Surgical Site Infection After Breast Surgery—A Bicentric Retrospective Case–Control Study in Saudi Arabia

<b>Background:</b> Surgical site infections (SSIs) are common postoperative complications. Data on SSIs following breast surgery in Saudi Arabia are limited because these procedures are not included in the national SSI surveillance system. This study determined the SSI incidence rate, identified associated risk factors, and described the microbiological profiles of patients undergoing breast surgery at two tertiary hospitals in Saudi Arabia. <b>Methods:</b> This bicentric retrospective case-control study analyzed 1841 breast surgeries performed at two tertiary hospitals between July 2021 and July 2024. Demographic, surgical, and microbiological data were extracted from electronic medical records. SSIs were defined according to National Healthcare Safety Network criteria. Descriptive statistics summarized patient and surgical characteristics and SSI rates. A matched case-control analysis (1:4 ratio based on age and hospital site) included 172 patients. Multivariable logistic regression was used to identify predictors of SSI. <b>Results:</b> The cumulative SSI incidence was 2.4%, and most infections occurred within 30 days of surgery (69%). Gram-negative organisms were predominant in microbiologically positive cases (53.6%), mainly <i>Klebsiella pneumoniae</i> and <i>Pseudomonas aeruginosa</i>, whereas <i>Staphylococcus aureus</i> (including MRSA) accounted for 25%. Immunocompromised status (OR 3.32, 95% CI 1.35-8.14) and surgical drain use (OR 4.07, 95% CI 1.68-9.87) were independently associated with SSI. <b>Conclusions:</b> The incidence of SSIs after breast surgery in Saudi Arabia was relatively low. The predominance of Gram-negative pathogens and the identification of immunocompromised status and surgical drain use as major risk factors highlight opportunities for targeted infection prevention strategies. Further studies should validate these findings in larger and more diverse populations and healthcare settings.