Optisch-Molekulare Diagnostik und Systemtechnologie

Panton–Valentine leukocidin (PVL) is a staphylococcal toxin associated with chronic/recurrent skin and soft tissue infections (SSTIs) and necrotizing pneumonia. Its detection in clinical isolates of Staphylococcus aureus warrants aggressive therapy and infection control measures. However, PVL detection relies on molecular methods of limited use, especially in outpatient or resource-poor settings. In order to aid the development of a lateral flow (LF) test for PVL, clinical isolates from SSTIs were collected in 2020/21 at three laboratories in two cities in the Eastern part of Germany. After the exclusion of duplicate and serial isolates, 83 isolates were eligible. These were tested using an experimental LF test for PVL production. They were also characterized using DNA microarrays, facilitating the detection of virulence and resistance markers as well as the assignment to clonal complexes and epidemic/pandemic strains. Thirty-nine isolates (47%) were PVL-positive, and the LF results were in 81 cases (97.6%) concordant with genotyping. One false-positive and one false-negative case were observed. This translated into a diagnostic sensitivity of 0.974 and a diagnostic specificity of 0.977. The most common PVL-positive MSSA lineages were CC152 (n = 6), CC121 (n = 4), and CC5 and CC30 (each n = 2). Thirty isolates (36%) were mecA-positive. The MRSA rate among PVL-negatives was 20% (nine isolates), but among the PVL-positives, it was as high as 54% (n = 21). The most common PVL-MRSA strains were CC398-MRSA-VT (n = 5), CC5-MRSA-IV “Sri Lanka Clone” (n = 4), CC8-MRSA-[mec IV+Hg] “Latin American USA300” (n = 4), and CC22-MRSA-IV (PVL+/tst+) (n = 2). While the PVL rate was similar just like the German isolates from a previous study a decade before, the MRSA rate among PVL-positives was clearly higher. All PVL-MRSA strains detected, as well as the most common methicillin-susceptible lineage (CC152), are known to be common locally in other parts of the world, and might, thus, be regarded as travel-associated. Therefore, patients with suspected PVL-associated disease should be asked for their history of travel or migration, and, in case of hospitalization, they should be treated as MRSA cases until proven otherwise.