A retrospective review and multi-specialty, evidence-based guideline for the management of necrotising otitis externa

Diagnostic accuracy of eosinophil-to-lymphocyte ratio and eosinophil-to-neutrophil ratio as biomarkers for differentiating between fungal and bacterial infection in necrotising otitis externa

INTRODUCTION

Necrotizing otitis externa (NOE) is a serious, progressive, and potentially life-threatening infection of the external auditory canal, affecting soft tissue and bone. The most common organism causing NOE is Pseudomonas Aeruginosa and less common are Fungal infections. When managing a patient with NOE, a culture is taken from the EAC in order to tailor the appropriate antimicrobial treatment, however commonly, the culture is sterile. Inflammation biomarkers may be used as adjuncts to inform on the differential diagnosis and as prognostic markers.

AIM

To characterize and compare values and ratios of components of the complete blood count (CBC) at admission, at patients with positive swab culture.

METHODS

A retrospective study of NOE patients was conducted. We included all patients admitted between the years 2001-2023, for whom a culture swab tested positive. We compared CBC findings at hospitalization between bacteria and fungi-positive culture patients.

RESULTS

Eosinophils-to-Neutrophils Ratio (ENR) was significantly lower in the fungal group compared to the bacterial group 0.023 ± 0.02 and 0.04 ± 0.03, respectively (p-value = 0.025). Eosinophils-to-Leukocyte Ratio (ELR) was significantly lower in the fungal group compared to the bacterial group 0.058 ± 0.04 and 0.12 ± 0.1 respectively (p-value = 0.009). For definition of ELR ≤ 0.1 we found that, sensitivity was 88% (95%CI = 0.679-0.979) and NPV 90% (95%CI = 0.709-0.982). For definition of ENR ≤ 0.03 sensitivity was 88% (95%CI = 0.679-0.979) and NPV 88% (95%CI = 0.679-0.979).

CONCLUSION

Lower values of ELR and ENR in patients with NOE are associated with fungal infection and can serve as a tool in adjusting an appropriate antimicrobial therapy in cases of sterile or when no culture is available.

Management and Outcomes of Necrotizing Otitis Externa: A Retrospective Cohort Study in a Tertiary Referral Center

Objectives

Necrotizing otitis externa (NOE) is a rare infection of the ear that causes osteomyelitis. We aimed to evaluate treatment outcomes and the role of imaging in diagnosing and monitoring disease resolution in a single-center study of patients with NOE.

Methods

In this retrospective cohort study, patients with NOE who were diagnosed and treated in a tertiary otology center in Utrecht, The Netherlands, between January 1, 2013 and August 1, 2022, were included. Data were retrieved from the medical records on demographics, symptoms, physical and diagnostic findings, type and duration of treatment, and course of disease.

Results

A total of 24 cases were included. Patients were often elderly (mean age = 75 years) and diabetic (88%). Pseudomonas aeruginosa was the most commonly found microorganism (63%). Twenty-two cases (92%) received intravenous antibiotic treatment, and 7 cases (29%) received additional systemic antifungal treatment. The mean duration of systemic treatment was 29 weeks. In 20 out of 22 cases (91%), imaging was used to determine the end point of treatment. None of the cases with a total resolution of disease activity (n = 5) on 18F-fluorodeoxyglucose-positron emission tomography-computed tomography imaging at the time of cessation of therapy showed clinical relapse, compared with 1 out of 4 cases on gallium single-photon emission computerized tomography.

Conclusion

Based on the experience from our center, we demonstrated that patients with NOE can successfully be treated with prolonged systemic treatment. Molecular imaging is reasonably successful for disease evaluation and decision-making on the eradication of disease.

Necrotizing Otitis Externa: A Proposal for Diagnostic and Therapeutic Approach

Introduction  Necrotizing otitis externa has a high impact on the quality of life of patients and has shown a significant increase in its incidence in recent years. There has been a change in the profile of affected patients and a lack of consensus on the management of these patients. Objective  To develop a practical and effective care protocol to standardize the diagnostic and therapeutic management of necrotizing otitis externa. Methods  A retrospective cohort study of necrotizing otitis externa patients between January 2015 and December 2020. Results  There were 34 patients with two bilateral cases, totaling 36 ears. The mean age was 68.5, with a higher prevalence of males (76%). Diabetes was present in 97% of the samples. The involvement of cranial pairs was identified in 35% of the sample. Pseudomonas aeruginosa was the most frequent pathogen isolated, found in 50% of the cases. Among the cultures with bacterial agents isolated, 35% showed resistance to ciprofloxacin. The most frequent exam was computed tomography (94%). Hospital admission was indicated for 31 patients (91%), and ceftazidime was the most prescribed drug (35.5%). There were 11 recurrences (32%), and 12 patients (35%) had complications during treatment. Among the unfavorable outcomes, 12% persisted with some degree of peripheral facial paralysis, 6% maintained dysphagia, and 9% died of the disease. Conclusions  The present study developed a diagnostic and therapeutic protocol for the effective management of necrotizing otitis externa. This protocol is a dynamic tool and should be revised and updated as new demands emerge during its implementation.

Rare Cause of Skull Base Osteomyelitis: A Challenging Diagnosis and Management With a Literature Review

This is a case of skull base osteomyelitis (SBO) caused by a rare fungal species, Scedosporium apiospermum. This is a clinical case report with a review of the literature. SBO is a potentially life-threatening infection of the temporal bone. The patient presented to our hospital with a two-month history of left otalgia, otorrhea and reduced hearing, after failed initial intravenous antibiotic therapy. Thorough examination and further investigation confirmed the diagnosis of SBO caused by a rare fungal species, S. apiospermum. The patient was subsequently started on a long-term course of antifungals which led to an improvement of symptoms. This case highlights the importance of early recognition and considering early antifungal treatment in patients with persistent otalgia and otorrhea, particularly in those who have failed to respond to intravenous antibiotics. Further research is needed to better understand the optimal timing and duration of antifungal therapy in these patients.

Cranial nerve palsy prevalence and associated factors in patients with malignant otitis externa

Objective

To identify the prevalence of cranial nerve (CN) palsy and its associated factors in malignant otitis externa (MOE).

Methods

In a retrospective study, records of MOE patients from 2011 to 2014 were reviewed. MOE and CN involvement were evaluated based on patient demographics, clinical, and paraclinical data.

Results

Overall, 119 MOE patients with a mean age of 65.9 ± 11.3 were included. 69.7% were male, and 63.0% had a history of diabetes. The most common symptoms and signs were otalgia (97.5%), otorrhea (44.5%), and ear canal erythema/edema (24.4%). Thirty-three patients (27.7%) had CN involvement. The facial nerve was mostly involved (26.1%). Skull base osteomyelitis (SBO) was present in 59 patients. When excluding patients younger than 30 and older than 80, age decade was correlated with CN palsy. 66.9% of patients with CN palsy and 65.6% without CN palsy were male, which was significantly different. The following factors were not significantly different between patients with and without CN palsy: Comorbidities, signs and symptoms, diagnostic delay, erythrocyte sedimentation rate level, fasting blood sugar, hemoglobin A1c level, antifungal therapy, hospitalization duration, and SBO on imaging. Tinnitus was correlated with SBO evidence on imaging (specificity: 96.7%).

Conclusion

CN involvement occurs in about three out of 10 MOE patients. Male gender and advanced age may be related to a higher incidence rate of CN palsy. Tinnitus can be a specific indicator of SBO. These findings could help in better decision-making for early interventions.

Level of Evidence

4.

Systematic review of the diagnosis and management of necrotising otitis externa: Highlighting the need for high-quality research

OBJECTIVES

To present a systematic review and critical analysis of clinical studies for necrotising otitis externa (NOE), with the aim of informing best practice for diagnosis and management.

DESIGN

Medline, Embase, Cochrane Library and Web of Science were searched from database inception until 30 April 2021 for all clinical articles on NOE. The review was registered on PROSPERO (ID: CRD42020128957) and conducted in accordance with PRISMA guidelines.

RESULTS

Seventy articles, including 2274 patients were included in the final synthesis. Seventy-three percent were retrospective case series; the remainder were of low methodological quality. Case definitions varied widely. Median patient age was 69.2 years; 68% were male, 84% had diabetes and 10% had no reported immunosuppressive risk factor. Otalgia was almost universal (96%), with granulation (69%) and oedema (76%) the commonest signs reported. Pseudomonas aeruginosa was isolated in 62%, but a range of bacterial and fungal pathogens were reported and 14% grew no organism. Optimal imaging modality for diagnosis or follow-up was unclear. Median antimicrobial therapy duration was 7.2 weeks, with no definitive evidence for optimal regimens. Twenty-one percent had surgery with widely variable timing, indication, or procedure. One-year disease-specific mortality was 2%; treatment failure and relapse rates were 22% and 7%, respectively.

CONCLUSION

There is a lack of robust, high-quality data to support best practice for diagnosis and management for this neglected condition. A minimum set of reporting requirements is proposed for future studies. A consensus case definition is urgently needed to facilitate high-quality research.

Exploring theories for the exponential 16-year rise in incidence of necrotising otitis externa in England

Background

Necrotising otitis externa is a severe, life-threatening infection. Epidemiological data demonstrate a dramatic rise in reported cases in England from 2002 to 2017. The reasons for this remain elusive.

Methods

A quantitative descriptive study was undertaken using epidemiological data from the Hospital Episode Statistics database. Cases from 2002 to 2017 were compiled and analysed. Four potential theories were explored to explain the rise in incidence.

Results

Within the 16-year period, 7327 necrotising otitis externa cases were reported. Annual necrotising otitis externa incidence increased 1142 per cent within the 16-year period, from 123 recorded cases in 2002 to 1405 cases in 2017. This correlates with an increasing prevalence of diabetes, an ageing population and likely increased physician awareness of necrotising otitis externa. There is insufficient evidence to support antibiotic resistance as a significant associated factor.

Conclusion

Correlation does not imply causation. It is likely that a combination of factors is contributing to the rise in necrotising otitis externa incidence, including increased physician recognition, diagnosis and accurate clinical coding.

Characteristics, management and outcome of a large necrotising otitis externa case series: need for standardised case definition

Background

Necrotising otitis externa is a severe ear infection for which there are no established diagnostic or treatment guidelines.

Method

This study described clinical characteristics, management and outcomes for patients managed as necrotising otitis externa cases at a UK tertiary referral centre.

Results

A total of 58 (63 per cent) patients were classified as definite necrotising otitis externa cases, 31 (34 per cent) as probable cases and 3 (3 per cent) as possible cases. Median duration of intravenous and oral antimicrobial therapy was 6.0 weeks (0.49–44.9 weeks). Six per cent of patients relapsed a median of 16.4 weeks (interquartile range, 23–121) after stopping antimicrobials. Twenty-eight per cent of cases had complex disease. These patients were older (p = 0.042), had a longer duration of symptoms prior to imaging (p < 0.0001) and higher C-reactive protein at diagnosis (p = 0.005). Despite longer courses of intravenous antimicrobials (23 vs 14 days; p = 0.032), complex cases were more likely to relapse (p = 0.016).

Conclusion

A standardised case-definition of necrotising otitis externa is needed to optimise diagnosis, management and research.

Retrospective analysis of outcomes of outpatient parenteral antimicrobial therapy (OPAT) for necrotising otitis externa

Necrotising otitis externa (NOE) is an uncommon but life-threatening infection that requires prolonged systemic antimicrobial therapy. This study aims to identify factors associated with treatment response and outcome in patients with NOE treated through outpatient parenteral antimicrobial therapy (OPAT). We performed a retrospective analysis of patients with NOE treated over a 4-year period (January 2018-January 2022) at a tertiary referral hospital in Derbyshire, UK. We defined OPAT failure as unplanned readmission within 30 days of discontinuation of OPAT. Prolonged duration of therapy was defined as length of parenteral antimicrobial treatment of more than 8 weeks. A total of 46 cases of NOE were reviewed. OPAT failure and prolonged therapy were recorded in 9 (19.6%) and 23 (50.0%) episodes respectively. Facial nerve involvement (odds ratio [OR], 14.54; 95% confidence interval [CI], 2.76-76.60; p = 0.002), dementia (OR, 7.65; 95% CI, 1.23-47.46; p = 0.029), Charlson comorbidity score (OR, 1.41 per unit increase; 95% CI, 1.00-2.00; p = 0.049) and peak CRP level (OR, 1.03 per unit increase; 95% CI, 1.00-1.06; p = 0.027) were associated with increased risk of treatment failure. Facial nerve involvement (OR, 16.30; 95% CI, 2.60-102.31; p = 0.003) and peak CRP level (OR, 1.04; 95% CI, 1.01-1.07; p = 0.016) were also associated with an increased need for prolonged antimicrobial therapy. In addition, extent of disease (based on imaging findings) was linked to prolonged therapy (OR, 22.89; 95% CI, 3.62-144.76; p = 0.001). NOE could be effectively managed as outpatient via OPAT. However, vigorous antimicrobial treatment and close monitoring of patients with pre-existing comorbidities, facial nerve paralysis, extensive disease and markedly elevated inflammatory markers are essential to optimise clinical outcomes.

Necrotising Otitis Externa Antibiotic therapy complications: A retrospective cohort analysis

NOE is a rare but life-threatening condition. Treatment is long-term intravenous antibiotics. However, there is no evidence on the complications of antibiotic treatment in this complex cohort of patients In our study, patients on average are treated with two different antibiotic regimes 63% of these changes in regimen are due to direct adverse effects from treatment including drug intolerance and lack of significant clinical response leading to deterioration and morbid complications Patients requiring multiple antibiotic regimes have a statistically longer duration of treatment. These adverse effects appear to occur more frequently in patients with additional comorbidities. This novel data provides information clinicians can use when initiating treatment for NOE and counsel patients appropriately.