Purpose: This study aimed to elucidate the etiologies, microbiological profiles, antibiotic susceptibilities of bacteria and outcomes of patients with auricular perichondritis.
Patients and Methods: This was a single-center retrospective study. Inpatients diagnosed with auricular perichondritis at a university teaching hospital in eastern China between January 2013 and December 2022 were included in this study.
Results: A total of 127 patients were enrolled, with an average age of 50.6 ± 16.9 years. In addition to cases in which the etiology remained undetermined in 37% of the patients, postoperative infection emerged as the predominant cause (37.8%), followed by trauma (18.1%). Among the 61 cultured isolates, 21.3% were gram-positive bacteria, 55.7% were gram-negative bacteria, and 23.0% were fungal isolates. The most frequent isolate was Pseudomonas aeruginosa (30/61, 49.2%). Notably, the incidence of fungal infections was markedly higher among postoperative patients than among post-traumatic patients (41.7% vs 7.1%, p = 0.03). The proportions of gram-negative bacteria (60.0% vs 50.0%) and fungal isolates (28.6% vs 15.4%) exhibited an increasing trend during the period of 2018– 2022, as compared to the previous period of 2013– 2017. The bacterial isolates exhibited high susceptibility to vancomycin (100%), amikacin (100%), cefepime (94.6%), and ceftazidime (90.9%). In contrast, overall susceptibility to fluoroquinolones was relatively low (65.2– 67.4%), demonstrating a declining trend in the susceptibility of Pseudomonas aeruginosa. Notably, 78.7% of the patients received an initial treatment regimen covering Pseudomonas aeruginosa. Within 30 days of discharge, 8.5% (6/71) experienced an infection recurrence.
Conclusion: Auricular perichondritis predominantly originates from iatrogenic (postoperative) infections. Antibiotic therapy covering Pseudomonas aeruginosa is a sensible and appropriate empirical treatment in the majority of patients with auricular perichondritis. However, increased resistance to fluoroquinolones has become a notable concern, suggesting the need to seek new, more aggressive strategies.

Keywords: auricular perichondritis, antibiotic sensitivity, Pseudomonas aeruginosa, fluoroquinolones