Regional variation in Panton-Valentine leukocidin positivity smong S. aureus isolates in complicated skin and skin structure infections
Abstract number: 1733_818
Strauss R., Amsler K., Jacobs M., Bush K., Noel G.
Objectives: Panton-Valentine leukocidin (PVL)-positive methicillin-resistant S. aureus (MRSA) has been recognized as a virulent pathogen that can cause severe skin and respiratory tract infections. PVL-positive methicillin-susceptible S. aureus (MSSA) has also been increasingly described in severe skin infections. The prevalence of PVL-encoding genes among S. aureus isolates were analysed from a multicentre trial comparing ceftobiprole, in investigational broad-spectrum cephalosporin with anti-MRSA activity, to vancomycin in the treatment of patients with complicated skin and skin structure infections (cSSSI).
Methods:S. aureus isolates were analysed for PVL by multiplex PCR (n = 415). In vitro susceptibility (CLSI methodology) and a mecA probe were used to identify MRSA.
Results: The trial involved 92 sites from 15 countries on 4 continents. Of the 784 patients enrolled, S. aureus was isolated in 494 baseline samples obtained from pus, leading edge of cellulitis, or debrided tissue. Overall, 47% (195/415) of S. aureus isolates were PVL positive. There were large regional differences in the prevalence of MRSA and MSSA among S. aureus isolates. In Europe, 40/239 (16.7%) S. aureus were MRSA, compared to the USA, where 129/185 (69.7%) of S. aureus were MRSA (P < 0.001). PVL results were available for 447/497 S. aureus isolates (89.9%). PVL-positive MRSA isolates were most commonly seen in the USA, with significantly lower rates of PVL-positive MRSA in Europe (P < 0.001) (Table). In contrast, PVL-positive MSSA most commonly occurred in Asia/Africa and Europe. Clinical cure rates of cSSSI due to PVL-positive S. aureus were comparable between ceftobiprole- and vancomycin-treated subjects (95.0% vs 95.0%). Cure rates of cSSSI due to PVL-positive MRSA were 93.9% for ceftobiprole-treated subjects and 86.2% for vancomycin-treated subjects. Frequency of PVL positivity among S. aureus isolates is shown in the table.
Conclusion: Prevalence of PVL-positive MRSA and PVL-positive MSSA differed widely among geographic regions. In this phase 3 cSSSI trial, PVL-positive S. aureus isolates from US subjects were substantially more likely to be MRSA than MSSA. This may be reflective of the high prevalence of USA300 isolates as an important cause of cSSSI in the USA. Outside the USA, the PVL toxin gene was more likely to be found in MSSA than in MRSA isolates.
|Session name:||European Society of Clinical Microbiology and Infectious Diseases|
|Location:||ICC, Munich, Germany|
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