Check the melting temperature of the FilmArray BCID panel to avoid missed detection of vanM-type enterococci

Ying Zhou; Yang Yang; Jing Wu; Yan Guo; Renru Han; Xiaogang Xu

doi:10.1016/j.mimet.2022.106646

Check the melting temperature of the FilmArray BCID panel to avoid missed detection of vanM-type enterococci

J Microbiol Methods. 2023 Jan:204:106646. doi: 10.1016/j.mimet.2022.106646. Epub 2022 Dec 5.

Authors

Ying Zhou¹, Yang Yang¹, Jing Wu², Yan Guo¹, Renru Han¹, Xiaogang Xu³

Affiliations

¹ Institute of Antibiotics, Huashan Hospital, Fudan University, Key Laboratory of Clinical Pharmacology of Antibiotics, National Health Commission, Shanghai, China.
² Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai 200040, China.
³ Institute of Antibiotics, Huashan Hospital, Fudan University, Key Laboratory of Clinical Pharmacology of Antibiotics, National Health Commission, Shanghai, China; National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China; Shanghai Huashen Institute of Microbes and Infections, Shanghai 200052, China. Electronic address: xuxiaogang@fudan.edu.cn.

PMID: 36481432
DOI: 10.1016/j.mimet.2022.106646

Abstract

Purpose: We aimed to evaluate whether the FilmArray blood culture identification (BCID) panel holds the ability to detect vanM-type vancomycin-resistant enterococci (VRE) clinical isolates effectively.

Methods: Twenty VRE clinical strains, including 10 vanA-type VRE and 10 vanM-type VRE, were collected from patients in five tertiary hospitals, Shanghai, China. By conventional PCR and sequencing, the strains were identified and van genotypes were confirmed. All VRE strains were investigated using the FilmArray BCID panel. All results, including enterococcus assay, vanA/B assay, DNA melting curves and melting temperature (Tm), were recorded. We also compared these results with those obtained via the conventional PCR and sequencing.

Results: According to the instructions of the FilmArray BCID panel, the Enterococcus assay is used to identify species and vanA/B assay is used to detect van genes. In all vanA-type VRE, the Enterococcus assay and vanA/B assay were positive. The results correctly showed that the tested strains were VRE. However, in 10 vanM-type VRE, the Enterococcus assay was positive and vanA/B assay were negative. The results mistakenly showed that the tested strains were vancomycin-sensitive enterococci (VSE). In the vanA/B assay, the melting curves of vanM-type VRE were similar to that of vanA-type VRE, but the Tm values were lower. The Tm values were then compared against the expected Tm range for the vanA/B assay. The Tm values of vanM-type VRE fall outside the assay-specific Tm range, resulting in negative reports. Thus, by adjusting the expected Tm range for the Enterococcus assay, the FilmArray BCID panel holds the ability to detect vanM-type VRE.

Conclusions: The vanM-type VRE isolates can be effectively detected by optimizing the expected Tm range for the vanA/B assay.

Keywords: Enterococcus faecium; Resistance; Vancomycin; vanM.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Anti-Bacterial Agents
Bacterial Proteins / genetics
Carbon-Oxygen Ligases / genetics
China
Enterococcus faecium*
Gram-Positive Bacterial Infections* / diagnosis
Humans
Microbial Sensitivity Tests
Temperature
Vancomycin
Vancomycin-Resistant Enterococci*

Substances

Bacterial Proteins
Vancomycin
Carbon-Oxygen Ligases
Anti-Bacterial Agents