CHANGING PATTERN OF PHAGE GROUP-II STAPHYLOCOCCUS-AUREUS INFECTIONS -FROM COMMUNITY TO HOSPITAL

Changes in Staphylococcus aureus strains of phage group II were evalua ted over a 30-year period. Strains of this group were previously known to be mainly community-acquired, to be rather sensitive to antibiotic s and to occur in infections with better clinical outcome. During the period 1961 to 1990 a total of 551,563 S. aureus strains was character ized according to antibiotic resistance, phage type and site of isolat ion. Clinical information was obtained on 16,781 bacteraemia cases. St rains of group II occurred until 1983 with a rather constant frequency around 16% of the S. aureus population. Since then, a constant increa se in frequency has taken place and since 1990 they are the most frequ ently isolated phage pattern (22%). Bacteraemia caused by these strain s occurs today with the same frequency in hospital and community as st rains of other phage patterns. Moreover, these strains have changed fr om being highly susceptible, to being more resistant to penicillins an d tetracycline than the rest of the population. Resistance to methicil lin remained low in group II strains throughout the period (about 0.2% ). Mortality rate and the proportion of patients with underlying disea ses have been the same in recent years regarding group II strains as w ith other strains. This study indicates that the previous distinction between community acquired and hospital-acquired S. aureus infections is no longer valid.