Related Experiment Video
Updated: Feb 8, 2026

Standardization of Basket Use in Sialendoscopy: A Ten-Year Retrospective Study
Published on: June 6, 2025
Estimation of missed bloodstream infections without the third blood culture set: a retrospective observational
A Collazos-Blanco1, F Pérez-García1, C Sánchez-Carrillo1
1Department of Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio Marañón, Madrid, Spain.
Objectives:
The question of whether to obtain two or three sets of blood cultures to assess the aetiology of bloodstream infections (BSIs) remains open to debate. Few studies have assessed the proportion of BSIs missed without the third blood culture set (BCS). The aim of our study was to determine the proportion of BSIs that would be missed without the third BCS in a hospital where obtaining three BCSs is the standard of care.
Methods:
We performed a descriptive retrospective study in Hospital Gregorio Marañón (Madrid) from 2010 to 2013. We included all episodes of BSI in which three BCSs were systematically obtained.
Results:
We included 4000 episodes of BSI between 2010 and 2013. Without the third BCS, we would have missed 298 (7.5%) episodes of BSI: 141 (47.3%) by gram-positive microorganisms, 147 (49.3%) by gram-negative microorganisms, and 10 (3.4%) by yeasts. In 132/298 (44.3%) of the episodes another clinical sample was obtained within a week of the BCS extraction; in 101/298 (33.9%), the same microorganism was present in a significant clinical sample other than blood.
Conclusions:
Our data suggest that performing a third BCS is useful, as not doing this could result in an unacceptable number of BSIs going undetected.
Related Concept Videos
Observational Studies
There are three types of observational studies – Prospective, retrospective, and cross-sectional.
Prospective Study
Prospective studies, also known as longitudinal or cohort studies, are carried out by collecting future data from groups sharing similar characteristics. One...
Naturalistic Observations
What are Estimates?
The estimate for the mean of a sample is denoted by ͞x, whereas the mean of the population is designated as μ. Further, parameters such...
Blood Studies I: ABG and VBG
Arterial Blood Gas (ABG)
Arterial Blood Gas (ABG) studies are crucial for assessing the lungs' ability to supply oxygen and remove carbon dioxide, reflecting the patient's ventilation status. They also help understand the kidneys' capacity to...
Estimation of k and VD of Aminoglycosides
Bioavailability Study Design: Single Versus Multiple Dose Studies

