Capillary-Tube Scanner for Mechanized Microbiology

Growing microcolonies of bacteria can be detected by their light-scattering property. We have described a system in which growing bacteria in glass capillaries filled with nutrient agar are counted as the capillaries move through a narrow beam of light. Increased counts after incubation indicate the presence of viable organisms in the original sample; the equipment can detect colonies when they grow to a diameter of 8 microm. Aerobic, anaerobic, and facultative organisms can grow in the capillary environment. The sensitivities of several organisms to antibiotics were determined by adding antibiotics to the agar before the capillaries were filled.