SUMMARY Rationale: Prophylactic antibiotics in laparoscopic surgeries, including Metabolic Bariatric Surgery (MBS), are routinely provided to reduce postoperative infections, especially at wound incision sites. However, since incisional wound infections in laparoscopic MBS are rare and morbidity is very low, the benefit of antibiotic prophylaxis is questionable.

Objective: Evaluate the non-inferiority of omitting antibiotic prophylaxis in MBS. Compare postoperative outcomes between Group A (no antibiotics) and Group B (standard antibiotic care) to determine if omission increases complications, particularly wound infections.

Study Design: Randomized controlled trial (RCT), double-blind.

Study Population: Patients with obesity eligible for MBS.

Intervention:

• Group A (No Antibiotic Prophylaxis): Undergo MBS without antibiotics to test safety regarding postoperative complications, focusing on surgical site infections (SSIs).
• Group B (Standard Antibiotic Prophylaxis): Receive standard one-time antibiotics before incision.

Main Study Parameters/Endpoints: Compare the incidence of incisional and organ/space SSIs within six weeks post-surgery between Group A and Group B to determine if omitting antibiotics affects infection rates.

Nature and Extent of the Burden and Risks:

Rationale:

1. Cost-Effectiveness: Reducing antibiotic use could lower surgical costs.
2. Resource Utilization: Simplifying protocols save hospital resources.
3. Antibiotic Resistance: Reducing use helps combat resistant bacteria.
4. Adverse Reactions: Fewer antibiotics may reduce side effects.

Risk Assessment:

1. Increased Infection Rates: Monitor SSI and organ/space SSI rates closely.
2. Anastomotic Leaks and Reoperations: Assess the impact on leaks and operations.
3. Readmissions and Postoperative Interventions: Evaluate the effect on readmission and intervention rates.

Group Relatedness:

Comparing groups with and without antibiotics provides evi-dence-based insights into the safety of modifying standard practices to optimize health outcomes and resource use.

Inclusion Criteria:

° Patients must be older than 18 and meet the eligibility criteria for MBS as outlined by the International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) and the Dutch Federation of Medical Specialists for the surgical treatment of obesity.

Exclusion Criteria:

• Patients undergoing immunotherapy or corticosteroid treatment for Crohn's disease or rheumatoid arthritis.
• Patients with a history of endocarditis require prophylactic antibiotics.
• Patients with known severe allergies to antibiotics.
• Patients with active infections or recently treated with antibiotics (within the last 30 days).
• Patients with compromised immune systems, including those with HIV/AIDS or undergoing chemotherapy.
• Patients with chronic liver or kidney disease.
• Patients with uncontrolled diabetes (HbA1c > 9%).
• Patients with a history of previous metabolic bariatric surgery.
• Pregnant or breastfeeding women.
• Patients with any other medical condition that, in the opinion of the investigator, would compromise the patient's safety or the study's integrity.

The analysis will be performed on a blinded dataset after the completion of the medical/scientific review. All protocol violations will be identified and resolved, and the dataset will be declared complete. All data will be collected in a data management system (Castor EDC, Amsterdam, The Netherlands; https://www.castoredc.com) and handled according to Good Clinical Practice guidelines, Data Protection Directive certificate, and complied with Title 21 CFR Part 11. Furthermore, the data centers, where all the research data were stored, are certified according to ISO27001, ISO9001, and Dutch NEN7510.

After the study been peer-reviewed for 20 years available.

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