Metamycoplasma hominis, formerly Mycoplasma hominis, is a well described bacterium, existing as a coloniser of the urogenital tract in adults.¹ It is a recognised human pathogen, though the role of M.hominis in disease is often uncertain due to its presence in asymptomatic adults, the difficulty in isolating the organism with conventional media and the propensity for microbiological cultures to be mixed with other organisms.² The bacterium is considered an opportunistic agent in urogenital infections and pregnancy complications, and less commonly in extragenital manifestations such as wound and soft tissue infections, bacteraemia, endocarditis, septic arthritis, central nervous disease and post-transplant complications.³ ⁴ Host factors such as immunosuppression, malignancy, urogenital manipulation and surgery complications are associated with extragenital M.hominis infection; very few cases are described in immunocompetent patients.⁵ ⁶
Unlike the related species, Mycoplasma pneumoniae, M.hominis is a rare cause of respiratory infection, despite reported morbidity and mortality in immunocompromised patients.⁶ We present a case of M.hominis isolated from the bronchoalveolar lavage of an adult male with HIV infection, who presented to hospital emergency with a reduced GCS on the background of IV drug use. He was subsequently admitted to the Intensive Care Unit on suspicion of sepsis, infective endocarditis, aspiration pneumonia and embolic stroke.
The true incidence of M.hominis pneumonia is unknown and its importance may be underestimated.⁵ In critically ill patients this potential pathogen should be considered, particularly as many antibiotics used empirically for pneumonia are ineffective against M.hominis.⁵ ⁶ ⁷