Panton-Valentine leukocidin–positive Staphylococcus aureus in skin and soft tissue infections from primary care patients

Objectives To characterize deep skin and soft tissue infections (dSSTI) caused by Panton-Valentine leukocidin (PVL)-positive versus PVL-negative Staphylococcus aureus isolates. Methods We performed a retrospective analysis of patients' records including S. aureus isolates from outpatients with dSSTI. Samples had been submitted by primary care physicians, i.e. general practitioners, surgeons, dermatologists and paediatricians, located in Berlin, Germany, in 2007–2017. Bacterial isolates were identified and tested for antimicrobial susceptibility by VITEK 2; PVL was detected by PCR. Results In total, 1199 S. aureus isolates from 1074 patients with dSSTI were identified, and 613 (51.1%) of 1199 samples were PVL+. The median age of patients with PVL+ S. aureus was lower than in patients with PVL− S. aureus (34 years, range 0–88 years, vs. 44 years, range 0–98 years; p < 0.0001). PVL was associated with repeated/multiple samples compared to single sample submission (69/92, 75% vs. 448/982, 45.6%, p < 0.0001; odds ratio (OR), 3.6; 95% confidence interval (CI), 2.2–5.8). Interestingly, the highest PVL positivity rate was found in isolates from gluteal (82/108, 75.9%; OR, 3.6; 95% CI, 2–5) or axillary (76/123, 61.8%; OR, 2; 95% CI, 1.1–3.3) localizations compared to isolates from the arm. The PVL positivity rate did not increase over time. Yet we noticed an increase in the trimethoprim/sulfamethoxazole (SXT) resistance rate in PVL+ isolates, mainly methicillin-sensitive S. aureus, when considering SXT resistance rates of 2007–2012 versus 2013–2017 (35/226, 15.5% vs. 74/289, 25.6%; p 0.01). Conclusions In outpatients, gluteal and axillary dSSTI are indicative of PVL+ S. aureus. Providing SXT as a complementary treatment for dSSTI should be based on susceptibility testing.