Abstract
Background:
Macrorhabdus ornithogaster, a yeast-like fungus, has the potential to infect various bird species, including companion birds. Although birds infected with M. ornithogaster may often remain asymptomatic, the infection can develop into chronic wasting gastritis and even progress to gastric cancer, highlighting the importance of early detection of M. ornithogaster infection. Despite direct fecal examination being a commonly used diagnostic method, the polymerase chain reaction (PCR) is anticipated to offer a higher detection rate. However, the actual diagnostic accuracy of the PCR for M. ornithogaster remains unknown.
Case Description:
Ninety fecal samples collected from companion birds that visited or were admitted to a hospital, regardless of their stage of Macrorhabdus diagnosis or treatment, were subjected to PCR testing. An accuracy analysis was then performed, considering symptomatology, direct fecal testing, and sequencing. The PCR test had a sensitivity of 83.33 %, specificity of 95.00 %, false negative rate of 16.67%, false positive rate of 5.00%, positive predictive value of 89.29%, negative predictive value of 91.94%, prevalence of 33.33 %, positive likelihood ratio of 16.67, negative likelihood ratio of 0.18, and diagnostic odds ratio of 95.00.
Conclusion:
The findings suggest that the PCR for Macrorhabdus possesses high diagnostic accuracy, with the ability to accurately identify uninfected individuals as negative. While the direct fecal examination is appropriate for routine primary screening, in cases where M. ornithogaster is not detected by fecal testing, the PCR may provide a more accurate and definitive diagnosis due to its high specificity.

Key words: Companion birds, Diagnostic accuracy, Direct fecal examination, Macrorhabdus ornithogaster, PCR