Molecular Epidemiological Analysis of Group A Streptococci Isolated from Children in Chaoyang District of Beijing, 2011:emm Types, Virulence Factor Genes and Erythromycin Resistant Genes

Group A streptococcus （GAS） causes a wide range of diseases in the human population. GAS diseases are more common in children than in adults, with clinical manifestations ranging from pharyngitis and impetigo to invasive infections and post streptococcal sequelae, such as acute rheumatic fever and acute post-streptococcal glomerulonephritis[1]. GAS harbors a host of virulence factors that contribute to its complex pathogenicity and differences in the disease severity and frequency. M protein, one of the major virulence factors, is encoded by the emm gene induces a type of specific host immune response and confers antiphagocytic properties.

Efficacy of xylitol and fluoride mouthrinses on salivary mutans streptococci

Objective:To evaluate the level of salivary Mutatis streptococci(MS) after rinsing with xylitol, fluoride,and a combination of xylitol and fluoride solutions,compared with distilled water. Methods:Eighty healthy 8-9 years old subjects with high level of MS(】 10~5 CFU/mL) were equally divided into 4 groups.Subjects rinsed their moutlis for 1 min with 10 mL of 0.05%(w/v) sodium fluoride(NaF),12.5%(w/v) xylitol or 0.05%(w/v) NoF + 12.5%(w/v) xylitol 3 times daily over 10 weeks.Distilled water rinsed group served as a control.Paraffin-stimulated whole saliva samples were collected at baseline,5 weeks,and 10 weeks after rinsing to determine the level of salivary MS by culturing on Mitis Salivarius Bacitracin agar.The statistical significance was calculated by Kruskol Wallis,Mann Whitney U,and Wilcoxon signed-rank tests at a significant level of P【 0.05.Results:Significant reductions in MS count were observed in subjects using 0.05%NaF + 12.5%xylitol over other groups within 5 weeks and after 10 weeks and 12.5%xylitol alone after 10 weeks compared with baseline.Conclusions:The present study provides evidence for the inhibitory effect of xylitol,used in combination with fluoride,delivered in the form of mouthrinse, on salivary MS in the group of schoolchildren.

The prevalence of virulent clonal strains of mutans streptococci in vivo and co-culture succession of the strains in vitro—Virulence potential of mutans streptococci

Purpose:To examine selected putative virulent prop-erties of mutans streptococci in two groups with dif-ferent caries activity and to examine co-culture hy-bridization of the strains in vitro. Methods: A set of strains from caries-free subjects (115) and another set from caries-active subjects (165) were isolated. Each strain was characterized for three virulence determi-nants. The clinical bacteria were then cocultured by three strains exhibiting the highest levels of virulence. Isolate colonies of last filial generation bacteria were enrichment-incubated and estimated for virulence again. RAPD-PCR and MLEE analyses were processed for parental bacteria and last filial genera-tion one. Results: No difference associated with caries activity of the subjects from whom the isolates origi-nated. Virulent properties of a filial generation strains was not different in the same generation, but was very different from their parent strains. Conclu-sion: The coexist properties of virulent polyclonal strain of MS may hold in a very general conditional sense in a dental plaque ecosystem in vivo, however, one of the co-culture strains may became dominant and displa- ced the others as the result of continuous ecological succession in vitro.

Dental Plaque Streptococci and Their Amoxicillin Resistance in Children with Congenital Heart Anomalies: Results of a Prospective Study

Children with congenital heart diseases (CHD) are considered to be at higher risk of development of a Bacterial Endocarditic (BE) from infectious diseases of the oral cavity and following dental treatments. They represent the largest group of patients with special medical needs who appear in the daily dental practice. Maintenance of oral health and oral hygiene is suitable to reduce the incidence of bacteremia. Oral hygiene is more important in reducing the risk of BE than the administration of antibiotic-prophylaxis before dental procedures. The purpose of this study was to identify the strains of streptococci viridians group from dental plaque and their amoxicillin resistance at children with congenital heart disease. The study was carried out in University Dentistry Clinical Center of Kosova, Department of Pediatric Dentistry in cooperation with the Micro-biologic Department. Participants in this study (n = 90) were children between 6 - 15 years old, divided in the control group of healthy children (n = 30), and two study groups, first group, children with CHD who have not taken antibiotics within last three months (n = 30) and second group, children with CHD who have taken antibiotics within three months (n = 30). The gram positive cocci were identified using the automated system, VITEK 2 (BioMerux), while for determining amoxicillin resistance cocci the disc diffusion method was used. By analyzing the three groups of children regarding isolated dental plaque streptococci, in general the Viridans group of streptococci (VGS) has dominated our results, with a higher percentage of streptococcus Mitis group (37.2%). The highest resistance of VGS against amoxicilin was in the group of children with CHD, which have been using antibiotics within 3 months (23.3%). In the other two groups the resistance against amoxicillin was found in a lower percentage (3.3%). Based on the results of our study we can conclude that frequent use of amoxicillin may result in an increasing antimicrobial resistance of streptococci.

Long-term survival of salivary streptococci on dental devices made of ethylene vinyl acetate

Bacterial infection associated with the use of medical or dental devices is a serious concern.Although devices made of ethylene vinyl acetate（EVA） are often used in the oral cavity,there are no established standards for their storage.We investigated bacterial survival on EVA sheets under various storage conditions to establish a standard for hygienic storage of such dental devices.Bacterial counts were evaluated,which showed a significant decrease after washing with sterilized water,mechanical brushing and rinsing,and using Mouthguard Cleaner as compared to untreated samples.In addition,no bacteria were detected on samples stored 2 days or longer in a ventilated environment,whereas they were detected for up to 14 days on samples without any cleaning stored in a closed environment.Bacterial counts for the untreated samples gradually declined,while surviving bacteria on samples treated with sterilized water and mechanical brushing showed a rapid decrease.Additionally,bacterial identification using polymerase chain reaction（PCR） revealed that Streptococcus oralis was dominantly detected on salivary samples after 14 days of storage among both two subjects.For effective hygienic storage of dental devices made of EVA,washing with sterilized water is important to remove absorbed salivary compounds along with storage in a ventilated environment.

The effect of chlorhexidine on plaque index and mutans streptococci in orthodontic patients:A pilot study

Aim: The purpose of this study was to assess chlorhexidine effects on plaque index and salivary levels of mutans streptococci (MS) when used as the immersion solution for removable orthodontic appliances and added to their acrylic resin composition. Methods: Forty-five patients (6 to 12 years old) were randomly assigned into three groups with 15 patients each. Group I (control)—without orthodontic appliances disinfection;Group II—removable orthodontic appliances which had been immersed in 0.12% chlorhexidine digluconate overnight (8 hours), and Group III—orthodontic appliances in which 0.12% chlorhexidine digluconate solution had been incorporated into their resin composition. Saliva was collected for quantification of MS and evaluation of plaque index was performed before and after installation of orthodontic appliance at 0, 2, 4, 6, 8, and 10 weeks. Data were analyzed by using analysis of variance. Results: Number of MS colonies in saliva and plaque index showed no statistically differences among groups at the different periods (p > 0.05). Conclusions: It could be concluded that chlorhexidine incorporation into the acrylic resin of removable orthodontic appliances at 0.12% concentration and immersion of the appliance into 0.12% chlorhexidine solution were not effective in reducing plaque index and the number of MS in saliva.

Effect of Magnolia Officinalis Extract on Cariogenic Activity of Mutans Streptococci

目的:从中药厚朴中提取抗变链活性成分,并研究其对变形链球菌致龋特性的影响。方法:本研究应用薄层层析,萃取分离,硅胶色谱柱层析等现代中药化学实验方法,从生药厚朴中提取出有效成分MO2,用微量液体稀释法检测不同血清型变形链球菌对MO2的敏感性。以S.mutans MT703和S.sobrinus B13为实验菌株,分析MO2对其细胞表面疏水能力和合成水不溶性葡聚糖能力的影响。结果:MO2能降低细胞表面疏水率,抑制葡糖基转移酶催化合成水不溶性葡聚糖。随着MO2浓度的升高,细胞表面疏水率下降;80μg/ml的MO2对S.mutansMT703合成水不溶性葡聚糖的抑制率为45.4%,对S.sobrinusB13合成水不溶性葡聚糖的抑制率达43.5%。结论:厚朴提取物MO2对变形链球菌致龋能力有较强抑制作用。

Granulicatella adiacens: A Rare Cause of Infective Endocarditis: A Case Report

Granulicatella adiacens (G. adiacens), formerly classified as a nutritionally variant streptococci (NVS), is a commensal organism in the mouth. It is known to be a rare cause of infective endocarditis (IE). This case report presents a case of IE caused by G. adiacens in a 63-year-old man with mitral valve prolapse (MVP), severe mitral regurgitation (MR), and dual vessel disease (DVD). G. adiacens was isolated from two of three blood cultures, and the organism was sensitive to penicillin, vancomycin, cefotaxime, and gentamicin. He was successfully treated with a combination of ceftriaxone and gentamicin. Prompt identification of the organism and determination of antibiotic sensitivity pattern led to successful treatment. This case report showcases the challenges in diagnosis, and treatment, giving insight to healthcare providers on a rare entity.

β-溶血性链球菌对红霉素、克林霉素耐药性及对大环内酯类抗生素耐药机制研究

目的探讨BHS的耐药性及耐药基因携带情况。方法采用药敏纸片法测定BHS对红霉素、克林霉素的药物敏感性,应用PCR法检测其对大环内酯类药物耐药基因ermB、mefA。结果BHS群对红霉素及林可酰胺类药物克林霉素的耐药率较高。ermB基因阳性率为84.4%,其中GCS、GFS对该基因携带率最高均为100%,7株红霉素敏感菌株中检测出ermB基因,与耐药表型不符。mefA基因阳性率为3.1%,均在红霉素耐药菌株中检出。有1株同时携带ermB、mefA基因。结论BHS群对大环内酯类药物及林可酰胺类药物耐药率较高,其对红霉素耐药主要与核糖体糖蛋白甲基化有关。

草绿色链球菌感染性心内膜炎的病原学特征及临床特点分析

目的探讨草绿色链球菌引起感染性心内膜炎(IE)的病原学特征和临床特点。方法选取2016年6月至2021年12月中国医科大学附属第一医院收治的57例血培养阳性IE患者的临床资料。分析其病原菌构成及草绿色链球菌的耐药情况;将患者分为草绿色链球菌组和非草绿色链球菌组,对2组临床特点进行对比。结果血培养分离病原菌,草绿色链球菌32株,占56.1%,其中戈登链球菌株数最多(11株)。草绿色链球菌耐药性分析结果显示,草绿色链球菌对红霉素和阿奇霉素的耐药性最高,分别为81.3%和78.1%;未见青霉素G、万古霉素、利奈唑胺耐药菌株,青霉素G中介率达28.1%。临床特点分析结果显示,2组先天性心脏病(非主动脉二叶畸形先心病)、入院前病程、二尖瓣赘生物以及心功能不全结果有统计学差异(P<0.05)。结论草绿色链球菌是IE的最常见致病菌;青霉素仍是经验治疗草绿色链球菌IE的首选药物;病程长、生长二尖瓣赘生物和未发生心功能不全的临床特点对IE患者发生草绿色链球菌感染的病原体评估具有一定的提示作用。

喜炎平联合二代青霉素治疗猩红热疗效及对A族链球菌阳性率的影响

目的探讨喜炎平联合二代青霉素治疗猩红热疗效及对A族链球菌阳性率的影响。方法选取2017年1月—2020年12月吉林市儿童医院收治的100例猩红热患儿作为研究对象,应用随机数表法分为对照组和观察组,每组50例。对照组患儿进行常规静脉滴注一代青霉素,观察组采取二代青霉素联合喜炎平静脉滴注,比较两组患者的临床疗效、治疗后患儿的睡眠质量评分、猩红热症状评分、症状改善及痊愈时间、治疗前后A族链球菌阳性率以及不良反应情况。结果治疗后,观察组总有效率高于对照组,差异有统计学意义(P<0.05)。治疗后,两组患儿的GAS菌株和SpeC、SpeA菌株阳性表达情况明显降低,且观察组较对照组更低,差异有统计学意义(P<0.05)。治疗前,两组的睡眠质量评分、猩红热症状评分比较,差异无统计学意义(P>0.05);治疗后,两组以上两项指标评分都有明显下降的趋势,且观察组评分低于对照组,差异有统计学意义(P<0.05)。同时观察组患儿痊愈时间与症状改善时间也明显低于对照组,差异有统计学意义(P<0.05)。两组不良反应发生率比较,差异无统计学意义(P>0.05)。结论喜炎平联合二代青霉素治疗猩红热疗效显著,能够降低A族链球菌阳性率,快速减轻患儿临床症状,使睡眠质量得到提高,同时其也有较高的安全性,在临床上有一定的应用价值,值得临床应用。

学龄前儿童乳牙釉质发育缺陷对口腔中变形链球菌水平的影响

自从Clarke首先从人类龋齿中分离出变形链球菌到目前,已公认变形链球菌是引起龋齿发生的最主要的细菌。变形链球菌具有粘附和聚集的能力,尽管它粘附、聚集的机制尚不完全清楚,但口腔中的某些因素可以影响变形链球菌的殖居。本研究采用病例对照的方法,比较有无釉质发育缺陷的儿童口腔中变形链球菌的水平,探讨釉质发育缺陷对口腔中变形链球菌殖居的影响。

生殖道B族溶血性链球菌、支原体和沙眼衣原体感染与胚胎发育停止的关系

目的研究生殖道B族溶血性链球菌(GBS)、支原体和沙眼衣原体(CT)感染与胚胎发育停止之间的关系。方法以74例孕早中期胚胎发育停止的患者(研究组)和62例孕早中期正常妊娠引产患者(对照组)为研究对象,采集阴道分泌物、宫腔内吸出物和羊水标本进行GBS培养,同时检测宫颈支原体和CT。结果研究组和对照组阴道分泌物GBS培养阳性率分别为12.16%(9/74)和9.68%(6/62),差异无统计学意义(P=0.662);所有患者的宫腔内吸出物或羊水GBS培养均为阴性。研究组解脲支原体和人型支原体培养的阳性率分别为32.43%(24/74)和16.22%(12/74),明显高于对照组的10.35%(12/62)(P=0.0103)和6.45%(4/62)(P=0.042)。研究组和对照组的CT阳性率分别为8.11%(6/74)和8.06%(5/62),差异无统计学意义(P=0.905)。研究组和对照组GBS合并支原体感染率分别为4.05%(3/74)和6.45%(4/62),差异无统计学意义(P=0.743);GBS合并CT感染率分别为0和1.61%(1/62),差异无统计学意义(P=0.475);支原体合并衣原体感染率分别为2.70%(2/74)和0,差异无统计学意义(P=0.325);3种病原体合并感染率均为0。结论部分妊娠妇女生殖道可携带GBS,但与胚胎发育停止无关。支原体感染可能是导致胚胎发育停止的原因之一。

2岁以内儿童口腔变形链球菌定居时间与喂养方式和饮食习惯的关系

目的 了解变形链球菌 (MS)在儿童口腔内的定居时间与喂养方式和饮食习惯的关系。方法 选取 6～2 4个月的儿童 180例 ,按年龄分为 6组 ,每组各 30例。记录儿童牙齿萌出数目 ,采集儿童口腔内的菌斑或唾液 ,在实验室作细菌培养和鉴定 ,同时进行问卷调查。结果 儿童口腔内MS的定居时间与断奶时间、喂养方式及夜间进食习惯相关。结论 合理喂养方式和入睡习惯可以阻断或延迟儿童口腔内MS的定居 。

变形链球菌在牙齿表面定植与婴幼儿年龄变化关系的研究

目的 了解变形链球菌在婴幼儿牙面上的定植时间。方法 本研究调查了变形链球菌在婴幼儿牙面上定植的时间 ,选取 8～ 3 0个月的婴幼儿 1 1 6名 ,并对其中 1 1名婴儿进行了跟踪检查。结果 变形链球菌可在1 0个月婴儿的牙面定植 ,1 2个月以内的婴儿定植率为 1 6.67% ,1 6～ 1 8个月幼儿为 56.5% ,1 9～ 2 4个月的为63 .6% ,3 0个月时达 70 .0 %。在牙面有MS定植的儿童中 ,50 .8%儿童MS的检出时间是在 1 3～ 2 4个月。对 1 1名婴儿跟踪调查 ,发现在 1 2个月后有 7名儿童牙面MS检查由阴性转成阳性 ,占 63 .6% ,感染时间平均为 1 8.71±3 .58个月。结论 在本研究中婴幼儿感染MS的时间较早 ,预防龋病的发生和MS的定植应从婴儿牙齿萌出时开始。

不同龋敏感儿童牙菌斑内口腔链球菌的PCR-DGGE分析

目的 应用PCR-变性梯度凝胶电泳（DGGE）技术，分析不同龋敏感儿童牙菌斑内口腔链球菌菌群及其菌种组成的多样性。方法 牙菌斑组织取自45例学龄前儿童，根据乳牙龋失补牙面（dmfs）指数分为无龋（dmfs=0）、中龋（dmfs=4～6）和高龋（dmfs〉8）（n=15）。分别提取细菌总DNA，进行链球菌属mp B特征序列的PCR扩增及DGGE分析，克隆、测序并与核酸序列数据库的序列进行比对。结果 无龋儿童菌斑中口腔链球菌菌群的基因型分布均显著高于中龋和高龋儿童（P〈0．05）；变异链球菌群是高龋组中的优势菌群。结论 PCR—DGGE技术结合rnpB基因克隆文库分析可较灵敏、直观地反映牙菌斑中链球菌属各菌群及其菌种的组成情况。

链球菌合成透明质酸的研究进展

透明质酸是一种具有极大商业价值的线性、高分子粘多糖,微生物的生物合成是透明质酸来源的首选。主要综述链球菌合成透明质酸的研究概况,分析了目前存在的主要问题及解决途径,并对其前景进行了展望。

感染性心内膜炎血培养病原菌的分布及耐药性分析

目的对感染性心内膜炎患者血培养分离菌的分布及对常用抗菌药物的耐药性进行分析,为临床合理选用抗菌药物提供依据。方法采用VITEK-2-Compact系统鉴定细菌,药敏试验采用纸片扩散法,万古霉素对葡萄球菌的药敏试验采用E-Test方法,数据分析应用WHONET 5.6软件。结果共分离141株病原菌,草绿色链球菌、凝固酶阴性葡萄球菌和金黄色葡萄球菌为最常见病原菌,分别为53株、34株和18株。草绿色链球菌对红霉素、克林霉素的耐药率均为50%,对青霉素、头孢曲松、头孢噻肟和左氧氟沙星的耐药率均低于10%。凝固酶阴性葡萄球菌对青霉素类、头孢菌素类及红霉素的耐药率均大于80%。金黄色葡萄球菌对青霉素的耐药率最高为94.4%,对左氧氟沙星和红霉素的耐药率分别为27.8%和22.2%,对其他抗菌药物的耐药率均小于20%。耐甲氧西林的凝固酶阴性葡萄球菌和耐甲氧西林的金黄色葡萄球菌的发生率分别为85.3%和11.1%。结论临床医生要密切关注分离菌的变迁及耐药性情况,合理使用抗菌药物。

随意引物PCR用于口腔链球菌基因分型的初步研究

目的：探讨口腔链球菌基因分型，比较细菌相互间基因差异。方法：设计２对１０碱基随意引物，提取变链球菌、血链球菌染色体ＤＮＡ，分别用一对引物进行ＰＣＲ扩增。结果：变链球菌、血链球菌扩增的ＤＮＡ基因片段有较大区别。设计不同序列引物，扩增的ＤＮＡ片段亦不同，可以分辨不同的基因位点。结论：随意引物ＰＣＲ检测方法稳定。

变形链球菌变链素粗提物活性的初步研究

目的 :测定变链菌临床株变链素粗提物的抑菌活性和热稳定性 ,为对变链素的进一步研究提供基础。方法 :用氯仿抽提 ,对其进行抗菌活性检测和热稳定性检测。结果 :10ml液体的粗提物 ,可形成直径 19mm的抑菌环 ,表明粗提物具有抗菌活性 ;将粗提物加热到 80℃ ,抗菌活性可维持 12 0min ,表明其中含有热稳定性抗菌物质。结论 :变链素的粗提物能反映变链素的活性和性质 ,适合于大量临床株的研究。