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Characteristics of complicated skin and skin structure infections due to staphylococci and the presence of Panton-Valentine leukocidin

Abstract number: 1732_83

Strauss R., Amsler K., Jacobs M., Bush K., Noel G.

Objectives: An association has been proposed between Panton-Valentine leukocidin (PVL) and virulence in methicillin-resistant Staphylococcus aureus (MRSA) causing skin or respiratory tract infections. In a multicentre trial comparing ceftobiprole (BPR), an investigational cephalosporin, to vancomycin (VAN) in patients with complicated skin and skin structure infections (cSSSI), PVL-positive S. aureus characteristics were analysed and assessed for both MRSA and methicillin-susceptible (MSSA) isolates.

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. Infection type was categorised as abscess, wound, or cellulitis. Infections with a depth either to the fascial plane or muscle were considered deep infections.

Results: Of 784 patients enrolled, S. aureus was identified in 494 baseline isolates from pus, leading edge of cellulitis, or debrided tissue. PVL was significantly more common in abscesses compared to wound infections or cellulitis among both MRSA (P < 0.001) and MSSA infections (P < 0.005). There was a trend for higher WBC counts among PVL-positive MRSA and MSSA isolates compared to PVL-negative MRSA and MSSA isolates. PVL-positive MRSA infections were associated with significantly lower rates of fever (P < 0.001) and lower levels of C-reactive protein (CRP) (P < 0.005) compared to PVL-negative MRSA infections. Lower overall cure rates were observed in PVL-positive MRSA infections (overall 89.3%; BPR 93%; VAN 85%). Overall cure rates for PVL-negative MRSA and PVL-positive or negative MSSA were >94% in both treatment arms.

 % MRSA% MSSA
PVL(+)PVL(-)PVL(+)PVL(-) 
Infection type, % abscess70.5 (67/95)*26.3 (15/57)68.0 (68/100)*48.2 (79/164)
Deep infections, %33.6 (32/95)38.6 (22/57)26.0 (26/100)34.1 (56/164)
WBC > 104, %32.2 (28/87)21.3 (10/47)41.4 (36/87)31.0 (45/145)
Temperature >38°C14.7 (14/95)*42.1 (24/57)44.0 (44/100)40.2 (66/164)
CRP > 50 mg/dL28.0 (26/93)*51.9 (28/54)36.2 (34/94)41.4 (67/162)

Conclusion: PVL-positive MRSA and MSSA were widely prevalent in cSSSI. The presence of PVL in both MRSA and MSSA was significantly associated with abscess compared to wound infections or cellulitis in this cSSSI trial. Lower fever and CRP levels in patients with PVL-positive MRSA infections may indicate impaired host responses to PVL-positive S. aureus. The presence of PVL was associated with lowest cure rates in patients with MRSA infections; however, cure rates in patients treated with BPR exceeded 90%.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Subject:
Location: ICC, Munich, Germany
Presentation type:
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