Table 2. Methicillin-resistant Staphylococcus aureus (MRSA) strains found in >10 persons in relation to contact with a health-care facility, 1997–1999, Finlanda Persons with hospital contact (%) Persons without hospital contact (%) Multiresistanceb HVR type Yr first identified in Finland aHVR, hypervariable region; E, epidemic, strain isolated in more than one health-care facility; O, outbreak, strain isolated in one health-care institute. bResistance to more than three antibiotic groups in addition to β-lactams. (29), were almost exclusively found in persons who had con- tacts with hospitals. Despite the fact that the HVR type A seems to coincide with nonmultiresistance, the hypervariable region itself has not Total 116 51 50 36 35 26 16 15 14 13 13 12 12 12 RESEARCH No Yes Yes Yes No No No No No Yes No Yes Yes Yes A D C C A A A A A C A C B B 1993 1992 1998 1995 1996 1997 1997 1997 1997 1997 1993 1998 1991 1997 Strain type Mikkeli clone (O11, E12) E5 (UK EMRSA 16) Kemi clone E1 E24 E27 E31 E22 E19 E20 O25 UK EMRSA-15 Pori clone (O15) Iberian clone (E6, E7, E10, O8) 75 (65) 50 (98) 49 (98) 36 (100) 25 (71) 17 (65) 6 (38) 7 (47) 13 (93) 13 (100) 8 (62) 12 (100) 11 (92) 12 (100) 41 (35) 1 (2) 1 (2) 0 (0) 10 (29) 9 (35) 10 (63) 8 (53) 1 (7) 0 (0) 5 (38) 0 (0) 1 (8) 0 (0) Figure. Pulsed-field gel electrophoresis (PFGE) profiles of the 14 most common methicillin-resistant Staphylococcus aureus (MRSA) strain types identified, Finland, 1997–1999. Lanes 1, 9, 17: S. aureus NCTC 8325 (molecular weight marker); lanes 2–4: strain types associated with community acquisition (Mikkeli clone, E22, E31); lane 5: E1; lane 6: E24; lane 7: E5; lane 8: Kemi clone; lane 10: E27; lane 11: UK EMRSA-15; lane 12: E19; lane 13: Pori clone; lane 14: E20; lane 15: Iberian clone; and lane 16: O25. been shown to contain any antibiotic resistance markers (17,30,31). Some of the multiresistant strains actually have deletions in this area (31). The hypervariable region has been analyzed by polymerase chain reaction and sequencing to dis- tinguish different mec DNA types (32,33). The method identi- fied five different subclones in 50 isolates representing one epidemic strain in Germany (33). Our study had several limitations. First, some of the MRSA isolates classified as community acquired may have been isolated from nursing-home residents, since not all Fin- nish nursing homes report to the National Discharge Register. The possibility of misclassification concerns a small number of isolates, since only 10 of all persons with community- acquired MRSA were >64 years of age. Second, the differ- ences in local sampling policies may affect the number and type of community-acquired MRSA identified. National guidelines for MRSA prevention in Finland are primarily directed to hospital use, and sampling and screening policies in community setting are not specified. Third, we did not gather clinical data and risk factors (6,34,35) other than previ- ous hospital stays for MRSA acquisition. Further information should be collected from persons with community-acquired MRSA to develop a hypothesis on risk factors specific for community acquisition. In conclusion, a large proportion of MRSA-positive per- sons may have acquired their strains outside the hospital set- ting, and their MRSA strains were nonmultiresistant, showed an HVR type A, and differed genotypically from epidemic strains found in hospitalized patients. None of the epidemic multiresistant hospital strains were prevalent in nonhospital- ized persons. Our findings suggest that MRSA may also Emerging Infectious Diseases • Vol. 8, No. 6, June 2002 605