Hospital-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) in Italy.
The aim of our study was to trace the dynamic changes of hospital-associated methicillin-resistant Staphylococcus aureus (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. 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 SCCmec, 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. 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 ccrA2B2), ST8-MRSA-I (4 strains), ST15-MRSA-I (1 out of 4 carrying ccrA2B2) and ST30-MRSA-I (2 out of 5 carrying no ccrAB-types and ccrC) were the predominant earliest STs among the MRSA strains in 1980. A temporal shift in the susceptibility levels to glycopeptides was observed: strains with vancomycin MIC of >or= 2 mg/L increased from 19.4% to 35.5%. 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.
Campanile
Floriana
F
Department of Microbiology, University of Catania, Italy. f.campanile@unict.it
Bongiorno
Dafne
D
Borbone
Sonia
S
Stefani
Stefania
S
D015373:Bacterial Typing Techniques; D016000:Cluster Analysis; D003428:Cross Infection / Q000382:microbiology*; D016172:DNA Fingerprinting / Q000379:methods; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005838:Genotype; D006761:Hospitals; D006801:Humans; D007558:Italy; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D017422:Sequence Analysis, DNA; D013203:Staphylococcal Infections / Q000382:microbiology*
D004269:DNA, Bacterial