血清降钙素原鉴别病毒性感染、一般性细菌感染和重症细菌性感染的临床应用价值

目的:研究血清中降钙素原在病毒性感染、一般性细菌感染和重症细菌性感染患者中的应用价值。方法:选择2014年6月~2016年12月在我院重症医学科进行诊治的感染患者60例,按照患者感染的严重程度分为病毒性感染患者(A组)15例,一般细菌感染组(B组)22例以及重症细菌性感染组(C组)23例。三组患者均采取纠正水电解质平衡、抗生素抗感染和营养支持等对症治疗,并在入院后第1、3、5、7 d检测患者的血清降钙素原水平,比较三组治疗前后血清降钙素原水平的差异,观察三组血清降钙素原≥0.5μg/L的例数。结果:B组血清降钙素原≥0.5μg/L的例数为20例,占90.91%,C组血清降钙素原≥0.5μg/L的例数为21例,占91.30%,B组和C组之间相比无明显差异(P0.05),但A组血清降钙素原≥0.5μg/L的例数为3例,占20.00%,明显低于B组和C组血清降钙素原≥0.5μg/L的例数,差异均具有统计学意义(P0.05);C组入院后第1、3、5、7 d的血清降钙素原水平均明显高于B组的血清降钙素原水平,差异均具有统计学意义(P0.05);重症细菌性感染患者中,血清降钙素原≥0.5μg/L的患者存活率明显低于血清降钙素原0.5μg/L的患者(P0.05)。结论:血清中降钙素原水平对于重症感染患者的临床诊断和治疗具有较好的应用价值,对于医生判断重症感染患者的预后情况具有很好的效果,值得临床广泛应用推广。     

呼吸道不同部位的微生物分布特点及药敏分析

目的指导临床合理选用抗生素,预防减少呼吸道感染的发生及深入.方法取痰、喉室的分泌物及喉癌术后气管内的分泌物进行细菌培养和药敏试验.结果呼吸科呼吸道感染的病原菌中以白色念球菌居首位,其次革兰阴性杆菌检出率高,对亚胺培南的耐药性最低.耳鼻喉科声带息肉患者喉室的病原菌中以草绿链球菌居首位,对阿莫西林-棒酸,头孢1、2代敏感.耳鼻喉科喉癌术后气管切开患者下呼吸道感染的病原菌中,既有革兰阳性菌（以肺炎链球菌为主）又有革兰阴性杆菌（以铜绿假单胞菌、醋酸钙不动杆菌为主）,革兰阴性杆菌较革兰阳性菌多,均对头孢他啶有较高的敏感率.结论由于细菌的分布特点不一,耐药性不一样,最好依据细菌学选择敏感抗生素,当病原菌不明时,需要经验用药时则根据其筛查出的细菌排序的流行趋势选择抗生素.     

非小细胞肺癌并发下呼吸道感染患者病原微生物分布及其与病情进展的相关性

目的探究非小细胞肺癌(NSCLC)合并下呼吸道感染患者病原菌分布及与病情进展相关性。方法选取2015年6月至2018年8月延安大学附属医院肿瘤内科收治的NSCLC患者126例。采集NSCLC患者痰液进行细菌培养及鉴定。观察不同种属病原菌在NSCLC并发下呼吸道感染患者中的分布情况。结果 NSCLC并发下呼吸道感染患者中革兰阴性菌检出率为61.18%,革兰阳性菌检出率为24.71%,真菌检出率为14.12%。革兰阴性菌中大肠埃希菌检出率为40.38%,肺炎克雷伯菌检出率为32.69%,铜绿假单胞菌检出率为13.46%,鲍曼不动杆菌检出率为7.69%,其他细菌检出率为5.77%。革兰阳性菌中溶血葡萄球菌检出率为42.86%,金黄色葡萄球菌检出率为38.10%,肺炎链球菌检出率为9.52%,粪肠球菌检出率为9.52%。真菌中白假丝酵母检出率为58.33%,热带假丝酵母检出率为25.00%,光滑假丝酵母检出率为16.67%。年龄≥60岁、吸烟、TNM分期III^IV期、营养不良、住院时间≥14 d的NSCLC合并下呼吸道感染患者病原菌检出率均高于年龄<60岁、不吸烟、I^II期、营养良好、住院时间<14 d的患者(均P<0.05)。结论革兰阴性菌更易感染NSCLC合并下呼吸道感染患者。患者TNM分期、年龄等病情进展因素与病原菌感染率具有相关性。     

小儿下呼吸道感染痰培养标本病原菌构成分析

目的了解小儿下呼吸道感染病原菌的分布及对常用抗菌药物的耐药状况。方法对2710例小儿下呼吸道感染患者痰标本进行培养,用VITEK-2Compact微生物鉴定系统鉴定菌种和药敏试验,WHO-NET5．4软件对数据进行分析。结果共分离病原菌675株,革兰阴性杆菌457株,占67．7％,主要为大肠埃希菌、肺炎克雷伯菌;革兰阳性球菌159株,占23．5％,主要为金黄色葡萄球菌、肺炎链球菌;真菌59株,占8．7％,主要为白色假丝酵母菌。结论小儿下呼吸道感染病原菌以革兰阴性杆菌为主,耐药性较为严重,应不断加强耐药性监测,合理使用抗菌药物。     

自然感染途径建立肺炎链球菌感染性肺炎小鼠模型

目的探索自然感染途径制备肺炎链球菌感染性肺炎小鼠模型的方法,为肺炎链球菌性肺炎的相关研究提供实验基础。方法肺炎链球菌标准菌株(CMCC 31203)经血平板培养18 h后配成2麦氏浊度。小鼠浅麻醉状态下,破损鼻黏膜,滴注一定量肺炎链球菌菌液。于3、7、14和21 d分别处死小鼠,取肺脏进行组织病理学观察,确定肺炎小鼠模型制备的最佳方式。结果鼻黏膜破损组小鼠3 d时肺泡间隔内毛细血管扩张,肺泡腔内以红细胞和纤维素渗出为主;7 d时病变以纤维素和中性粒细胞浸润为主;14 d时肺泡腔内渗出减少,炎症开始减轻;21 d时肺脏外观趋于正常,肺泡腔内渗出物质基本溶解吸收。结论以3×107CFU的肺炎链球菌菌液通过破损的鼻黏膜感染7 d时可以制备出比较典型、稳定的肺炎小鼠模型。     

妇科肿瘤患者术后盆腔感染情况调查、 病原菌分布及其危险因素分析

目的调查妇科肿瘤患者术后盆腔感染的情况以及病原菌分布,并探讨术后发生盆腔感染的危险因素。方法回顾性分析自2013年1月到2017年1月在东南大学附属中大医院接受妇科肿瘤手术治疗的384例患者的临床资料。统计妇科肿瘤术后盆腔感染的发生率及病原菌的分布情况。将发生盆腔感染的患者分为感染组,未发生盆腔感染的患者分为未感染组,对比两组的临床资料,并通过多因素Logistic回归分析,归纳妇科肿瘤患者术后发生盆腔感染的危险因素。结果术后发生盆腔感染41例,感染率为10.68%,培养出病原菌54株,其中革兰阳性菌14株,占25.93%,革兰阴性菌35株,占64.81%,真菌5株,占9.26%。感染组患者年龄60岁的比例、手术持续时间2h的比例、合并慢性基础疾病的比例、开放手术的比例、术前化疗的比例、术后留置引流管的比例和术后卧床时间7d的比例均显著高于未感染组(均P0.05);多因素Logistic回归分析结果显示,年龄大、手术持续时间长、合并慢性基础疾病、开放手术、术前化疗、术后留置引流管、术后卧床时间长均是妇科肿瘤患者术后盆腔感染的危险因素(均P0.05)。结论妇科肿瘤患者术后较容易并发盆腔感染,病原菌主要为革兰阴性菌。多种因素可增加术后盆腔感染的风险,临床应加强防控措施,降低妇科肿瘤患者术后盆腔感染的发生率。     

阑尾炎患者术后创口细菌感染特征及耐药性分析

目的探究急性阑尾炎患者术后切口细菌感染的细菌谱及药物敏感情况。方法选择2015年1月至2019年1月于我院行阑尾切除术后切口感染的66例患者作为研究对象,分析其伤口分泌物细菌培养结果和病原菌药敏情况。结果送检的66例标本中共有59例检出细菌,共分离病原菌15种,66株;其中有7例标本为两种细菌混合感染。检出的细菌中,革兰阳性菌39株,革兰阴性菌27株,其中革兰阳性菌以金黄色葡萄球菌、化脓性链球菌、溶血葡萄球菌为主;革兰阴性菌以大肠埃希菌、阴沟肠杆菌、铜绿假单胞菌为主。药敏试验显示,主要革兰阳性菌对头孢唑林、头孢拉定的敏感性较低,而对氨苄西林、阿莫西林、头孢他啶、头孢噻肟、美罗培南、亚胺培南以及利奈唑胺均具有较高的敏感性。主要革兰阴性菌对氨苄西林、阿莫西林、头孢唑林、头孢拉定以及头孢噻肟均不敏感,对头孢他啶、美罗培南、亚胺培南的敏感率大于50.00%,具有较高的敏感性。结论对于阑尾炎术后切口感染的患者,应加强无菌操作和病房环境清洁,在药敏试验结果明确前,建议使用头孢他啶或相对应的第三代头孢菌素进行抗感染治疗。     

利奈唑胺治疗耐药革兰阳性球菌所致医院获得性肺炎1例

近年来,医院获得性感染中革兰阳性菌感染呈上升趋势,而耐甲氧西林金黄色葡萄球菌(MRSA)已成为医院感染中的常见病原菌,具有多重耐药特征,给临床治疗带来困难。利奈唑胺是第1个应用于临床的新型唑烷酮类抗生素,对葡萄球菌、链球菌、肠球菌等耐药革兰阳性菌有广谱抗菌作用。本文报道1例耐药革兰阳性球菌所致医院获得性肺炎患者,予利奈唑胺治疗后胸部CT示炎症明显吸收,血常规恢复正常,未再发热,病情好转出院。结果显示,利奈唑胺能有效治疗耐药革兰阳性球菌所致医院获得性肺炎。     

糖尿病足感染的细菌学调查及耐药性分析

目的 了解临床糖尿病足患者感染的细菌分布及耐药性分析.方法 2009年至2010年,共调查135例糖尿病足患者.结果 检出细菌株数为107株,其中革兰阳性菌44株,占41.1％;革兰阴性菌57株,占53.3％;真菌6株,占5.6％.需氧菌感染80例,检出率59.3％.以金葡菌、链球菌、变形杆菌和大肠埃希菌为主要感染菌.金黄色葡萄球菌的耐药率明显低于其他葡萄球菌.大肠埃希菌治疗以亚胺培南首选,也可选用β-内酰胺类加酶抑制剂.结论 检出革兰阴性菌57株,革兰阳性菌44株,应根据药敏情况合理应用抗菌素.     

脑卒中昏迷患者气管切开后并发肺部感染的病原菌分布及预防对策

目的:探讨脑卒中昏迷患者气管切开后并发肺部感染的病原菌分布及危险因素,并提出预防措施。方法:回顾性分析2016年1月至2017年2月我院收治的脑卒中昏迷患者96例,分析脑卒中昏迷患者肺部感染发生率及病原菌分布情况,同时采用单因素和多因素logistic回归分析肺部感染的危险因素,从而提出相应的预防措施。结果:96例脑卒中昏迷患者气管切开术后肺部感染的发生率为48.96%(47/96);共分离培养病原菌104株,包括革兰阴性菌69株(66.35%)、革兰阳性菌20株(19.23%)和真菌15株(14.42%);单因素分析结果显示,脑卒中昏迷患者气管切开术后肺部感染与年龄、基础疾病、气管切开时间、卧床时间、使用广谱抗菌药物、吸烟史、人工气道、吸痰次数及雾化吸入次数密切相关(P0.05),而与患者性别、体重、脑卒中类型无关(P0.05);多因素logistic回归分析结果显示,年龄45岁、合并患有基础疾病、气管切开时间5 d、使用广谱抗菌药物、吸烟史及建立人工气道均为脑卒中昏迷患者气管切开术后肺部感染的危险因素(P0.05),ROC分析结果为:气管切开时间的临界点(阈值C)是4.3天,其灵敏度和特异度将分别为0.851和0.918。结论:脑卒中昏迷患者气管切开后并发肺部感染的病原菌以革兰阴性菌为主,年龄45岁、合并患有基础疾病、气管切开时间5 d、使用广谱抗菌药物、吸烟史及建立人工气道能够导致脑卒中昏迷患者气管切开术后发生肺部感染,并且气管切开时间超过4.3天,脑卒中昏迷患者肺部感染的风险将大大增加,应根据病原学特征及其危险因素,采取针对性措施,降低肺部感染的发病风险。     

Bacteriocin ST91KM, produced by Streptococcus gallolyticus subsp. macedonicus ST91KM, is a narrow-spectrum peptide active against bacteria associated with mastitis in dairy cattle

Streptococcus gallolyticus subsp. macedonicus ST91KM produces a bacteriocin (macedocin ST91KM) active against Streptococcus agalactiae, Streptococcus dysgalactiae subsp. dysgalactiae, Streptococcus uberis, Staphylococcus aureus, and Staphylococcus epidermidis. Macedocin ST91KM is, according to tricine-SDS PAGE, between 2.0 and 2.5 kDa in size. Antimicrobial activity remained unchanged after 2 h of incubation at pH 2.0-10.0 and after 100 min at 100 degrees C. The peptide was inactivated after 20 min at 121 degrees C and when treated with proteolytic enzymes. Treatment with alpha-amylase had no effect on activity, suggesting that the mode of action does not depend on glycosylation. Amplification of the genome of strain ST91KM with primers designed from the macedocin precursor gene (mcdA) produced 2 fragments (approximately 375 and 220 bp) instead of one 150-bp fragment, as recorded for macedocin produced by Streptococcus gallolyticus subsp. macedonicus ACA-DC 198. Strain ACA-DC 198 was not available. However, DNA amplified from strain LMG 18488 (ACA-DC 206), genetically closely related to strain ACA-DC 198, revealed 99% homology to the mcdA of strain ACA-DC 198 (accession No. DQ835394). Macedocin ST91KM may thus be a second putative bacteriocin described for Streptococcus gallolyticus subsp. macedonicus.     

Sequencing and comparative genome analysis of two pathogenic Streptococcus gallolyticus subspecies: genome plasticity, adaptation and virulence

Streptococcus gallolyticus infections in humans are often associated with bacteremia, infective endocarditis and colon cancers. The disease manifestations are different depending on the subspecies of S. gallolyticus causing the infection. Here, we present the complete genomes of S. gallolyticus ATCC 43143 (biotype I) and S. pasteurianus ATCC 43144 (biotype II.2). The genomic differences between the two biotypes were characterized with comparative genomic analyses. The chromosome of ATCC 43143 and ATCC 43144 are 2,36 and 2,10 Mb in length and encode 2246 and 1869 CDS respectively. The organization and genomic contents of both genomes were most similar to the recently published S. gallolyticus UCN34, where 2073 (92%) and 1607 (86%) of the ATCC 43143 and ATCC 43144 CDS were conserved in UCN34 respectively. There are around 600 CDS conserved in all Streptococcus genomes, indicating the Streptococcus genus has a small core-genome (constitute around 30% of total CDS) and substantial evolutionary plasticity. We identified eight and five regions of genome plasticity in ATCC 43143 and ATCC 43144 respectively. Within these regions, several proteins were recognized to contribute to the fitness and virulence of each of the two subspecies. We have also predicted putative cell-surface associated proteins that could play a role in adherence to host tissues, leading to persistent infections causing sub-acute and chronic diseases in humans. This study showed evidence that the S. gallolyticus still possesses genes making it suitable in a rumen environment, whereas the ability for S. pasteurianus to live in rumen is reduced. The genome heterogeneity and genetic diversity among the two biotypes, especially membrane and lipoproteins, most likely contribute to the differences in the pathogenesis of the two S. gallolyticus biotypes and the type of disease an infected patient eventually develops.     

Identification of bacteriocin-like inhibitors from rumen Streptococcus spp. and isolation and characterization of bovicin 255

Streptococci obtained from rumen sources were tested for the production of antibacterial compounds using a deferred-antagonism plating assay. Of 35 isolates tested, 7 were identified that inhibited the growth of other streptococci. None of the inhibitory activity was due to bacteriophage. Three isolates, LRC0253, LRC0255, and LRC0476, were selected for further characterization. Analysis of 16S ribosomal DNA indicated that LRC0476 was a strain of Streptococcus bovis, while isolates LRC0253 and LRC0255 are likely strains of Streptococcus gallolyticus. The antibacterial compounds produced by these bacteria were protease sensitive, remained active in a pH range from 1 to 12, and did not lose activity after heating at 100 degrees C for 15 min. The inhibitory peptide from strain LRC0255 was purified using pH-dependent adsorption and desorption to bacterial cells, followed by ammonium sulfate precipitation and reversed-phase chromatography and gel filtration. The peptide was 6 kDa, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. An oligonucleotide probe based on the N-terminal sequence of the purified peptide was used to identify the gene encoding the inhibitory peptide. The antibacterial peptide has characteristics that are very similar to those described for class II bacteriocins of gram-positive bacteria.     

Isolation of tannin-degrading bacteria isolated from feces of the Japanese large wood mouse, Apodemus speciosus, feeding on tannin-rich acorns

Bacteria with tannase activity were isolated from the feces of the Japanese large wood mouse, Apodemus speciosus. They were largely classified into two groups: Gram-positive cocci and Gram-positive bacilli. Genotypic analysis using a species-specific PCR assay as well as biochemical tests identified all cocci as Streptococcus gallolyticus. A PCR assay targeting a genus-specific sequence in the 16S/23S rDNA spacer region and additional 16S rDNA sequencing indicated that the bacilli belong to the genus Lactobacillus, with L. animalis and L. murinus being closely related taxa. Subsequent estimation of guanine-plus-cytosine content, amplified ribosomal DNA restriction analysis, and DNA/ DNA hybridization assay confirmed that the bacilli are homologous to each other but different from L. animalis or L. murinus. Consequently, a novel species of the genus Lactobacillus may be proposed. To date, this study is the first to report on the isolation of tannase-positive bacteria from the feces of a rodent species. These bacteria may play an essential role for the host organism in digesting tannin-rich acorns available in their natural habitats, thereby endowing them with a greater ecological advantage.     

A novel multiplex PCR/RFLP assay for the identification of Streptococcus bovis/Streptococcus equinus complex members from dairy microbial communities based on the 16S rRNA gene

The Streptococcus bovis/Streptococcus equinus complex (SBSEC) comprises pathogenic species associated with different degrees with human infections but also spontaneously fermented dairy products. We aimed therefore at developing a specific identification assay for the SBSEC targeting the 16S rRNA gene comprising a multiplex PCR followed by a differentiating restriction fragment length polymorphisms (RFLP). The multiplex PCR assay was positively applied on 200 SBSEC isolates including reference strains. The assay did not yield false-positive amplifications with strains of closely related bacteria and isolates of non-SBSEC streptococci, lactococci, enterococci, and other genera of dairy origin. The downstream RFLP using MseI and XbaI enabled further discrimination of Streptococcus infantarius/S.?bovis (biotype II.1) from Streptococcus gallolyticus (biotype I and II.2)/Streptococcus alactolyticus and S.?equinus. Furthermore, the newly developed primers can be used directly for Sanger sequencing. Conclusively, this novel PCR/RFLP assay is applicable in the complex dairy microbial communities and provides an important tool to assess the prevalence of members of the SBSEC in dairy products.     

Transformation of a type 4 encapsulated strain of Streptococcus pneumoniae

Streptococcus pneumoniae strain JNR.7/87 is a highly virulent, type 4 encapsulated Gram-positive bacterium whose transformability has not been tested previously, and whose genome is currently being sequenced. The strain was transformed at very low efficiency by addition of exogenous competence-stimulating peptide: However, the efficiency was too low and irreproducible to be useful in many genetic studies. Therefore, the effects on transformation efficiency of changing different components of competence-stimulating peptide-induced transformation have been examined. Screening of growth media was followed by optimization of pre-induction culture acidification, glycine concentration, and induction time. An optimized protocol was developed whereby S. pneumoniae strain JNR.7/87 was transformed reproducibly with a streptomycin resistance (SmR) marker at an efficiency of approximately 10(5) colony forming units per 10(8) cells.     

Sample preparation of Gram-positive bacteria for identification by matrix assisted laser desorption/ionization time-of-flight.

A new sample preparation method was developed for fresh, whole-cell Gram-positive bacteria to be analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI ToF MS). With fresh, whole-cell Gram-negative bacteria of the Enterobacteriaceae family, we had previously achieved spectra consisting of >50 peaks and mass ranges of 2-25 kDa. Because similar spectral quantity could not be achieved for Gram-positive bacteria, using this same protocol, we investigated an alternative approach that focuses on the thick peptidoglycan layer of the cell wall. Gram-positive bacteria were incubated with 0.05-0.5 mg/ml lysozyme for 30 min prior to being analyzed by MALDI ToF MS. Lysozyme is an enzymatically stable, 14-kDa protein that specifically cleaves between peptidoglycan disaccharide subunits. A significant increase in overall number of peaks (>50) in the 2-14 kDa range was observed without interference from the presence of lysozyme. We show that for four different species (Staphylococcus aureus, S. haemolyticus, Streptococcus pyogenes, and S. agalactiae) reproducible subset of peaks were found within spectra from a reference strain and two unrelated clinical isolates. The data suggests that this sample preparation may be useful for increasing the overall number of peaks within spectra for subsequent development of bacterial identification strategies.     

Genome sequence of the bacteriocin-producing oral probiotic Streptococcus salivarius strain M18

Streptococcus salivarius is a Gram-positive bacterial commensal and pioneer colonizer of the human oral cavity. Many strains produce ribosomally synthesized proteinaceous antibiotics (bacteriocins), and some strains have been developed for use as oral probiotics. Here, we present the draft genome sequence of the bacteriocin-producing oral probiotic S. salivarius strain M18.