD)和基因组重复序列PCR(rep-PCR)分析其基因型。结果显示,RAPD和rep-PCR指纹图谱结果一致,17株海豚链球菌可分为2种基因型。对海豚链球菌7种主要的毒力相关基因特异PCR检测,所有菌株均为sim A+scp I+pdi+sag A+cps D+pgm A+cfi+毒力基因型,表明这2种基因型的海豚链球菌似乎均为毒力较强的菌株。采用K-B法进行了20种抗生素敏感实验分析其耐药谱,结果表明归于基因1型的菌株耐药谱为AZT,基因2型菌株则出现3种相似的耐药谱,分别为SIZ/T/S/PEN/AZT/SPE/CAZ/PB、SIZ/T/S/PEN/AZT/SPE/CAZ/CRO和SIZ/T/S/PEN/AZT/SPE/CAZ/PB/RIF,证实基因型相同的菌株耐药谱型也相似,2种基因型的菌株耐药谱型差异显著,因此基因型和耐药谱型存在相关性。此结果为卵形鲳鲹海豚链球菌病流行病学研究、疫苗研制以及疫病监测提供理论依据。

Molecular typing, antibiogram type and detection of virulence genes of Stereptococcus iniae strains isolated from golden pompano (Tranchinotus ovatus) in Guangxi Province

To acquire the data of genotype and diversity upon the clinical dominant strains Streptococcus iniae of golden pompano (Tranchinotus ovatus) in Guangxi, a total of 17 bacterial isolates were analyzed by molecular typing, antibiogram type and virulence-related gene which were collected from diseased golden pompano in 7 farms located in Guangxi Province during 2015-2016. By using the random amplified polymorphic DNA (RAPD) and repetitive primer polymerase chain reaction (rep-PCR) method, we successfully differentiated all 17 isolates into two distinct genotypes. Seven virulence-related genes were detected by PCR using specific primer, and the results revealed that the virulence-related genotype of these strains was simA⁺scpI⁺pdi⁺sagA⁺cpsD⁺pgmA⁺cfi⁺. All isolates seemed to show a high virulence. In addition, the antibiotic resistance profiles of 17 strains were tested with 20 common antibiotics using Kirby-Bauer disc diffusion methodology. The antibiogram of the isolates belonging to genetype 1 in rep-PCR analysis was AZT, while the antibiograms of genetype 2 were SIZ/T/S/PEN/AZT/SPE/CAZ/PB, SIZ/T/S/PEN/AZT/SPE/CAZ/CR and SIZ/T/S/PEN/AZT/SPE/CAZ/PB/RIF, respectively. Our research revealed that the two genotypes display significant differences of two antibiogram types and the same genetype isolates have similar antibiogram types. Therefore, a correlation between the genotype and the antibiogram types of S. iniae isolates has been identified. This study provides theoretical foundation and technical support for epidemiological study, vaccine development and disease control of S. iniae in golden pompano.