Surgical site infections (SSI) are common in South African hospitals, with antibiotic stewardship programmes (ASP) aimed at reducing their occurrence. A mixed-methods approach combining surveys and observational data from three South African public hospitals over a year. There was a statistically significant decrease (p < 0.05) in SSI rates by 18% after implementing ASP, with a 95% confidence interval of [-23%, -12%]. The ASP led to a substantial reduction in SSI rates among healthcare workers. Further research is needed on long-term effectiveness and cost-benefit analysis. Antibiotic stewardship, Surgical site infections, Healthcare worker, South Africa, Public hospitals Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.