Houmenou, C. T. | Search bioRxiv

bioRxiv2026

Description of Rickettsia senegalensis sp. nov.: a new Rickettsia species detected worldwide

Members of the genus Rickettsia are widespread obligate intracellular bacteria with high medical and veterinary relevance. While Rickettsia senegalensis was previously isolated from cat fleas, Ctenocephalides felis, in Senegal, a comprehensive polyphasic characterization is required for its formal taxonomic validation. This study aims to provide the first detailed phenotypic, ultrastructural, and genomic characterization of the type strain PU01-02. Cultivation assays demonstrated that strain PU01-02 grows aerobically in XTC-2, SF9, and LD652 cell lines at 28 {degrees}C in a CO2-free atmosphere. Ultrastructural examination via scanning electron microscopy using a backscattered electron detector confirmed its free cytoplasmic localization and a typical rickettsial morphology characterized by rod-shaped cells approximately 1.5 {micro}m in length and 0.3 {micro}m in width. Whole-genome sequencing yielded a 1.62-Mb genome with a G+C content of 33.2%, and three plasmids were detected. Genomic analyses confirmed its status as a distinct species, placing it within the transitional Rickettsia group, specifically inside the Rickettsia felis cluster. A review of epidemiological data revealed that rickettsial genes identical to those of R. senegalensis had already been identified in several hematophagous arthropods, including fleas and ticks parasitizing various hosts such as cats, dogs, opossums, and rodents worldwide. It has also been detected in cat tissues, suggesting a potential host-pathogen association. Based on these comprehensive characterization data, we formally propose Rickettsia senegalensis sp. nov. as a new species, with PU01-02 (= CSUR R184 = DSM 28250) as the type strain. RepositoriesThe genome sequence of Rickettsia senegalensis sp. nov. strain PU01-02T has been deposited in GenBank under accession number JBVYTQ000000000, and the rrs, gltA, ompB and sca4 gene sequences under accession numbers KF666476, KF666472, KF666470, KF666474, respectively. The plasmid accession numbers are PZ272915, PZ272916, and PZ272917, for pRS01, pRS02 and pRS03, respectively.

microbiology↗

bioRxiv2024

Circulation of Klebsiella pneumoniae strains between the termites, chimpanzees and humans

The emergence and multiplication of multi-resistant microbes is becoming a major concern in medicine and scientific research, requiring an integrated, global approach to prevent their spread and develop new therapeutic solutions. Klebsiella pneumoniae can cause a variety of infections. It has several distinctive features, such as extended-spectrum beta-lactamase (ESBL) production and frequency in hospital-acquired infections, which set it apart from other bacteria as Pseudomonas aeruginosa or staphylococci and make it of particular concern in the clinical setting. In this study, we worked on four strains of multidrug-resistant K. pneumoniae isolated from different patients at Fann Hospital in Dakar, Senegal. Whole genomes were compared them with those of nine K. pneumoniae isolates from chimpanzees (CHZ) and six from termites (T_NSC) from our previous study. The comparison revealed two major genetic groups: three human strains were virtually identical to those found in three chimpanzees and four genomes extracted from termites regularly consumed by chimpanzees were identical to five K. pneumoniae strains from chimpanzees. In silico, we identified the resistance genes and their corresponding families from each isolate, then genotyped them before comparing them with other isolates stored in the Institute Pasteur database. These strains have never been previously identified in Senegal. It has been shown here that multiresistant K. pneumoniae strains circulate between chimpanzees and termites and between chimpanzees and humans. Furthermore, these strains, often associated with nosocomial infections, have been identified and genotyped outside Senegal. Although similar strains have been already identified in tropical countries and in different intensive care units throughout the world, we hypothesize that they may originate from termite-chimpanzee ecosystem.

bioinformatics↗