No abstract

In the genus Klebsiella, the growth response in nutrient broth at 100C correlates inversely with the operational definition of a fecal coliform and not merely with the ability to grow at 44.5°C. Of the fecal coliform-positive Klebsiella, 97% did not grow at 100C after 72 h of incubation. Conversely, 97% of the fecal coliformnegative isolates grew at 10°C. The amount of growth at 100C varied among the fecal coliform-negative isolates and was found to correlate with indole production and pectin liquefaction. Low-temperature growth associated with specific biochemical tests can be used to differentiate several groups in the genus Klebsiella. Three main groups were discerned. Group I consists of indole-negative, pectinnonliquefying, fecal coliform-positive isolates that do not grow at 100C. Group II isolates are differentiated from group I by a fecal-coliform-negative response and growth at 10°C. Group III are indole-positive, pectin-liquefying, fecal coliformnegative isolates that grow at 100C. In our culture collection, isolates of group I are most frequently of human/animal clinical origins, whereas isolates of groups II and III are predominantly derived from the environment.