Gram-negative germs with and without multi-resistance are garnering more and more importance. The aim of this study was to investigate the frequency and rate of resistance against antibiotics and to clarify the impact of Gram-negative bacteria, especially with high rates of resistance, for the treatment of venous leg ulcers. This is a retrospective, monocentric, non-randomised open study. Included were all data within 1 year of bacterial swabs of venous leg ulcers. We performed summarization, pooling, and descriptive analysis for frequencies and crossover. We analysed 679 swabs of 285 patients with venous leg ulcers. The mean patient age was 69.78 years. There were 76.1% Gram-positive and 58.2% Gram-negative germs detected; 56.5% of the swabs showed multi-resistance. Gram-negative bacteria were associated with more pain. Exacerbation and relevant aggravation of wounds that led to stationary treatment occurred more frequently. With polihexanid treatment, we saw less Gram-negative flora. This study showed an immediate impact of Gram-negative germs on the patient's pain, the risk for aggravation, and the choice of treatment. Further studies for prophylaxis and treatment of Gram-negative germs in venous leg ulcer therapy are needed.