口服Cocktail A乳酸菌制剂对人肠道乳酸菌群影响的研究

目的评价口服Cocktail A乳酸菌制剂后人肠道乳酸菌群的变化。方法用需氧和厌氧定量培养方法分离并鉴定烧伤病房中30例腹泻患者给予Cocktail A乳酸菌制剂治疗前后肠道中的细菌,并以正常健康体检者的粪便培养鉴定结果作为对照。同时对未鉴定出的细菌用16S rRNA基因进行鉴定。结果腹泻患者肠道中的菌群与健康体检者肠道中的菌群相比,乳酸菌的数量和种类少,而口服乳酸菌制剂治疗后肠道中的植物乳杆菌、明串珠球菌、戊糖片球菌、副酪蛋白乳杆菌大量增加。结论口服Cocktail A乳酸菌制剂能调节肠道的菌群失调。     

Genetic identification of antagonistically active lactobacillus strains isolated from the oral cavity of healthy individuals

Examination of dental deposits from 45 healthy individuals detected 3 lactobacillus strains showing a high antagonism toward test cultures. The api 50 CH "bio Merieux" test systems were employed to identify strains as Lactobacillus fermentum 39, Lactobacillus rhamnosus 24 and Lactobacillus paracasei 50. The results of analyzing the sequences of the 16S rRNA genes of the test strains confirmed this identification, except for the latter strain. The taxonomic status of the third strain L. rhamnosus 50 was determined by the bioinformative analysis of the nucleotide sequence of the 16S rRNA genes.     

Comparison between two PCR-based bacterial identification methods through artificial neural network data analysis

The 16S ribosomal ribonucleic acid (rRNA) and 16S-23S rRNA spacer region genes are commonly used as taxonomic and phylogenetic tools. In this study, two pairs of fluorescent-labeled primers for 16S rRNA genes and one pair of primers for 16S-23S rRNA spacer region genes were selected to amplify target sequences of 317 isolates from positive blood cultures. The polymerase chain reaction (PCR) products of both were then subjected to restriction fragment length polymorphism (RFLP) analysis by capillary electrophoresis after incomplete digestion by Hae III. For products of 16S rRNA genes, single-strand conformation polymorphism (SSCP) analysis was also performed directly. When the data were processed by artificial neural network (ANN), the accuracy of prediction based on 16S-23S rRNA spacer region gene RFLP data was much higher than that of prediction based on 16S rRNA gene SSCP analysis data (98.0% vs. 79.6%). This study proved that the utilization of ANN as a pattern recognition method was a valuable strategy to simplify bacterial identification when relatively complex data were encountered.     

Fatal Nocardia farcinica bacteremia in a patient with lung cancer

Nocardia farcinica is an emerging pathogen in immunocompromised patients, accounting for approximately 20% of Nocardia clinical isolates in various countries. A case of fatal N. farcinica bacteremia in a 52-year-old man with lung cancer is described. He was admitted with severe respiratory distress, and despite the early onset of empirical antibiotic treatment, he failed to respond and died of septic shock 24 hours later. N. farcinica was isolated from blood cultures obtained at hospital admission and was identified by conventional methods. Strain identification was confirmed by nucleotide sequencing of the 16S rRNA gene. N. farcinica bacteremia is a life-threatening infection. Because of the actinomycete's highly-resistant antibiotic profile, early identification and antibiotic susceptibility testing are necessary to improve the chances of survival.     

胆固醇结石患者胆囊细菌的T-RFLP研究

目的应用T-RFLP分析胆固醇结石中微生物群落结构。方法应用末端标记限制性片段长度多态性（Terminal Restriction Fragment Length Polymorphism,T-RFLP）和克隆文库分析,以微生物群落16S rRNA基因（16S rDNA）为目标,对8例常规细菌培养阴性的纯胆固醇患者胆囊结石和胆汁中的微生物群落结构进行解析和比较。结果发现8例纯胆固醇结石患者胆汁中未找到细菌存在的证据,结石中细菌16S rDNA阳性率为37.5%（3/8）,细菌16S rDNA片段测序表明细菌群落与肠杆菌科和微球菌科的微生物有较高的相似性,同时细菌群落中检出了大量的未培养微生物（Uncultured bacterium clone）。结论运用T-RFLP方法分析16S rDNA克隆片段能够有效评估纯胆固醇结石中的细菌群落结构的多样性。     

Campylobacter showae bacteremia with cholangitis

We report a case of Campylobacter showae bacteremia associated with cholangitis. A 71-year-old man with advanced bile duct cancer was admitted to our hospital because of cholangitis with shock, hypoglycemia, and impaired renal function. After replacement of the biliary drainage tube, pus was drained from the tube. Specimens for blood and bile cultures were obtained, and fluid resuscitation and antimicrobial treatment were then begun. Although anaerobic blood culture yielded small curved gram-negative rods, the isolate could not be identified by conventional identification methods. The isolate was identified as C. showae by 16S rRNA gene sequencing analysis. We consider here the pathogenicity of C. showae and the association of C. showae with cholangitis.     

"Streptococcus milleri" endocarditis caused by Streptococcus anginosus

Unlike other viridans streptococci, members of the "Streptococcus milleri group" are often associated with abscess formation, but are only rare causes of infective endocarditis. Although it has been shown that almost all S. intermedius isolates and most S. constellatus isolates, but only 19% of S. anginosus isolates, were associated with abscess formation, no report has addressed the relative importance of the 3 species of the "S. milleri group" in infective endocarditis. During a 5-year period (April 1997 through March 2002), 6 cases of "S. milleri" endocarditis (out of 377 cases of infective endocarditis), that fulfil the Duke's criteria for the diagnosis of infective endocarditis, were encountered. All 6 "S. milleri" isolates were identified as S. anginosus by 16S ribosomal RNA (rRNA) gene sequencing. Three patients had underlying chronic rheumatic heart disease and 1 was an IV drug abuser. Five had monomicrobial bacteremia, and 1 had polymicrobial (S. anginosus, S. mitis, Granulicatella adiacens, and Slackia exigua) bacteremia. Two patients died. None of the 6 isolates were identified by the Vitek system (GPI) or the API system (20 STREP) at >95% confidence. All 6 isolates were sensitive to penicillin G (MIC 0.008-0.064 microg/mL), cefalothin, erythromycin, clindamycin, and vancomycin. Accurate identification to the species level, by 16S rRNA gene sequencing, in cases of bacteremia caused by members of the "S. milleri group", would have direct implication on the underlying disease process, hence guiding diagnosis and treatment. Infective endocarditis should be actively looked for in cases of monomicrobial S. anginosus bacteremia, especially if the organism is recovered in multiple blood cultures.     

江苏省苏州市1例人感染猪链球菌病例调查

目的 调查苏州市1例人感染猪链球菌病例的流行病学和病原学特点,为防控提供依据。 方法 现场访谈查看患者的感染途径和感染来源,并进行溯源调查;对患者及80份生猪扁桃体、鼻咽拭子标本中分离的菌株进行VITEK2 compact生化鉴定和聚合酶链式反应检测,检测种属特异性基因（16S rRNA）和4种毒力基因（cps-2J、sly、ef 和mrp）。 结果 经流行病学调查,患者可能在清洗猪肉过程中经手部伤口感染。患者分离株种属特异性16S rRNA 基因、毒力基因cps-2J、sly和 ef 基因均呈阳性。2份猪鼻咽拭子标本经生化鉴定为猪链球菌2型,毒力基因sly呈阳性。 结论 该病例可能为偶然感染强毒株。健康猪群猪链球菌2型检出率低、毒力低,不足以威胁健康人群;应保持警惕,做好生猪检疫工作,加强监测和宣传教育,在接触生猪制品时,做好个人防护,防止感染猪链球菌病。      

4株威克汉姆无绿藻的鉴定及基因特征分析

目的对临床分离的4株无绿藻进行菌种鉴定和基因特征分析。方法对临床分离的4株酵母样微生物进行培养特性和形态学特征分析,商品化Vitek 2细菌鉴定系统(配套YST卡)和MALDI-TOF MS微生物鉴定系统鉴定;PCR扩增其16S rRNA基因和28S rRNA基因,并进行系统发育分析,以确定其分类学地位。结果该4株微生物在沙保氏葡萄糖琼脂培养基上培养3 d可形成灰白色、光滑、湿润的"酵母样真菌"菌落;光镜下观察可见大量圆形、卵圆形或椭圆形的孢子囊,且其内含内孢子,形似桑葚状或草莓状,与酵母菌的菌体形态差异显著;Vitek YST和MALDI-TOF MS系统,均鉴定为威克汉姆无绿藻。该4株微生物同时存在代表原核生物的16S rRNA基因以及代表真核生物的28S rRNA基因,其中,16S rRNA基因序列与威克汉姆无绿藻相似度最高,在99.7%以上;28S rRNA基因经克隆测序发现其存在多拷贝,且同一菌株不同克隆序列之间相似度在91.9%～100%。16S rRNA基因和28S rRNA基因系统发育分析均显示,该4株微生物与威克汉姆无绿藻聚类在同一个分枝。结论该4株微生物可鉴定为威克汉姆无绿藻,且单拷贝的小亚基16S rRNA更适合作为其菌种鉴定的靶基因。     

Staphylococcus pseudolugdunensis sp. nov., a pyrrolidonyl arylamidase/ornithine decarboxylase-positive bacterium isolated from blood cultures

Twelve coagulase-negative staphylococcal isolates recovered from blood cultures with positive pyrrolidonyl arylamidase and ornithine decarboxylase reactions were identified as Staphylococcus lugdunensis by the clinical microbiology laboratory. However, none of these 12 isolates were recognized by a S. lugdunensis translation elongation factor Tu (tuf) gene-specific probe. Under the API STAPH V4.0 identification system (bioMérieux, Durham, NC), 8 of these 12 isolates could not be identified with low discrimination scores, and 4 were identified as Kocuria varians/rosea with identification probabilities that ranged from 95.5% to 99.6%. All 12 isolates possessed identical partial 16S rRNA gene sequences, and the full 16S rRNA gene sequences of the prototype strain B006 were closely related to a tentatively assigned “Staphylococcus pettenkoferi”. All 12 isolates had identical partial tuf gene sequences corresponding to 666 to 858 nucleotide positions, and the 1188-base pair full tuf sequences of B006 strain were mostly related to 2 Staphylococcus epidermidis isolates with a 93.02% similarity. Two isolates, which were recovered from the same patient over a 16-day interval, were considered to be a pathogen causing an intravenous line-associated infection; the remaining 10 isolates were considered to be skin contaminants. Biochemical tests currently used in the clinical microbiology laboratory to identify S. lugdunensis appear to lack specificity in identifying these isolates. On the basis of the close biochemical reactions with S. lugdunensis and phylogenetic evidence, these isolates are proposed the designation Staphylococcus pseudolugdunensis sp. nov.     

First Korean Case of Robinsoniella peoriensis Bacteremia in a Patient with Aspiration Pneumonia

Robinsoniella peoriensis has recently been identified as a Gram-positive, spore-forming, anaerobic rod originally recovered from swine manure storage pits. To date, 6 cases of R. peoriensis infection have been reported, including 2 cases of bacteremia, 1 of abdominal fluid collection, and 3 of wound infection. In the present study, we report a 76-yr-old man with R. peoriensis bacteremia who developed aspiration pneumonia. Gram staining of a purified colony revealed Gram-positive, rod-shaped bacteria. Biochemical identification using API 20 A (bioMérieux, France) indicated presence of Clostridium spp. We performed both 500-bp and full-gene sequencing of 16S rRNA of the isolate. The sequence was analyzed with MicroSeq ID 16S rRNA Library v2.0 (Applied Biosystems, USA), GenBank Basic Local Alignment Search Tool (BLAST) (http://www.ncbi.nlm.nih.gov/genbank), and EzTaxon database v2.1 (http://www.eztaxon.org). The 500-bp 16S rRNA sequence of the blood culture isolate showed 99.16-99.79% similarity with R. peoriensis and the full-gene 16S rRNA sequence showed 98.87-99.50% similarity with R. peoriensis. The organism was confirmed as R. peoriensis by using all of the mentioned databases except for MicroSeq, which did not include the RNA sequence of this bacterium. This case suggests that identification of R. peoriensis might be challenging in clinical laboratories with no access to molecular methods, as certain commercial identification systems may not identify, or may misidentify, this organism. To the best of our knowledge, this is the first report of the isolation of R. peoriensis in Korea.     

Identification of oral bacteria by 16S rRNA gene analysis in elderly persons requiring nursing care

After incubation of saliva from 58 semi-bedridden elderly persons, the cultures were identified based on the 16S rRNA gene base sequence to compare the identification by the conventional culture method. As a result, the 16S rRNA gene base sequence of 198 strains identified by the culture method showed 98.5% or more homology in some of the Human Oral Microbiome database, and the identification of bacterial species and genus was possible. When an organism identified by the 16S rRNA gene sequencing method was compared with that by the culture method, the concordance rates were 54.5% at the genus level and 35.9% at the species level. Streptococcus mitis strains most frequently isolated from saliva that were identified by the culture method were identified as the same species by the 16S rRNA gene sequencing method (32/35), and all the 11 Streptococcus salivarius strains identified by the culture method were identified as the same species by the 16S rRNA gene sequencing method. All the strains identified as Streptococcus anginosus group by the culture method and 8 of the 9 strains identified as Prevotella species by the culture method were identified as the same group and genus by the 16S rRNA gene sequencing method. When an oral microbial flora test with saliva samples from elderly persons is performed, the 16S rRNA gene sequence identification enables us to identify major indigenous bacteria and pathogenic bacteria and is considered useful as a means of supplementing the conventional culture method.     

Comparative molecular and microbiological diagnosis of 19 infective endocarditis cases in which causative microbes were identified by PCR-based DNA sequencing from the excised heart valves

Infective endocarditis (IE) is traditionally diagnosed by microbiological analysis of blood cultures, following which therapeutic antibiotics are chosen based on antimicrobial sensitivity tests. However, such conventional techniques do not always lead to an accurate etiological diagnosis. Recently, PCR analysis of the 16S rRNA gene has been employed to identify organisms isolated from excised heart valves. In this study, we analyzed 19 valve samples from patients with confirmed IE, as identified by Duke's criteria. Using broad-range PCR amplification, followed by direct gene sequencing, pathological agents were identified in all samples. Although blood cultures yielded negative results in 4 cases, PCR analysis of valve samples showed positive identification of causative organisms. In 3 cases, there was a difference between blood culture and PCR in identification of pathological agents, which are likely to be misidentified by the conventional method based on the phenotypic database. Postoperative antibiotics were chosen considering the severity of lesions and the results of PCR, Gram staining, and valve cultures. All patients were cured without relapse. The broad-range PCR method was therefore beneficial for the management of IE because it enabled us to identify pathogens directly from the site of infection, even organisms that were difficult to culture or likely to be misidentified by the conventional culture method. Identification of the agents provided precise knowledge of the microbiological spectrum involved in the cases of IE.     

The usefulness of multiplex PCR for the identification of bacteria in joint infection

Background: The diagnosis of septic arthritis (SA) relies on synovial analysis and conventional culture. But, these methods lack of sensitivity and culture is time consuming to establish a definite diagnosis. This study evaluated a new multiplex PCR assay which entailed screening PCR for Gram typing and identification PCR for species identification using two primer mixes. Methods: A total of 80 synovial fluid samples from patients with suspected SA were collected. Culture, multiplex PCR, and 16S rRNA gene PCR were performed. Results: The analytical sensitivity of multiplex PCR assay was 10¹ CFU/ml for each type of bacteria. There was no cross‐reactivity with common bacterial pathogens. Bacteria were detected in 20, 25, and 26 of 80 samples for culture, multiplex PCR, and 16S rRNA gene PCR, respectively. Nineteen (95%) of 20 culture‐positivesamples and 6 (10%) of 60 culture‐negative samples were positive for the multiplex PCR. Five of six samples which were positive only from multiplex PCR were also positive in 16S rRNA gene PCR. The multiplex PCR showed 2 false‐negative in 27 true‐positive samples but no false‐positive. The sensitivity and specificity of the multiplex PCR were 92.6 and 100%, and the agreement with culture and 16S rRNA gene PCR were 91.3 and 96.3%, respectively. The time to detection for multiplex PCR was a maximum of 6 hr. Conclusion: This multiplex PCR assay offers high sensitivity and improved detection speed relative to culture. The appropriate combination of this new multiplex PCR assay with culture may contribute to the accurate and rapid diagnosis of SA. J. Clin. Lab. Anal. 24:175–181, 2010. © 2010 Wiley‐Liss, Inc.     

玫瑰单胞菌一株的鉴定及分析

目的 确定临床脓液标本中1株革兰阴性球杆菌K8756的分类学位置.方法 抽取患者深部脓肿物,置于Amies培养基室温保存、运输.脓液标本分区划线接种血平板、巧克力平板,置于35 ℃含5%CO2培养箱.采用API、Vitek2细菌鉴定系统,结合传统形态学检查、手工生化实验对分离株进行鉴定.从纯培养物提取脂肪酸、甲基化,采用气相色谱仪分析脂肪酸成分.PCR扩增16SrRNA基因并测序,对所测得的核酸序列进行同源性比对及系统发育分析.结果 血平板、巧克力平板分离到1株缓慢生长的革兰阴性球杆菌K8756.API 20NE生化编码为1245045(72 h),提示为人苍白杆菌;Vitek2 GN鉴定卡重复实验3次,提示为皮氏罗尔斯顿菌或支气管炎鲍特菌.但基于16SrRNA基因序列的系统发育分析表明,菌株K8756属于玫瑰单胞菌的成员,与该属的合格发表种黏液玫瑰单胞菌MDA5527T核酸匹配度高达100%(菌株K8756的GenBank登录号为GU207841).其菌落形态、表型特征及主要细胞脂肪酸成分亦与黏液玫瑰单胞菌相似.结论 菌株K8756(=GIMCC 1.0030)在分类学上属于黏液玫瑰单胞菌.16S rRNA基因序列分析是鉴定临床疑难菌株及新发现菌株的重要手段.

Abstract：

Objective To identify one runny mucoid-like Gram-negative bacteria with pink pigment isolated from clinical pus sample. Methods The pus sample was aseptically extracted from a deep lesions of one patient, then stored in Amies medium at room temperature for transportation. One sheep blood plate and one chocolate plate were used to detect the possible pathogens from the specimens. After inoculation, the plates were placed in a humidified incubator with 5% CO2 at 35 ℃. To identify the obtained isolates, we used the commercial Vitek2 and API systems, combining some traditional morphological examination and classical biochemical and physiological characteristics. For pure cultures, the cellular fatty acids were extracted, methylated, and determined by gas chromatography method. The 16S rRNA gene was amplified and sequenced by a commercial broad-spectrum PCR primers. The phylogenetic tree based on 16S rRNA gene was constructed by Mega 4.1 software using the neighbour-joining methods with 1 000 bootstrap replications. Results One runny mucoid-like Gram-negative bacterium, named K8756, was isolated both on sheep blood and chocolate plates after 72 h incubation. The API 20NE profile was 1245045 after a 3-day culture, which would be identified as Ochrobactrum anthropi with a good confidence of 98% probability. It was identified as Ralstonia pickettii and Bordetella bronchiseptica by VITEK 2 GN kits. However, further comparative 16S rRNA gene sequences showed that strain K8756 was closely related to the valid published Roseomonas mucosa MDA 5527 with 100% identity. Colonial morphologic features, phenotypic characteristics and major cellular fatty acid composition were also with high similarity to Roseomonas mucosa. Conclusions Strain K8756( = GIMCC 1.0030 ) is identified as Roseomonas mucosa by the polyphasic phenotypic and genotypic characteristics. The comparative analysis based on 16S rRNA gene sequences is a useful method for identifying the problematic and newly named bacteria.     

罕见豚鼠耳炎奴卡菌的鉴定及其药物敏感性分析

目的探讨罕见豚鼠耳炎奴卡菌的鉴定方法并评价其药物敏感性。方法采用形态、生理生化表型鉴定与16S rRNA序列分析相结合的方法鉴定菌株,使用微量肉汤法检测其药物敏感性。结果临床分离的奴卡菌被鉴定为豚鼠耳炎奴卡菌,其对哌拉西林、红霉素、头孢他啶、头孢哌酮、庆大霉素、头孢西丁、哌拉西林/他唑巴坦耐药,万古霉素、左氧氟沙星、亚胺培南、依替沙星、环丙沙星、阿米卡星、复方磺胺甲基异噁唑敏感。结论 16SrRNA基因序列分析法可用以鉴定豚鼠耳炎奴卡菌,磺胺类药物治疗有效。     

Two cases of bacteremia caused by Leptotrichia trevisanii in patients with febrile neutropenia

We present two cases of bacteremia caused by Leptotrichia trevisanii: a 12-year-old girl with recurrent myeloid leukemia of the mandible and a 66-year-old man with esophageal carcinoma. As this filamentous bacillus showed indefinite Gram staining and the identification based on biochemical enzymatic reactions was not definitive, identification required 16s rRNA analysis. For this organism, drug sensitivity testing showed susceptiblity to each β-lactam antibiotics and clindamycin, but resistance to fluoroquinolone and erythromycin. This filamentous bacillus needs careful identification and appropriate antibiotic treatment.     

The use of polymerase chain reaction to detect septicemia in critically ill patients.

OBJECTIVE: To describe the use of bacterial DNA amplification of conserved bacterial 16S ribosomal DNA nucleotide sequences by polymerase chain reaction (PCR) to detect the presence of septicemia in critically ill septic patients. DESIGN: Case series of blood samples from septic patients comparing the PCR results with conventional blood culture results. SETTING: A general intensive care unit in a tertiary referral hospital. PATIENTS: Two sets of samples (n = 101 and n = 55) from patients diagnosed as clinically septic and requiring blood cultures. They were classified by internationally accepted criteria into systemic inflammatory response syndrome, severe sepsis, and septic shock groups. INTERVENTIONS: Blood samples taken in a sterile fashion concurrently for blood culture, and PCR of the bacterial 16S ribosomal RNA gene in leukocytes and plasma. Two different DNA extraction techniques for PCR were tried sequentially. MEASUREMENTS AND MAIN RESULTS: Blood culture and PCR positivity were measured in relation to the clinical classification of severity of sepsis. Using the initial extraction method (n = 101), ten patients were positive by both PCR and blood culture, eight patients were PCR positive and blood culture negative, and seven patients were blood culture positive and PCR negative. From the clinical criteria, PCR detected at least six true positives that had been missed on blood culture and missed four true Gram-positive bacteremias. When the initial code was broken, this deficiency was rectified using the improved extraction technique (n = 55), in which ten patients were positive by PCR and blood culture, 29 patients were PCR positive and blood culture negative, and two patients were PCR negative and PCR positive. CONCLUSIONS: We conclude that the use of PCR (for the 16S ribosomal DNA in the plasma) was significantly more sensitive than the use of conventional blood culturing techniques for the detection of bacteremia in seriously ill patients. This could prove to be a valuable adjunct to conventional blood cultures.     

Catheter-related bloodstream infection by Microbacterium paraoxydans in a pediatric patient with B-cell precursor acute lymphocytic leukemia: A case report and review of literature on Microbacterium bacteremia

Microbacterium species are coryneform gram-positive rods that are widely distributed in the environment and have been recently recognized as rare pathogens in humans. However, information about the epidemiologic and clinical characteristics of Microbacterium species is scarce. We herein reported an 11-year-old girl with acute leukemia who was found to have catheter-related bloodstream infection in her neutropenic phase. Gram-positive bacilli repeatedly grew on the blood cultures and were later confirmed by 16S rRNA analysis as Microbacterium paraoxydans. A literature review found available clinical courses in 21 cases (7 pediatric cases) of Microbacterium spp. bacteremia. Our case and those in literature suggested that Microbacterium spp. bacteremia often occurs in patients with indwelling central venous catheters; the literature review further suggested that removal of central venous catheters is required in most cases and that 16S rRNA sequence was useful in identifying in detail the species of Microbacterium.     

Distinguishing coagulase-negative Staphylococcus bacteremia from contamination using blood-culture positive bottle detection pattern and time to positivity

AimDetection of coagulase-negative Staphylococcus in blood culture may be a result of either bacteremia or contamination. This often leads to diagnostic uncertainly. Our objective was to develop a method for differentiating whether a coagulase-negative Staphylococcus sp. positive blood culture represents bacteremia or contamination based on positive bottle detection pattern and time to positivity (TTP).MethodsThis study included 155 and 51 adults with positive blood cultures for Staphylococcus epidermidis and Staphylococcus hominis, respectively, over a three-year period from 2016 to 2018. Positive blood culture cases were categorized as either bacteremia or contamination based on the clinically available information, and the detection pattern and TTP in each category were investigated.ResultsA total of 57, 92, and 6 S. epidermidis positive blood cultures were categorized as bacteremia, contamination, and undetermined, respectively, whereas 15 and 36 S. hominis positive blood cultures were categorized as bacteremia and contamination, respectively. For positive blood cultures categorized as bacteremia, all four bottles in two sets of blood cultures were positive in 47/47 S. epidermidis and 14/14 S. hominis, respectively, whereas either one bottle in each of two sets or three bottles in two sets were positive in 10/19 S. epidermidis and 1/4 S. hominis, respectively; most of those TTPs were <48 h. Among them, the TTP in catheter-related blood stream infection was <24 h.ConclusionAlthough clinical assessment is crucial to differentiate between bacteremia and contamination, a combination of positive bottle detection pattern and TTP is a valuable diagnostic auxiliary tool.