BACKGROUND
Bloodstream infections (BSI) pose a significant threat due to high mortality rates and the challenges posed by antimicrobial resistance (AMR). In 2019, an estimated 4.95 million deaths were linked to bacterial AMR. The highest impact was seen in resource-limited settings (RLS). For diagnosis of BSI, performant continuously-monitoring blood culture systems (CMBCS) have been optimized. However, in RLS, the implementation of CMBCS is hindered by budget constraints and unsuitable environmental conditions. Manufacturers from growing economies are currently producing affordable in vitro diagnostics, which could fill the gap in capacity, but so far these are not established outside their domestic markets.

METHODS
This study evaluated the performance, usability, and interchangeability of Chinese CMBCS in a laboratory setting using simulated blood cultures with a panel of 20 BSI-associated strains. Four systems were selected for the assessment: Autobio BC60, Mindray TDR60, Scenker Labstar50, and DL-biotech DL-60.

FINDINGS
Overall, all evaluated CMBCS demonstrated good performance with high yield (96.7-100%) and specificity (97.5-100%), comparable to the reference system (bioMérieux 3D). In addition, when used as "manual" blood cultures in a conventional incubator with visual growth detection, performance was also satisfactory: yield was between 90 and 100% and specificity was 100% for all BCBs. Both the CMBCS and the BCBs were easy to use and lot-to-lot variability in BCBs was minimal. The interchangeability testing indicated that the BCBs from different brands (all except Scenker) were compatible with the various automates, further highlighting the potential for a harmonized "universal BCB."

INTERPRETATION
Based on this in vitro study, we recommend the use of these systems in settings with challenging environments and limited resources. The Autobio system performed best for automatic detection and DL-Biotech BCBs for manual cultures respectively (combination of performance, price, usability). The appropriateness for use in RLS should still be confirmed in a field study.

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Affordable blood culture systems from China: in vitro evaluation for use in resource-limited settings