Estimation of missed bloodstream infections without the third blood culture set: a retrospective observational single-centre study

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.

Association between source control and mortality in 258 patients with intra-abdominal candidiasis: a retrospective multi-centric analysis comparing intensive care versus surgical wards in Spain

Early empiric therapy and adequate resuscitation have been identified as main predictors of outcome in patients with candidemia or bacteremia. Moreover, source control is a major determinant in infectious sites when feasible, as a main technique to reduce microbiological burden. A retrospective, multicenter, cohort study was performed at surgical wards and intensive care units (ICU) of three University Hospitals in Spain between 2010 and 2014, with the aim of improving understanding of the interaction between source control, early antifungal therapy, and use of vasoactives in patients with intra-abdominal candidiasis (IAC). Source control was defined as all physical actions taken to control a focus of infection and reduce the favorable conditions that promote microorganism growth or that maintain the impairment of host defenses. Two hundred and fifty-eight patients with IAC were identified. Sixty-one patients were at ICU for diagnosis. Mortality was higher in the ICU group compared to what was documented for the non-ICU group (35 % vs 19.5 %, p = 0011). Adequate source control within 48 h of diagnosis was achieved in 60 % of the cohort. In multivariate analysis, inadequate source control was identified as the only common risk factor for 30-day mortality in both groups (ICU group OR: 13.78 (95% CI: 2.60-72.9, p = 0.002) and non-ICU group OR: 6.53 (95% CI: 2.56-16.61, p = <0.001). The population receiving both adequate source control and adequate antifungal treatment was the one associated with a higher survival rate, in both the ICU and surgical groups. Source control remains a key element in IAC, inside and outside the intensive care unit. Early antifungal treatment among ICU patients was associated with lower mortality.

An algorithm to diagnose influenza infection: evaluating the clinical importance and impact on hospital costs of screening with rapid antigen detection tests

Rapid antigen detection tests (RADTs) are immunoassays that produce results in 15 min or less, have low sensitivity (50 %), but high specificity (95 %). We studied the clinical impact and laboratory savings of a diagnostic algorithm for influenza infection using RADTs as a first-step technique during the influenza season. From January 15th to March 31st 2014, we performed a diagnostic algorithm for influenza infection consisting of an RADT for all respiratory samples received in the laboratory. We studied all the patients with positive results for influenza infection, dividing them into two groups: Group A with a negative RADT but positive reference tests [reverse transcription polymerase chain reaction (RT-PCR) and/or culture] and Group B with an initial positive RADT. During the study period, we had a total of 1,156 patients with suspicion of influenza infection. Of them, 217 (19 %) had a positive result for influenza: 132 (11 %) had an initial negative RADT (Group A) and 85 (7 %) had a positive RADT (Group B). When comparing patients in Group A and Group B, we found significant differences, as follows: prescribed oseltamivir (67 % vs. 82 %; p = 0.02), initiation of oseltamivir before 24 h (89 % vs. 97 %; p = 0.03), antibiotics prescribed (89 % vs. 67 %; p = <0.01), intensive care unit (ICU) admissions after diagnosis (23 % vs. 14 %; p = 0.05), and need for supplementary oxygen (61 % vs. 47 %; p = 0.01). An influenza algorithm including RADTs as the first step improves the time of administration of proper antiviral therapy, reduces the use of antibiotics and ICU admissions, and decreases hospital costs.