Infection trials in mice suggest thatMacrorhabdus ornithogasteris not capable of growth in mammals

Abstract

The objective of this study was to determine if Macrorhabdus ornithogaster, a yeast recovered from the junction of the proventriculus and ventriculus of the stomach of parrots and other birds, can infect mice. Fifteen healthy ARC (S) female mice (age 10 weeks) were incoculated with M. ornithogaster by gavage at (two different dosage rates [n = 5]) or intraperitoneal injection (n = 5) (one dosage rate). They were euthanized 5 days later and examined for gross and microscopic evidence of infection. Macrorhabdus ornithogaster was not found to colonize the stomach, peritoneum, or viscera of the challeneged mice. The results of this study show that M. ornithogaster is not able to infect mice by the oral and intraperitoneal routes of administration and suggest that infection in mammals is unlikely to occur.

Analysis for the diagnostic accuracy of PCR detection of Macrorhabdus in companion birds

“…Macrorhabdus ornithogaster is classified as an anamorphic ascomycetous yeast that is characterized by an elongated shape, spanning 2–3 × 20–80 μm in size ( Tomaszewski et al , 2003 ; Kojima et al , 2022 ). The M. ornithogaster infects the stomachs of various bird species, including companion birds such as budgies and canaries, and domestic poultry such as chickens and ostriches ( Van Herck et al , 1984 ; Martins et al , 2006 ; Behnke and Fletcher, 2011 ; Hanafusa et al , 2013 ; Lanzarot et al , 2013 ; Arabkhazaeli et al , 2016 ; Püstow and Krautwald-Junghanns, 2017 ; Rinder et al , 2017 ; Kojima et al , 2022 ). The pathogen is localized in the intermediate zone linking the proventriculus and ventriculus, where it grows on the luminal surface and possibly penetrates koilin ( Van Herck et al , 1984 ; Hanafusa et al , 2013 ).…”

“…The M. ornithogaster infects the stomachs of various bird species, including companion birds such as budgies and canaries, and domestic poultry such as chickens and ostriches ( Van Herck et al , 1984 ; Martins et al , 2006 ; Behnke and Fletcher, 2011 ; Hanafusa et al , 2013 ; Lanzarot et al , 2013 ; Arabkhazaeli et al , 2016 ; Püstow and Krautwald-Junghanns, 2017 ; Rinder et al , 2017 ; Kojima et al , 2022 ). The pathogen is localized in the intermediate zone linking the proventriculus and ventriculus, where it grows on the luminal surface and possibly penetrates koilin ( Van Herck et al , 1984 ; Hanafusa et al , 2013 ). Although Macrorhabdus infections may often remain asymptomatic, it has been implicated in chronic fatal wasting disease in companion birds, and when it is onset, gastritis symptoms persist even after eradication, leading to nausea, vomiting, undigested stools, stomach bleeding, diarrhea, and grinding, and in some cases develop into gastric cancer ( Speer et al , 2004 ; Hannafusa et al , 2007 ; Powers et al , 2019 ; Kojima et al , 2022 ).…”

Verification of accuracy of qPCR method for intravital diagnostics of Macrorhabdus ornithogaster in avian droppings

“…It colonises the avian proventriculus and ventriculus, mainly in the isthmus (Phalen 2014). It has also not been identified in other organs, in the external environment or in mammals (Hanafusa et al 2013). In many cases, it simply attaches to the mucous membrane without any signs of inflammation (Gerlach 2001;Hanafusa et al 2007;Kheirandish and Salehi 2011).…”

“…It colonises the avian proventriculus and ventriculus, mainly in the isthmus ( Phalen 2014 ). It has also not been identified in other organs, in the external environment or in mammals ( Hanafusa et al. 2013 ).…”