Hospital-associated methicillin-resistant <it>Staphylococcus aureus </it>(HA-MRSA) in Italy

• Main Authors: Borbone Sonia (Author), Bongiorno Dafne (Author), Campanile Floriana (Author), Stefani Stefania (Author)
• Format: Book
• Published: BMC, 2009-06-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 10.1186/1476-0711-8-22; 1476-0711
• Keywords: Therapeutics. Pharmacology; RM1-950; Infectious and parasitic diseases; RC109-216; Microbiology; QR1-502
• Source: Annals of Clinical Microbiology and Antimicrobials, Vol 8, Iss 1, p 22 (2009)

<p>Abstract</p> <p>The aim of our study was to trace the dynamic changes of hospital-associated methicillin-resistant <it>Staphylococcus aureus </it>(HA-MRSA) lineages in Italy, comparing the genotypic backgrounds of contemporary isolates over a period of 17 years, with those of a sample of early MRSA strains from 1980.</p> <p>In total, 301 non-repetitive MRSA clinical isolates, recovered from 19 Italian hospitals between 1990 and 2007 were selected and analyzed for their antibiotic resistance, typed by PFGE and SCC<it>mec</it>, grouped into clonal-types and further characterized using Multi Locus Sequence Typing (MLST). A sample of fifteen early MRSA strains from 1980 was also used for comparison.</p> <p>The most interesting feature was the recent increase of ST228-MRSA-I (formerly the Italian clone; PFGE E) over the period 2000-2007 (57%), when compared to the period 1990-1999 (29%), and its stability to date, associated with a decrease of the highly epidemic ST247-MRSA-IA (formerly the Iberian clone; PFGE A), (23% from 1990 to 1999, 6% from 2000 to 2007). ST1-MRSA-I (1 out of 2 strains carrying <it>ccr</it>A₂B₂), ST8-MRSA-I (4 strains), ST15-MRSA-I (1 out of 4 carrying <it>ccr</it>A₂B₂) and ST30-MRSA-I (2 out of 5 carrying no <it>ccr</it>AB-types and <it>ccr</it>C) were the predominant earliest STs among the MRSA strains in 1980.</p> <p>A temporal shift in the susceptibility levels to glycopeptides was observed: strains with vancomycin MIC of ≥ 2 mg/L increased from 19.4% to 35.5%.</p> <p>In conclusion, we describe the alternation of MRSA clones that occurred in hospitals from 1990 to 2007 and the increase of the glycopeptide MIC levels, reflecting a worldwide trend. We document the detection of ST1, ST8, ST15 and ST30 in the 1980 isolates; we hypothesize their possible latency and their appearance as the current CA-MRSA clones.</p>