Biology subjects

Amachawadi, R. G.

Publications and source records attributed to Amachawadi, R. G..

3 recordsLinked to original sources

bioRxiv2026

Comparative Genomics of Bovine and Human Fusobacterium necrophorum Strains Reveal Subspecies- and Host-associated Differences in Virulence and Antimicrobial Resistance

Fusobacterium necrophorum (FN) is an important opportunistic pathogen implicated in necrotizing infections, including liver abscesses, calf diphtheria, metritis, and foot rot in cattle, and tonsillopharyngitis in humans. However, FN also exists as a commensal member of the bovine reproductive microbiota with potential negative, as in metritis, and even positive associations with pregnancy outcomes. The genomic features that enable FN to colonize diverse hosts and anatomical niches as either a commensal or a pathogen is poorly understood. We addressed these knowledge gaps by performing comparative genomic analysis of 137 FN strains (80 newly sequenced, 57 publicly available) from clinical and non-clinical sources across human and bovine hosts. We investigated the pangenome structure, virulence gene repertoire, antimicrobial resistance genes (ARG) prevalence, as well as host-and subspecies-associated genomic signatures of two FN subspecies: subsp. necrophorum (FNN) and subsp. funduliforme (FNF). Comparative genomics revealed an open pangenome with high accessory diversity, and phylogenetic analysis separated the strains into two distinct subspecies clades. Functional profiling revealed substantial metabolic divergence between subspecies, with FNN showing higher prevalence of carbohydrate transport systems and advanced glycation-related pathways, while FNF showed enrichment in threonate metabolism and hemolysin-related systems. Virulence gene analysis identified 84 variants across multiple functional categories with subspecies- and host-specific distributions. Antimicrobial resistance genes, primarily tetracycline resistance genes [tet(O), tet(M), tet(40)] and the macrolide resistance gene erm(B), were detected in 22.6% of strains, with higher prevalence in bovine than human strains. Overall, our results suggest that pathogenic potential of FN appears to be determined by the interplay between an open pangenome, subspecies-specific metabolic and virulence repertoires, host-associated adaptation, and niche specialization. IMPORTANCEFusobacterium necrophorum, comprising two subspecies, necrophorum (FNN) and funduliforme (FNF), is a major pathogen in cattle and humans, yet it also occurs as a commensal inhabitant in healthy cattle, particularly in the rumen, hindgut, semen, and the female reproductive tract. However, emerging evidence indicates it also occurs as a non-clinical inhabitant, particularly in the bovine reproductive tract, where it may be associated with improved pregnancy outcomes. We conducted a comparative genomic analysis of 137 F. necrophorum strains, including FNN (n = 12) and FNF (n = 125), sourced from humans (n=53) and cattle (n=84) across seven anatomical niches spanning both healthy and diseased sources. We identified subspecies- and host-specific metabolic pathways, antimicrobial resistance profiles, and distinct virulence gene distributions that underpin the ecological versatility of Fusobacterium necrophorum. Overall, these findings provide a genomic framework for understanding its host adaptation and niche specialization across bovine and human hosts.

microbiology↗

bioRxiv2024

Genomic and metabolic characterization of Trueperella pyogenes isolated from domestic and wild animals

Trueperella pyogenes is an important bacterial pathogen implicated in infections such as mastitis, metritis, pneumonia, and liver abscesses in both domestic and wild animals as well as endocarditis and prosthetic joint infections in humans. Understanding the genomic and metabolic features that enable T. pyogenes to colonize different anatomical sites within a host and its inter-kingdom transmission and survival is important for the effective control of this pathogen. We employed whole genome sequencing, phenotype microarrays, and antimicrobial susceptibility testing to identify genomic, metabolic and phenotypic features as well as antimicrobial resistance (AMR) genes in T. pyogenes recovered from different livestock, companion and wildlife animals. For comparative genomic analysis, 83 T. pyogenes genomes, including 60 isolated in the current study and 23 publicly available genomes were evaluated. These genomes represented T. pyogenes strains originated from 16 different body sites of 11 different animal hosts (e.g. bovine, swine, ovine, cervid, bison, equine, chamois, feline). Additionally, 49 T. pyogenes isolates (bovine, ovine, deer, swine and feline) were evaluated for phenotypic antimicrobial resistance using disk diffusion, and for metabolic profiling using the Biology GENIII MicroPlates. We identified that T. pyogenes strains are not host- or body site-specific. The presence of conserved virulence genes (plo and fimA), as well as genotypic and phenotypic AMR may contribute to T. pyogeness ability to cause infections in livestock, wildlife, and pets. Most of the tested isolates metabolized diverse carbon sources and chemical compounds, suggesting that this metabolic versatility may contribute to T. pyogenes survival, competitive advantage, and pathogenic potential. ImportanceTrueperella pyogenes is an important animal pathogen with zoonotic potential, posing a significant health concern to both animals and humans due to its ability to cause infections across different animal host species and tissues. Current understanding of this pathogens adaptability and survival mechanisms is limited. Here, we evaluated the genomic, virulence, metabolic, and antimicrobial resistance characteristics of T. pyogenes recovered from 16 different body sites of 11 different animal hosts (livestock, companion, and wild animals). We identified multiple antimicrobial resistance and virulence genes that may enable T. pyogenes for sustained infection and transmission. Additionally, T. pyogenes strains displayed metabolic versatility which could also contribute to its ability to thrive in diverse environments. Understanding the genomic and metabolic, and antimicrobial resistance characteristics that enable T. pyogenes to colonize different anatomical sites within a host and its transmission between different animal species is important for the effective control of this pathogen.

microbiology↗

bioRxiv2022

High proportions of single-nucleotide variations associated with multidrug resistance in swine gut microbial populations

BackgroundAntimicrobial resistance (AMR) is a significant global public health concern associated with millions of deaths annually. Agriculture has been attributed as a leading factor in AMR and multidrug resistance (MDR) associated with swine production estimated as one of the largest agricultural consumers of antibiotics. Therefore, studying and understanding AMR in swine has global relevance. AMR research has received increased attention in recent years. However, we are still building our understanding of genetic variation within a complex gut microbiome system that impacts AMR and MDR. In order to evaluate the gut resistome, we evaluated genetic variation before, during, and after antibiotic treatments. We studied three treatment groups: non-antibiotic controls (C), chlortetracycline (CTC) treated, and tiamulin (TMU) treated. We collected fecal samples from each group and performed metagenomic sequencing for a longitudinal analysis of genetic variation and functions. ResultsWe generated 772,688,506 reads and 81 metagenome assembled genomes (MAGs). Interestingly, we identified a subset of 11 MAGs with sustained detection and high sustained entropy (SDHSE). Entropy described genetic variation throughout the MAG. Our SDHSE MAGs were considered MDR as they were identified prior to, throughout, and after CTC and TMU treatments as well as in the C piglets. SDHSE MAGs were especially concerning as they harbored relatively high variation. Consistently high variation indicated that these microbial populations may contain hypermutable elements which has been associated with increased chance of AMR and MDR acquisition. Our SDHSE MAGs demonstrated that MDR organisms (MDRO) are present in swine, and likely additional hosts contributing to global AMR. Altogether, our study provides comprehensive genetic support of MDR populations within the gut microbiome of swine.

microbiology↗