Molecular Evidence of a Broad Range of Pathogenic Bacteria in Ctenocephalides spp.: Should We Re-Examine the Role of Fleas in the Transmission of Pathogens?

Georgios Dougas; Athanassios Tsakris; Stavroula Beleri; Eleni Patsoula; Maria Linou; Charalambos Billinis; Joseph Papaparaskevas

doi:10.3390/tropicalmed6010037

Molecular Evidence of a Broad Range of Pathogenic Bacteria in Ctenocephalides spp.: Should We Re-Examine the Role of Fleas in the Transmission of Pathogens?

Trop Med Infect Dis. 2021 Mar 17;6(1):37. doi: 10.3390/tropicalmed6010037.

Authors

Georgios Dougas¹, Athanassios Tsakris¹, Stavroula Beleri², Eleni Patsoula², Maria Linou³, Charalambos Billinis^{4

5}, Joseph Papaparaskevas¹

Affiliations

¹ Department of Microbiology, Medical School, National and Kapodistrian University of Athens, 115 27 Athens, Greece.
² Department of Public Health Policy, School of Public Health, University of West Attica, 11521 Athens, Greece.
³ Hellenic Pasteur Institute, 11521 Athens, Greece.
⁴ Faculty of Veterinary Science, University of Thessaly, 43100 Karditsa, Greece.
⁵ Faculty of Public and Integrated Health, University of Thessaly, 43100 Karditsa, Greece.

Abstract

The internal microbiome of common cat and dog fleas was studied for DNA evidence of pathogenic bacteria. Fleas were grouped in pools by parasitized animal. DNA was extracted and investigated with 16S metagenomics for medically relevant (MR) bacteria, based on the definitions of the International Statistical Classification of Diseases and Related Health Problems (WHO). The MR bacterial species totaled 40, were found in 60% of flea-pools (N = 100), and included Acinetobacterbaumannii, Bacteroidesfragilis, Clostridiumperfringens, Enterococcusfaecalis, E. mundtii, Fusobacteriumnucleatum, Haemophilusaegyptius, Kingellakingae, Klebsiellapneumoniae, Leptotrichiabuccalis, L. hofstadii, Moraxellalacunata, Pasteurellamultocida, Propionibacteriumacnes, P. propionicum, Proteusmirabilis, Pseudomonasaeruginosa, Rickettsiaaustralis, R. hoogstraalii, Salmonellaenterica, and various Bartonella, Staphylococcus, and Streptococcus species. B. henselae (p = 0.004) and B. clarridgeiae (p = 0.006) occurred more frequently in fleas from cats, whereas Rickettsiahoogstraalii (p = 0.031) and Propionibacteriumacnes (p = 0.029) had a preference in fleas from stray animals. Most of the discovered MR species can form biofilm, and human exposure may theoretically occur through the flea-host interface. The fitness of these pathogenic bacteria to cause infection and the potential role of fleas in the transmission of a broad range of diseases should be further investigated.

Keywords: Ctenocephalides; Enterococcus faecalis; Klebsiella pneumoniae; Legionella; Pseudomonas aeruginosa; bacteremia; disease transmission; flea infestations; infectious; metagenomics.