Pilot study of dogs with suppurative and non-suppurative Malassezia otitis: A case series.

BACKGROUND: Rarely, Malassezia otitis presents as a painful, erosive otitis with an otic discharge containing Malassezia and neutrophils on cytology. There are no published reports of this type of suppurative Malassezia otitis (SMO). The role of Malassezia hypersensitivity in otitis is still unknown, and no association has been demonstrated with SMO. We compared Malassezia IgE levels, intradermal test and histology changes in SMO dogs with the more conventional Malassezia otitis (MO) presentation. RESULTS: Three dogs (case 1, case 2 and case 3) were diagnosed with SMO, one dog (case 4) was diagnosed with unilateral MO and unilateral SMO, and one dog (case 5) was diagnosed with MO. Only one case (case 4) with SMO/MO had a positive Intradermal Allergy Test (IDAT) and elevated IgE levels for Malassezia. Histopathology findings from SMO revealed: interface dermatitis (case 1 and 3), lymphocytic dermatitis (case 2) and chronic hyperplastic eosinophilic and lymphoplasmacytic dermatitis (case 4). Histopathology findings from MO showed perivascular dermatitis (case 4 and 5). All the cases were treated successfully. CONCLUSIONS: SMO presents with a distinct clinical phenotype in comparison with conventional MO. No consistent aetiology could be isolated. In these clinical cases it is possible that previous treatments could have influenced the results. More research is needed to understand the possible aetiologies and the pathogenesis of SMO.

Prevalence and in vitro antifungal susceptibility of commensal yeasts in the external ear canal of cats.

BACKGROUND: Lifestyle factors such as hair length, the frequency of ear cleaning and bathing, age, cat rearing, and sex may contribute to opportunistic yeast infections in the external ear canal of cats. This study aimed to determine the prevalence of commensal yeast organisms in cats' external ear canals, evaluate their predisposing lifestyle factors, and test the susceptibility of Malassezia pachydermatis to antifungal agents. RESULTS: A total of 53 cats (33 male and 20 female) seronegative for feline leukemia virus and feline immunodeficiency virus were enrolled in this study. Their mean age (± standard deviation) was 6.04 (± 3.49) years. Fungal cultures and polymerase chain reaction tests were performed to identify the yeast species derived from the external ear canal. The association between lifestyle factors and the presence of M. pachydermatis was evaluated using Fisher's exact test. The susceptibility of M. pachydermatis to antifungal agents was also analyzed. M. pachydermatis was the most frequently recovered yeast species, with a prevalence of 50.94 % (95 % confidence interval [CI]: 36.84-64.94 %). There was an association between hair length and a positive culture for M. pachydermatis (p = 0.0001). The odds of a negative culture for M. pachydermatis among short-haired cats was 11.67 (95 % CI, 3.22-42.24) times higher than that among long-haired cats (p = 0.0002). There was also an association between the frequency of ear cleaning and the presence of M. pachydermatis (p = 0.007). The odds of a negative culture for M. pachydermatis in cats that were receiving ear cleaning at intervals of ≤ 2 weeks was 5.78 (95 % CI, 1.67-19.94) times greater than that of cats receiving ear cleaning at intervals greater than 2 weeks or never (p = 0.0055). Ranges of minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations for itraconazole, ketoconazole, miconazole, and terbinafine against M. pachydermatis were ≤ 0.063-4 and ≤ 0.063-≥32, ≤ 0.063-8 and 0.125-≥32, ≤ 0.063-≥32 and 0.5-≥32, and ≤ 0.016-1 and 0.125-8 µg/ml, respectively. CONCLUSIONS: M. pachydermatis was the most commonly identified yeast organism in the external ear canal of healthy cats. Hair length and the frequency of ear cleaning played a role in the colonization of M. pachydermatis. The M. pachydermatis isolates had various MIC levels for common fungicides.

Description and comparison of the skin and ear canal microbiota of non-allergic and allergic German shepherd dogs using next generation sequencing.

Atopic dermatitis is one of the most common skin diseases in dogs. Pathogenesis is complex and incompletely understood. Skin colonizing bacteria likely play an important role in the severity of this disease. Studying the canine skin microbiota using traditional microbiological methods has many limitations which can be overcome by molecular procedures. The aim of this study was to describe the bacterial microbiota of the skin and ear canals of healthy non-allergic and allergic German shepherd dogs (GSDs) without acute flare or concurrent skin infection and to compare both. Bacterial 16S rRNA gene amplicon sequence data revealed no differences of bacterial community patterns between the different body sites (axilla, front dorsal interdigital skin, groin, and ear canals) in non-allergic dogs. The microbiota at the different body sites of non-allergic GSDs showed no significant differences. Only for the samples obtained from the axilla the bacterial microbiota of allergic dogs was characterized by a lower species richness compared to that of non-allergic dogs and the bacterial community composition of the skin and ear canals of allergic dogs showed body site specific differences compared to non-allergic dogs. Actinobacteria was the most abundant phylum identified from the non-allergic dogs and Proteobacteria from allergic dogs. Macrococcus spp. were more abundant on non-allergic skin while Sphingomonas spp. were more abundant on the allergic skin. Forward step redundancy analysis of metadata indicated that the household the dogs came from had the strongest impact on the composition of the skin microbiome followed by sex, host health status and body site.

Changes in the ear canal microbiota of dogs with otitis externa.

AIMS: Otitis externa (OE), one of the most common ear diseases in dogs, is caused by bacterial pathogens such as Staphylococcus sp. To understand the network of microbial communities in the canine ear canal affected with OE, we performed a cross-sectional study using next-generation sequencing. METHODS AND RESULTS: Ear swab samples were collected from 23 OE-affected and 10 healthy control dogs, and the 16S rRNA gene sequenced using Illumina MiSeq. The otic microbiota in the OE-affected dogs showed significantly decreased alpha diversity compared to controls. The community composition also differed in the affected group, with significantly higher relative abundance of the phylum Firmicutes and the genus Staphylococcus (P = 0·01 and 0·04 respectively). Contrary to our expectations, the severity of the disease did not impact the otic microbiota in OE-affected dogs. CONCLUSIONS: The ear canal microbiota of OE-affected dogs is distinct from that of healthy dogs, irrespective of disease status. SIGNIFICANCE AND IMPACT OF THE STUDY: This study, one of the few detailed analyses of the otic microbiota, can provide practical information for the appropriate treatment of canine OE.

External ear canal mycobiome of some rabbit breeds.

The genus Malassezia is part of the normal skin mycobiota of a wide range of warm-blooded animals. In this genus, M. cuniculi is the only species described from rabbits. However, Malassezia species are rarely studied in lagomorphs. In the present study, the presence of Malassezia was assessed in samples from the external ear canal of healthy rabbits of different breeds. Cytological and culture techniques, Sanger sequencing, and Next-generation sequencing (NGS) were used to describe the ear mycobiota in the samples. Although no growth was observed in the cultured plates, cytological examination revealed the presence of round cells similar to those of Malassezia yeasts. For metagenomics analysis, the D1/D2 domain of the large subunit of the ribosomal DNA (LSU rDNA) was PCR amplified and the resulting reads were mapped against a custom-made cured database of 26S fungal sequences. NGS analysis revealed that Basidiomycota was the most abundant phylum in all the samples followed by Ascomycota. Malassezia was the most common genus presenting the highest abundance in the external ear canal. Malassezia phylotype 131 and M. cuniculi were the main sequences detected in the external auditory canal of rabbits. The study included both lop-eared and erect-eared rabbits and no differences were observed in the results when comparing both groups. This is the first attempt to study the external ear canal mycobiome of rabbits of different breeds using NGS. LAY SUMMARY: In the present study, the presence of Malassezia was assessed in samples from the external ear canal of healthy rabbits of different breeds. Cytological and culture techniques, Sanger sequencing, and Next-generation sequencing (NGS) were used to describe the ear mycobiota in the samples.

A Comparison of Triamcinolone Acetonide Econazole Cream and Nystatin Suspension in Treatment of Otomycosis.

OBJECTIVES/HYPOTHESIS: To compare the efficacy and adverse effects of triamcinolone acetonide econazole cream and nystatin suspension in the treatment of otomycosis, and to determine the clinical features, predisposing factors, and etiology of otomycosis. STUDY DESIGN: A prospective study. METHODS: A prospective clinical trial was conducted on 786 patients diagnosed with otomycosis. The study population was randomly divided into two treatment groups of triamcinolone acetonide econazole cream (TAEC) and nystatin suspension in a 1:1 ratio. After clearing all fungal deposits in the external auditory canal, the antimycotic drugs were locally applied for at least 2 weeks. The efficacy and adverse effects were compared between the two antifungal reagents by statistical analysis. Meanwhile, patient clinical data were collected to find out the clinical features, predisposing factors, and etiology. RESULTS: Pruritis was the most common symptom and Aspergillus niger was the leading fungal pathogen. There was high association (44.5%) of otomycosis with a history of unclean ear picking. The cure rate was 97.6% in the TAEC group and 73.5% in the nystatin group (P < .01). Treatment with TAEC resulted in 2.4% of patients complaining of discomforts (irritant dermatitis, otalgia, or headache) versus 59.8% of patients complaining discomforts treated with nystatin (P < .01). The residue rate of antifungals was 1.9% in the TAEC group and 89.9% in the nystatin group (P < .01) at the end of treatment. CONCLUSIONS: Thoroughly cleaning of the external auditory canal followed by local use of TAEC under endotoscope is an effective, convenient, and well-tolerated treatment for otomycosis. LEVEL OF EVIDENCE: 1 Laryngoscope, 131:E1640-E1646, 2021.

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

BACKGROUND: Necrotising otitis externa is a progressive infection of the external auditory canal which extends to affect the temporal bone and adjacent structures. Progression of the disease process can result in serious sequelae, including cranial nerve palsies and death. There is currently no formal published treatment guideline. OBJECTIVE: This study aimed to integrate current evidence and data from our own retrospective case series in order to develop a guideline to optimise necrotising otitis externa patient management. METHODS: A retrospective review of necrotising otitis externa cases within NHS Lothian, Scotland, between 2013 and 2018, was performed, along with a PubMed review. RESULTS: Prevalent presenting signs, symptoms and patient demographic data were established. Furthermore, features of cases associated with adverse outcomes were defined. A key feature of the guideline is defining at-risk patients with initial intensive treatment. Investigations and outcomes are assessed and treatment adjusted appropriately. CONCLUSION: This multi-departmental approach has facilitated the development of a succinct, systematic guideline for the management of necrotising otitis externa. Initial patient outcomes appear promising.

The otic microbiota and mycobiota in a referral population of dogs in eastern USA with otitis externa.

BACKGROUND: Canine otitis externa (OE) is a common inflammatory disease that is frequently complicated by secondary bacterial and/or yeast infections. The otic microbial population is more complex than appreciated by cytological methods and aerobic culture alone. HYPOTHESIS/OBJECTIVES: Differences in bacterial and fungal populations of the external ear canal will correlate with specific cytological and culture-based definitions of bacterial and Malassezia otitis. ANIMALS: Forty client-owned dogs; 30 with OE and 10 with healthy ears. METHODS AND MATERIALS: Prospective study comparing cytological samples, aerobic bacterial cultures and culture-independent sequencing-based analyses of the external ear canal. Subjects with OE included 10 dogs with only cocci [≥25/high power field (HPF)] on cytological evaluation and culture of Staphylococcus spp.; 10 dogs with rods (≥25/HPF) and exclusive culture of Pseudomonas aeruginosa; 10 dogs with only yeast on cytological results morphologically compatible with Malassezia spp. (≥5/HPF). RESULTS: Staphylococcus was the most abundant taxa across all groups. Ears cytologically positive for cocci had decreased diversity, and all types of OE were associated with decreased fungal diversity compared to controls. CONCLUSIONS AND CLINICAL IMPORTANCE: Cytological and culture-based assessment of the ear canal is not predictive of the diverse microbiota of the ear canal in cases of Pseudomonas or Malassezia otitis. Less abundant bacterial taxa in cases of staphylococcal OE are worth scrutiny for future biological therapy.

Diagnosis and treatment of otomycosis in southern China.

To analyse and discuss the clinical features and pathogenic characteristics, diagnosis and treatment of patients with otomycosis in southern China. Two hundred fifty-six patients from southern China diagnosed with otomycosis were randomly separated into two groups: the drug filling group and drug smearing group. Patients in the drug filling group were first examined and then had the pathogenic secretions in their external auditory canals cleared by otoendoscopy. Then, the local antifungal cream triamcinolone acetonide clotrimazole was injected into the external auditory canal. The same treatment was undertaken 1 week later and repeated once or twice more. Patients in the drug smearing group were also treated by otoendoscopy. Then, they were told to smear their external auditory canals once per day with the antifungal cream. All cases were followed for more than 6 months after the 3- to 4-week treatment. The main symptoms and otoendoscopic examination were used to evaluate the prognosis. Aspergillus was the commonest fungus. The cure rate was 93% in the drug filling group and 81% in the drug smearing group. Otomycosis is very common in southern China, but it lacks characteristic features in its early stages. Once diagnosed, the local lesions in the external auditory canal should be cleared thoroughly using otoendoscopy, and then, the local antifungal cream is injected into external auditory canal. The cure rate can be significantly improved with the foregoing treatment.

External ear cytological results and resident flora of clinically normal alpacas (Vicugna pacos).

BACKGROUND: Otitis is common in alpacas. Suppurative otitis media/interna can be an extension from the external ear canal or from a respiratory infection. Cytological evaluation provides rapid and inexpensive information to assist in therapeutic decision; to date, there is no published information regarding the normal cytological results and flora of the alpaca external ear canal. HYPOTHESIS/OBJECTIVES: To describe normal resident cytological findings and flora and possible variation over time, we sampled clinically normal alpaca external ear canals during two different seasons. ANIMALS: Fifty privately owned, healthy alpacas of different ages and sexes in two northeastern United States flocks. METHODS AND MATERIALS: One ear per alpaca had both cytological swabs (ectoparasites, inflammatory and epithelial cells, bacteria and yeast) and sterile swabs (bacterial and fungal cultures) taken. This was done in August 2017 and repeated in January 2018. RESULTS: Yeast organisms were noted cytologically in 2-4% of the samples. Prevalence of total yeast genera was 6% in August and 30% in January. Cytologically, rod-shaped bacteria [maximum 4-10/high power field (HPF); median 0-0.5/HPF] were seen in 50% of alpacas in August and 26% in January. Coccal bacteria (maximum 6-10/HPF; median 0/HPF) were seen in 32% of alpacas in August and 16% in January. No statistically significant findings were noted between sampling months. Common bacterial genera isolated in August were Bacillus (44%), Arthrobacter (40%) and nonhaemolytic Staphylococcus (26%), and in January were Bacillus (42%) and Pantoea (38%). CONCLUSIONS AND CLINICAL IMPORTANCE: This information may be useful when evaluating alpaca external ear canal samples, which subsequently may help dictate empirical therapy.

Not 'just' a foreign body in the ear canal.

Foreign bodies are commonly seen by the Ear, Nose and Throat emergency team with cotton wool being the most common aural foreign body seen in the adult population. Most complications secondary to aural foreign bodies described in the literature are minor and rarely require any surgical intervention. Here, we present two cases with impacted cotton wool as aural foreign bodies which resulted in suppurative labyrinthitis and osteomyelitis causing profound sensorineural hearing. These cases highlight the importance of considering aural foreign bodies in the differential diagnosis in those presenting with unilateral symptoms as significant complications, although rare, can occur, particularly in those with delayed diagnosis.

Quantification of Malassezia pachydermatis by real-time PCR in swabs from the external ear canal of dogs.

Malassezia pachydermatis is part of the normal microbiota of canine skin and external ear canal, and is also associated with otitis externa in dogs. Laboratory detection of Malassezia otitis relies on the presence of elevated numbers of the yeast on cytologic examination of otic exudate. Although cytology has high specificity, it has low sensitivity, resulting in false-negatives and posing a challenge for clinicians to accurately diagnose Malassezia otitis. We developed a quantitative PCR (qPCR) to detect and quantify M. pachydermatis yeasts and validate the method with swabs from external ear canals of dogs. Our qPCR uses the ß-tubulin gene, a single-copy gene, as a target. The limit of quantification was established as 0.18 ng/reaction, equivalent to 2.0 × 104 genome equivalents (gEq). Swabs from healthy dogs yielded quantification values of ≤2.7 × 104 gEq in the qPCR, whereas swabs from dogs with otitis yielded quantification values of ≥2.5 × 105 gEq. Our qPCR assay provides accurate quantification of M. pachydermatis yeasts from swab samples from dogs, is more sensitive than cytology, and could be used to monitor response to treatment. Our assay could also be valuable in a research setting to better understand the pathogenesis of M. pachydermatis.

Cotton bud in external ear canal causing necrotising otitis externa and subdural abscess.

Necrotising otitis externa (NOE) is an infection originating in the soft tissues of the external auditory canal (EAC) spreading to the surrounding bone and rarely causing intracranial complications. It is usually caused by Pseudomonas aeruginosa and has historically occurred in elderly patients with diabetes or immunodeficiency. EAC foreign body is a risk factor for otitis externa but has not been described in NOE. A healthy 31-year-old man presented with new-onset seizures and worsening left-sided otalgia and otorrhoea. Brain imaging revealed left temporal subdural abscesses superior to the petrous bone. A retained cotton bud was identified in the left EAC, along with osseocartilaginous junction and mastoid granulation tissue. The foreign body was removed; a cortical mastoidectomy performed and intravenous antibiotic administered. At 10 weeks, the patient remained well, with no neurological deficit and no residual ear symptoms, and CT demonstrated complete resolution of the intracranial abscesses.

Ear canal microbiota - a comparison between healthy dogs and atopic dogs without clinical signs of otitis externa.

BACKGROUND: The canine skin microbiota has been evaluated using relatively new microbiological techniques; studies have shown a difference in the composition of bacterial populations between healthy dogs and those with canine atopic dermatitis (cAD). However, little has been reported concerning the ear canal microbiota despite the fact that otitis externa is a common problem in dogs with cAD. HYPOTHESIS/OBJECTIVES: The study evaluated the ear canal microbiota of healthy dogs and atopic dogs without clinical signs of otitis. ANIMALS: Nine healthy privately owned dogs and 11 dogs with a diagnosis of cAD. METHODS AND MATERIALS: Ear swabs from the two groups were used for global bacterial DNA extraction. V1-V3 hypervariable 16S rDNA amplicon libraries were prepared for each sample and sequenced with MiSeq Illumina sequence (V3 kit). Taxonomical assignment and clustering were performed with Mothur using SILVA database. RESULTS: The ear canal microbiota showed changes in diversity similar to those reported for canine skin and seemed to be stable during the period of the study (28 days). Evidence of dysbiosis was observed in the atopic dogs, with increased abundance of Staphylococcus spp. and Ralstonia spp. (P < 0.05). Escherichia spp. also were found to be more abundant in healthy dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: This study demonstrated a shift in bacterial populations between allergic and healthy dogs. The observed results in the ear canal are similar to those reported on the skin and could explain the propensity of allergic dogs to develop bacterial otitis.

Isolation of Candida auris from Ear of Otherwise Healthy Patient, Austria, 2018.

The emerging pathogen Candida auris is isolated mostly from hospitalized patients and often shows multidrug resistance. We report on the isolation of this yeast in Austria from an outpatient's auditory canal. The isolate showed good susceptibility against antifungals except for echinocandins; the patient was treated successfully with topical administration of nystatin.

[Turicella otitidis, contributions to its role in the etiology of ear infections]. / Turicella otitidis, aportaciones a su posible papel en la etiología de la patología infecciosa del oído.

OBJECTIVE: Turicella otitidis is a gram-positive bacillus coryneforme described, after 16S RNA sequencing, in 1994 by Funke et al as a microorganism involved in otitis media, and it is in health conditions a habitual colonizer of the external auditory canal. Since its description, more than twenty years ago, few cases of otitis related to or directly attributed to this microorganism have been published. METHODS: Description of a case of mastoiditis that required surgery and other cases of otic pathology in which T. otitidis was isolated, in the second semester of 2017 in our institution. They were reported only when they grew in pure culture. The identification was made by mass spectrophotometry and an antibiogram was performed. RESULTS: In our institution in the second half of 2017, 5 cases of otitis media were documented, some of them complicated, in which T. otitidis was isolated. The most of patients were children with recurrent otic pathology, and in some cases the sample was taken before the administration of antibiotics. CONCLUSIONS: Since the inclusion of new vaccines that protect against microorganisms typically causing otitis media, is possible there are a change in the etiology of this disease and that microorganisms anecdotally isolated until now have become protagonists. The improvement in the microbiological identification provided by tools such as mass spectrometry will help to clarify if there are or not a change in the etiology of these diseases.

[The species composition and sensitivity of pathogenic microflora responsible for the development of otitis externa diffusa to the components of Polidexa]. / Vidovoi sostav i chuvstvitel'nost' vozbuditelei naruzhnogo otita k komponentam preparata Polideksa.

The objective of the present work was to study microflora of the external auditory meatus in the patients presenting with bacterial otitis externa diffusa. The authors have analyzed the results of microbiological investigations involving 102 patients with this condition undergoing the treatment with 'Polidexa'. The characteristic of species composition of microflora associated with otitis externa diffusa is presented. The sensitivity of the most common pathogens responsible for the development of this pathology towards antibiotics contained in ear drops has been analysed. The advantages of the use Polidexa for the treatment of this acute ear disease are described.

Comprehensive Analysis of the Fungal Microbiota of the Human External Auditory Canal Using Pyrosequencing.

We previously reported that the Malassezia microbiota of the external auditory canal were composed principally of Malassezia slooffiae and Malassezia restricta. In the present study, the fungal microbiota of the external auditory canal were comprehensively analyzed by pyrosequencing on an FLX-454 platform. Of 17 samples tested, the fungal microbiota of 14 samples were composed of > 90% Malassezia species; either M. slooffiae or M. restricta was abundant in individual samples. The external auditory canal exhibits a lower fungal diversity than do other bodily sites.