Background: Microtia, or congenital malformation (smallness or absence) of the outer ear, can be treated with ear prosthetics and/or surgery. Methods: Between January 2011 and December 2021, following plastic surgery, microbial strains from patients with microtia were collected, identified, and counted. WHONET 5.6 was used to analyze in vitro drug resistance of the microbial strains, according to procedures outlined by the Clinical and Laboratory Standards Institute (document M100, 2021). Data regarding surgical techniques, the duration of infection, and other clinical details were also collected. Results: A total of 261 patients were included in the study. Among these, 235 Gram-positive bacteria were detected, with Staphylococcus aureus (140/235) and coagulase-negative staphylococci (84/235) accounting for the majority. There were also 26 Gram-negative bacteria, of which Enterobacter (11/26) and Pseudomonas aeruginosa (7/26) were the most common. According to the results of testing for antimicrobial resistance, S. aureus was highly sensitive to cotrimoxazole, levofloxacin, vancomycin, chloramphenicol, and linezolid, whereas coagulase-negative staphylococci were highly sensitive to vancomycin and linezolid. Both were highly resistant to penicillin and erythromycin. In this study, the pathogenic bacteria involved in postoperative infections varied overall, but the most prevalent was S. aureus. The infections appeared mainly in the late postoperative period. A total of 24,548 procedures were performed in the same period, and the infection rate was 1.06%. Conclusions: Gram-positive bacteria are the major cause of infection following plastic surgery for microtia. The bacterial species, degrees of antimicrobial resistance, and length of infection varied among the various surgical procedures.