MOLECULAR DIAGNOSTICS OF INFECTIOUS-DISEASES

Over the past several years, the development and application of molecu lar diagnostic techniques has initiated a revolution in the diagnosis and monitoring of infectious diseases. Microbial phenotypic characteri stics, such as protein, bacteriophage, and chromatographic profiles, a s well as biotyping and susceptibility testing, are used in most routi ne laboratories for identification and differentiation. Nucleic acid t echniques, such as plasmid profiling, various methods for generating r estriction fragment length polymorphisms, and the polymerase chain rea ction (PCR), are making increasing inroads into clinical laboratories. PCR-based systems to detect the etiologic agents of disease directly from clinical samples, without the need for culture, have been useful in rapid detection of unculturable or fastidious microorganisms. Addit ionally, sequence analysis of amplified microbial DNA allows for ident ification and better characterization of the pathogen. Subspecies vari ation, identified by various techniques, has been shown to be importan t in the prognosis of certain diseases. Other important advances inclu de the determination of viral load and the direct detection of genes o r gene mutations responsible for drug resistance. Increased use of aut omation and user-friendly software makes these technologies more widel y available. In all, the detection of infectious agents at the nucleic acid level represents a true synthesis of: clinical chemistry and cli nical microbiology techniques.