MCQs PATHOLOGY: Spirochaetes

6.1 Which possesses an axial filament? A. Any spirochaete B. Branching forms of Nocardia astéroïdes C. Filamentous forms of Haemophilus influenzae D. Hfr strains of Escherichia coli E. Pathogenic mycoplasmas

6.2 Which organism stains Gram-negative with a very loose irregular spiral morphology and a tendency to colonize epithelial surfaces? F. Borrelia vincenti G. Leptospira canicola H. Spirillum minus J. Treponema pallidum K. Vibrio cholerae

6.3 Which is NOT a property of Leptospira icterohaemorrhagiae? L. Cannot be cultivated in non-living media M. Demonstrable by dark ground and fluorescence microscopy N. Induces type specific immunity in man O. Shows active rotational but no translatory movement P. Tight regular spiral with one or more secondary curves.
Answers

6.1 A. AU spirochaetes possess an axial filament composed of several flageUa-like filaments arising from each end of the organism, which winds around the protoplasmic cylinder of the cell body within the cell wall. The filaments are almost certainly the organelles of motility, composed of contractile flagellin protein.

6.2 F. Borrelia are the only spirochaetes with a loose spiral morphology. Treponema pallidum has rigid tight spirals and Leptospira canicola has the fine regular spiral typical of the leptospira. Borrelia vincenti is a normal oral commensal but may act as an opportunistic pathogen, especially in the mouth and throat.

6.3 L. Leptospira are readily cultivated aerobically at 30°C in peptone broth enriched with 10 per cent inactivated (heated at 56°C for 30 minutes) serum. They will also produce colonies on semi-solid nutrient agar supplemented by 10 per cent serum and haemoglobin. All the other statements are true.