Clinical relevance of new diagnostic methods for bloodstream infections

Schrenzel, Jacques

doi:10.1016/j.ijantimicag.2007.06.030

Cited by 42 publications

(33 citation statements)

References 24 publications

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“…Nucleic acid amplification techniques offer superior sensitivity and can be designed to achieve almost universal species coverage or to provide additional information on antimicrobial susceptibility (16,34). But as for sequence-based identification directly from venipuncture blood (39), routine use in blood culture processing is impeded by complex sample handling and high assay costs. Various groups have successfully applied direct inoculation of biochemical typing systems for rapid pathogen identification from blood culture bottles.…”

Section: Discussionmentioning

confidence: 99%

Rapid Identification of Bacteria from Positive Blood Culture Bottles by Use of Matrix-Assisted Laser Desorption-Ionization Time of Flight Mass Spectrometry Fingerprinting

Martin¹,

Rohde²,

Wolters³

et al. 2010

J Clin Microbiol

272

200

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Early and adequate antimicrobial therapy has been shown to improve the clinical outcome in bloodstream infections (BSI). To provide rapid pathogen identification for targeted treatment, we applied matrix-assisted laser desorption-ionization time of flight (MALDI-TOF) mass spectrometry fingerprinting to bacteria directly recovered from blood culture bottles. A total of 304 aerobic and anaerobic blood cultures, reported positive by a Bactec 9240 system, were subjected in parallel to differential centrifugation with subsequent mass spectrometry fingerprinting and reference identification using established microbiological methods. A representative spectrum of bloodstream pathogens was recovered from 277 samples that grew a single bacterial isolate. Species identification by direct mass spectrometry fingerprinting matched reference identification in 95% of these samples and worked equally well for aerobic and anaerobic culture bottles. Application of commonly used score cutoffs to classify the fingerprinting results led to an identification rate of 87%. Mismatching mostly resulted from insufficient bacterial numbers and preferentially occurred with Gram-positive samples. The respective spectra showed low concordance to database references and were effectively rejected by score thresholds. Spiking experiments and examination of the respective study samples even suggested applicability of the method to mixed cultures. With turnaround times around 100 min, the approach allowed for reliable pathogen identification at the day of blood culture positivity, providing treatment-relevant information within the critical phase of septic illness.

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Section: Discussionmentioning

confidence: 99%

Rapid Identification of Bacteria from Positive Blood Culture Bottles by Use of Matrix-Assisted Laser Desorption-Ionization Time of Flight Mass Spectrometry Fingerprinting

Martin¹,

Rohde²,

Wolters³

et al. 2010

J Clin Microbiol

272

200

View full text Add to dashboard Cite

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“…In contrast, DNA-based procedures may offer faster and more reliable diagnoses (3,30). PCR amplification of microbial genes, followed by detection of amplified products by gel electrophoresis or real-time PCR monitoring using fluorescent dyes or target-directed fluorescent probes, is a quick process allowing pathogen detection within a few hours (18).…”

mentioning

confidence: 99%

“…PCR amplification of microbial genes, followed by detection of amplified products by gel electrophoresis or real-time PCR monitoring using fluorescent dyes or target-directed fluorescent probes, is a quick process allowing pathogen detection within a few hours (18). Identification of microorganisms can be performed by PCR algorithms, taxon-specific oligonucleotide microarrays, or sequencing amplicons (30).…”

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confidence: 99%

Diagnosis of Bacteremia in Whole-Blood Samples by Use of a Commercial Universal 16S rRNA Gene-Based PCR and Sequence Analysis

et al. 2009

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In a prospective, multicenter study of 342 blood samples from 187 patients with systemic inflammatory response syndrome, sepsis, or neutropenic fever, a new commercial PCR test (SepsiTest; Molzym) was evaluated for rapid diagnosis of bacteremia. The test comprises a universal PCR from the 16S rRNA gene, with subsequent identification of bacteria from positive samples by sequence analysis of amplicons. Compared to blood culture (BC), the diagnostic sensitivity and specificity of the PCR were 87.0 and 85.8%, respectively. Considering the 34 BC-positive patients, 28 were also PCR positive in at least one of the samples, resulting in a patient-related sensitivity of 82.4%. The concordance of PCR and BC for both positive and negative samples was (47 ؉ 247)/342, i.e., 86.0%. In total, 31 patients were PCR/sequencing positive and BC negative, in whom the PCR result was judged as possible or probable to true bacteremia in 25. In conclusion, the PCR approach facilitates the detection of bacteremia in blood samples within a few hours. Despite the indispensability of BC diagnostics, the rapid detection of bacteria by SepsiTest appears to be a valuable tool, allowing earlier pathogen-adapted antimicrobial therapy in critically ill patients.Bloodstream infection is a life-threatening condition with a high mortality rate, especially in intensive care and neutropenic patients (5,19,35,38). Pathogenic bacteria are the most frequent causes of bloodstream infection, although fungi can also be isolated in a minority of patients (7,17,21,32,34). Currently, inoculation of blood cultures (BC) is the standard method for microbiological diagnosis of bloodstream infections. However, the limitations of BC include relatively low sensitivities and a long time-to-result for detection and identification of the pathogen, generally over 2 days, and even longer for fastidious organisms (13,20,27).In contrast, DNA-based procedures may offer faster and more reliable diagnoses (3, 30). PCR amplification of microbial genes, followed by detection of amplified products by gel electrophoresis or real-time PCR monitoring using fluorescent dyes or target-directed fluorescent probes, is a quick process allowing pathogen detection within a few hours (18). Identification of microorganisms can be performed by PCR algorithms, taxon-specific oligonucleotide microarrays, or sequencing amplicons (30).PCR amplification of conserved regions of the bacterial genome, in particular the 16S rRNA gene, combined with sequence analysis is a well-established technique for the identification of bacterial pathogens (18). The main advantages of targeting the 16S rRNA gene are the broad range of pathogens detectable and the independence of this method from the in vitro viability of strains (6). The high sensitivity of detection by PCR of bacterial DNA (15) suggests its use in the diagnosis of bacteremia (16). Initial disadvantages of PCR, notably the incidence of false-positive results from bacterial DNA contaminating PCR reagents (4, 39), have been counteracted by the devel...

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“…The data pertaining to the origin and clinical significance of those "falsepositive" samples are often ambiguous and might result from yet-unknown host-pathogen interactions (24). Consequently, the usage of broad-range primers should be carefully balanced in favor of the detection of particular species.…”

Section: Discussionmentioning

confidence: 99%

Truncated Human Cytidylate-Phosphate-Deoxyguanylate-Binding Protein for Improved Nucleic Acid Amplification Technique-Based Detection of Bacterial Species in Human Samples

Sachse

Straube

Lehmann³

et al. 2009

J Clin Microbiol

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A trunk of human cytidylate-phosphate-deoxyguanylate-binding protein/CXXC finger protein 1 (CFP1), immobilized onto an aminohexyl-Sepharose column, can be used as a preanalytical tool for the selective enrichment of bacterial DNA from mixed solutions with high amounts of human background DNA for nucleic acid amplification technique-based detection of pathogens. The transcriptional activator protein exhibits a high affinity for nonmethylated CpG dinucleotide motifs, which are differentially distributed in prokaryotic and higher eukaryotic genomes. The feasibility of the affinity chromatography (AC) step was tested with DNA from severely septic patients. AC using 16S rRNA gene primers substantially increased PCR sensitivity. Approximately 90% of eukaryotic DNA was removed, which significantly increased the signal-to-noise ratio. Threshold cycle values revealed that sensitivity was elevated at least 10-fold. The change in the ratio of bacterial DNA to human DNA increased from 26% to 74% the likelihood of culture-independent PCR-based identification of bacterial presence. Compared to the results seen with blood culture (which is the clinical gold standard for systemic infections, exhibiting 28% positives), the combination of AC and PCR achieves a significant increase in sensitivity and contributes to shortening the time to results for the initiation of guided antibiotic therapy.The routine methods utilized in clinical microbiology laboratories, such as the demonstration of the presence of pathogens in samples from patients suspected of systemic infections, are predominantly culture based and exhibit drawbacks due to antibiotic treatment of the patient prior to sample withdrawal (e.g., from blood, wound swabs, or cerebrospinal fluid), low abundance of causative agents in exclusive samples, and, frequently, noncultivable or growth-repressed organisms. The gold standard, blood culture (BC), for example, returns negative results for 80% to 90% of all invasive infection incidents even when the presence of an infection is obvious from the medical history and additional clinical diagnostics. Cultural results usually take periods of 24 to 72 h to be obtained, whereas a sample can be reliably declared negative within up to 7 days' incubation (26, 27). These results are therefore only the basis for further microbial diagnostics, e.g., species differentiation and/or generation of antibacterial susceptibility profiles, which are also laborious and time-consuming processes. The derivation of an antibiotic therapy from the results obtained with the gold standard (e.g., in the case of sepsis) within the first "golden hours" would determine the course and prognosis for the case (17); however, such an approach is currently not feasible, while adequate (directed) and early antibiotic therapies are mandatory for the avoidance of mortal outcomes (7,8,11,28). In the case of sepsis, an increase of mortality of 7% to 8% per hour was proven after delay of adequate antibiotic treatment (12). Moreover, the rise in the rate of infective disea...

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Clinical relevance of new diagnostic methods for bloodstream infections

Cited by 42 publications

References 24 publications

Rapid Identification of Bacteria from Positive Blood Culture Bottles by Use of Matrix-Assisted Laser Desorption-Ionization Time of Flight Mass Spectrometry Fingerprinting

Rapid Identification of Bacteria from Positive Blood Culture Bottles by Use of Matrix-Assisted Laser Desorption-Ionization Time of Flight Mass Spectrometry Fingerprinting

Diagnosis of Bacteremia in Whole-Blood Samples by Use of a Commercial Universal 16S rRNA Gene-Based PCR and Sequence Analysis

Truncated Human Cytidylate-Phosphate-Deoxyguanylate-Binding Protein for Improved Nucleic Acid Amplification Technique-Based Detection of Bacterial Species in Human Samples

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