AMPLIFICATION METHODS IN DIAGNOSTIC BACTERIOLOGY (SELECTED EXAMPLES)

This paper will review the significance of results obtained by DNA amplification methods performed on clinical materials for the detection of bacterial pathogens. They will be compared with conventional culture, antigen detection or serological methods with respect to speed, sensitivity and specificity. PCR has provided promising results in the identification of Bordetella pertussis, Chlamydia pneumoniae, Legionella pneumophila, Streptococcus pneumoniae, Mycoplasma pneumoniae and the various pathogroups of diarrheagenic Escherichia coli. PCR and LCR have also shown encouraging results when used in the diagnosis of sexually transmitted diseases caused to Chlamydia trachomatis. In patients with Lyme disease, the sensitivity of PCR is still insufficient, when compared to serological methods. Here PCR is an adjunct in the diagnosis and no substitute for clinical materials have also proved to be both problematic and challenging. Problems in using the PCR include determining the optimal target selection, quantifying the sample volume necessary for analysis, determining a standard for sample preparation, and optimizing amplification reactions. There are also difficulties with PCR inhibitors present in the clinical material and with monitoring the performance of the technique. PCR results are highly reliable and reproducible between laboratories when standardized reagents and protocols are used. An important step in this direction is the commercial availability of PCR kits. Such kits also simplify the handling of PCR, thus requiring less technical expertise, and allowing broader use for diagnosis. In the near future, additional studies must provide a correlation between PCR results and conventional methods with larger numbers of samples. Moreover, as a final evaluation, PCR detection methods must prove their benefit with respect to clinical management.