What are the criteria for terminating treatment for necrotizing (malignant) otitis externa?

Delayed diagnosis of central skull-base osteomyelitis with abscess: case report and learning points

“…He remains under regular outpatient review as recurrence rates have been estimated up to 20%. 5 Our case demonstrates the difficulty in reaching a correct diagnosis quickly. The lesion was initially misdiagnosed as a neoplasm.…”

“…Figure 3 An axial computed tomography guided biopsy was performed using a paramaxillary and subzygomatic approach Figure 4 Fat-saturation axial T1 post IV gadolinium post-treatment scan showing a marked reduction in size of the preclival abscess with a residual rim-enhancing cleft seen on the right side (arrow); the clivus signal has now returned to normal and the dural enhancement has also resolved The optimal length of therapy for any form of osteomyelitis, long bone or skull base, is not known. 4,5 Based on a review of the literature, Courson advocates at least 6 weeks of systemic antibiotics following which antibiotic duration is guided by clinical, radiological and inflammatory marker response. Our patient required two courses of antibiotic to achieve satisfactory treatment, totalling 20 weeks.…”

Malignant otitis externa in a healthy non-diabetic patient

“…MOE is typically seen in elderly diabetic or immunocompromised patients, and a workup to rule out diabetes or compromised immune function should Eur Arch Otorhinolaryngol be performed if MOE is diagnosed in a patient who is not known to be diabetic or immunocompromised [1]. MOE usually presents as severe otitis externa, and patients are often treated with repeated and failing courses of different antibiotics until a diagnosis of MOE is considered [1,6]. In 1987, Cohen [7] proposed diagnostic standards for MOE consisting of earache, otorrhea, ear canal swelling, granulation tissue in the EAC, microabscesses in mastoid cells (all findings in our patient), and positive technetium 99 ( 99 Tech) bone scan and/or no clinical response after 1 week of local treatment.…”

“…Thus, Pseudomonas aeruginosa is the most commonly isolated pathogenic bacteria, although fungi and Staphylococcus aureus and Staphylococcus albus are also seen [1,2,6]. Hobson et al [2] reviewed the records of 20 patients with MOE treated between 1995 and 2012 and found that of 9 patients with cultures positive for Pseudomonas aeruginosa all had diabetes, while only 55 % of non-Pseudomonas-infected patients had diabetes.…”

“…99 Tech scanning has been traditionally used for the diagnosis of osteomyelitis as it is very sensitive for osteoclast activity; however, it cannot differentiate between active infection and bone remodeling [6]. CT is sensitive for identifying abscess formation and bone erosion, but not for specifically diagnosing active bone infection [1,7].…”