Putative azithromycin-resistance mutations in Chlamydia trachomatis are globally distributed but arose before azithromycin was discovered

Sharma, P.; Dean, D.; Read, T. D.

doi:10.1101/2025.11.10.687758

Home/Archive/bioRxiv

bioRxiv · 10.1101/2025.11.10.687758

Putative azithromycin-resistance mutations in Chlamydia trachomatis are globally distributed but arose before azithromycin was discovered

Sharma, P.·Dean, D.·Read, T. D.

View original source ↗Export metadata ↓

Abstract

Azithromycin is widely used to treat Chlamydia trachomatis infections, yet the extent of resistance to the drug across the species has not been addressed. We surveyed mutations and substitutions linked to putative azithromycin resistance across 1,354 high-quality C. trachomatis genomes. Mutations in the rplV gene encoding three non-synonymous substitutions, compared to the canonical C. trachomatis reference strain D//TW-3/Cx sequence, were found to be common but largely conserved within lineages causing prevalent urogenital and anorectal infections and lymphogranuloma venereum (LGV). Time-scaled phylogenetic analysis suggested that these mutations predate the clinical introduction of azithromycin. In contrast, no consistent resistance-associated patterns were observed in 23S rRNA or rplD genes. This large-scale genomic surveillance provides critical insights into the evolutionary trends of putative azithromycin resistance in C. trachomatis and underscores the importance of integrating genomic monitoring with phenotypic susceptibility testing to accurately assess and manage antimicrobial resistance.

Source connections

Published article ↗

Explore related subjects

genomics Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Sharma, P., Dean, D., Read, T. D.. 2025-11-12. Putative azithromycin-resistance mutations in Chlamydia trachomatis are globally distributed but arose before azithromycin was discovered. https://doi.org/10.1101/2025.11.10.687758

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Integrative Nanopore and Illumina sequencing reveals age-associated tRNA modification and CCA-tail dynamics in yeast

Aging is characterized by a progressive loss of proteostasis. Transfer RNAs (tRNAs) are essential regulators of translation, yet their dynamics during aging remain poorly understood due to challenges in sequencing highly modified RNAs. Here we present a benchmarked Nanopore direct RNA sequencing (RNA004 chemistry) resource that profiles the Saccharomyces cerevisiae tRNAome during replicative aging at single-molecule resolution. Using in vitro transcribed tRNA controls, we establish modification detection thresholds and validate key findings with orthogonal Illumina sequencing. While overall tRNA abundance remains largely stable, our resource reveals age-associated terminal A cleavage at the 3' CCA tail of mature tRNAs, targeted T-loop and anticodon modification changes, and single-molecule evidence of modification co-occurrence. This dataset provides a resource for exploring tRNA regulation, translation fidelity, and longevity.

genomics↗

bioRxiv2026

A hydrogen-producing mitochondrion in an anaerobic eukaryotrophic rhizarian

Diverse eukaryotes thrive under low oxygen conditions, in part through highly modified mitochondrion-related organelles (MROs) that use alternate metabolic pathways to support ATP production and cofactor recycling. Anaerobic lifestyles have evolved repeatedly across the eukaryotic tree of life, each providing an independent opportunity to understand how eukaryotes adapt to life in low oxygen conditions. Here, we use single-cell transcriptomics to reconstruct the MRO metabolism of PCE SSF, a benthic eukaryotrophic flagellate and the first cultivated representative of Novel Clade 12 (NC12; Rhizaria), an independently anaerobic rhizarian lineage. PCE SSF possesses an anaerobic hydrogen-producing mitochondrion capable of hydrogenosome-type substrate-level phosphorylation. It also retains a nearly complete but likely branched tricarboxylic acid pathway that lacks citrate synthase and malate dehydrogenase. The function of citrate synthase may instead be fulfilled by the typically cytosolic ATP citrate lyase, previously reported in this context only in the anaerobic cercozoan, Brevimastigomonas motovehiculus. Unlike B. motovehiculus, however, PCE SSF retains only Complex II and the NuoE/NuoF subunits of the electron transport chain and lacks a mitochondrial genome. Together, these features indicate an atypical and reduced mitochondrial metabolism, highlighting the diversity of evolutionary solutions to anaerobic energy metabolism in eukaryotes.

genomics↗

bioRxiv2026

Targeted CRISPRi screening reveals unexpected resilience across the RNA polymerase III transcriptome

Increased RNA polymerase III (Pol III) activity and tRNA abundance are widely linked to cancer cell growth, yet the functional requirement for individual Pol III genes and core components remains unclear, in part due to the difficulty of achieving gene-specific perturbation of highly conserved loci. Here, we developed an inducible CRISPR interference platform and a custom single-guide RNA (sgRNA) library enabling gene-specific targeting of Pol III-transcribed genes and Pol III machinery. Genome-wide screening identified several Pol III dependencies in diploid fibroblasts and HEK293T cells, including multiple initiator methionine tRNA genes among the strongest fitness dependencies. Unexpectedly, glioblastoma models remained largely insensitive to repression of both individual Pol III genes and core Pol III components, despite efficient target repression. These findings establish a general strategy for gene-specific interrogation of conserved Pol III genes and indicate that glioblastoma models tolerate extensive perturbation of Pol III genes and machinery.

genomics↗