Clinical Studies
Necrotizing otitis externa: diagnosis, treatment, and outcome in a case series☆,☆☆

https://doi.org/10.1016/j.diagmicrobio.2016.10.017Get rights and content

Highlights

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    A delay of NOE diagnosis exists, affecting disease outcome.

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    P. aeruginosa was the main causative organism (50%), with a 30% multidrug-resistance rate. A high rate (35%) of fungal pathogens was noted.

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    Treatment with a single antibiotic agent may be insufficient. Treatment should be altered according to microbiologic culture results.

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    Cranial neuropathies and CT finding of adjacent structural involvement correlate with adverse prognosis.

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    We state the importance of limited surgical intervention and microbiologic cultures in disease treatment.

Abstract

We reviewed 25 cases of patients diagnosed with necrotizing otitis externa in our tertiary university-affiliated medical center between 2009 and 2015. Mean overall hospitalization duration was 14.52 days, 95% of the patients showed specific seasonal incidence. Mean duration of symptoms prior to hospitalization was 6 weeks and the duration correlated with outcome. Only 8% of the patients presented with cranial neuropathies; however, this presentation correlated with adverse outcome. Pseudomonas aeruginosa was the main causative organism (50%), with a 30% multidrug-resistance rate. A high rate (35%) of fungal pathogens was noted. Seventeen patients (68%) were eventually operated; however, only 5 patients needed extensive surgery under general anesthesia. Computed tomography (CT) evidence of adjacent structures' involvement correlated with adverse outcome. Eighty percent of our patients improved clinically. The overall death rate was 12% and the disease-related mortality rate was 8%. Our findings state the importance of limited surgical intervention and microbiologic cultures in disease treatment. This is particularly important in patients with cranial neuropathies and CT finding of adjacent structural involvement that correlate with adverse prognosis. A rising pseudomonal antibiotic resistance and fungal infections may challenge antibiotic treatment in the future.

Section snippets

Background

Necrotizing otitis externa (NOE) is a severe infection that typically affects the elderly, diabetic, and immunocompromised patients (Chandler, 1968).

Another term is skull-base osteomyelitis, which describes the pathophysiology and local spread of the disease process (Nadol, 1980).

P. aeruginosa is the main causative organism. Fungal pathogens may cause NOE, particularly in immunocompromised patients who are not diabetic (Carfrae and Kesser, 2008).

Infection usually begins in the external auditory

Methods

The study was approved by the Sheba Medical Center ethics committee. The database of the Department of Otolaryngology–Head and Neck Surgery in our tertiary university-affiliated medical center was searched for cases of NOE treated between 2009 and 2015.

The patients were diagnosed with NOE upon admission, or during their hospitalization. The diagnosis was based on the following criteria:

  • 1)

    Severe, unremitting otalgia or sensation of aural fullness with duration of over 2 weeks.

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    Physical findings

Background and clinical characteristics

A total of 25 cases, 7 women (28%) and 18 men (72%) met our diagnostic criteria with a mean age of 73.8 (range, 27–93).

Diabetes mellitus (DM) was present in 84% of the patients (21/25), 14 (66%) of them were insulin dependent. Mean hemoglobin A1c (HbA1C) level was 7.8 (range, 5.2–9.8). The patients' main clinical characteristics are shown in Table 1.

Two patients were defined as immunodeficient: 1 patient was under immunosuppressing therapy postrenal transplant and the other received

Discussion

NOE is a severe disease associated with morbidity and mortality. Before the era of effective antipseudomonal regimens, NOE was managed surgically and was associated with a mortality rate of nearly 50%.

The development of modern antibiotics, especially antipseudomonal, has reduced mortality significantly (Carfrae and Kesser, 2008, Chen et al., 2010, Rubin Grandis et al., 2004). Nonetheless, even with today's effective treatment, NOE may still be an aggressive, persistent, and even fatal disease.

Conclusions

NOE remains an elusive, highly variable, severe, and potentially fatal clinical condition despite recent advancement in treatment. Lack of diagnostic criteria, established prognostic factors, and treatment guidelines still exists. This study presents many clinical findings and aspects of the disease in a cohort of patients diagnosed based on predetermined criteria. Our study shows a rising community-acquired pseudomonal antibiotic resistance and higher rate of fungal infection than previously

References (17)

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☆

Funding: None

☆☆

Conflict of interests: None

1

Glikson Eran and Sagiv Doron contributed equally to this manuscript.

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