Antibacterial effects of chitosan-based hydrogels containing Trachyspermum ammi essential oil on pathogens isolated from dogs with otitis externa.

BACKGROUND: Growing antibiotic resistance has made treating otitis externa (OE) increasingly challenging. On the other hand, local antimicrobial treatments, especially those that combine essential oils (EOs) with nanoparticles, tend to be preferred over systemic ones. It was investigated whether Ajwain (Trachyspermum ammi) EO, combined with chitosan nanoparticles modified by cholesterol, could inhibit the growth of bacterial pathogens isolated from OE cases in dogs. In total, 57 dogs with clinical signs of OE were examined and bacteriologically tested. Hydrogels of Chitosan were synthesized by self-assembly and investigated. EO was extracted (Clevenger machine), and its ingredients were checked (GC-MS analysis) and encapsulated in chitosan-cholesterol nanoparticles. Disc-diffusion and broth Micro-dilution (MIC and MBC) examined its antimicrobial and therapeutic properties. RESULTS: Staphylococcus pseudintermedius (49.3%) was the most common bacteria isolated from OE cases, followed by Pseudomonas aeruginosa (14.7%), Escherichia coli (13.3%), Streptococcus canis (9.3%), Corynebacterium auriscanis (6.7%), Klebsiella pneumoniae (2.7%), Proteus mirabilis (2.7%), and Bacillus cereus (1.3%). The investigation into the antimicrobial properties of Ajwain EO encapsulated in chitosan nanoparticles revealed that it exhibited a more pronounced antimicrobial effect against the pathogens responsible for OE. CONCLUSIONS: Using chitosan nanoparticles encapsulated with EO presents an effective treatment approach for dogs with OE that conventional antimicrobial treatments have not cured. This approach not only enhances antibacterial effects but also reduces the required dosage of antimicrobials, potentially preventing the emergence of antimicrobial resistance.

Fungal Otitis Externa (Otomycosis) Associated with Aspergillus Flavus: A Case Image.

A 48-year-old man presented with a chief complaint of intermittent right ear otorrhea of several-month duration, occasional otalgia and progressive unilateral hearing impairment. He also reported frequent episodes of headache and pressure in the sinuses and maxilla. Previous systemic treatment with antibiotics failed to alleviate the symptoms. A head/neck CT showed completely normal mastoid, middle ear and external auditory canal regions without any evidence of opacification or bone erosion. Otoscopic examination of the right ear disclosed aggregates of dried, brown, fibrillar material and debris occluding the external auditory canal and obstructing the otherwise intact tympanic membrane. Dilation of the external auditory canal or thickening of the tympanic membrane were not appreciated. The canal was debrided and the fibrillar material was placed in formalin. Histopathologic examination revealed numerous branching, septated fungal hyphae organized in densely-packed clusters. In other areas, the fungal hyphae abutted or were attached to lamellated collections of orthokeratin. As highlighted by GMS staining, the fungi were morphologically compatible with Aspergillus species. The clinicopathologic findings supported a diagnosis of fungal otitis externa, while the numerous anucleate squamous cells were compatible with colonization of an underlying, probably developing, cholesteatoma. Culture of material isolated from the external auditory canal confirmed the presence of Aspergillus flavus. In this illustrative case, we present the main clinical and microscopic characteristics of Aspergillus-related otomycosis developing in the setting of a tautochronous cholesteatoma.

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.

Predictive role of facial nerve palsy improvement in malignant external otitis.

PURPOSE: To evaluate the effects of different factors on facial nerve palsy improvement in patients with malignant external otitis (MEO) and the predictive role of improvement on MEO. METHODS: Data were collected from all MEO patients with facial paralysis who were hospitalized between 2012 and 2017 at a tertiary referral center. We contacted patients at least 6 months after their admission to evaluate their facial nerve function and survival rate. RESULTS: In a study of 19 samples with a mean age of 69.1 years, 9 patients (47.7%) had some or complete improvement, while 10 (52.6%) had no or very minimal improvement. In this study, there was no statistically significant difference between patients with and without facial nerve palsy improvement in terms of age, sex, usage of antifungal treatment alongside antibiotics, duration of hospital stays, HbA1c level, presentation of hearing loss and vertigo, the severity of facial palsy, comorbidity score, mean of fasting blood sugar, leukocytosis, first ESR and ESR drop, CRP and physiotherapy. We found a positive correlation between improving facial palsy and patients' survival rates. CONCLUSION: Considering the possible influence of facial paralysis improvement prognosis on MEO patients' survival, it could affect our approach to the disease.

Auritidibacter ignavus, an Emerging Pathogen Associated with Chronic Ear Infections.

We describe detection of the previously rarely reported gram-positive bacterium Auritidibacter ignavus in 3 cases of chronic ear infections in Germany. In all 3 cases, the patients had refractory otorrhea. Although their additional symptoms varied, all patients had an ear canal stenosis and A. ignavus detected in microbiologic swab specimens. A correct identification of A. ignavus in the clinical microbiology laboratory is hampered by the inability to identify it by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Also, the bacterium might easily be overlooked because of its morphologic similarity to bacterial species of the resident skin flora. We conclude that a high index of suspicion is warranted to identify A. ignavus and that it should be particularly considered in patients with chronic external otitis who do not respond clinically to quinolone ear drop therapy.

Antimicrobial effect of chamomile-containing over-the-counter ear and eye drops.

Chamomile (Matricaria chamomilla) is a plant with known antimicrobial, anti-inflammatory, and analgesic properties. Homeopathic drops containing chamomile extract are often used for ear pain and chronic ear infections. We aimed to evaluate the antimicrobial effect of over-the-counter eardrops containing chamomile against organisms causing bacterial conjunctivitis and otitis externa. Liquid cultures of Streptococcus aureus and Pseudomonas aeruginosa were exposed to increasing concentrations of eardrops containing chamomile extract. Liquid cultures of S. aureus and Streptococcus pneumoniae were exposed to increasing concentrations of chamomile eye drops for 5, 10, 15, and 45 min. Colony forming units (CFUs) were assessed after 18 h. Viability assays for these organisms were performed using the resazurin microdilution assay. We observed a reduction in the number of P. aeruginosa CFUs when the bacteria were exposed to any of the three concentrations of the chamomile drops as early as 5 min, with maximal reduction upon exposure to the 30% concentration at 45 min. Reduction in S. aureus CFUs, on the other hand, was observed for all three concentrations as maximal in the 5 min of exposure. We observed a marked reduction in the number of S. aureus CFUs upon exposure to any of the three preparations of chamomile-containing eye drops, which was almost immediate at 10% concentration. Streptococcus pneumoniae reduction happened at 5 min and continued through the 45-min observation period for all three concentrations. Our findings suggest that over-the-counter ear drops containing chamomile extract could potentially be used as a non-prescription treatment for mild cases of otitis externa and bacterial conjunctivitis.

[Efficacy and safety of topical combination therapy in patients with acute otitis externa].

AIM: To study the structure of the microbial landscape in patients with acute otitis externa, as well as to evaluate the efficacy and safety of the combined drug chloramphenicol/clotrimazole/beclomethasone/lidocaine (Candibiotic) as an empirical therapy of this disease. MATERIALS AND METHODS: In this retrospective study of real clinical practice, outpatient records of 963 patients who applied to the KDO of the Sverzhevsky Research Clinical Institute of Otorhinolaryngology with symptoms of otitis externa in the period from 2017 to 2022 were selected. Additional analysis was carried out on the clinical records of patients who received the combined drug Candibiotic. The endpoints of this analysis included data on the clinical and microbiological efficacy of therapy, as well as safety information. RESULTS: According to microbiological testing, 60.6% of microorganisms belonged to bacterial flora, 26% were bacterial-fungal associations, 11.6% were monofungal flora, in 1.8% of cases there was no growth of microorganisms. The most frequently isolated microorganisms were: Pseudomonas spp (n=291; 29.16%), Staphylococcus spp. (n=214; 21.4%), Candida spp. (n=194; 19.4%), Aspergillus spp. (n=133; 13.3%). Most of the patients (71.0%) received Candibiotic. In 69.7% of patients, the resolution of the clinical symptoms of otitis externa occurred within 7 days of therapy with Candibiotic. Complete eradication of microorganisms occurred in 87% of cases. Adverse events were recorded only in 3 (0.04%) cases. CONCLUSION: The study demonstrated an extremely high level of clinical efficacy and safety of therapy in patients with acute external infectious otitis who received the Candibiotic, which can be used as an initial empirical therapy in patients with otitis externa.

Identification of bacteria associated with canine otitis externa based on 16S rDNA high-throughput sequencing.

Bacteria are regarded as predisposing and perpetuating factors causing otitis externa (OE), whereas auricular anatomy is a predisposing factor. This study aims to investigate bacterial populations in the external auditory canals of healthy dogs and dogs with OE. Four categories of ear swabs included healthy erect-ear dogs, erect-ear dogs with OE, healthy pendulous-ear dogs and pendulous-ear dogs with OE. After bacterial DNA extraction, 16S rDNAs were amplified using specific primers within a V3/V4 region. Following DNA library construction, high-throughput sequencing was performed on MiSeq (Illumina). CLC Microbial Genomics Module was used to determine the rarefaction curve, bacterial classification, relative abundance, richness and diversity index. The results demonstrated that healthy dogs had higher bacterial richness and diversity than the dogs with OE. Comparable with culture-dependent methods described previously, this study revealed predominant Corynebacterium spp., Pseudomonas spp., Staphylococcus spp., and Proteus spp. in OE cases. Furthermore, high-throughput sequencing might disclose some potential emerging pathogens including Tissierella spp., Acinetobacter spp., and Achromobacter spp., which have not been reported in previous canine OE cases. Nevertheless, larger sample sizes are further required for an extensive evidence-based investigation.

Comparison between clinical evaluations and laboratory findings and the impact of biofilm on antimicrobial susceptibility in vitro in canine otitis externa.

BACKGROUND: In canine otitis externa (OE), biofilm-producing bacteria are frequently present but biofilm may be underdiagnosed clinically. HYPOTHESIS/OBJECTIVES: The study aimed to investigate an association between clinical and cytological findings with bacteriological data from dogs with OE, to establish, through Environmental Scanning Electron Microscope (ESEM) examination, whether the presence of biofilm in vivo can be predicted and to evaluate the impact of biofilm on antimicrobial susceptibility tests. MATERIALS AND METHODS: Fifty-six dogs showing clinical signs of OE were enrolled. One cotton swab each was collected for ESEM, bacterial culture and susceptibility testing and for cytology. Staphylococcus pseudintermedius (n = 42, 48.8%) and Pseudomonas aeruginosa (n = 26, 30.2%) were tested for their ability to form biofilm. Minimum Inhibitory Concentrations (MIC), Minimal Biofilm Inhibitory Concentrations (MBIC) and Minimal Biofilm Eradication Concentrations (MBEC) towards enrofloxacin, gentamicin, polymyxin B and rifampicin were determined. RESULTS: Pseudomonas aeruginosa was positively associated with the biofilm clinical evaluation (p < 0.01) and neutrophils (p < 0.05), nuclear streaks (p < 0.01) and rods bacteria (p < 0.01) on cytology. S. pseudintermedius was associated with a low presence of neutrophils. There was a statistical correlation between clinical and cytological biofilm presence (p ≤ 0.01), but none with the biofilm production assay nor ESEM biofilm detection. No differences were found comparing the results of MIC and MBIC. MBEC results showed higher values than MIC and MBIC for all antimicrobials tested (p ≤ 0.001). CONCLUSIONS AND CLINICAL RELEVANCE: Biofilm presence in OE was often underdiagnosed. Even if there is no specific clinical or cytological pattern related to biofilm, its presence should always be suspected.

Evaluation of in vitro activity of herbal formula Di Er You and herb Coptis against bacteria isolated from dogs with otitis externa.

OBJECTIVE: To determine the in vitro activity of the herbal formula Di Er You (DEY) and the single-herb Coptis against bacteria cultured from dogs with otitis externa. ANIMALS: 32 client-owned dogs diagnosed with otitis externa. METHODS: A sample of otic debris from each patient was collected and plated onto a fresh Sheep's Blood Agar plate in the hospital. After bacterial growth was confirmed, 4 wells were created, numbered randomly, and treated with saline (placebo), DEY, Coptis, and Zymox Otic Enzymatic Solution with 1% Hydrocortisone (Zymox). After 24 hours of incubation, the diameter of the zone of inhibition (dZOI) of each treatment was measured and recorded, and compared among treatments. A sample of the bacterial colonies grown was submitted to an outside lab for bacterial identification. RESULTS: The mean ± SD dZOI values for saline, DEY, Coptis, and Zymox treated wells were 0.25 ± 1.41, 12.47 ± 3.92, 14.25 ± 7.12, and 3.22 ± 5.12, respectively. Post hoc multiple comparisons test revealed that (1) saline-treated wells had significantly smaller dZOI values than the other 3 groups (all P < .001), (2) Zymox treated wells had significantly smaller dZOI values than either herbal treated groups (both P < .001), and (3) DEY treated wells had significantly smaller dZOI values than those treated with Coptis (P = .0042). CLINICAL RELEVANCE: The results from this in vitro study suggested that both DEY and Coptis could be effective treatments in inhibiting the growth of bacteria in dogs with otitis externa. Prospective randomized controlled clinical trials are warranted to confirm these findings.

Management and Clinical Outcomes of 37 Patients with Necrotizing Otitis Externa: Retrospective Review of a Standardized 6-Week Treatment Pathway.

BACKGROUND: Necrotizing otitis externa is an invasive infection, affecting older patients, with significant associated morbidity. Despite this, there are no randomized controlled trials that address management, and therefore, treatment approaches may vary considerably. We describe the management and outcomes of 37 patients managed using a multidisciplinary treatment pathway for necrotizing otitis externa over a 5-year period. The pathway is based on a standardized antibiotic regime of 3 weeks of intravenous ceftazidime plus oral ciprofloxacin, followed by a further 3 weeks of ciprofloxacin. METHODS: This is a retrospective review of all patients diagnosed with necrotizing otitis externa since the introduction of our pathway in 2016. We include data on patient demographics, comorbidities, microbiology, length of stay, and length of antimicrobial treatment. Outcome data, including mortality, relapse and treatment failure, and adverse effects of treatment, are presented. RESULTS: The median age of our patients was 82 years. About 54% of patients had diabetes mellitus or another cause of immunocompromise. Pseudomonas aeruginosa was isolated in 68%. The median duration of inpatient stay was 9 days, and median treatment duration was 6 weeks. Of 37 patients, 32 were cured (86%), and of the remaining 5 patients, there were 2 mortalities unrelated to necrotizing otitis externa and 3 patients with recurrent infections due to anatomical abnormalities. CONCLUSION: We note favorable treatment outcomes when using a standardized multidisciplinary pathway and a 6-week course of antibiotic therapy.

A case of fungal otitis externa caused by coinfection of Candida auris and Aspergillus flavus.

Fungal otitis externa is a disease encountered occasionally and is caused mostly by Aspergillus or Candida spp. We report a woman with fungal otitis externa who also had typical findings in the external auditory canal. The results of a culture showed coinfection with Candida auris and Aspergillus flavus. Identification of both species was performed by sequencing analysis of the 26S rDNA (D1/D2) and ß-tubulin regions. Additionally, the newly developed CHROMagar™ Candida Plus medium was a useful tool for the easy and rapid identification of C. auris. To the best of our knowledge, this is the first report of fungal otitis externa caused by coinfection with C. auris and A. flavus. This case showed good susceptibility to many antifungal drugs and fortunately had a good clinical course with 1% bifonazole cream, which was applied to the fungal coinfection. Notably, C. auris is a multidrug-resistant yeast-like fungus. The increase in drug-resistant fungi and co-infections caused by these pathogens can make the diagnosis and treatment more complex and difficult. To solve these problems, performing rapid and accurate identification and susceptibility testing using chromogenic medium and molecular biological analysis would be useful.

Acute Otitis Externa: Rapid Evidence Review.

Acute otitis externa is an inflammatory condition that affects the external ear canal. It is usually of rapid onset and is generally caused by bacterial infection. The primary bacterial infections are Pseudomonas aeruginosa and Staphylococcus aureus. Acute otitis externa presents with pain (otalgia), redness, and swelling of the canal. It is more common in children and young adults. Tenderness on movement of the pinna or tragus is the classic finding. Analgesics and topical antibiotics are the mainstays of therapy. Topical medications include acetic acid 2%, aminoglycosides, polymyxin B, and quinolones with and without corticosteroids. There is no evidence that any one preparation is clinically superior to another, and the choice of treatment is based on factors such as cost, whether the tympanic membrane is intact, and patient adherence. Oral antibiotics are indicated only if evidence of cellulitis occurs outside of the ear canal or if associated conditions such as immunocompromise, diabetes mellitus, or conditions that would not allow for the use of topical treatment are found. Duration of topical treatment is usually seven to 10 days. Keys to prevention include avoiding injury to the ear canal and keeping it free of water.

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.

The stability and in vitro antibacterial efficacy of enrofloxacin and gentamicin solutions against Staphylococcus pseudintermedius over 28 days.

BACKGROUND: Many clinicians prepare compounded otic solutions to treat otitis externa (OE). Research evaluating the stability and antimicrobial efficacy of these solutions is limited. HYPOTHESIS/OBJECTIVES: This study determined the chemical stability and in vitro bactericidal efficacy of compounded solutions of enrofloxacin and gentamicin during storage for 28 days. MATERIALS AND METHODS: Solutions of enrofloxacin (10 mg/mL, 1%) and gentamicin (3 mg/mL, 0.3%) were prepared with normal saline and 1 mg/mL dexamethasone. Solutions were stored at room temperature (25°C) for 0, 14 and 28 days. The chemical stability of the antibiotics and dexamethasone were determined using liquid chromatography tandem mass spectrometry in triplicate. Efficacy assessment was made with 10 isolates of Staphylococcus pseudintermedius obtained from dogs with OE. Serial 10-fold dilutions of the bacteria with the compounded solutions were prepared and the colony count results were converted into colony-forming units (cfus). The mean cfu/mL and cfu/mL reduction rates were compared between Day (D)0, D14 and D28. All of the antimicrobial testing solutions were performed in triplicate. RESULTS: Chromatography showed that both antibiotics and dexamethasone were stable for 28 days. No significant differences were observed in the antibiotic bactericidal efficacy of stored solutions at D0, D14 or D28. CONCLUSIONS AND CLINICAL RELEVANCE: Solutions of 1% enrofloxacin and 0.3% gentamicin in normal saline with 0.1% dexamethasone maintained chemical stability and bactericidal efficacy over 28 days. These solutions can be considered as alternatives to commercial preparations for treatment of canine OE when indicated.

Fungal necrotizing external otitis: diagnosis, management and outcomes of 15 cases.

Fungal necrotizing external otitis (NEO) is a rare disease. It is an aggressive and potentially fatal infection. The most commonly reported pathogen is Candida. We aim through this study to share our experience in the management of fungal necrotizing external otitis and discuss its diagnosis tools, anti-fungal treatment choice, and outcomes. We included fifteen patients with diagnosis criteria of fungal NEO; clinical features of NEO with positive culture swabs and/or positive serologic test to a fungal pathogen. The mean age was of 70 years with a prevalence of males. The main symptoms were otalgia (n=15) and otorrhea (n=7). Facial palsy was observed in four cases. Fungal pathogens were Candida(n=10) and Aspergillus (n=5). Complications were observed in eight cases: extension to the temporo-mandibular (n=4), abscess in the retropharyngeal space (n=2), abscess in the parapharyngeal space (n=1) and thrombophlebitis of the internal jugular vein (n=1). Six patients were treated with fluconazole, eight with voriconazole, and one patient with itraconazole. After a mean duration of 52 days of antifungal therapy, fourteen patients have been cured with normalization of the ear symptoms, biological, and imaging features. One patient died of septic shock. No recurrence of the disease was observed after a follow-up of 12 months in all cases.

Effects of an enzyme agent containing mutanase and dextranase for treatment of biofilms in bacteria- and yeast-infected canine otitis externa.

The purpose of this study was to evaluate in detail both the in vivo and in vitro efficacy of the enzyme agents, ZYMOX® Plus Otic (ZYMOX-P), in the treatment of canine otitis externa (OE). Eight dogs with a diagnosis of non-seasonal severe chronic OE were recruited for the study. ZYMOX-P was administered for 2-4 weeks. The Otitis Index Score (OTIS3) and bacteria or yeast colony growth were measured. Also, minimum biofilm (BF) formation inhibition concentration (MBIC) and BF bactericidal concentration (BBC) were measured in vitro. OTIS3 showed a statistically significant reduction after treatment (88.2%, p⟨0.001; pre-treatment = 11.0 ± 0.9; post-treatment = 1.3 ± 0.4, mean ± SEM). The individual OTIS scores, erythema, edema, erosions/ ulcerations, exudate and pruritus showed significant reduction (85.7%, 95.7%, 83.3%, 80.0%, and 89.3%, respectively). Microscopic examination revealed the presence of BF exopolysaccharide in all 8 ear samples when stained with alcian blue. Seven of the 8 dogs (87.5%) showed a reduction in colony growth. ZYMOX-P was effective at 34-fold and 16-fold dilutions on MBIC and BBC, respectively. These findings indicate that ZYMOX-P has efficacy against BF-related infection and is beneficial when used for the management of canine OE.

Necrotizing external otitis: analysis of relapse risk factors in 66 patients managed during a 12 year period.

BACKGROUND: Necrotizing external otitis (NEO) is a severe infection of the skull base that occurs generally in the elderly and/or in diabetic recipients. There are few data in the literature about the therapeutic management of this complex bone infection. OBJECTIVES: To analyse relapses after NEO treatment completion, and to describe the clinical features of NEO. METHODS: We performed a retrospective cohort study in the Lyon regional reference centre for the management of complex bone and joint infections. Consecutive cases of NEO from 1 January 2006 to 31 December 2018 were included. The primary outcome was the relapse of NEO. Variables were analysed using Cox regression survival analysis with adjusted hazard ratio (aHR) and Kaplan-Meier curve. RESULTS: Sixty-six patients were included. Median age was 75 (IQR 69-81) years and 46 (70%) patients were diabetic. Eleven patients (17%) had temporomandibular arthritis, 10 (15%) cranial nerve paralysis, 2 (3%) cerebral thrombophlebitis, and 2 (3%) contiguous abscess. Microbiological documentation was obtained in 56 patients and revealed Pseudomonas aeruginosa in 44/56 patients (79%). Nine (14%) cases had no microbiological documentation. Antibiotic therapy was dual for 63 (95%) patients. During a median follow-up of 27 (IQR 12-40) months, 16 out of 63 (25%) patients experienced a relapse. Fungal infection was significantly associated with relapse [aHR 4.1 (95% CI 1.1-15); P = 0.03]. CONCLUSIONS: NEO is a severe bone infection, mainly (but not exclusively) caused by P. aeruginosa, which occurs in elderly and diabetic recipients. Fungal infections at baseline significantly impact the outcome.

High rates of multidrug resistance in bacteria associated with small animal otitis: A study of cumulative microbiological culture and antimicrobial susceptibility.

The etiology of otitis in dogs and cats is multifactorial and complex, involving bacterial and fungal pathogens. As empiric antimicrobial prescription is a common practice when treating such cases, antimicrobial resistance may represent a complicating factor. The aim of this study was to describe microbiological features and susceptibility profiles of pathogens associated with 142 cases of external otitis, comprising 138 dogs and 4 cats.. The specimens were processed to identify bacterial and fungal etiologies following standard microbiological methods. Antimicrobial susceptibility was determined in vitro against 15 antibiotics and 3 antifungals. Further, Staphylococcus spp. isolates were screened for the detection of ß-lactamase enzymes using cefinase paper discs. Pseudomonas spp. and isolates from Enterobacteriaceae family were screened for colistin (Polymyxin E) resistance and for the mcr-1-mediated colistin resistance gene by PCR. The presence of mixed cultures of Enterobacteriaceae, Pseudomonas spp. and Staphylococcus spp., and co-infections with Malassezia spp., emphasizes the polymicrobial etiology of external otitis in small animals. Emerging rates of multidrug resistance observed in almost 50% of the isolates may alert for a near future of challenging veterinary cases unresponsive to first-line antimicrobials. In addition, these results highlight a potential public health concern of multidrug resistant bacteria, given the proximity of pets and their owners. This study addressed central aspects of external otitis, providing microbiologists and clinicians updated information on the etiology and treatment of challenging cases of multidrug resistant bacteria. It also provides priceless surveillance value in monitoring resistant bacteria in small animals.