Purpose: Soluble Triggering Receptor Expressed on Myeloid cells-1 (sTREM-1) has proven to be a good biomarker for sepsis. For the diagnosis ventilator-associated pneumonia (VAP), however, there have only been a few, relatively small, studies on the role of this receptor. The aim of the study was to evaluate the usefulness of sTREM-1 in bronchoalveolar lavage fluid (BALF) from Intensive Care Unit patients as rapid diagnostic test for VAP. Methods: The concentration of sTREM-1 in 240 BALF samples was measured using a quantitative sandwich enzyme immunoassay. Two researchers who were blind to the assay results determined whether a VAP was present or not. Clinical suspicion of a VAP was confirmed by the presence of C2% cells containing intracellular organisms and/or a quantitative culture result of C10 4 colony forming units per millilitre BALF. Results: The mean concentration of sTREM-1 was significantly higher in the BALF of patients with confirmed VAP than in that of patients without confirmed VAP. However, the area under the receiveroperating characteristic curve was 0.58 (95% confidence interval 0.50-0.65, P = 0.04). Conclusions: The results imply that the sTREM-1 assay in BALF may not be discriminative for VAP.
BackgroundEarly administration of appropriate antibiotic therapy in bacteraemia patients dramatically reduces mortality. A new method for RApid Molecular Antibiotic Susceptibility Testing (RAMAST) that can be applied directly to positive blood cultures was developed and evaluated.Methodology/Principal FindingsGrowth curves and antibiotic susceptibility of blood culture isolates (Staphylococcus aureus, enterococci and (facultative) aerobic Gram-negative rods) were determined by incubating diluted blood cultures with and without antibiotics, followed by a quantitative universal 16S PCR to detect the presence or absence of growth. Testing 114 positive blood cultures, RAMAST showed an agreement with microbroth dilution of 96.7% for Gram-negative rods, with a minor error (false-susceptibility with a intermediate resistant strain) rate of 1.9%, a major error (false resistance) rate of 0.8% and a very major error (false susceptibility) rate of 0.6%. Agreement for S.aureus was 97.9%, with a very major error rate of 2.1%. Enterococcus species showed 95.0% agreement, with a major error rate of 5.0%. These agreements are comparable with those of the Phoenix system. Starting from a positive blood culture, the test was completed within 9 hours.Conclusions/SignificanceThis new rapid method for antibiotic susceptibility testing can potentially provide accurate results for most relevant bacteria commonly isolated from positive blood cultures in less time than routine methods.
BackgroundRapid identification (ID) and antibiotic susceptibility testing (AST) of the causative micro-organism of bloodstream infections result in earlier targeting of antibiotic therapy.In order to obtain results of ID and AST up to 24 hours earlier, we evaluated the accuracy of direct inoculation of the Phoenix system from positive blood cultures (BACTEC) by using Serum Separator Tubes to harvest bacteria from positive blood cultures. Results were compared to those of standard Phoenix procedure. Discrepancies between the two methods were resolved by using the API system, E-test or microbroth dilution.ResultsID with the direct method was correct for 95.2% of all tested Enterobacteriaceae (n = 42) and 71.4% of Pseudomonas aeruginosa strains (n = 7).AST with the direct method showed a categorical agreement for Gram-negative rods (GNR) of 99.0%, with 0.7% minor errors, 0.3% very major errors and no major errors. All antibiotics showed an agreement of >95%.The direct method for AST of Staphylococcus (n = 81) and Enterococcus (n = 3) species showed a categorical agreement of 95.4%, with a minor error rate of 1.1%, a major error rate of 3.1% and a very major error rate of 0.4%. All antibiotics showed an agreement of >90%, except for trimethoprim-sulfamethoxazole and erythromycin.ConclusionsInoculation of Phoenix panels directly from positive blood cultures can be used to report reliable results of AST of GNR a day earlier, as well as ID-results of Enterobacteriaceae. For Staphylococcus and Enterococcus species, results of AST can also be reported a day earlier for all antibiotics, except for erythromycin and trimethoprim-sulfamethoxazole.
Broad-range real-time PCR and sequencing of the 16S rRNA gene region is a widely known method for the detection and identification of bacteria in clinical samples. However, because of the need for sequencing, such identification of bacteria is time-consuming. The aim of our study was to develop a more rapid 16S real-time PCR-based identification assay using species-or genus-specific probes. The Gram-negative bacteria were divided into Pseudomonas species, Pseudomonas aeruginosa, Escherichia coli, and other Gram-negative species. Within the Gram-positive species, probes were designed for Staphylococcus species, Staphylococcus aureus, Enterococcus species, Streptococcus species, and Streptococcus pneumoniae. The assay also included a universal probe within the 16S rRNA gene region for the detection of all bacterial DNA. The assay was evaluated with a collection of 248 blood cultures. In this study, the universal probe and the probes targeting Pseudomonas spp., P. aeruginosa, E. coli, Streptococcus spp., S. pneumoniae, Enterococcus spp., and Staphylococcus spp. all had a sensitivity and specificity of 100%. The probe specific for S. aureus showed eight discrepancies, resulting in a sensitivity of 100% and a specificity of 93%. These data showed high agreement between conventional testing and our novel real-time PCR assay. Furthermore, this assay significantly reduced the time needed for identification. In conclusion, using pathogen-specific probes offers a faster alternative for pathogen detection and could improve the diagnosis of bloodstream infections.
Inadequate therapy in bloodstream infections is suggested to be associated with higher mortality. We evaluated the reduction in inappropriate antibiotic therapy using rapid identification and antibiotic susceptibility testing (FAST) compared to standard of care (SOC) testing in patients with bloodstream infections. The FAST method used polymerase chain reaction (PCR) for identification and to detect growth in the presence or absence of antibiotics after only 6 h. For SOC testing, the BD Phoenix system was used. Patients with blood cultures growing Staphylococcus, Streptococcus or Enterococcus species or Gram-negative rods were randomised for FAST or SOC tests. A total of 129 patients were randomised for FAST and 121 patients for the SOC group. At the time SOC results became available, 78 patients in the FAST group could have been switched to more appropriate therapy. Although FAST results were highly accurate (agreement with SOC was 94%), they were only implemented in a minority (16) of patients. However, significantly fewer patients in the FAST group used inappropriate therapy at the time of SOC results (p = 0.025). The time to results in the FAST group was reduced by 15.6 h (p < 0.001). In the patients switched after FAST, this was done after a mean of 42.3 h compared to 61.4 h in those switched after SOC tests (p < 0.001). In bacteraemic patients, FAST resulted in significantly more patients using appropriate antibiotic therapy at the time SOC results were available and 15.6 h earlier than SOC tests. However, the implementation of FAST results was not optimal and no benefit on clinical outcome was shown.
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