Objective: We aimed to investigate the risk factors for surgical site infections (SSI) and the effectiveness of prophylactic antibiotic use. Methods:The demographic characteristics, comorbidities, and microbiological examinations of patients diagnosed with SSI who had a cholecystectomy, vaginal hysterectomy, knee prosthesis, hip prosthesis, and gastric surgery between January the 1st, 2014 and December the 31st, 2019 were retrospectively analysed. The diagnosis of healthcare-associated infections and SSI was based on the Centers for Disease Control and Prevention criteria. Results:We detected Gram-negative bacteria in 30% of knee prosthesis infections (60% carbapenem-resistant), 60% of hip prosthesis infections (39% carbapenem-resistant), 36% of vaginal hysterectomy (no carbapenem resistance), 50% of cholecystectomy (no carbapenem resistance), and 20% of gastric surgery (no carbapenem resistance). Staphylococci were the causative agents in 30% of knee prosthesis infections (30% methicillin-resistant) and 20% of hip prosthesis infections (38% methicillin-resistant). Conclusion:We detected multidrug resistance in microorganisms isolated from knee and hip replacement infections. Antibiotic resistance is a big problem, and antibiotic prophylaxis is insufficient to prevent SSI. Doctors should follow up with the patient who underwent surgery closely and take microbiological samples to select appropriate antibiotics when SSI develops.