High medical impact of implementing the new polymeric bead-based BacT/ALERT® FAPlus and FNPlus blood culture bottles in standard care

Impact of 24/7 loading of blood culture bottles in a new automated incubator on the diagnosis of bloodstream infections

Blood culturing (BC) remains the gold standard for bloodstream diagnosis but its workflow is slow. We aimed reducing this time by implementing a new automated incubator with a 24/7 BC workflow. With this new strategy, time to incubation was shorter (1.52 h vs 6.82 h), positivity rates were higher (10.6% vs 8.9%, p<0.05), and the number of BSI diagnostics increased (16.1% vs 13.8% patients and 2.3 vs 1.9 density episode per 1000 hospital days). Our results show that implementing automatic loading of BC bottles with a 24/7 strategy not only shortened time to diagnosis but significantly increased the BSI diagnosis rate.

Clinical evaluation of FAPlus/FNPlus bottles compared with the combination of SA/SN and FA/FN bottles in the BacT/Alert blood culture system

Background : The comparison of the performance of FAPlus/FNPlus bottles and combination of SA/SN and FA/FN bottles is not yet reported. Methods : We used human blood samples to investigate microorganism detection rates and the time to positivity (TTP) in a before-vs.-after study (a combination of SA/SN and FA/FN bottles from September 2012 to August 2013 vs. FAPlus/FNPlus bottles from September 2013 to August 2014). Results : The microorganism detection rate was significantly higher in the later period than in the earlier period (11.2% vs. 9.6%, P < 0.001), particularly for Enterococcus and Streptococcus species, nonfermentative Gram-negative bacilli, and Helicobacter cinaedi. TTP for pathogens was longer when FAPlus/FNPlus bottles were used than when a combination of SA/SN and FA/FN bottles was used (14.9 vs. 13.3 h, P = 0.014), particularly, in the case of Gram-negative bacilli including Escherichia coli. Conclusion : The microorganism detection rate was improved with the use of FAPlus/FNPlus bottles compared with the combination of SA/SN and FA/FN bottles ; however, FAPlus/FNPlus bottles seemed to be inferior to SA/SN and FA/FN bottles in terms of TTP. J. Med. Invest. 67 : 90-94, February, 2020.

Comparison of the Performance of Three Blood Culture Systems in a Chinese Tertiary-Care Hospital

In this study, we evaluated the performance of three blood culture systems in a Chinese tertiary-care hospital. Samples of simulated bacteremia were prepared using 10 mL of fresh blood from healthy humans and bacterial suspensions of known cell density. Portions of the specimens were treated with an antibiotic or antifungal drug at specified concentrations to simulate antibacterial drug treatment. We analyzed three blood culture systems: BACTEC Plus, BacT/Alert, and VersaTREK. Both time-to-detection (TTD) of 10 types of bacteria and five types of yeasts in samples without antibiotic treatment and positive detection rate of samples treated with different concentrations of antibiotic or antifungal drugs were compared among the culture systems. We also retrospectively analyzed the use of the culture systems in our hospital from 2015 to 2018. In the simulated study, in the absence of antibiotics, the VersaTREK REDOX 1 displayed the shortest TTD for Pseudomonas aeruginosa, Haemophilus influenzae, Staphylococcus aureus, Streptococcus pneumoniae, Candida albicans, and Candida glabrata (P < 0.001). Among the anaerobically cultured samples, BACTEC lytic/10 anaerobic/F displayed the shortest TTD for Escherichia coli, S. aureus, Enterococcus faecalis, S. pneumoniae, Bacteroides fragilis, and Bacteroides vulgatus (P < 0.001). Comparatively, BacT/Alert FA/FN showed no advantages. In antibiotic-treated samples, overall recovery rates for the BACTEC, BacT/Alert, and VersaTREK systems were, were 70.2, 43.7, and 27.4%, respectively. BACTEC facilitated higher recovery rate than the other two systems (P < 0.001). In antifungal treatment, the overall recovery rates for the BACTEC, BacT/Alert, and VersaTREK systems were 93.9, 98.3, and 69.4%, respectively. BACTEC Plus showed a recovery rate comparable to that of BacT/Alert (P = 0.835), and the recovery rate of both these systems was higher than that of VersaTREK (P < 0.001). The TTD values and positive rates determined in the retrospective study were consistent with those obtained in the simulated study. The combination of BACTEC PLUS Aerobic/F and BACTEC lytic/10 anaerobic/F culture systems displayed the best clinical performance. Furthermore, the BacT/Alert FAN culture system was found to be more resistant to antifungal drugs and levofloxacin, whereas the VersaTREK system is considered more suitable for primary blood cultures without antibiotic supplementation.

Multicenter Clinical Evaluation of BacT/Alert Virtuo Blood Culture System

BacT/Alert Virtuo is an advanced, automated blood culture system incorporating improved automation and an enhanced detection algorithm to shorten time to detection. A multicenter study of the investigational Virtuo system (bioMérieux, Inc., Durham, NC) compared to BacT/Alert 3D (BTA3D) for detection of bacteremia/fungemia in four bottle types, SA and FA Plus (aerobic) and SN and FN Plus (anaerobic), was performed in a clinical setting with patient samples in a matched system design clinical trial. Blood was added to paired aerobic or anaerobic bottles, with the volume in each bottle in each pair required to be ≤10 ml and with the volumes required to be within 30% of each other. Of 5,709 bottle sets (52.5% aerobic pairs and 47.5% anaerobic pairs), 430 (7.5%) were positive for bacterial or fungal growth, with 342 (6.0%) clinically significant and 83 (1.5%) contaminated. A total of 3,539 sets (62.0%) were volume compliant, with 203 sets (5.7%) clinically significant. The positivity rates for volume-compliant bottle pairs determined by the two systems were comparable, with 68.7% of clinically significant isolates detected by both instruments, 15.7% by Virtuo only, and 15.7% by BTA3D only. Virtuo detected microbial growth nearly 2 h sooner overall than BTA3D (mean, 15.9 h versus 17.7 h). Shorter time to detection by Virtuo was related to organism group, with the time to detection being significantly shorter for enteric Gram-negative bacilli and enterococci (means, 3.6 h and 2.3 h shorter, respectively). This large clinical study demonstrated that the Virtuo blood culture system produced results comparable to those seen with the long-established BTA3D system, with significantly shorter time to detection.

Performance of two blood culture systems to detect anaerobic bacteria. Is there any difference?

We studied the performance characteristics of two blood culture (BC) bottles/systems, (i) BacT/ALERT-FN Plus/3D (bioMérieux, Marcy l'Étoile, France) and (ii) BACTEC-Lytic/9000 (Becton Dickinson, Sparks, USA) for detection of growth and time-to-positivity (TTP) against a balanced and diverse collection of anaerobic bacterial strains (n = 48) that included reference strains (n = 19) and clinical isolates (n = 29) of 32 species (15 Gram-negative and 17 Gram-positive). Standard suspension of bacteria was inoculated to each bottle in duplicates and incubated in the corresponding system. Overall, 62.5% (n = 30) of strains were detected by both BC bottle types. Comparing the two, 70.8% (n = 34) and 79.2% (n = 38) of strains were detected by BacT/ALERT-FN Plus and BACTEC-Lytic bottles, respectively (p = 0.38). Among Gram-negative anaerobes (n = 25) the detection rate was 76.0% (n = 19) vs. 92.0% (n = 23) (p = 0.22), respectively. Among Gram-positive anaerobes (n = 23) the detection rate was 65.2% (n = 15) in both bottles (p = 1). The average TTP per bottle was calculated only for the strains detected by both systems (n = 30) and was 40.85 h and 28.08 h for BacT/ALERT-FN Plus and BACTEC-Lytic, respectively (p < 0.001). The mean difference was 12.76 h (95% CI: 6.21-19-31 h). Six anaerobic strains were not detected by any system, including Gram-negative Porphyromonas gingivalis, and five Gram-positive strains: Finegoldia magna, Peptostreptococcus anaerobius, Propionibacterium acnes, Clostridium novyi and Clostridium clostridioforme. Furthermore, Eggerthella lenta and Prevotella bivia were detected only by BacT/ALERT-FN Plus, while Prevotella disiens and Prevotella intermedia were detected only by BACTEC-Lytic bottles. There were no major differences in detection rate among clinical and reference strains. Anaerobic bacteria represent a minority of BC isolates, however, far from ideal detection rate was observed in this study for both tested bottle/system combinations. Nevertheless, in those cases where both gave positive signal, BACTEC-Lytic was superior to BacT/ALERT FN Plus with 12.76 h shorter mean TTP. Improvements of media in blood culture bottles available for detection of anaerobes are warranted.

Comparison of BacT/Alert FAN and FAN Plus Bottles with Conventional Medium for Culturing Cerebrospinal Fluid

We compared the BacT/Alert system FAN and FAN Plus media to conventional media for culturing cerebrospinal fluid (CSF) with 2,545 samples. FAN/FAN Plus bottles showed better performance for isolating microorganisms in CSF than conventional media (positive rate, 7.2% [182/2,545] versus 3.1% [80/2,545]). The incremental recovery rate of Cryptococcus neoformans from FAN Plus bottles was higher than that from FAN bottles.

Performance of BacT/Alert resin-based FN plus bottles compared with BacT/Alert charcoal-based FN bottles for the detection of anaerobes in experimentally seeded blood cultures

Recently new resin-based BacT/Alert FAN Plus bottles containing antibiotic-binding polymeric beads, were introduced as an improvement of the charcoal-based FAN bottles for the recovery of bacteria and fungi. To assess the performance of the novel anaerobic FN plus bottles in the detection of anaerobic organisms, we compared the detection rate and the time to detection (TTD) in spiked resin-based FN Plus bottles and charcoal-based FN bottles. The bottles were experimentally seeded with reference strains or clinical strains collected from positive blood cultures. Five reference strains and fifty-five clinically significant anaerobic isolates were investigated, of which 91% (61/67) showed growth in both types of bottles within an incubation time of 5 days. A significant prolonged median TTD of 45 h for anaerobic microorganisms was observed in the resin-based bottles versus 29 h in the charcoal-based bottles (P < 0.0001). Bacteroides spp., associated with higher virulence and higher mortality rates in bloodstream infections, were detected faster in the charcoal-based bottles as compared to the resin-based bottles. In conclusion recently improved resin FN bottles showed a significantly increased median TTD for the recovery of anaerobic isolates.