Yes, it is catalase positive. This is because it is capable of breaking down hydrogen peroxide (H2O2) to give water and oxygen. The presence of bubbles when hydrogen peroxide is added to E. coli on a microscope slide is a phenotypic (observable physical characteristic) proof that it is catalase positive. Vital Tips for Preventing E. coli in Your Home Most strains of E. coli bacteria live in your intestine and are harmless. 2  However, some strains found on raw food and spoiled remains make people very sick. 3  Follow the steps â¦.
Spotting between periods can be a sign that the hormones that regulate your menstrual cycle are âout of sync.â Certain medications, particularly birth control pills, can trigger hormonal fluctuations that lead to spotting.
2. an indication, such as a scent or spoor, of the presence of an animal. 3. Med any objective evidence of the presence of a disease or disorder. 4. Astrology See sign of the zodiac. any direct indicator of an occurrence, e.g. the appearance of spots is a sign of measles (natural signs).