MEASUREMENT OF MOTILITY OF HELICOBACTER-PYLORI, CAMPYLOBACTER-JEJUNI AND ESCHERICHIA-COLI BY REAL-TIME COMPUTER TRACKING USING THE HOBSON BACTRACKER

Aims-(1) To make precise measurements and comparisons of various aspec ts of motility of three gastrointestinal pathogens, Helicobacter pylor i, Campylobacter jejuni, and Escherichia coli, in log phase growth; (2 ) to provide background information on motility data to study the infl uence of pH, viscosity, and chemotactic factors, thereby gaining a bet ter understanding of bacterial pathogenesis. Methods-Computer image pr ocessing technology and phase contrast microscopy (Hobson BacTracker) were used to measure several indices of bacterial motility in real tim e. Ten clinical isolates of each species in log phase Liquid culture w ere studied. Results-C jejuni moved fastest, with a median curvilinear velocity (CLV) of 38.76 mu m/s (range 29.08 to 52.82). Next was H pyl ori, median CLV 25.02 mu m/s (range 12.07 to 29.07). E coli was the sl owest, median CLV 12.73 mu m/s (range 8.20 to 18.04). The straight lin e velocities showed similar trends. Measurement of track linearity (TL ) showed that C jejuni moved the straightest (TL 60.3%), H pylori move d in wide circles (TL 28.7%), and E coli showed spinning movement with out much linear displacement (TL 18.3%). There were significant differ ences in these three variables between the species studied, but no sig nificant differences in measurements of time and frequency of halts be tween movement runs. Conclusions-The BacTracker provides a useful tech nical aid for measuring several indices of bacterial motility objectiv ely, reproducibly, and precisely, which is difficult to achieve withou t computer assistance. Accurate quantification of motility provides a basis for studying the factors which influence bacterial motility. It can provide phenotypic measurements of the effect of flagellar gene de pletion.