Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Comparison of Multiple Carbapenemase Tests Based on an Unbiased Colony Selection Method

Version 1 : Received: 20 December 2023 / Approved: 21 December 2023 / Online: 21 December 2023 (10:27:01 CET)

How to cite: Wang, H.-Y.; Tseng, Y.-J.; Lin, W.-Y.; Wang, Y.-C.; Lin, T.-W.; Hsu, J.-F.; Wu, M. Y.-C.; Wu, C.-H.; Kalpana, S.; Lu, J.-J. Comparison of Multiple Carbapenemase Tests Based on an Unbiased Colony Selection Method. Preprints 2023, 2023121629. https://doi.org/10.20944/preprints202312.1629.v1 Wang, H.-Y.; Tseng, Y.-J.; Lin, W.-Y.; Wang, Y.-C.; Lin, T.-W.; Hsu, J.-F.; Wu, M. Y.-C.; Wu, C.-H.; Kalpana, S.; Lu, J.-J. Comparison of Multiple Carbapenemase Tests Based on an Unbiased Colony Selection Method. Preprints 2023, 2023121629. https://doi.org/10.20944/preprints202312.1629.v1

Abstract

Carbapenemase-producing organisms (CPOs) present a major threat to public health, demanding precise diagnostic techniques their detection. Discrepancies among CPO tests have raised concerns, partly due to limitations in detecting bacterial diversity within host/specimen. We explored the impact of unbiased colony selection on carbapenemase testing and assessed its relevance on various tests. Based on "FirstAll" for unbiased colony selection to reduce bias, we compared modified carbapenem inactivation method/EDTA-modified carbapenem inactivation method (mCIM/eCIM), Carba5, the CPO panel, and multiplex PCR (M-PCR). Initially, we compared FirstAll to conventional colony selection for mCIM. Second, we used M-PCR as a reference, to evaluate test performance across seven CPO species. The results revealed that FirstAll selection improved carbapenemase detection, revising false-negative in 10.5% of K. pneumoniae isolates. In addition, 12.4% of CPOs tested positive for multiple carbapenemase genes. Both the Carba5 test and CPO panel showed suboptimal performance (sensitivity/specificity: Carba5 75.5%/89.0%, CPO panel 78.1%/74.0%). Carba5 test provided specific carbapenemase class assignments but CPO panel failed in 20.3% of cases. Carba5 test and the CPO panel results correlated well with ceftazidime-avibactam minimal inhibitory concentrations (MICs). Concordance for class A/D with MICs was 88.3% for Carba5 and 92.0% for the CPO panel; whereas for class B, it was 86.5% for Carba5 and 76.2% for the CPO panel. In conclusion, FirstAll as the unbiased colony selection impacted carbapenemase testing. With FirstAll, the diagnostic performance of either Carba5 or the CPO panel was compromised. The utilization of ceftazidime-avibactam guided by either the CPO panel or Carba5 was appropriate.

Keywords

carbapenemase; unbiased colony selection; mCIM/eCIM; Carba5; CPO panel

Subject

Biology and Life Sciences, Immunology and Microbiology

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