Duarte Rafael S, Miranda Otávio P, Bellei Bruna C, Brito Maria Aparecida V P, Teixeira Lúcia M
Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, CCS, Bloco I, Cidade Universitária, Rio de Janeiro, RJ 21941-590, Brazil.
J Clin Microbiol. 2004 Sep;42(9):4214-22. doi: 10.1128/JCM.42.9.4214-4222.2004.
Information on the characteristics of Streptococcus agalactiae obtained from bovine sources in Brazil is still very limited. The aim of this study was to assess the phenotypic and genotypic diversity among S. agalactiae isolates from milk of dairy cows presenting clinical or subclinical mastitis in the southeast region of Brazil. Phenotypic characterization was based on physiological and serological tests. Antimicrobial susceptibility tests were carried out by the disk method. Genetic diversity was evaluated by using random amplified polymorphic DNA-PCR (RAPD-PCR) (by using the primer 1254) and pulsed-field gel electrophoresis (PFGE) (by using SmaI as the restriction enzyme) and by PCRs for detection of genes associated with resistance to erythromycin and tetracycline as well as PCRs for detection of genes coding for cell surface-associated proteins. According to the results of physiologic tests, 45 (52.9%) isolates showed beta-hemolysis and 44 (51.7%) were susceptible to bacitracin. Fourteen different biotypes were detected. The two most frequent biotypes comprised strains that were non-beta-hemolytic; fermented galactose, lactose, and salicin; produced protease; and were negative for DNase production. Serotype III was predominant (66 isolates [77.6%]), followed by serotypes II, Ia, Ib, and VI. Resistance to tetracycline and erythromycin was found in 38 (44.7%) and 9 (10.5%) isolates, respectively, with tet(O) (31.7%) and erm(B) (100%) being the most frequently occurring resistance genes. Three genes coding for surface proteins, bca, lmb, and scpB, were detected in 55 (64.7%), 7 (8.2%), and 43 (50.5%) isolates, respectively. In most cases, isolates from animals in the same herd presented closely related genetic profiles (determined by either RAPD-PCR or PFGE), which were distinct from those of isolates from different herds.
关于从巴西牛源中分离出的无乳链球菌特性的信息仍然非常有限。本研究的目的是评估巴西东南部患有临床或亚临床乳腺炎的奶牛乳汁中分离出的无乳链球菌菌株之间的表型和基因型多样性。表型特征基于生理和血清学测试。采用纸片法进行药敏试验。通过随机扩增多态性DNA-PCR（RAPD-PCR）（使用引物1254）和脉冲场凝胶电泳（PFGE）（使用SmaI作为限制性内切酶）评估遗传多样性，并通过PCR检测与红霉素和四环素耐药相关的基因以及检测编码细胞表面相关蛋白的基因。根据生理测试结果，45株（52.9%）菌株呈现β溶血，44株（51.7%）对杆菌肽敏感。检测到14种不同的生物型。两种最常见的生物型包括非β溶血的菌株；发酵半乳糖、乳糖和水杨苷；产生蛋白酶；且DNase产生呈阴性。血清型III占主导（66株[77.6%]），其次是血清型II、Ia、Ib和VI。分别在38株（44.7%）和9株（10.5%）菌株中发现对四环素和红霉素耐药，tet(O)（31.7%）和erm(B)（100%）是最常见的耐药基因。分别在55株（64.7%）、7株（8.2%）和43株（50.5%）菌株中检测到编码表面蛋白的三个基因bca、lmb和scpB。在大多数情况下，来自同一牛群动物的菌株呈现密切相关的遗传图谱（通过RAPD-PCR或PFGE确定），这与来自不同牛群的菌株的遗传图谱不同。
