Phenotypic Diversity and Stability of the Intestinal Coliform Flora in Piglets During the First 3 Months of Age

The intestinal coliform bacterial populations in six piglets and their sows from two litters in the same stable were studied by the aid of an automated system for biochemical fingerprinting (The PhenePlate, or PhP system). Faecal samples from sows were collected once a week until weaning, and from piglets once a week during their first 3 mth of life. Altogether 1248 coliform isolates from 52 faecal samples were studied. The phenotypical diversity of the coliform bacteria in each faecal sample was measured as Simpson’s diversity index (D,), and the similarities between the bacteria in different samples were measured as population similarity coefficients (S,,). The D, of the sows was initially high, but decreased in one sow during an outbreak of diarrhoea which occurred during week 3 of the study. The D, of the piglets varied between samples, and showed no tendency to increase with age. Two piglets included in the study died during the diarrhoeal outbreak, and they generally carried intestinal floras showing lower D, during their first 3 wk of life than those which survived (mean value 0.454 versus 0.744). The coliform population within each piglet was usually quite stable before the diarrhoeal outbreak, but in all piglets the population was drastically changed during and after the outbreak. Piglets within each litter shared similar coliform populations during the first week of life, but piglets from different litters had no coliforms in common. On day 75, the piglets were removed from their sows and mixed with others in different litters, and after that coliform populations of piglets from different sows showed a tendency to become more similar to each other. Samples collected during the diarrhoeal outbreak from different piglets did not contain similar coliform populations which is a strong indication that the aetiological agent of the outbreak was not any coliform bacterium. The present study shows a useful way to investigate intestinal bacteria in both man and animals. The methods are very simple to use, and fully computerised data treatment makes it possible to study large numbers of bacterial isolates