Introduction: Post-operative infections are one of the leading causes of mortality and morbidity in surgery. They represent a serious complication in trauma surgery and limit the potential benefit of surgical interventions. Material and method: Our work is a prospective descriptive study carried out over a period of one year, going from January to December 2017, the samples of which were taken at the level of the traumatology-orthopedics department, then analyzed in the bacteriology laboratory, the Ibn Tofail hospital, CHU Mohamed VI of Marrakech. All patients who had undergone surgery and subsequently developed postoperative infection at least 72 hours after surgery were included in the study. Result: During the study period 55 postoperative infections were diagnosed in 78 operated subjects. The number of germs isolated is 112, 70% of which are BGN and 30% CGP. The distribution by bacterial family demonstrated the predominance of Enterobacteriaceae which represented 46% of isolates, followed by Staphylococci (26%), then nonfermenting BGNs (24%), and Streptococci (4%). The level of resistance of bacteria had shown that all A. baumannii strains were resistant to imipenem, 70% of Enterobacteriaceae showed high level resistance, then 50% of P. aeruginosa were resistant to ceftazidime, and the MRSA rate was 47%. Multidrug resistant bacteria are dominated by ABRI (34%), followed by ESBL-producing Enterobacteriaceae (EBLSE) (29%), MRSA (20%), Carbapenemasous Enterobacteriaceae (ECARBA) (10%) and PARC (7%). ECARBAs exhibit a high level of resistance to aminoglycosides. Both EBLSEs and ABRI were resistant to aminoglycosides and quinolones. For MRSA, only teicoplanin and vancomycin remain active on these bacteria. Finally, PARC showed strong resistance to all antibiotic families. All strains were sensitive to colistin. Conclusion: There are multiple risk factors for postoperative infections in trauma, the most important of which are related to inadequate practices in adequate care, sometimes unsatisfactory technical platforms, advanced state of pathologies