Changes in the phage typing patterns of Staphylococcus aureus strains at Concepción, Chile, in the last 30 years.

Staphylococcus aureus is a ubiquitous pathogen still implicated as a common cause of community- and hospital-acquired infections. This micro-organism has demonstrated an immense adapting capacity to rapid environmental changes. In recent years, multiresistant strains have caused increasing nosocomial infections in several parts of the world. In the period 1993-94, 455 clinical isolates were typed on the basis of traditional phage typing procedure and these data were compared with others from similar studies carried out at the Department of Microbiology, University of Concepción in 1960, 1972, and 1982. Throughout the years, phage groups have been shifting from group I to group III and examination of phage types show that types 80 and 80/81 which were the most virulent and resistant by the 1960s, had disappeared. Nowadays, types 75 and 54/75 are most frequently found, and these have been associated with methicillin-resistant S. aureus.