Lophomonas blattarum: A new flagellate causing respiratory tract infections

Abstract

Lophomonas blattarum is a flagellate protozoan parasite which was originally described as a commensal in the gut of cockroaches. From the 1990s, reports started coming out of peoples Republic of China about its possible role in bronchopulmonary infections, and this was followed by reports from some other parts of the world as well. There had been some skepticism regarding the misidentification of bronchial ciliated epithelial cells as L. blattarum, but recent use of molecular diagnosis has come as an aid in clearing the controversy. This review focuses on the various aspects of the parasite including its biology, epidemiology, clinical manifestations, laboratory diagnosis, and the treatment aspects. Molecular diagnosis has recently been employed and more reports concerning its validation is needed. More basic research concerning the genomic and proteomic analysis is necessary to develop reliable molecular and serological tests for this parasite in future.

Keywords: Bronchopulmonary infections; Lophomonas blattarum; epidemiology; laboratory diagnosis; treatment.

Figure 1

The detailed structure of Lophomonas blattarum. Note the wine-glass-shaped calyx, axial filament, and parabasal “collar” of tubules, visible in the light microscope. (After Kudo[7] and Beams and Sekhon[8])

Figure 2

(left) Flagellate protozoan parasite in fresh sputum sample. Note the pyriform shape, granular cytoplasm with a large vacuole and the tuft of flagella at the apical end (arrow). (Wet mount × 1200; bar, 15 μm). (Right) Similar flagellate protozoon in a sputum smear (Wheatley's trichrome srtain × 1000; bar, 15 μm). (Reproduced from Martinez-Giron and van Woerden)[3]

Figure 3

A ciliated bronchial ciliated cell and Lophomonas blattarum in wet mount of sputum specimen: (left) Ciliated bronchial cell-note the columnar shape, and terminal bar and inserted cilia at the apical end. (Right) Lophomonas blattarum – note the oval shape, granular cytoplasm with phagocytosed particles and a tuft of flagella (arrow) (×1000; bar: 6 μm) (Reproduced from Martinez-Giron and van Woerden)[3]

Figure 4

Stained sample of sputum showing ciliated bronchial cells (left) and Lophomonas blattarum (right). The cilia are regularly oriented, whereas the flagella have an irregular arrangement (Papanicolaou stain × 1000; bar, 12 μm). (Reproduced from Martinez-Giron and van Woerden)[3]