The chance identification of unusual-appearing bacteria in bronchoalveolar lavage fluid

A well-known indication for the cytologic examination of bronchoalveolar lavage (BAL) fluid is the identification of infectious organisms. However, an important distinction must be made as to whether the organisms seen represent a true opportunistic lower respiratory tract infection or a non-pathologic contamination.

We describe herein the case of a 13-month-old male infant who presented with persistent chest congestion and tracheobronchitis and who underwent BAL as part of his clinical work-up. On cytological examination of the BAL fluid, the Romanowsky-stained cytospin slides contained numerous squamous epithelial cells with some showing rare striated rod-like structures on their surfaces. The peculiar structures also had rounded ends and were very large when compared to adjacent known bacterial cocci.

We have determined that the striated rod-like structures in the infant's BAL fluid were indeed bacteria, Simonsiella sp. Simonsiella has reportedly been found in up to 32% of oral swabs in normal humans and it is considered a commensal and non-pathogenic organism. The characteristically large size, the association with normal oral-derived squamous cells and the striated appearance is diagnostic and will hopefully eliminate any possibility of confusion with a truly pathogenic organism.