Genomic characterization and assessment of the virulence and antibiotic resistance of the novel species Paenibacillus sp. strain VT-400, a potentially pathogenic bacterium in the oral cavity of patients with hematological malignancies.

George Tetz,Maria Vecherkovskaya,Victor Tetz

doi:10.1186/s13099-016-0089-1

George Tetz, Maria Vecherkovskaya + Show 1 more

Open Access

https://doi.org/10.1186/s13099-016-0089-1

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Abstract

BackgroundPaenibacillus sp. strain VT-400, a novel spore-forming bacterium, was isolated from patients with hematological malignancies.MethodsPaenibacillus sp. strain VT-400 was isolated from the saliva of four children with acute lymphoblastic leukemia. The genome was annotated using RAST and the NCBI Prokaryotic Genome Annotation Pipeline to characterize features of antibiotic resistance and virulence factors. Susceptibility to antibiotics was determined by the Kirby–Bauer disc diffusion method. We used a mouse model of pneumonia to study virulence in vivo. Mice were challenged with 7.5 log10–9.5 log10 CFU, and survival was monitored over 7 days. Bacterial load was measured in the lungs and spleen of surviving mice 48 h post-infection to reveal bacterial invasion and dissemination.ResultsWhole-genome sequencing revealed a large number of virulence factors such as hemolysin D and CD4+ T cell-stimulating antigen. Furthermore, the strain harbors numerous antibiotic resistance genes, including small multidrug resistance proteins, which have never been previously found in the Paenibacillus genus. We then compared the presence of antibiotic resistance genes against results from antibiotic susceptibility testing. Paenibacillus sp. strain VT-400 was found to be resistant to macrolides such as erythromycin and azithromycin, as well as to chloramphenicol and trimethoprim–sulphamethoxazole. Finally, the isolate caused mortality in mice infected with ≥8.5 log10 CFU.ConclusionsBased on our results and on the available literature, there is yet no strong evidence that shows Paenibacillus species as an opportunistic pathogen in immunocompromised patients. However, the presence of spore-forming bacteria with virulence and antibiotic resistance genes in such patients warrants special attention because infections caused by spore-forming bacteria are poorly treatable.

Highlights

Paenibacillus sp. strain VT-400, a novel spore-forming bacterium, was isolated from patients with hematological malignancies
We described Paenibacillus sp. strain VT-400, a novel spore-forming bacterium isolated from the saliva of patients with acute lymphoblastic leukemia [10]
We describe Paenibacillus sp. strain VT-400, a novel bacterium isolated from the saliva of four children with hematological malignancies, and investigate its potential to cause pneumonia

Summary

Introduction

Paenibacillus sp. strain VT-400, a novel spore-forming bacterium, was isolated from patients with hematological malignancies. Strain VT-400, a novel spore-forming bacterium, was isolated from patients with hematological malignancies. Most commensal bacteria are not yet culturable, and molecular techniques based on cloning and sequencing the ribosomal 16S RNA have been used instead to identify species in the human microbiome [7]. These techniques are prone to false negatives, such as when one bacterial species masks another, and underestimate bacterial diversity [8, 9]. Strain VT-400, a novel spore-forming bacterium isolated from the saliva of patients with acute lymphoblastic leukemia [10].

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