Original articleEvaluation of the usefulness of a quantitative blood culture in the diagnosis of catheter-related bloodstream infection: Comparative analysis of two periods (2002 and 2012)Evaluación de la utilidad del hemocultivo cuantitativo en el diagnóstico de la bacteriemia relacionada con catéter: análisis comparativo de dos periodos (2002 y 2012)
Introduction
Intravascular catheters (IVCs) are commonly used in most medical centers. These devices are not only applied in hospitalized and emergency patients for administration of intravenous fluids or medication, but also in outpatients. A great variety of IVCs are available and all types are susceptible to colonization by microorganisms. The incidence of catheter-related bloodstream infection (CRBSI) is estimated at 0.1 to 5/1000 catheter-days.1, 2, 3, 4 Once a long-term catheter is successfully placed, attempts are made to maintain it as long as it is needed, as replacement is not without risk and another suitable vascular access may not be available.
Three methods are currently used for diagnosing CRBSI without removing the IVC: quantitative blood culture (pour plate method),5 semiquantitative blood culture (lysis-centrifugation),6, 7, 8, 9 and qualitative blood culture, using differential time to positivity on an automatic system.7, 8, 9, 10 Since 1988, quantitative blood culture (QBC) has been used in our center (sensitivity of 94%, specificity of 100%).5 The aims of this study are to determine the usefulness of this technique in two different periods: that is, to know what percentage of QBCs enable a microbiological diagnosis of CRBSI, to ascertain the IVC colonization rate in our setting, and to determine the percentage of CRBSI diagnoses that would have been missed if QBC had not been performed in all catheters or lumens in patients using several devices or IVCs with 2 or more lumens.
Section snippets
Material and methods
A retrospective observational study investigating the usefulness of our QBC method for the diagnosis of CRBSI was carried out in Vall d’Hebron Hospital (Barcelona, Spain), a 1000-bed reference hospital within the publically-funded health system. Two years were analyzed and compared: 2002 and 2012.
Results
A total of 4521 QBCs performed to investigate suspected CRBSI were included in the study, 1996 performed in 2002 (409 patients) and 2525 (1026 patients) in 2012. QBCs were positive in 24% (476/1996) in 2002 and 16% (415/2525) in 2012 (P < 0.0001). The larger number of QBCs performed in 2012 correspond to the Hematology Department (855 vs 638), Emergency Department (701 vs 45), and outpatient facilities (85 vs 10).
The percentage of positive QBCs in 2012 was found to have significantly decreased
Discussion
The present study, together with our previous one,5 has enabled us to confirm the continuing utility of the QBC technique applied in our hospital to diagnose or rule out CRBSI. Of particular note, the results illustrate the importance of obtaining samples from each and every lumen of the patient's IVCs to avoid missed diagnoses. Over the years we have continued to use the same criterion for the diagnosis of CRBSI: simultaneous QBCs in which the number of CFU/mL isolated from blood drawn from
Conflict of interest statement
The authors declare no conflict of interest.
Acknowledgments
The authors are grateful to the hospital nursing and the microbiology staff, to J.J. González-López for providing helpful comments during the writing of the manuscript and to C. Cavallo for language support.
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2019, Clinical Microbiology and InfectionCitation Excerpt :Current guidelines recommend obtaining two or more blood culture sets (BCSs) with 10 mL in each bottle [3] or obtaining two to three samples with 20–30 mL per set [1,2,4–7]. Data on the added value of the third BCS are scarce, and this potential increase in the recovery rate is not usually correlated with the mean blood volume obtained per set [8–10]. The standard of care for the diagnosis of BSI at our institution is to obtain three BCSs.
Intravascular Catheter–Related Bloodstream Infections
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2018, Medicina IntensivaCitation Excerpt :After inoculation, the blood and detergent should be gently mixed before centrifugation is performed. Another currently used method for diagnosing CRBSI is the pour plate method.57 Briefly, for each quantitative blood culture, 1–3 ml of blood is mixed with 20 ml of previously melted brain heart infusion agar at ∼56 °C in Petri plates, then the plates are incubated aerobically for 4 days at 35–37 °C.
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2018, Infection Control and Hospital Epidemiology