Nucleic acid detection methods, such as polymerase chain reaction (PCR), can often detect specific microbial pathogens, virulence markers and antimicrobial resistance genes more rapidly and with greater sensitivity and specificity than culture and conventional identification and susceptibility testing. Multiplex PCR can detect multiple genes in a single assay; this capability will be greatly extended by new techniques such as the DNA chip. However, limitations and pitfalls of nucleic detection methods remain.