DETECTION AND IDENTIFICATION OF PREVIOUSLY UNRECOGNIZED MICROBIAL PATHOGENS

Features of a number of important but poorly explained human clinical syndromes strongly indicate a microbial etiology. In these syndromes, the failure of cultivation-dependent microbial detection methods revea ls our ignorance of microbial growth requirements. Sequence-based mole cular methods, however, offer alternative approaches for microbial ide ntification directly from host specimens found in the setting of unexp lained acute illnesses, chronic inflammatory disease, and from anatomi c sites that contain commensal microflora. The rapid expansion of geno me sequence databases and advances in biotechnology present opportunit ies and challenges: identification of consensus sequences from which r eliable, specific phylogenetic information can be inferred for all tax onomic groups of pathogens, broad-range pathogen identification on the basis of virulence-associated gene families, and use of host gene exp ression response profiles as specific signatures of microbial infectio n.