Identification and characterisation of a novel multidrug-resistant streptococcus, Streptococcus toyakuensis sp. nov., from a blood sample

Takeaki Wajima; Atsuya Hagimoto; Emi Tanaka; Yoshiaki Kawamura; Hidemasa Nakaminami

doi:10.1016/j.jgar.2022.04.018

Identification and characterisation of a novel multidrug-resistant streptococcus, Streptococcus toyakuensis sp. nov., from a blood sample

J Glob Antimicrob Resist. 2022 Jun:29:316-322. doi: 10.1016/j.jgar.2022.04.018. Epub 2022 Apr 29.

Authors

Takeaki Wajima¹, Atsuya Hagimoto², Emi Tanaka³, Yoshiaki Kawamura⁴, Hidemasa Nakaminami²

Affiliations

¹ Department of Clinical Microbiology, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan; Department of Microbiology, Faculty of Pharmacy, Meijo University, Nagoya, Japan. Electronic address: twajima@meijo-u.ac.jp.
² Department of Clinical Microbiology, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan.
³ Department of Clinical Microbiology, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan; Department of Microbiology, Faculty of Pharmacy, Meijo University, Nagoya, Japan.
⁴ Laboratory of Microbiology, School of Pharmacy, Aichi Gakuin University, Nagoya, Japan.

PMID: 35500839
DOI: 10.1016/j.jgar.2022.04.018

Abstract

Objectives: In 2018, we isolated multidrug-resistant α-haemolytic streptococci TP1632 from the blood of a 34-year-old patient with bacteraemia. This study aimed to characterise α-haemolytic streptococci TP1632 and elucidate its multidrug resistance mechanisms.

Methods: TP1632 was characterised by whole genome sequencing and biochemical testing. Based on the genome sequence, digital DNA-DNA hybridization (dDDH) and average nucleotide identity based on BLAST (ANIb) values were calculated. In addition, antimicrobial-resistance mechanisms were evaluated by ResFinder and transformation assay using Streptococcus mitis.

Results: TP1632 showed resistance to β-lactams, macrolides, and quinolones. Genomic analysis revealed that dDDH and ANIb values between TP1632 and S. mitis were 56.3% and 93.63%, respectively, indicating TP1632 as the novel species. TP1632 exhibited macrolide resistance genes such as mef(A), msr(D), and erm(B) and tetracycline resistance gene tet(M). In addition, amino acids at position 81 in GyrA and 79 in ParC were tyrosine and isoleucine, respectively. When penicillin-binding proteins of TP1632 were introduced into S. mitis, recombinants showed β-lactam resistance. Thus, acquired resistance genes and low affinities towards antimicrobial agents contribute to multidrug resistance.

Conclusion: Our findings indicated that multidrug-resistant TP1632 is a novel species in the genus Streptococcus. Furthermore, antimicrobial resistance of this strain could transfer horizontally among α-haemolytic streptococci. These data indicated the risk of emergence of multidrug-resistant streptococci not only as a pathogen but also a reservoir of antimicrobial resistance. This isolate was proposed as a novel species, Streptococcus toyakuensis sp. nov. The type strain is TP1632^T (= JCM 34623^T = CCUG 75492^T).

Keywords: Bacterial; Multidrug resistance; Multiple; Streptococcus; Viridans streptococci.

Publication types

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

MeSH terms

Adult
Anti-Bacterial Agents* / pharmacology
Anti-Bacterial Agents* / therapeutic use
DNA
Drug Resistance, Bacterial / genetics
Humans
Macrolides*
Microbial Sensitivity Tests
Streptococcus

Substances

Anti-Bacterial Agents
Macrolides
DNA