广东地区吉富罗非鱼无乳链球菌病的流行情况与耐药性

为了调查广东省惠州、肇庆、珠海、湛江4个吉富罗非鱼主养区链球菌病的流行情况和耐药性,并进一步分析β-内酰胺酶基因与青霉素类药物的耐药性关系。本实验通过传统的方法对菌株进行分离纯化,扩增特异性基因cfb以及16s r DNA对各菌株进行鉴定;采用k-b法测定分离菌株的药物敏感性;通过PCR检测β-内酰胺酶类基因在分离菌株中的分布情况,并用Statistic6.0统计分析各β-内酰胺酶基因与青霉素类药物的耐药关系。实验结果表明,吉富罗非鱼无乳链球菌的阳性率从高到低的顺序为惠州(46.46%)湛江(43.24%)肇庆(17.30%)珠海(4.17%);药敏结果显示各地区无乳链球菌分离株对青霉素(耐药率为94.29%)和磺胺二甲基嘧啶(耐药率为86.40%)普遍耐药,对恩诺沙星最为敏感(耐药率为3.99%);β-内酰胺酶基因分布与细菌耐药性统计结果显示,无乳链球菌基因组中的9个β-内酰胺酶基因在各分离菌株中的分布呈高度多态性,其中SAG0658基因与氨苄青霉素抗性显著相关,提示SAG0658基因在无乳链球菌耐氨苄青霉素过程中发挥主要作用;此外,9个β-内酰胺酶基因与青霉素抗性无相关性,说明其在菌株对青霉素耐药过程中并未发挥明显作用,提示分离菌株对青霉素的耐药性可能依赖其他途径。

Epidemic and antibiotic resistance of Streptococcus agalactiae isolated from tilapia (GIFT Oreochromis niloticus) in Guangdong Province

In order to investigate the epidemic and the antibiotic resistance of Streptococcus agalactiae isolated from Tilapia (Tilapia nilotica) cultured in Huizhou, Zhaoqing, Zhuhai, Zhanjiang cities of Guangdong province. The relationship between beta-lactamase gene and the resistance of penicillin in S. agalactiae was further analyzed. Isolated were identified by amplified specific gene cfb and 16s rDNA; In this study, k-b method was adopted to determine the antimicrobial sensitivity of isolates; the distribution of beta-lactamase gene in strains was detected by PCR assay; and the relationship between beta-lactamase gene and penicillin drugs was analyzed by stastic 6.0. The results showed that the ranking of positive rate of S. agalactiae carried in Tilapia was: Huizhou (46.46%) > Zhanjiang (43.24%) > Zhaoqing (17.30%)> Zhuhai (4.17%). Drug sensitive tests showed that all isolates from the four cities were highly resistant to penicillin G (with the resistant rate of 94.29%) and sulfamethazine (with the resistant rate of 86.40%), but were sensitive to enrofloxacin (with the resistant rate of only 3.99%). The diversity of the 9 beta-lactamase genes was highly distributed in the isolates. The relevance between the beta-lactamase genes and antibiotic resistance showed that the SAG0658 was significantly correlated with the resistance of ampicillin, suggesting that the SAG0658 might play an important role in the resistance of S. agalactiae to ampicillin. However, there was no significant correlation between the nine beta-lactamase genes and the resistance of penicillin G, indicating that there might be other mechanisms underlying the resistance of S. agalactiae to penicillin G.