Multidrug-Resistant Iberian Epidemic Clone of Methicillin-Resistant Staphylococcus aureus Endemic in a Hospital in Northern Portugal

ABSTRACT

Forty-two methicillin-resistant Staphylococcus aureus (MRSA) isolates collected during 1992–1995 at a hospital in the north of Portugal were characterized by a variety of genomic fingerprints. Hybridization of ClaI and SmaI restriction digests with the mecA- and Tn554-specific DNA probes was used to identify polymorphs and determine their localization in chromosomal DNA preparations, and pulsed-field gel electrophoretic analysis of SmaI digests was used to determine chromosomal backgrounds. A major clone (and its variants) carrying the mecA polymorph I, Tn554 type E in the PFGE background of pattern A, accounted for 85% of all MRSA tested in 1992–1993 and 66% in 1994–1995. This clone is closely related to the epidemic Iberian clone that was associated with outbreaks in Spain during 1989–1993 and was endemic in 1992–1993 in two hospitals in Lisbon (Portugal).