Related Experiment Video
Updated: Aug 15, 2025
Whole Genome Sequencing of Candida glabrata for Detection of Markers of Antifungal Drug Resistance
Published on: December 28, 2017
Identification of cfxA gene variants and susceptibility patterns in β-lactamase-producing Prevotella strains
Sodai Yokoyama1, Masahiro Hayashi2, Takatsugu Goto2
1United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu City, Gifu, Japan.
Objectives:
Antimicrobial-resistant isolates of Prevotella species, especially those resistant to β-lactams, have become increasingly common. Here, we aimed to elucidate the underlying mechanisms contributing to the emergence and spread of antimicrobial resistance in Prevotella species.
Methods:
Prevotella species were isolated from a variety of clinical specimens. β-lactamase production was determined using nitrocefin discs, and the determination of minimum inhibitory concentration (MIC) to ten antimicrobials was done by the agar dilution method. Four resistance genes (cfxA, tetQ, ermF, and nim) and cfxA-flanking regions were detected using polymerase chain reaction. cfxA and the flanking regions were sequenced, and a phylogenetic tree was constructed based on CfxA amino acid sequences using the UPGMA method.
Results:
Among the 45 Prevotella isolates identified, 35 (77.8%) produced β-lactamases and had the cfxA genes. The tetQ, ermF, and nim genes were detected in 53.3%, 17.8%, and 0% of the 45 isolates, respectively. Among the 33 sequenced cfxA alleles, cfxA2 (45.5%) was the most frequent, followed by cfxA3 (42.4%) and a novel variant (cfxA7, 12.1%). The novel CfxA7 β-lactamase had a novel L155F substitution not previously reported in CfxA variants. The MICs of all β-lactam agents tested, excluding cefmetazole and meropenem, were lower among cfxA7-positive isolates than in cfxA2-and cfxA3-positive isolates.
Conclusions:
Differences in MICs of penicillins and cephalosporins may be due to amino acid substitutions in the CfxA variants, CfxA2, CfxA3, and CfxA7, among Prevotella isolates. Possession of cfxA-mobA, tetQ, and ermF may increase the risks of the emergence and spread of multidrug-resistant Prevotella species.
Insights
Antimicrobial resistance in Prevotella species is rising, particularly to beta-lactams. This study identified key resistance genes like cfxA, tetQ, and ermF, and a novel CfxA7 variant, offering insights into multidrug resistance mechanisms.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Antimicrobial resistance in Prevotella species, especially to beta-lactams, is a growing concern.
- Understanding the genetic mechanisms of resistance is crucial for combating its spread.
Purpose of the Study:
- To investigate the mechanisms of antimicrobial resistance in Prevotella species.
- To identify specific resistance genes and their prevalence in clinical isolates.
Main Methods:
- Isolation and identification of Prevotella species from clinical specimens.
- Determination of beta-lactamase production and minimum inhibitory concentrations (MICs) to ten antimicrobials.
- Detection and sequencing of resistance genes (cfxA, tetQ, ermF, nim) and flanking regions.
Main Results:
- 77.8% of Prevotella isolates produced beta-lactamases and harbored cfxA genes.
- Prevalence of tetQ and ermF genes were 53.3% and 17.8%, respectively; nim gene was absent.
- A novel cfxA variant, cfxA7, with an L155F substitution, was identified, showing lower MICs to certain beta-lactams compared to cfxA2 and cfxA3 variants.
Conclusions:
- Amino acid substitutions in CfxA variants (CfxA2, CfxA3, CfxA7) may influence resistance to penicillins and cephalosporins.
- Co-occurrence of cfxA-mobA, tetQ, and ermF genes increases the risk of multidrug-resistant Prevotella species emergence and spread.
