Indagine sulla diffusione di stafilococchi resistenti alla meticillina in Liguria

Introduction. Staphylococcus aureus is a major opportunistic pathogen especially in nosocomial settings. An increasing proportion of strains has intrinsic resistance to methicillin (MRSA) and recent reports documented the emergence of MRSA also in the community.The aim of this study was to evaluate methicillin-resistance in Liguria. Methods. 767 isolates of Staphylococcus spp have been collected from 10 laboratories, including 508 S. aureus: 292 (57.5%) hospital-acquired, 188 (37%) community-acquired, and 28 (5.5%) from healthcare settings; 259 coagulase- negative staphylococci (CNS): (193 (74.5%) hospital-acquired, 56 (21.6%) community-acquired, and 10 (3.9%) healthcare settings. Susceptibility tests were carried out by the disk diffusion method (CLSI, 2006) using cefoxitin (CFX) (Oxoid, Milan). MRSA has been also evaluated by PBP2’ latex agglutination test (Oxoid, Milan) on 52 randomly selected S. aureus. Results. The data obtained indicated an incidence of MRSA in nosocomial settings up to 45.2%, while among the community-acquired isolates the percentage was 6.4%. With respect to CNS the figures were 61,8% and 10,6% for the nosocomial-and community-acquired organisms respectively. A 99% agreement between data of the coordinating centre and the various laboratories was found. Methicillin-resistance was confirmed in 52 S. aureus by PBP2’ latex agglutination test. Conclusions. Present findings indicate that MRSA in community in the Ligurian area exists and this phenomenon requires future surveillance.