In 1995, Haemophilus influenzae became the first free-living organism
to have its entire genome sequence published. Since then, many similar
projects have been started and, by the millennium, the genomes of a s
ignificant number of important human pathogens will have been sequence
d. During this period of increasing access to microbial sequence data,
parallel advances have occurred in techniques that allow the large-sc
ale study of the entire genetic complement of micro-organisms. In the
near future, these approaches will enable researchers to unravel furth
er the complexity of microbial pathogenesis and identify new virulence
determinants. Many of these will be suitable targets for development
as diagnostic reagents, antimicrobial agents and vaccine candidates. A
lthough it is difficult to predict the full impact that this almost ov
erwhelming volume of information will have on the practice of microbio
logy, it is clear that it will result ultimately in new ways of diagno
sing and combating infectious diseases.