Preadmission systemic antibiotic treatment in necrotizing otitis externa (NOE)

Purpose: Necrotizing otitis externa (NOE) is a serious life-threatening infection, with Pseudomonas (PA) aeruginosa being the primary causative agent. Over the last two decades the use of systemic anti-PA antibiotics expanded substantially and are now prescribed regularly by physicians. Meanwhile, studies indicate shifting trends in the incidence of the offending pathogen in NOE. The objective of the study is to assess whether preadmission antibiotic treatment influence the incidence offending pathogens and sterile cultures in NOE. Also, we aim to evaluate the effects of preadmission antibiotic treatment on NOE severity and disease progression. Methods: A retrospective case series analysis was performed, including all patients admitted in a single tertiary center due to NOE. Results: 83 patients were included in the study. Among them 17 patients received no oral antibiotics prior to admission (NoAb-NOE), and 65 patients received systemic antibiotics prior to admission. There was no statistical difference between the groups regarding the incidence of the pathogen or sterile culture. Furthermore, there was no statistical difference regarding duration of hospitalization, need for surgery or readmission. Conclusion: Preadmission antibiotic treatment does not influence the incidence of offending pathogens or rate of sterile culture in NOE. Moreso, preadmission antibiotic has no effect on disease progression or severity in NOE. Our findings suggest that sterile culture NOE is probably due to the low sensitivity of superficial swabs and not secondary to partially treated disease. Deep tissue culture should be considered in the setting of NOE patients.