Blood stream infection (BSI),a blood-borne disease caused by microorganisms such as bacteria,fungi,and viruses,can lead to bacteremia,sepsis,and infectious shock,posing a serious threat to human life and health.Identifying the pathogen is central to the precise treatment of BSI.Traditional blood culture is the gold standard for pathogen identification,while it has limitations in clinical practice due to the long time consumption,production of false negative results,etc.Nanopore sequencing,as a new generation of sequencing technology,can rapidly detect pathogens,drug resistance genes,and virulence genes for the optimization of clinical treatment.This paper reviews the current status of nanopore sequencing technology in the diagnosis of BSI.
Humans ; Nanopore Sequencing ; Sepsis/diagnosis* ; Bacteremia/microbiology* ; Bacteria ; Blood Culture/methods*

Shewanella algae infections are rare in humans. Previously reported cases of S. algae have mainly been associated with direct contact with seawater. We report a case of primary S. algae bacteremia occurring after the ingestion of raw seafood in a patient with liver cirrhosis that presented a fulminent course of necrotizing fasciitis.
Bacteremia/*blood ; Fasciitis, Necrotizing/*microbiology ; Fatal Outcome ; Humans ; Korea ; Liver Cirrhosis/physiopathology ; Male ; Middle Aged ; Seafood/microbiology ; Sepsis/*microbiology ; Shewanella/*pathogenicity ; Vibrio/*pathogenicity ; Vibrio Infections/*blood

BACKGROUND: Optimal blood culture performance is critical for successful diagnosis and treatment of sepsis. To understand the status of blood culture, we investigated several aspects of the procedure at 9 university hospitals. METHODS: The process of ordering blood culture sets and sampling volume for adults and children was investigated from January 2010 to April 2010, while the positive rate of detection and growth of skin contaminants were compared in 2009. Microbial growth in aerobic and anaerobic bottles was investigated prospectively. RESULTS: A majority of the hospitals used 2 sets of bottles for adults and 1 bottle for children. The average blood volume in each set was 7.7 mL for adults and 2.1 mL for children. The positive rate of microorganisms was 8.0%, and the isolation rate of the normal flora of the skin was 2.1%. Bacterial growth rates in aerobic and anaerobic bottles only were 31.8% and 24.5% respectively. CONCLUSIONS: Ordering blood culture sets and sampling volumes did not comply with CLSI guidelines. However, the rate of positive cultures and skin contamination rates were acceptable. Anaerobic bottles are useful in enhancing the yield of microorganisms.
Adult ; Bacteremia/blood/*microbiology ; Bacteria, Aerobic/isolation & purification ; Bacteria, Anaerobic/isolation & purification ; Blood/microbiology ; Child ; Hospitals, University ; Humans ; Prospective Studies ; Republic of Korea ; Skin/microbiology

To study the pathogens incidences in cord blood and the efficiency of different detective methods, 60 samples were drawn and reserved from collected and processed cord blood, respectively. The BACTEC 9050 system, improved Martin/thioglycollate broth (22 degrees C) and thioglycollate broth (35 degrees C) were employed to detected bacteria (including fungus) at the same time. Two hundred and six cord blood serum samples were used to detect the HBV DNA and HCV RNA by molecular biology technique, HBsAg, Anti-HBC, Anti-HCV, Anti-HCMV-IgM, HTLV-1, HTLV-2, HIV-1 and HIV-2 by ELISA and RBC agglutination test were used to detect the TPHA. Results showed that using BACTEC 9050 system, the incidence of bacteria and fungus was 3.33% and 0% respectively in collected cord blood; in processed cord blood, the rates increased to 6.67% and 1.67%, respectively. The sensitivity of BACTEC 9050 was higher than that of Martin/thioglycollate broth (22 degrees C/35 degrees C) culture. In 206 serum samples, the positive rate of HBV DNA was 5.8%, HCV RNA was 2.4%, HBsAg was 2.4%, HCMV-IgM was 1.89%, HCV was 2.4% and Anti-HBC was 29.4%. In those samples that Anti-HBC was positive, the positive rate of HBV DNA was 6.7%. It was concluded that the incidences of microbiological contamination in cord blood were high. The routine culture system would lead to false negative results of obligate anaerobes. It was necessary to replace the current culture system with improved system, such as BACTEC 9050 system. The molecular biology technique would make up for the default of ELISA.
Bacteremia ; epidemiology ; Blood Specimen Collection ; Fetal Blood ; microbiology ; virology ; Fungemia ; epidemiology ; Humans ; Polymerase Chain Reaction ; Probability ; Viremia ; epidemiology

INTRODUCTIONThe aim of this study was to externally validate the Cham score for the prediction of bacteraemia in emergency department (ED) patients with non-hospital acquired pneumonia.

MATERIALS AND METHODSThis is a secondary analysis of a dataset collected to identify independent predictors of bacteraemia in adult ED patients with non-hospital acquired pneumonia. The primary outcome of interest was the predictive performance (sensitivity, specificity, negative predictive value) of the score with respect to bacteraemia. Secondary outcomes included the performance of the score in patients not known to be intravenous (IV) drug users, the predictive performance of pneumonia severity index (PSI) class IV/V and PSI class IV/V or IV drug use as predictors and the clinical impact of score application on test ordering. Data analysis was by clinical performance and receiver operator characteristic curve analysis.

RESULTSA total of 200 patients were studied; 14 true positive blood cultures (7%, 95% CI, 4% to 11%). The Cham score had a sensitivity of 92.9% (95% CI, 64.2% to 99.6%), specificity of 26.3% (95% CI, 20.3% to 33.4%) and negative predictive value (NPV) of 98% (87.0% to 99.9%). Area under the receiver operating characteristic (ROC) curve was 0.71 (95% CI, 0.56 to 0.86). Using PSI class IV/V or known IV drug use as predictors had sensitivity of 92.9% (95% CI, 64.2% to 99.6%), specificity of 51.1% (95% CI, 43.7% to 58.4%) and NPV of 99% (95% CI, 93.5% to 99.9%).

CONCLUSIONIn retrospective external validation, the Cham score performed better than in derivation with acceptable sensitivity and NPV. Simplified criteria (PSI class IV/V or known IV drug use), as yet not validated, had similar sensitivity and NPV but would avoid blood cultures in a higher proportion of patients.

Aged ; Aged, 80 and over ; Bacteremia ; blood ; diagnosis ; Bacteriological Techniques ; utilization ; Emergency Service, Hospital ; Female ; Hematologic Tests ; utilization ; Humans ; Male ; Middle Aged ; Pneumonia, Bacterial ; blood ; microbiology ; Retrospective Studies

BACKGROUND: Panton-Valentine leukocidin (PVL) is a pore-forming toxin secreted by some Staphylococcus aureus strains and associated with skin and soft tissue infections; these strains are epidemiologically associated with current outbreaks of community-acquired methicillin-resistant S. aureus (MRSA) and with necrotizing pneumonia in healthy adults in USA and Europe. This study was performed to investigate the presence of PVL-positive S. aureus and the significant infections known to be caused by this organism. METHODS: A total of 573 strains of S. aureus blood isolates at university-affiliated hospital during 2002 to 2005 were selected. The presence of PVL was investigated using PCR. Additional 12 staphylococcal toxin genes were also examined in PVL-positive S. aureus strains, and MRSA isolates were typed for the staphylococcal cassette chromosome mec (SCCmec). RESULTS: PVL genes were detected in 5 (0.9%) of 573 S. aureus strains, including 1 MRSA and 4 MSSA. The PVL-positive MRSA isolate was SCCmec type IV, and no other staphylococcal toxins were detected. The median age of the patients infected with PVL-positive S. aureus was 36 yr. Three cases of bacteremia were preceded by skin and soft-tissue infections. CONCLUSIONS: Bacteremia caused by PVL-positive S. aureus strain were detected in 5 patients in Korea, and some of the patients were associated with severe skin and soft-tissue infections. In addition, the PVL-positive MRSA strain of SCCmec type IV, a characteristic of community-acquired MRSA isolates in USA and Europe, also exists in Korea, and can cause the severe infections known to be associated with this organism.
Adult ; Bacteremia/*microbiology ; Bacterial Proteins/genetics ; Bacterial Toxins/*blood ; Exotoxins/*blood ; Female ; Humans ; Korea ; Leukocidins/*blood ; Male ; Methicillin/pharmacology ; Methicillin Resistance/drug effects ; Middle Aged ; Polymerase Chain Reaction/methods ; Staphylococcal Infections/*microbiology ; Staphylococcus aureus/genetics/*isolation & purification

BACKGROUND: Panton-Valentine leukocidin (PVL) is a pore-forming toxin secreted by some Staphylococcus aureus strains and associated with skin and soft tissue infections; these strains are epidemiologically associated with current outbreaks of community-acquired methicillin-resistant S. aureus (MRSA) and with necrotizing pneumonia in healthy adults in USA and Europe. This study was performed to investigate the presence of PVL-positive S. aureus and the significant infections known to be caused by this organism. METHODS: A total of 573 strains of S. aureus blood isolates at university-affiliated hospital during 2002 to 2005 were selected. The presence of PVL was investigated using PCR. Additional 12 staphylococcal toxin genes were also examined in PVL-positive S. aureus strains, and MRSA isolates were typed for the staphylococcal cassette chromosome mec (SCCmec). RESULTS: PVL genes were detected in 5 (0.9%) of 573 S. aureus strains, including 1 MRSA and 4 MSSA. The PVL-positive MRSA isolate was SCCmec type IV, and no other staphylococcal toxins were detected. The median age of the patients infected with PVL-positive S. aureus was 36 yr. Three cases of bacteremia were preceded by skin and soft-tissue infections. CONCLUSIONS: Bacteremia caused by PVL-positive S. aureus strain were detected in 5 patients in Korea, and some of the patients were associated with severe skin and soft-tissue infections. In addition, the PVL-positive MRSA strain of SCCmec type IV, a characteristic of community-acquired MRSA isolates in USA and Europe, also exists in Korea, and can cause the severe infections known to be associated with this organism.
Adult ; Bacteremia/*microbiology ; Bacterial Proteins/genetics ; Bacterial Toxins/*blood ; Exotoxins/*blood ; Female ; Humans ; Korea ; Leukocidins/*blood ; Male ; Methicillin/pharmacology ; Methicillin Resistance/drug effects ; Middle Aged ; Polymerase Chain Reaction/methods ; Staphylococcal Infections/*microbiology ; Staphylococcus aureus/genetics/*isolation & purification

This study was purposed to evaluate the diagnostic value of procalcitonin (PCT), C-reactive protein, interleukin-6 (IL-6), serum amyloid A (SAA) for bacteremia in patients with hematologic malignancy combined with febrile neutropenia. The total of 297 patients with hematologic malignancy combined with febrile neutropenia were analyzed retrospectively from 1253 patients admitted to West China hospital of Sichuan University from March 2011 to October 2012. They were divided into sepsis group (n = 95) and non-sepsis group (n = 202) according to blood culture. The results showed that the levels of PCT, CRP, IL-6 and SAA in sepsis group were higher than those in non-sepsis group, and there was statistically significant difference between these two groups (P < 0.05). The PCT had an AUC value of 0.974 (P < 0.05), and obviously higher than that of CRP (AUC = 0.681, P < 0.05), IL-6 (AUC = 0.661, P < 0.05) and SAA (AUC = 0.605, P < 0.05). When PCT had cut-off value of 1.06 ng/ml, sensitivity of 95.8%, specificity of 92.1%, and the Youden indicator of 0.879, the negative and positive predictive values were 97.8% and 85.0% respectively, the negative and positive likelihood ratios were 0.05 and 12.5 respectively, and all significantly higher than that of CRP, IL-6 and SAA. It is concluded that for patients with hematologic malignancy combined with febrile neutropenia and bacterial infection, the diagnostic value of serum PCT is superior to that of immune inflammatory factors (CRP, IL-6 and SAA), the PCT can predict the bacterium infection, provide laboratory evidence for rational antimicrobial drug usage and mortality reduction.
Adult ; Bacteremia ; diagnosis ; etiology ; C-Reactive Protein ; metabolism ; Calcitonin ; blood ; Calcitonin Gene-Related Peptide ; Febrile Neutropenia ; complications ; microbiology ; Female ; Hematologic Neoplasms ; complications ; microbiology ; Humans ; Interleukin-6 ; blood ; Male ; Middle Aged ; Protein Precursors ; blood ; Retrospective Studies ; Serum Amyloid A Protein ; metabolism

PURPOSE: Procalcitonin (PCT) is a current, frequently used marker for severe bacterial infection. The aim of this study was to assess the ability of PCT levels to differentiate bacteremic from nonbacteremic patients with fever. We assessed whether PCT level could be used to accurately rule out a diagnosis of bacteremia. MATERIALS AND METHODS: Serum samples and blood culture were obtained from patients with fever between August 2008 and April 2009. PCT was analyzed using a VIDAS(R) B.R.A.H.M.S PCT assay. We reviewed the final diagnosis and patient histories, including clinical presentation and antibiotic treatment. RESULTS: A total of 300 patients with fevers were enrolled in this study: 58 with bacteremia (positive blood culture) (group I); 137 with local infection (group II); 90 with other diseases (group III); and 15 with fevers of unknown origin (group IV). PCT levels were significantly higher in patients with bacteremia than in those with non-bacteremia (11.9 +/- 25.1 and 2.5 +/- 14.7 ng/mL, respectively, p < 0.001). The sensitivity and specificity were 74.2% and 70.1%, respectively, at a cut-off value of 0.5 ng/mL. A serum PCT level of < 0.4 ng/mL accurately rules out diagnosis of bacteremia. CONCLUSION: In febrile patients, elevated PCT may help predict bacteremia; furthermore, low PCT levels were helpful for ruling out bacteremia as a diagnosis. Therefore, PCT assessment could help physicians limit the number of prescriptions for antibiotics.
Bacteremia/blood/*diagnosis ; Biological Markers/blood ; C-Reactive Protein/analysis ; Calcitonin/*blood ; Early Diagnosis ; Female ; Fever/blood/*diagnosis/etiology ; Fever of Unknown Origin/blood/diagnosis/microbiology ; Humans ; Male ; Middle Aged ; Protein Precursors/*blood ; Sensitivity and Specificity ; Young Adult

Bacteremia induced by periodontal infection is an important factor for periodontitis to threaten general health. P. gingivalis DNA/virulence factors have been found in the brain tissues from patients with Alzheimer's disease (AD). The blood-brain barrier (BBB) is essential for keeping toxic substances from entering brain tissues. However, the effect of P. gingivalis bacteremia on BBB permeability and its underlying mechanism remains unclear. In the present study, rats were injected by tail vein with P. gingivalis three times a week for eight weeks to induce bacteremia. An in vitro BBB model infected with P. gingivalis was also established. We found that the infiltration of Evans blue dye and Albumin protein deposition in the rat brain tissues were increased in the rat brain tissues with P. gingivalis bacteremia and P. gingivalis could pass through the in vitro BBB model. Caveolae were detected after P. gingivalis infection in BMECs both in vivo and in vitro. Caveolin-1 (Cav-1) expression was enhanced after P. gingivalis infection. Downregulation of Cav-1 rescued P. gingivalis-enhanced BMECs permeability. We further found P. gingivalis-gingipain could be colocalized with Cav-1 and the strong hydrogen bonding between Cav-1 and arg-specific-gingipain (RgpA) were detected. Moreover, P. gingivalis significantly inhibited the major facilitator superfamily domain containing 2a (Mfsd2a) expression. Mfsd2a overexpression reversed P. gingivalis-increased BMECs permeability and Cav-1 expression. These results revealed that Mfsd2a/Cav-1 mediated transcytosis is a key pathway governing BBB BMECs permeability induced by P. gingivalis, which may contribute to P. gingivalis/virulence factors entrance and the subsequent neurological impairments.
Animals ; Rats ; Bacteremia/metabolism* ; Blood-Brain Barrier/microbiology* ; Caveolin 1/metabolism* ; Gingipain Cysteine Endopeptidases/metabolism* ; Permeability ; Porphyromonas gingivalis/pathogenicity* ; Transcytosis ; Virulence Factors/metabolism*