变形链球菌F-ATP酶亚基基因uncA遗传多态性的研究

目的研究变形链球菌临床分离株耐酸因子F—ATP酶亚基α的结构基因uncA的遗传多态性，并探讨基因多态性与细菌耐酸力及龋病发生的关系。方法分别从高龋、无龋个体中分离变形链球菌34和30株，其中包括18株高耐酸株、20株低耐酸株。从细菌组DNA扩增uncA，行限制性内切酶长度多态性分析（RFLP）及核酸测序比较。结果不同限制性内切酶RFLP产生不同的基因型，测序证实了导致多态出现的基因变异；内切酶Hph Ⅰ产生的A、B基因型在不同患龋个体分离菌株的分布不同（P〈0．05），A型uncA在高龋分离株的检出率高于无龋分离株；内切酶MboⅡ产生的C、D基因型在不同耐酸力菌株中的分布不同（P〈0．05），C型uncA在高耐酸力菌株的检出率高于低耐酸力菌株。结论变形链球菌F—ATP酶的α亚基基因uncA具有明显遗传多态性，酸性环境下生存力强的菌株可能出现基因的适应性变异，不同基因型uncA分布与菌株的耐酸力及致龋力相关。     

变形链球菌表面蛋白和葡糖基转移酶基因疫苗对唾液变形链球菌和牙菌斑的影响

目的　了解变形链球菌表面蛋白和葡糖基转移酶基因疫苗单独及联合免疫对定菌鼠唾液变链菌和牙面菌斑的影响。方法　 2 8d龄 Wistar大鼠 3 6只 ,随机分为 pc DNA3 - pac组、pc DNA3 - gtf B组、pc DNA3 - pac联合pc DNA 3 - gtf B组、变形链球菌灭活全菌组、pc DNA3空载体组和 PBS液组 ,进行三次双侧颌下腺腺周注射免疫 ,建立定菌鼠模型 ,作诱龋实验 3个月。唾液变链菌计数和菌斑计分。结果　唾液变链菌菌落计数和牙面菌斑计分在 pc D-NA3与 PBS组最高 ,其次为单基因疫苗免疫组 ,联合基因疫苗和灭活全菌细胞免疫组最低 ,各组间有显著性差异 ( P<0 .0 5 )。结论　 pc DNA3 - gtf B和 pc DNA3 - pac具有明显的免疫抑菌作用 ,联合基因疫苗免疫优于单基因疫苗     

lgY牙膏对口腔变形链球菌的抑制作用

目的研究含生物活性物IgY牙膏对口腔变形链球菌的抑制作用.方法将140位受试者随机分成实验组和对照组.每位受试者经过2个月洗脱期后,分别使用实验牙膏和空白对照牙膏.采用Dentocult SM方法分别测出基线值和使用1d、3d、7d、1个月后以及停止使用牙膏后2周的口腔变形链球菌水平.结果①实验组受试者口腔中变形链球菌水平的下降发生在使用实验牙膏刷牙后第1天,而对照组则发生在刷牙后的第3天.②随着刷牙时间延长,2组受试者口腔中变形链球菌水平逐步下降.③实验组停止使用实验牙膏刷牙后2周,仍有抑制变形链球菌的作用.结论与对照组相比,实验组牙膏有增强抑制口腔变形链球菌的作用.     

中药影响变形链球菌对唾液获得性膜粘附的研究

目的：研究不同传统中药提取物对变形链球菌在唾液获得性膜粘附的影响，进一步探讨中药防龋的可能机制。方法：采用唾液包被羟磷灰石（S－HA）形成实验性获得性膜的体外模式，以变形链球菌作为试验菌株，用不同的药物提取物分别处理S－HA和菌细胞，观察细菌对S－HA的粘附情况。结果：两组试验中大部分试验药物均能抑制菌细胞对S－HA的粘附，且随药物浓度的升高而逐渐增强。这些药物中，以五倍子的抑制作用表现更为显著，其在1、2、4mg/ml时的抑制率可达100％。结论：五倍子等传统中药能有效抑制变形链球菌对唾液获得性膜的早期粘附。     

The effect of milk and casein proteins on the adherence of Streptococcus mutans to saliva-coated hydroxyapatite

Experiments sought to determine the nature of the binding of milk proteins to hydroxyapatite (HA) and to saliva-coated hydroxyapatite (sHA), and to determine the effect of milk and casein on the adherence of Streptococcus mutans GS-5 to sHA. The binding of radiolabelled -casein to HA was reduced when incubated simultaneously with parotid saliva, and enhanced in the presence of milk. The binding of β- and κ-casein to HA was unaffected by the presence of parotid saliva and enhanced by the presence of milk. The in vitro bacterial adherence of Strep. mutans GS-5 to sHA beads was reduced when beads were coated with milk instead of buffer, or when bacteria were added to sHA in the presence of milk instead of buffer. Casein proteins (, β, κ) added to sHA simultaneously with bacteria inhibited the adherence of Strep. mutans GS-5 to sHA. κ-Casein, when bound to sHA, inhibited streptococcal adherence to sHA; - and β-casein, when bound to sHA, had no effect on streptococcal adherence. Fractionation of κ-casein by anion-exchange chromatography revealed the anti-adherence activity of κ-casein was mediated primarily by a 40,000 mol. wt. glycoprotein-containing fraction. These data show that milk, particularly κ-casein fractions, can modulate the adherence of Strep. mutans GS-5 to SHA surfaces in vitro.     

肺炎链球菌β-内酰胺酶TEM基因的发现

目的：探讨肺炎链球菌是否产β-内酰胺酶。方法：对2002年9月至2003年4月在苏州大学附属儿童医院就诊的呼吸道感染患儿痰标本中分离到的23株肺炎链球菌进行β-内酰胺酶TEM基因PCR检测与PCR扩增产物直接测序分析。结果：23株肺炎链球菌经TEM基因PCR检测21株阳性，阳性率达91．3％。测得1号菌株(SR001)基因序列为TEM-1型，已登录美国国立生物信息中心，注册号：AY392531。结论：从肺炎链球菌中检出β-内酰胺酶TEM基因。肺炎链球菌对青霉素耐药机制包括产β-内酰胺酶。     

Activity of telithromycin and seven other agents against 1034 pediatric Streptococcus pneumoniae isolates from ten central and eastern European centers

Objective  To test the activity of telithromycin against 1034 Streptococcus pneumoniae isolates from pediatric patients in ten centers from ten central and eastern European countries during 2000–2001, and to compare it with the activities of erythromycin A, azithromycin, clarithromycin, clindamycin, and quinupristin–dalfopristin.
Methods  The minimum inhibitory concentrations (MICs) of telithromycin, erythromycin A, azithromycin, clarithromycin, clindamycin, levofloxacin, quinupristin–dalfopristin and penicillin G were tested by the agar dilution method with incubation in air, and mechanisms of resistance to macrolides and quinolones were investigated.
Results  Strains were isolated from sputum, tracheal aspirates, ear, eye, blood, and cerebrospinal fluid. Among S. pneumoniae strains tested, 36% had raised penicillin G MICs (≥ 0.12 mg/L). Susceptibilities were as follows: telithromycin, quinupristin–dalfopristin and levofloxacin, ≥ 99%; clindamycin, 83%; and erythromycin A, azithromycin and clarithromycin, 78%. Of 230 (22.3%) erythromycin A-resistant S. pneumoniae strains, 176 (79.6%) had erm(B) , 38 (16.1%) had mef(A) , and 10 (4.3%) had mutations in 23S ribosomal RNA or in ribosomal protein L4. The rates of drug-resistant S. pneumoniae are high in all centers except Kaunas, Riga, and Prague.
Conclusion  Telithromycin had low MICs against all strains, irrespective of macrolide, azalide or clindamycin resistance. Ribosomal methylation was the most prevalent resistance mechanism among all resistant strains, except in Sofia, where the prevalence of the efflux mechanism was higher.     

Distribution of genotypes and antibiotic resistance genes among invasive Streptococcus agalactiae (group B streptococcus) isolates from Australasian patients belonging to different age groups.

Serotype distribution and antibiotic resistance (AR) among group B streptococci (GBS) affect GBS disease prevention strategies, but vary among patient groups. A multiplex PCR-based reverse line blot (mPCR/RLB) hybridisation assay was used to compare the distributions of GBS serotypes, serotype III subtypes and AR-associated genes among 666 invasive isolates from 663 patients, divided into five age groups: infants, early-onset (EO; 0-6 days) and late-onset (LO; 7-90 days); children (aged 3 months to 14 years); women of childbearing age (WCBA; aged 15-45 years); and other adults (males aged >15 years; females aged >45 years). Serotypes Ia and V and serosubtype III-1 accounted for 60% of infections. Serosubtype III-2, which corresponds to a virulent clone belonging to sequence type (ST)17, was relatively uncommon overall (7%), but was associated strongly with LO infant infections, in which it was significantly more common than in adult infections (25/104 (24%) vs. 9/392 (2%), p <0.0001) or in EO infections (25/104 (24%) vs. 14/155 (9%), p <0.005). Erythromycin resistance genes were found in 8% of all isolates (ermB 3%, ermA 2.5% and mefA/E 2%), in 11-15% of isolates of serotypes II and V and subtype III-1, but in none of the isolates of serosubtype III-2 (III-2, 0/49 vs. all others, 54/618 (9%), p <0.04). In summary, the virulent serosubtype III-2 was associated strongly with LO infant GBS infection, but was less likely than other serotypes or serosubtype III-1 to carry AR genes.