北京市2004年-2010年志贺菌菌型分布及毒力基因分析

目的:了解近年来北京市志贺菌菌型变化及毒力基因分布特征。方法:对2004年-2010年监测到的1413株志贺菌进行血清分型;应用荧光PCR方法进行ipaHs、et1和sen基因的检测。结果:宋内志贺菌741株(52.4%),福氏志贺菌664株(47.0%),痢疾和鲍氏志贺菌各4株(1.2%)。福氏志贺菌共分为19种血清型,以F4c、F2a、F1a为主。宋内志贺菌自2007年首次超过福氏成为优势菌型后,所占比例逐渐加大,2010年已达到79.3%。福氏志贺菌也逐步由F4c转向以F2a为主,并伴有其它血清型交替出现。ipaH s,et1和sen三种基因的携带率分别为95.4%,82.3%和57.5%。set1和sen在福氏志贺菌的携带率明显高于宋内志贺菌。结论:近8年北京市志贺菌菌型发生了显著变化,宋内志贺菌正逐步成为主导菌型。毒力相关基因在不同菌型的分布存在差异。     

衡阳市市售凉拌菜的卫生微生物质量监测

目的:了解衡阳市凉拌菜的总体微生物污染状况。方法:在2010年9月-2010年12月从超市、菜市场以及路边小摊采集各种凉拌菜,按照《食品微生物学检验》GB 4789-2010的方法检测。各指标参照国家标准GB 2726-2005进行结果评价。结果:共检测400份凉拌菜1,60份样品菌落总数超标1,76份样品大肠菌群数超标6,6份检出沙门菌;90份检出金黄色葡萄球菌;24份检出志贺菌。5种类型凉拌菜中,以豆制品的污染率最高。结论:本市凉拌菜的微生物污染较为严重。     

志贺菌属整合子的耐药贡献与稳定性研究

目的分析志贺菌属整合子对耐药性的贡献及其稳定性。方法对志贺菌属1类、2类整合子的耐药基因盒分别克隆、转化DH5α,观察阳性克隆菌对多种抗生素敏感性的变化。将整合子阳性克隆菌与多重耐药志贺菌进行质粒接合实验,并测定耐药性的改变。对10株耐药谱不同、携带整合子不同的志贺菌属细菌进行无抗生素压力下连续多次传代实验,检测其耐药性及整合子的变化。结果志贺菌属1类整合子耐药基因盒dfrA17-aadA5阳性克隆菌对链霉素和甲氧苄啶的最低抑菌浓度(minimal inhibitory concentration,MIC)分别提高了8倍和32倍;2类整合子耐药基因盒dfrA1-sat1-aadA1阳性克隆菌对链霉素和甲氧苄啶的MIC分别提高了64倍和32倍;整合子阳性克隆菌经质粒接合传递后对抗生素的MIC无改变。1株携带2类整合子的志贺菌属菌株经过多次传代培养后丢失整合子及其耐药性。结论志贺菌属整合子-耐药基因盒系统可引起特定抗生素的耐药性,对质粒接合传递耐药性无影响。志贺菌属的2类整合子可发生丢失。     

Safety and immunogenicity of an intranasal Shigella flexneri 2a Invaplex 50 vaccine

Background

Shigella flexneri 2a lipopolysaccharide 50 is a nasally delivered subunit vaccine consisting of a macromolecular complex composed of LPS, IpaB, IpaC and IpaD. The current study examined vaccine safety and immunogenicity across a dose range and the clinical performance of a new intranasal delivery device.

Methods

Volunteers (N = 36) were randomized to receive vaccine via the Dolphin™ (Valois of America, Congers, New York) intranasal spray device at one of three doses (240, 480, and 690 μg) on days 0, 14, and 28. Another group (N = 8) received the 240 μg dose via pipette. Vaccine safety was actively monitored and antigen-specific humoral and mucosal immune responses were determined.

Results

There were no serious adverse events and the majority of adverse events (98%) were mild. Antibody secreting cells (ASC), plasma, and mucosal immune responses to Shigella antigens were detected at all three dose levels with the 690 μg dose inducing the highest magnitude and frequency of responses. Vaccination with comparable doses of Invaplex 50 via the Dolphin™ resulted in higher plasma and ASC immune responses as compared to pipette delivery.

Conclusion

In this trial the S. flexneri 2a Invaplex 50 vaccine was safe, well-tolerated and induced robust levels of antigen-specific intestinal IgA and ASC responses. The spray device performed well and offered an advantage over pipette intranasal delivery.     

人源志贺菌毒力大质粒体外转移及致病性分析

目的 为了解志贺菌毒力大质粒能否在体外转移及其转移后是否仍具有致病性.方法 将人源福氏志贺菌及其毒力大质粒分别与鸡源鲍氏志贺菌混合,并在37℃培养箱和4℃冰箱中混合培养24h;用不同剂量的毒力大质粒转移菌株通过口服和腹腔注射分别人工感染雏鸡和小白鼠.结果 人源福氏志贺菌的毒力大质成功转移到丢失自身毒力大质粒的鸡源鲍氏志贺菌中;转移菌株对雏鸡和小白鼠均有致病性,且转移菌株的培养特性也有所改变.结论 当志贺菌的毒力大质粒裸露出来且具有适宜的条件时,可以在体外转移到相近的病原菌中,且新生成的转移菌株具有一定稳定性和致病性;志贺菌的高致病性需要有毒力大质粒和菌体的其他特殊致病因子同时存在才能完成.     

Correlation between the sulfamethoxazole-trimethoprim resistance of Shigella flexneri and the sul genes

The aim of this study was to discuss the correlation between the sulfamethoxazole-trimethoprim resistance of Shigella flexneri (S. flexneri) and the antibiotic resistance genes sul1, sul2, and sul3 and SXT element.From May 2013 to October 2018, 102 isolates of S. flexneri were collected from the clinical samples in Jinan. The Kirby–Bauer (K-B) test was employed to determine the antibiotic susceptibility of the S. flexneri isolates. The antibiotic resistance rate was analyzed with the WHONET5.4 software. The isolates were subject to the PCR amplification of the sul genes (sul1, sul2, and sul3) and the SXT element. On the basis of the sequencing results, the correlation between the sulfamethoxazole-trimethoprim resistance of the S. flexneri isolates and the sul genes was analyzed.The antibiotic resistance rates of the 102 S. flexneri isolates to ampicillin, streptomycin, chloramphenicol, tetracycline, and sulfamethoxazole-trimethoprim were 90.2%, 90.2%, 88.2%, 88.2%, and 62.7%, respectively. The antibiotic resistance rates of these isolates to cefotaxime, ceftazidime, and ciprofloxacin varied between 20% and 35%. However, these isolates were 100% susceptible to cefoxitin. Positive fragments were amplified from 59.8% (61/102) of the 102 S. flexneri isolates, the sizes of the sul1 and sul2 genes being 338 bp and 286 bp, respectively. The sequence alignment revealed the presence of the sul1 and sul2 genes encoding for dihydrofolate synthase. The carrying rate of the sul1 gene was 13.7% (14/102), and that of the sul2 gene was 48.0% (49/102). No target gene fragments were amplified from the 3 isolates resistant to sulfamethoxazole-trimethoprim. The sul3 gene and SXT element were not amplified from any of the isolates. The testing and statistical analysis showed that the resistance of the S. flexneri isolates to sulfamethoxazole-trimethoprim correlated to the sul1 and sul2 genes.The acquired antibiotic resistance genes sul1 and sul2 were closely associated with the resistance of the 102 S. flexneri isolates to sulfamethoxazole-trimethoprim.     

四川省某学校一起细菌性痢疾暴发疫情调查

目的调查某学校细菌性痢疾暴发疫情发生的原因,为制定防控措施提供科学依据。方法2019-05-20,四川省茂县某乡镇小学发生一起细菌性痢疾暴发疫情,根据暴发调查步骤制定病例定义开展病例搜索,对搜索到的病例进行个案调查并描述病例的三间分布情况,再开展病例对照研究和现场卫生学调查,以寻找此次疫情发生的危险因素,明确暴发原因。利用描述流行病学方法描述病例的时间、空间和人群分布特征,罹患率差异用χ^2检验,病例对照研究中计算OR值及95%可信区间。结果该次疫情历时7 d(2019-05-20/26),共有病例97例(确诊病例25例,临床诊断46例,疑似病例26例),罹患率为30.50%(97/277);患者以腹泻、腹痛、发热和里急后重为主要临床症状;流行曲线提示本次疫情属于点源暴露,可疑暴露日期5月20-22日;不同性别之间(37.68%和32.37%,χ^2=0.86,P>0.05)、住校生和走读生之间(34.62%和35.06%,χ^2=0.06,P>0.05)、各班级之间(20.59%、42.42%、50.00%、46.16%、35.71%、26.92%、21.62%、45.45%和25.00%,χ^2=15.17,P>0.05)罹患率差异无统计学意义;病例对照研究显示,喝生水是本次疫情发生的危险因素(OR=3.77,95%CI:1.16~12.27);共采集样本85份(水样7份,血样6份,病例粪便样31份,肛拭子10份,学校环境样19份,留样食品样12份),其中25份粪便标本检出福氏Ⅵ型志贺氏菌;7份水样卫生学检测总大肠菌群、耐热大肠菌群、大肠埃希氏菌超标。结论这是一起学校生活饮用水被福氏Ⅵ型志贺氏菌污染而导致的急性细菌性痢疾暴发疫情。     

点免疫结合试验和反向间接血凝试验检测粪便中福氏志贺氏菌的研究

采用单克隆抗体作为试剂,建立了两种用于快速检测粪便中福氏痢疾杆菌的方法—DIBA夹心法和RPHA法。长期以来困扰研究者的非特异性干扰问题,可能用煮沸标本上清的方法得到解决。检测114份病人标本的结果证明,用常规培养法检测阳性者,DIBA和RPHA检测均为阳性,两类方法的符合率为86.4％。由此证明两种快速免疫学方法不仅能检出完整的细菌细胞,而且也能检出其裂解产物。这两种方法,尤其是RPHA法具有较高的敏感性、特异性和快速性,且不需复杂的仪器设备,加之实验程序简单,甚适于在基层单位及农村地区应用。