Arbitrary primed polymerase chain reaction (AP PCR) assays are suited for the discrimination of isolates of all clinically relevant bacterial species. In a hospital setting, this type of DNA amplification test can be used for the timely detection of ongoing nosocomial outbreaks. For rapid screening of isolates of many medically important bacterial species, including Acinetobacter baumannii, Staphylococcus aureus, Serratia marcescens, Xanthomonas maltophilia and others, a single AP PCR assay can be used as a primary typing screen for genetic relatedness. In combination with epidemiological data, AP PCR testing is particularly useful for identifying true outbreaks caused by a single strain.