Methods for detection, prevalence and spread of resistance genes in staphylococci

Increasing numbers of antibiotically resistant bacterial pathogens of veterinary importance require exact and reliable methods for the detection of the resistance genes and their spreading. Using resistances to aminoglycosides, chloramphenicol, macrolide-lincosamide-streptogramin B antibiotics B antibiotics and tetracyclines in staphylococci as an example, molecular techniques are presented which include the detection of resistance genes by PCR assays or by hybridization with specific gene probes. The application of these methods led to the identification of most of these resistance genes on structurally closely, related plasmids in epidemiologically unrelated isolates of various staphylococcal species isolated from different animal sources in different geographical areas. With regard to the plasmid-specific plasmids, spreading of the resistance plasmids across strain-, species- or genus-specific borders via transduction, conjugation and mobilization is discussed.