A novel Arsenophonus species isolated from a bacteraemic patient
Background: We report the first human case of an invasive novel Arsenophonus species. The genus Arsenophonus of the order Enterobacterales, comprises of insect symbiotic intracellular bacteria with a wide host spectrum including triatomine bugs, bees, ticks, lice and parasitic wasps. Case Descriptio...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-03-01
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| Series: | International Journal of Infectious Diseases |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S1201971224005472 |
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| Summary: | Background: We report the first human case of an invasive novel Arsenophonus species. The genus Arsenophonus of the order Enterobacterales, comprises of insect symbiotic intracellular bacteria with a wide host spectrum including triatomine bugs, bees, ticks, lice and parasitic wasps. Case Description: The patient, a 70-year-old homeless man from Johannesburg, South Africa was admitted in February 2020 with symptomatic iron-deficiency anaemia. His physical examination revealed pedal oedema, pallor and bibasal lung crackles. He had poor dentition and body lice. He had evidence of systemic infection, with leukocytosis and a raised C-reactive protein. He was diagnosed with iron deficiency anaemia secondary to confirmed duodenitis, had chronic kidney disease and monoclonal gammopathy of unknown significance. He was treated empirically with amoxicillin-clavulanate for four days. He received a further four days of ceftriaxone after admission blood cultures flagged positive with an unknown Gram-negative bacillus. The bacterium was cultured from blood cultures on two separate occasions. The patient responded favourably to antibiotics and was discharged from the hospital.The Vitek®2 instrument misidentified the bacterium as Aeromonas salmonicida with 94% probability. The isolate was unidentifiable on the Vitek® MALDI mass spectrometer (MS) but was identified as Arsenophonus nasoniae with a low score of 1.62 on the Bruker MS.Whole genome sequencing was undertaken by extracting genomic DNA and sequencing it on the Illumina MiSeq platform. The genome of the new bacterium is 3158693 bp in size with a G+C content of 36.95 mol%. It has a genome-based average nucleotide identity of 92% with A. nasoniae DMS15247. We propose this bacterium to be a new species within the genus Arsenophonus, family Morganellaceae, order Enterobacterales, phylum Proteobacteria. The bacterium will be deposited in two different strain collections. Discussion: There are only two previous reports of possible human infection with A. nasoniae, one from a skin eschar and the other from a blood culture. The Arsenophonus species infecting our patient possibly originated from his body lice. Arsenophonus species are insect symbiotic bacteria and human infection is a rare phenomenon. Our patient had several immunocompromising conditions that may have predisposed him to this unusual infection. Infections with insect symbiotic bacteria are emerging in humans and should be considered as potential pathogens in patients with a clear history of insect infestation. Conclusion: We present the first description of human invasive infection with a new species of Arsenophonus genus that resolved on broad spectrum antibiotics. Rare infections with insect symbiotic bacteria are difficult to identify on routine microbiological testing but should be considered in patients with insect infestations. |
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| ISSN: | 1201-9712 |