Quality indicators for blood culture: 1 year of monitoring with BacT/Alert Virtuo at a French hospital

Abstract

Introduction. Blood culture (BC) remains the gold standard for the diagnosis of bloodstream infection. Clinical microbiology laboratories must ensure the quality of their BC process from receipt to definitive results. Aim. In this study, we followed the evolution of different quality indicators for BCs over the first year of implementation of the BacT/Alert Virtuo system in a French hospital. Methodology. In our laboratory, we instituted regular monitoring of several quality indicators to track (i) delays in sample registration, (ii) delays in loading BC bottles in our incubating system (BacT/Alert Virtuo) after registration, (iii) the volume of blood in bottles and (iv) the contamination rates. Results. For 53 892 BC bottles loaded in the BacT/Alert Virtuo from 23 January to 31 December 2019, the delays in sample registration, loading and unloading were respectively 3.5 h±0.016, 44 min±0.209 and 5.8 h±0.0727. Intriguingly, the automated process performed by the BacT/Alert Virtuo system to check the blood volume in bottles was only performed for 60 % of the loaded bottles. Among these, 30 % contained the recommended volume of blood (between 7 and 13 ml). Finally, the contamination rate was found to be 27.2 % for samples at our institution. Conclusions. The delays in sample registration, loading and unloading were found to be acceptable, even though they could be improved by ensuring a continuous service during the night duty period. Furthermore, the percentage of volumes measured is insufficient and must be improved and the majority of bottles do not contain the recommended blood volume.

Factors impacting the pre-analytical quality of blood cultures—Analysis at a tertiary medical center

“…Only 36.3% of collected BC bottles fulfilled the recommended BC filling volumes of 8 to 10 mL per bottle. Similar results have been shown in previous studies [6,[17][18][19].…”

Subculturing and Gram staining of blood cultures flagged negative by the BACTEC™ FX system: Optimizing the workflow for detection of Cryptococcus neoformans in clinical specimens

“…Because bacteremia and fungemia are life-threatening infections, the detection and identification of microorganisms from blood are crucial. Blood culture is commonly based on the measurement of CO 2 production, such as with the BACTEC™ FX (BD Diagnostics) system ( Chang et al, 2015 ; Peretz et al, 2015 ), or the measurement of CO 2 -derived pH changes, such as with the BacT/ALERT system (bioMérieux; Kim et al, 2015 ; Jacobs et al, 2017 ; Emeraud et al, 2021 ), by which 99% of positive Aerobic/F and Anaerobic/F bottles with BacT/Alert Virtuo (Virtuo) blood culture detection system are confirmed to be positive within 5 days ( Ransom et al, 2021 ). However, false-negative results can arise when the incubation time is set to 5 or 7 days, because of slowly proliferating microorganisms ( Peretz et al, 2015 ), insufficient blood volume ( Kim et al, 2015 ), or prior use of antimicrobial agents ( Houpikian and Raoult, 2005 ).…”

Changing culture: An intervention to improve blood culture quality in the emergency department

“…Underfilled BC bottles were defined as those containing ≤7 mL; this effectively allowed a margin of up to 1 mL below the published 8-10 mL recommended range as previously described. 6,13 Positive BCs were classified as either false positive (contaminant) or true positive (indicating bacteraemia) according to accepted methods 7,14 and specialist infectious disease input as documented in clinical records. For all study patients, data including demographics, presumed source of infection, key investigation results, disposition and mortality were obtained from relevant hospital records.…”