B族链球菌的红霉素耐药基因研究

目的 比较不同地区B族链球菌（GBS）对红霉素耐药性的差异及耐药基因谱特点。方法 用琼脂稀释法，测定红霉素、克林霉素对不同地区（北京，广州，俄罗斯圣彼得堡）的113株GBS的最低抑菌浓度（MIC），同时用PCR和核酸杂交的方法，检测红霉素耐药基因mreA、mefA、ermA、ermB、ermC在该批菌株中的出现规律及其与红霉素耐药性的关系。结果 （1）北京、广州两地GBS菌株总耐药率为46％，与克林霉素耐药性的一致率为93．8％；所有ermA基因均来自北京菌株，而广州菌株不含该基因。（2）含ermA和（或）ermB基因的GBS占所有菌株的30．09％，其耐药率高达97．06％，在已检测的GBS菌株中未发现ermC基因。（3）分别有53株和18株含mreA和mefA的GBS以及1株含ermA的菌株仍对红霉素敏感。2株GBS不含上述任何一种基因，但仍对红霉素耐药。结论 （1）北京、广州两地GBS对红霉素普遍具有较高的耐药率，且与大环内酯－林可霉素－链阳性霉素B类抗生素之间存在较严重的交叉耐药，临床使用抗生素时应尽量避免重复选择此类抗生素；（2）ermA和ermB是决定我国北京、广州GBS对红霉素耐药的重要基因；（3）GBS的耐药性还有其他分子生物学机制参与。     

B组链球菌的耐药性及红霉素耐药基因检测研究

目的探讨北京和广州地区B组链球菌（GBS）抗生素耐药菌谱及对红霉素耐药机制。方法GBS菌193株,其中140株和47株GBS分别来自北京和广州地区正常妇女阴道拭子标本,6株GBS菌株来自北京地区新生儿感染性肺炎和脑膜炎患儿体液标本中培养分离。应用标准的KB纸片法对临床常用7种抗生素耐药性检测。应用PCR法对102株（包括57株敏感株及45株耐药株）GBS进行红霉素耐药基因ermB、mefA检测。结果193株GBS菌均对青霉素类、头孢菌素类抗生素敏感;但青霉素和氨苄青霉素中介率均为17％;北京地区GBS的红霉素和林可霉素耐药率从1998年到1999年分别从8％增加到16％和从20％增加到28％;广州地区1999年分离的GBS菌株对红霉素和林可霉素耐药率分别为45％和26％,与北京地区1998、1999年分离的GBS菌株的红霉素耐药率比较,差异有统计学意义（P=0．000）。在45株红霉素耐药GBS菌中有40株同时对林可霉素耐药,5株表现为红霉素耐药而林可霉素敏感。20株GBS红霉素耐药仅含有ermB基因;13株红霉素耐药株仅含有mefA基因;同时含有ermB和mefA基因有6株。6株耐药株未能检测到ermB和mefA基因。结论青霉素、氨苄青霉素可作为治疗GBS感染首选药物;头孢菌素类抗生素可作为二线的选择药物。而红霉素和林可霉素作为预防和治疗GBS感染的药物应用价值应重新给予评价。在我国ermB基因介导的核糖体靶位点改变在GBS耐药机制中可能起主要作用。     

5岁以下健康儿童鼻咽部肺炎链球菌的流行病学研究

目的了解武汉地区儿童肺炎链球菌携带率、耐药性、耐药基因及血清型流行状况。方法采集鼻咽拭子,以琼脂稀释法测定肺炎链球菌对12种抗菌药物的最低抑菌浓度,聚合酶链式反应检测红霉素耐药基因,荚膜肿胀试验进行血清学分型。结果武汉地区儿童肺炎链球菌携带率为22．31％（135／605）。存活的133株细菌中,青霉素不敏感肺炎链球菌（PNSSP）发生率为45．9％（61／133）;头孢菌素第一代（头孢氨苄）、二代（头孢克洛）、三代（头孢克肟、头孢泊肟、头孢曲松）敏感率依次为6．0％、45．1％、54．9％、56．4％、88．7％;除1株环丙沙星低耐株外,未发现氟喹诺酮类耐药株。大环内酯类敏感率仅为14．3％～15．8％。在114株红霉素耐药株中,检出ermB基因76株（66．7％）,2株（1．8％）低耐株含有mefA基因,46株（40．4％）同时具有ermB和mefA基因。血清分型涉及17个血清群,主要分布在19、23、6、15和14血清群,7株细菌未能分群。PNSSP分布在19、23、6和未分型血清群。结论武汉地区肺炎链球菌耐药严重,红霉素耐药主要为核糖体修饰（ermB介导）引起。流行血清群以19、23、6为主。     

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目的研究北京儿童医院脓疱疮患儿临床分离A组β溶血性链球菌(GAS)及其对抗菌药物的敏感性情况。方法收集北京儿童医院2003—2008年收治的1735例脓疱疮儿童皮损部位分离出的52株GAS菌株,采用琼脂稀释法测定9种抗菌药物的最低抑菌质量浓度(MIC)值;用聚合酶链反应方法对上述菌株进行大环内酯类抗生素耐药基因ermB、ermA和mefA检测以及emm分型情况。结果分离株对四环素及大环内酯类抗生素耐药率均为100%,MIC>256mg/L;对青霉素、头孢拉啶及氧氟沙星的敏感率高达100%。大环内酯类抗生素耐药基因ermB、ermA和mefA和阳性率分别为92.30%、7.70%和0;分离株的emm分型最常见的为emm12.0(53.85%),emm1.0(36.54%)。结论北京儿童医院收治的脓疱疮儿童GAS感染流行菌株对大环内酯类抗生素耐药率很高,主要耐药机制为ermB编码的23SrRNA甲基化酶导致靶位改变,在北京地区青霉素类和头孢菌素类抗生素仍是治疗GAS感染首选药物。     

肺炎链球菌临床分离株耐药性与耐药机制研究

目的 探讨肺炎链球菌(SP)临床分离株的耐药性及对大环内酯类抗生素的耐药机制,为临床用药提供依据.方法 回顾性分析2002年7月至2005年7月年重庆医科大学附属儿童医院964株SP临床分离株的耐药性;采用聚合酶链式反应扩增30株耐药SP基因组DNA,琼脂糖电泳分析SP大环内酯类抗生素耐药基因表达.结果 共分离获得964株SP,对红霉素、阿奇霉素和青霉素(实为苯唑西林)耐药率分别为91.8%、90.0%和61.0%,多重耐药率十分严重,占93.2%,主要是对红霉素、阿奇霉素、复方新诺明、四环素和青霉素(实为苯唑西林)耐药;其中绝大多数SP临床分离株对氧氟沙星、利福平和万古霉素敏感.分析30株对红霉素和阿奇霉素均耐药的SP临床分离株的耐药机制,24株同时具有erm基因和mef基因,4株只有erm基因,1株只有mef基因,1株未检测到erm或mef基因.结论 该研究结果提示重庆地区小儿SP临床分离株对大环内酯类抗生素耐药率较国内其他地区高,耐药模式以红霉素、阿奇霉素、复方新诺明、四环素和青霉素(实为苯唑西林)为主.erm基因介导的靶修饰作用和mef基因介导的外流排出机制的共同作用是重庆地区SP临床分离株时大环内酯类抗生素主要的耐药机制.     

儿童肺炎链球菌分离株红霉素耐药性与相关耐药基因研究

目的检测儿童肺炎链球菌(SP)红霉素耐药性和相关耐药基因。方法对肺炎儿童进行痰培养,分离、鉴定SP菌株,经红霉素药敏试验检测SP药敏,通过PCR检测红霉素核糖体甲基化酶基因(ermB、ermA/B)、主动外排转运基因(mefA)3种基因表达。结果临床分离的31株SP,29株对红霉素耐药(93.5%),ermB基因阳性12株(38.7%),ermA/B基因阳性19株(61.3%),mefA基因阳性7株(22.6%),24株检出erm或和mef基因(77.4%),其中1株ermA/B、mefA基因表达均为阳性,1株ermB、ermA/B、mefA基因表达均为阳性。结论erm基因在SP有高表达,mef基因也有相当的表达,SP对红霉素具有高度耐药。     

160株儿童肺炎链球菌分离株的大环内酯类抗生素耐药特性研究

目的　研究 2 0 0 1年春季北京和西安市部分 0～ 5岁急性上呼吸道感染儿童鼻咽部肺炎链球菌分离株对红霉素及新型大环内酯类抗生素耐药特性。方法　使用超细鼻咽拭子从后鼻腔采取分泌物 ,用Optochin纸片做敏感性试验鉴定。采用E test方法及K B纸片扩散法对 16 0株肺炎链球菌分别进行 5种大环内酯类、6种其它相关抗生素敏感性检测。结果　 16 0株肺炎链球菌分离株中 ,90 6 %菌株的红霉素MIC等于或大于 1μg·mL-1为耐药株。在红霉素耐药的肺炎链球菌中 ,仅有 2 8%菌株的红霉素MIC在 1～ 4 μg·mL-1,为低水平耐药 ,97 2 %菌株的红霉素MIC在 16～≥ 2 5 6 μg·mL-1,为高水平耐药 ,其中 98 6 %耐药株的红霉素MIC≥ 2 5 6 μg·mL-1为极重度耐药。分离株对阿奇霉素、克拉霉素、罗红霉素、螺旋霉素耐药率与红霉素相似 ,分别为 90 6 %、89 4 %、88 1%和 88 1%。红霉素耐药表型分析显示 :以MLSB 耐药表型为主 ,占 97 2 % ;M耐药表型株仅为 2 8%。红霉素耐药分离株对克林达霉素、四环素、复方新诺明共同耐药率及多重耐药发生率分别为 96 6 %、97 2 %、85 6 %和 99 3% ,明显高于红霉素敏感组肺炎链球菌的 13 3%、73 3%、2 6 7%和 0。结论　北京和西安两地急性上呼吸道感染儿童鼻咽部肺炎链球菌分离株对红     

193株B组链球菌对抗菌药物的耐药性研究

目的　了解我国北京和广州地区B组链球菌 (GBS)抗生素耐药菌谱情况。方法　采用标准K B纸片法测定GBS菌对临床常用 7种抗生素耐药性。结果　 193株GBS菌均对青霉素类、头孢菌素类抗生素敏感 ;但青霉素和氨苄青霉素中度敏感率分别为 17%和 19% ;北京地区 1998年到 1999年分离GBS菌株对红霉素耐药率从8%增加到 16 % ,对克林霉素耐药率从 2 0 %增加到 2 8% ;广州地区 1999年分离的GBS菌株对红霉素和克林霉素耐药率分别为 4 5 %和 2 6 % ,与北京地区 1998年和 1999年分离的GBS菌株对红霉素的耐药率比较 ,经统计学处理P <0 0 5 ,差异有显著性。结论　青霉素、氨苄青霉素可作为治疗GBS感染首选药物 ;头孢菌素类抗生素可作为二线的选择药物。红霉素和克林霉素作为预防和治疗GBS感染的药物在国内会受到一定的限制。     

大环内酯类抗生素对肺炎链球菌儿童株体外抗菌活性

目的了解大环内酯类抗生素对杭州地区肺炎链球菌儿童株的体外抗菌活性。方法对2001年7月至2002年2月浙江大学儿童医院鉴定的100株肺炎链球菌临床株和2002年2月至6月自入托幼儿分离到的53株健康携带株 ,用Kirby_Bauer琼脂扩散法检测其对红霉素、阿奇霉素和克拉霉素3种常用抗生素的耐药性 ,用E_test法检测红霉素的最低抑菌浓度 (MIC)。结果92.8 %的菌株 (142株 )对红霉素耐药 ,敏感株仅7.2 % (11株 ) ;红霉素MIC范围为0.047μg/ml～>256μg/ml,其中MIC>256μg/ml的高水平耐药株达73.9 %(113株)。肺炎链球菌对阿奇霉素和克拉霉素的耐药率均为92.8 % ,与耐红霉素情况完全一致。结论①红霉素能很好地代表大环内酯类抗生素对肺炎链球菌的体外活性 ;②大环内酯类抗生素对肺炎链球菌的体外抗菌活性差 ,不宜作为治疗肺炎链球菌感染的常规用药。     

金黄色葡萄球菌儿童株耐药性研究和mecA基因检测

目的了解金黄色葡萄球菌（简称金葡菌）儿童株对常用抗生素的耐药特点,评价苯唑西林耐药性相关基因raecA-PCR的临床价值。方法用金葡菌乳胶凝集试验和Vitek系统GPI卡鉴定金葡菌,用纸片扩散法完成12种常用抗生素的药敏试验,同时用E-test法进行苯唑西林和万古霉素耐药性检测,并对所有菌株采用PCR技术检测mecA基因。结果金黄色葡萄球菌共259株,包括185株临床株和74株健康携带株,其中95．8％的菌株产生B内酰胺酶而对青霉素G耐药,91．1％的菌株对苯唑西林敏感,对头孢噻肟和头孢曲松的敏感率均为91．9％;对红霉素、四环素、克林霉素、甲氧苄啶磺胺甲基异恶唑、氯霉素、氧氟沙星和利福平的耐药率分别为48．3％、30．9％、21．6％、11．2％、10．0％、2．3％和1．5％;所有菌株均对万古霉素敏感。临床株对苯唑西林、头孢噻肟和头孢曲松的耐药率高于携带株（P〈0．05）,对红霉素的耐药率低于携带株（P〈0．01）。mecA-PCR结果显示：标准株ATCC25923和所有苯唑西林敏感株mecA基因均阴性,中介株mecA基因阳性1株,耐药株中均阳性。结论本研究中金葡菌对苯唑西林的耐药率不高,而mecA-PCR技术可以作为快速检测耐苯唑西林金葡菌的有效方法。     

Macrolide resistance among middle ear isolates of Streptococcus pneumoniae observed at eight United States pediatric centers: prevalence of M and MLSB phenotypes

BACKGROUND: Increasing macrolide resistance among middle ear isolates complicates treatment of otitis media in children. When macrolide resistance is mediated via an efflux pump (M phenotype), the MICs of erythromycin, clarithromycin and azithromycin are usually below 32 microg/ml, and the pneumococcus remains susceptible to clindamycin. The association of prior specific macrolide therapy with the isolation of a macrolide resistant strain has not been reported. OBJECTIVES: To determine the mechanism of macrolide resistance in Streptococcus pneumoniae recovered from the middle ears of children with otitis media and their association, if any, with ethnicity, age, serogroup/serotype and prior antibiotic therapy. METHODS: Middle ear isolates collected by members of the United States Pediatric Multicenter Pneumococcal Surveillance Group during a 6-year period from September 1994 through August 2000 were studied. Antibiotic susceptibility to penicillin and ceftriaxone was determined by microbroth dilution. Disc diffusion susceptibility to erythromycin and clindamycin was performed to categorize macrolide resistance mechanisms. The medical record was reviewed to determine demographics and history of previous antibiotic therapy. Isolates were serogrouped or serotyped by the capsular swelling method. RESULTS: Of the 1088 isolates available for testing, 51% were nonsusceptible to penicillin and 37% were nonsusceptible to erythromycin. Erythromycin resistance increased form 15% in 1994 through 1995 to 56% in 1999 through 2000. Seventy-five percent of macrolide-resistant strains were M phenotype. Macrolide resistance was less likely in isolates recovered from African-Americans and more likely in isolates obtained from children <3 years of age and from isolates obtained at time of tympanostomy tube placement. Neither erythromycin, nor clarithromycin nor azithromycin prescribed in the 30 days before infection was more likely than another to be associated with increased macrolide resistance. However, any macrolide alone or in combination with another antimicrobial taken before infection was associated with increased macrolide resistance among the S. pneumoniae organisms isolated from the middle ear. CONCLUSIONS: Macrolide resistance among middle ear isolates of S. pneumoniae increased during the 6-year study. The proportion of M phenotype remained constant at 75%, meaning that these isolates remain susceptible to clindamycin. Continued surveillance to document potential changes is essential.     

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??Abstract??Objective To investigate the genetic structure of Streptococcus pneumoniae serotype 19F isolates from children in Beijing. Methods A total of 130 isolates were identified as serotype 19F among 1033 S. pneumoniae strains collected from 1997 to 2006 and 2010. There were 120 isolates characterized by antibiotic susceptibility?? macrolide resistance gene and multilocus sequence typing??MLST??. Results Among the 120 strains?? only five strains were nonsusceptible to penicilln and the nonsusceptibility rate to cephalosporins increased from 1997 to 2010. There were 119??99.2%?? strains resistant to erythromycin?? 115??96.6%?? carried the ermB gene and 64??53.8%?? carried mefA gene?? 60??50.4%?? carried both genes. All isolates belonged to 31 sequence types?? ST983 was the most prevalent ST?? followed by ST271. From 1997 to 2010?? the percentage of CC271 increased from 14.3% in 1997-1998 to 92% in 2010?? whereas CC983 decreased from 64.3% to 0%. CC271 showed higher nonsuscetibility rate to β-lactam antibiotics than CC983. Conclusion The prevalence of serotype 19F of S.pneumoniae increases from 1997 to 2010 in Beijing. The increase of nonsusceptibility rate to β-lactam antibiotics is associated with the spread of international resistance clone CC271 due to the
selection of antibiotics overuse.     

High prevalence of erythromycin resistance of Streptococcus pyogenes in Greek children.

BACKGROUND: Macrolide resistance among Streptococcus pyogenes strains is increasing in many European countries. Greece was not considered a country with high prevalence of macrolide-resistant S. pyogenes strains, and until now the genetic mechanism of resistance was unknown. METHODS: During the 25-month period from December, 1998, to December, 2000, pharyngeal cultures for S. pyogenes were performed on 743 Greek children with the clinical diagnosis of pharyngitis. The children were 1 to 16 years old (median age, 7 years) and were living in Central and Southern Greece. S. pyogenes isolates were tested for their susceptibility to erythromycin, clarithromycin, azithromycin, clindamycin, penicillin G, amoxicillin/clavulanate and cefprozil. The erythromycin-resistant isolates were further studied for their genetic mechanism of resistance by means of PCR. RESULTS: Of a total of 275 S. pyogenes isolates recovered, 105 (38%) were erythromycin-resistant (MIC > or = 1 microgram/ml) [corrected], with 54, 45 and 1% of them carrying mef(A), erm(A) [subclass erm(TR)] and erm(B) gene, respectively. The prevalence of erythromycin-resistant strains was 29 and 42% during the time periods December, 1998, to December, 1999, and January, 2000, to December, 2000, respectively. All erythromycin-resistant isolates were also resistant to clarithromycin and azithromycin. The isolates carrying the erm(A) gene were inducibly resistant to clindamycin. The 275 S. pyogenes isolates had ceprozil MICs < or = 0.032 microgram/ml. CONCLUSIONS: The current high (38%) prevalence of erythromycin-resistant S. pyogenes in Central and Southern Greece requires continuous surveillance and careful antibiotic policy.     

难治性肺炎支原体肺炎患儿支气管肺泡灌洗液中肺炎支原体耐药基因检测分析

目的 分析难治性肺炎支原体肺炎(refractory Mycoplasmapneumoniaepneumonia,RMPP)患儿支气管肺泡灌洗液(bronchoalveolar lavage fluid,BALF)中肺炎支原体(Mycoplasmapneumoniae,MP)耐药性及耐药基因分布,并阐明23SrRNAⅤ...     

儿童肺炎链球菌分离株青霉素、红霉素耐药性与耐药相关基因研究

目的了解苏州地区儿童肺炎链球菌(Streptococcuspneumoniae,Sp)临床分离株青霉素、红霉素耐药的状况。方法对呼吸道感染患儿痰标本中分离到的26株Sp进行青霉素、头孢呋辛、头孢曲松、头孢噻肟、红霉素E test药敏试验,和与青霉素、红霉素耐药相关的pbp2B、ermB、ermA/B、mefA基因PCR检测,测得pbp2B基因产物进行测序并与SpR6株(青霉素敏感株,登录号:NC003098)序列比较。结果(1)pbp2B基因突变15株(58%),均为点突变,突变类型有A型11株(73%)、B型2株(13%)、C型1株(7%)、D型1株(7%);(2)11株无突变菌中青霉素、头孢呋辛、头孢曲松、头孢噻肟敏感株分别为9株(82%)、10株(91%)、11株(100%)、11株(100%);15株突变菌中青霉素、头孢呋辛、头孢曲松、头孢噻肟不敏感株分别为13株(87%)、11株(73%)、1株(7%)、1株(7%);11株A型突变株对青霉素均不敏感,10株对二代头孢不敏感;(3)ermB基因阳性9株(35%)、ermA/B基因阳性16株(62%)、mefA基因阳性7株(27%)、erm或(和)mef基因阳性21株(81%);(4)erm或(和)mef基因阳性株红霉素最低抑菌浓度为2～>256mg/L。结论pbp2B基因突变是本地区Sp青霉素耐药机制的主要遗传学基础之一;突变株中,A类突变率最高,表现对青霉素、二代头孢不敏感;ermA、ermB和mefA3种红霉素耐药基因单独或共同表达