Identification and antimicrobial susceptibility of microbial agents of otitis externa in dogs

In this study, a total of 277 unmedicated dogs with otitis externa were used. Overall, 413 agents were isolated from 277 ear swab samples; 52.7% of the cases were mono-infections (146 cases), and 37.1% of the cases were poly-infections (103 cases). In 10.1% (28) of the cases, neither bacteria nor yeasts were isolated. Coagulase-positive Staphylococcus spp. were the most frequently isolated bacteria and were found in 90 (21.8%) of the samples. Fifty-eight samples, (14%) were positive for Staphylococcus aureus, 51 (12.3%) for Pseudomonas aeruginosa, 27 (6.5%) for Proteus mirabilis, 27 (6.5%) for Malassezia pachydermatis, 21 (5%) for Corynebacterium spp., 21 (5%) for β-haemolytic Streptococcus spp., 15 (3.6%) for Staphylococcus pseudointermedius, 12 (2.9%) for Proteus spp., 12 (2.9%) for Escherichia coli, 9 (2.1%) for Acinetobacter calcoaceticus, 7 (1.6%) for Trichophyton mentagrophytes, 5 (1.2%) for Staphylococcus auricularis, and 46 (11.1%) for different bacteria and yeasts. A total of 14 different bacteria and yeasts were isolated and identified. Kirby-Bauer antibiotic susceptibility testing was carried out for 10 different antibiotics. The bacterial isolates were found to be resistant to amoxicillin-clavulanic acid (45%), gentamycin (28%), ampicillin/cloxacillin (69%), tobramycin (28%), amikacin (23%), enrofloxacin (47%), chloramphenicol (58%), doxycycline (65%), lincomycin/spectinomycin (58%) and polymyxin B (62%). In conclusion, it is important to test the antimicrobial sensitivity of aetiological agents of otitis externa before treatment so as to prevent the development of antibiotic resistance in bacteria and yeasts.

Avaliação de extratos vegetais em formulações farmacêuticas no tratamento da otite externa canina

A otite externa é um dos problemas mais frequentes dentro da dermatologia veterinária. Os produtos comerciais comumente utilizados apresentam antimicrobianos nas formulações, que podem induzir resistência bacteriana em casos crônicos ou recidivantes. Desta forma, os produtos otológicos compostos por extratos vegetais tornam-se uma alternativa viável e com menos efeitos deletérios. O objetivo deste trabalho foi avaliar o potencial terapêutico de duas formas farmacêuticas a base de extratos vegetais das plantas urucum (Bixa orellana) e trigo (Triticum aestivum) no tratamento da otite externa canina. Extratos oleosos de urucum e trigo foram usados na formulação do composto LCFO 1001 e extratos etanólicos das mesmas plantas foram usados para o composto LCFO 1002. Foram utilizados 44 cães com sinais clínicos de otite externa, os quais foram avaliados por otoscopia e citologia. Os cães foram divididos aleatoriamente em 3 grupos LCFO 1001 (n=16), LCFO 1002 (n=14) e grupo controle (n=14) sendo tratados uma vez ao dia durante 10 dias e reavaliados nos dias 3, 5, 7 e 10. Foi estabelecido um score de 0 a 3 de acordo com cada sinal clínico. Após 10 dias de tratamento houve redução dos sinais clínicos em todos os grupos, observou-se a equivalência dos compostos LCF0 1001 e LCFO 1002 com um produto ceruminolítico comercial. Também foi possível observar a redução no número de animais infectados por Malassezia pachydermatis e Staphylococcus pseudointermedius. Estes resultados comprovam que os compostos possuem ação na redução dos sinais clínicos da otite externa canina, assim como possuem ação antimicrobiana.

Isolamento de leveduras patogênicas da microbiota superficial de tamanduás mantidos em cativeiro

A composição da microbiota fúngica do pelame de animais silvestres ainda é pouco conhecida. Estabelecer parâmetros microbiológicos que permitam prever eventos infecciosos oportunistas nesses animais pode ser útil na preservação de espécies amaçadas de extinção. O objetivo dessa investigação foi isolar e identificar leveduras de potencial patogênico do pelame de tamanduás mantidos em cativeiro. Vinte e sete tamanduás, provenientes da Fundação Parque Zoológico de São Paulo (FPZSP) e Parque Municipal Quinzinho de Barros (Zôo-Sorocaba, SP) foram pesquisados. Catorze espécimes serão de tamanduá-bandeira (Mymercophaga tridactyla) e 13 de tamanduá-mirim (Tamandua tetradactyla), dos quais, 63% machos e 37%, fêmeas. A técnica do quadrado do carpete foi empregada na obtenção das amostras de pelame. As leveduras isoladas foram identificadas por meio de suas características morfológicas e por método semi-automatizado ID-32CÒ. Para descrever as variáveis obtidas por meio do instrumento de pesquisa, foram verificadas a frequência de ocorrência e os resultados foram expressos em valores relativos. Foram isoladas, no total, 33 leveduras a partir das amostras de pelame dos 27 tamanduás. As espécies de leveduras isoladas foram: oito Candida guilliermondii (24,2%), três C. famata (9,1%), três C. kefyr (9,1%), duas C. glabrata (6,1%), três Cryptococcus laurentii (9,1%), um C. humicola (3,0%), seis Geotrichum candidum (18,2%), três Malassezia pachydermatis (9.1%), duas Rhodotorula glutinis (6,1%) e dois Trichosporon asahii (6,1%). Pode-se concluir que leveduras reconhecidamente patogênicas podem colonizar a microbiota do tegumento de tamanduás-bandeira e tamanduás-mirim mantidos em cativeiro e representam potencial risco de infecção oportunista para esses animais.

Inhibitory Effects of Sulfonamide Derivatives on the β-Carbonic Anhydrase (MpaCA) from Malassezia pachydermatis, a Commensal, Pathogenic Fungus Present in Domestic Animals

Fungi are exposed to various environmental variables during their life cycle, including changes in CO2 concentration. CO2 has the potential to act as an activator of several cell signaling pathways. In fungi, the sensing of CO2 triggers cell differentiation and the biosynthesis of proteins involved in the metabolism and pathogenicity of these microorganisms. The molecular machineries involved in CO2 sensing constitute a promising target for the development of antifungals. Carbonic anhydrases (CAs, EC 4.2.1.1) are crucial enzymes in the CO2 sensing systems of fungi, because they catalyze the reversible hydration of CO2 to proton and HCO3-. Bicarbonate in turn boots a cascade of reactions triggering fungal pathogenicity and metabolism. Accordingly, CAs affect microorganism proliferation and may represent a potential therapeutic target against fungal infection. Here, the inhibition of the unique β-CA (MpaCA) encoded in the genome of Malassezia pachydermatis, a fungus with substantial relevance in veterinary and medical sciences, was investigated using a series of conventional CA inhibitors (CAIs), namely aromatic and heterocyclic sulfonamides. This study aimed to describe novel candidates that can kill this harmful fungus by inhibiting their CA, and thus lead to effective anti-dandruff and anti-seborrheic dermatitis agents. In this context, current antifungal compounds, such as the azoles and their derivatives, have been demonstrated to induce the selection of resistant fungal strains and lose therapeutic efficacy, which might be restored by the concomitant use of alternative compounds, such as the fungal CA inhibitors.

Diagnosis and therapeutic management of malasseziosis in dogs

Malassezia spp. are commensals of the normal cutaneous microbiota of humans and animals. These yeasts may become opportunistic pathogens under certain conditions and cause dermatitis and otitis externa in dogs. Malassezia pachydermatis is the most common cause of malasseziosis in dogs. In this study skin and ear swabs from suspected cases were cultured on Modified Dixon’s Agar (MDA). The isolates obtained were initially characterized on the basis of colony characteristics, result of Gram staining and microscopic morphology. Total DNA was extracted from the pure cultures of the isolates and subjected to confirmation by polymerase chain reaction (PCR) targeting large subunit ribosomal RNA gene. Positive cases were treated with oral itraconazole at 5 mg/kg bodyweight, orally once daily for 28 days.

Mycotic zoonoses risk from clipping instruments in Pet Shops in Sinop – MT

Pets have conquered the daily lives of families worldwide and because they have a close relationship with humans, they can transmit mycotic zoonoses such as dermatophytosis, malassezioses and candidosis. Studies show that fungi with pathogenic potential have already been granted in clipping instruments and bath articles in veterinary clinics and in Pet Shops. In the absence of data in the city of Sinop - MT, this study aimed to isolate fungi with pathogenic potential in clipping instruments used in the routine of Pet Shops and to identify etiological agents capable of causing mycotic zoonoses. Samples were carried out in 18 clipping instruments, without cleaning, from 10 Pet Shops (A, B, C, D, E, F, G, H, I, J) in the city of Sinop - MT with swabs and sterile carpets square and then seeded in Sabouraud agar with 0.05% chloramphenicol and mycobiotic agar, incubated at room temperature (25°C) for 30 - 45 days. The dermatophytes and non-dermatophyte filamentous fungi were identified using the microculture technique and urease test and as yeasts using a urease test, zymogram, auxanogram, germ tube and corn meal agar with polysorbate 80. Of the samples from 18 clipping instruments, 15 were positive for at least one fungal genus. The yeast that showed a high prevalence of isolation in clipping instruments from the studied Pet Shops (B, C, D, E, H and J) was Malassezia pachydermatis (86.7%), followed by the genus Candida spp. (C and D; 26.7%), filamentous fungi of the genus Aspergillus spp. (A; 13.3%), Microsporum canis (B; 13.3%) and Trichosporon spp. (J, 6.7%). Our results demonstrate that Pet Shops treat a large number of animals daily in a single environment, which may amplify the risk of spreading zoonoses, as an asymptomatic or sick carrier animal can potentially transmit the microorganism to other animals inside the store and thus to a large number of new pet owners. There is a need to reinforce the commercial requirements specialized in bathing and grooming in the city of Sinop - MT on the good practices of cleaning and disinfection of the elements used and the environment, eliminating or eliminating the risk of contracting mycotic zoonoses.

OCORRÊNCIA DE OTITE EXTERNA EM CÃES E GATOS ATENDIDOS EM UMA CLÍNICA ESCOLA DE MEDICINA VETERINÁRIA

Introdução: A otite externa caracteriza-se como uma inflamação aguda ou crônica do epitélio do meato auditivo, sendo uma das afecções mais comuns na rotina da clínica médica dos animais. Algum dos fatores que influenciam no aparecimento das otites são: morfologia das orelhas, limpeza excessiva do conduto auditivo, doenças sistêmicas e alterações climáticas. Objetivos: Objetivou-se com este trabalho, realizar um estudo retrospectivo da ocorrência de otite em cães e gatos atendidos na clínica escola de Medicina Veterinária. Material e métodos: No período de 2019 a 2021, foi realizado a partir de análises das fichas clínicas um levantamento dos casos diagnosticados de otite de cães e gatos atendidos na clínica médica de pequenos animais do Centro Universitário Cesmac, Marechal Deodoro, Alagoas. Foram analisados a espécie, sexo e raça dos animais acometidos, realizando a identificação dos microrganismos em ambos ouvidos, feita por exame microbiológico, com auxílio de swab estéril e meio de transporte Stuart. Resultados: Foram colhidas 26 amostras de secreção de conduto auditivo esquerdo e direito de 15 animais (13 cães e 2 gatos). Destes 13 cães, 53,84% (7/13) eram fêmeas; 46,16% (6/13) eram machos, dos 2 gatos, 100% (2/2) eram machos. Dos 13 cães, 46,15% (6/13) eram SRD; 23,07% (3/13) eram Dachshund; 15,38% (2/13) eram Pastor-Alemão; 07,69% (1/13) eram Pug e 07,69% (1/13) eram Labrador Retriever; dos 2 gatos, 100% (2/2) eram SRD. Do total de amostras avaliadas, foram observados os microrganismos Streptococcus sp. 15,38% (4/26); 11,53% (3/26) Staphylococcus sp + Klebisiella sp; 11,53% (3/26) Proteus sp + Staphylococcus sp; 11,53% (3/26) Bacillus sp; 07,69% (2/26) Pseudomonas sp; 07,69% (2/26) Staphylococcus sp + Streptococcus sp; 07,69% (2/26) Proteus sp; 07,69% (2/26) Bacillus sp + Staphylococcus sp; 07,69% (2/26) Malassezia pachydermatis; 07,69% (2/26) Pseudomonas sp. + Proteus sp + Staphylococcus sp; 03,84% (1/26) Proteus sp + Pseudomonas sp. Conclusão: Diante dos resultados, foi possível observar que o agente mais prevalente foi Streptococcus sp. Houve uma maior ocorrência de infecções em cães quando comparado com os gatos, não sendo observada predileção sexual. Ressalta-se a importância da realização da cultura e antibiograma para que seja feito o tratamento mais adequado para combater a infecção.

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.

Otitis externa canina por Aspergillus niger patogénico: reporte de caso

El presente artículo reporta un caso clínico de otomicosis por Aspergillus en un Cocker Spaniel Inglés macho de 8 años, con diagnóstico previo de anemia hemolítica inmunomediada. El paciente fue atendido por presentar dolor e incomodidad en ambos oídos. Se realizaron análisis sanguíneos, además de citología y cultivo microbiológico de secreción ótica. El Aspergillus niger junto con Malassezia pachydermatis fueron los agentes aislados, para lo cual se instauró una terapia antifúngica oral y tópica con resultados favorables después de 30 días de tratamiento. El moho aislado presentó algunos factores de virulencia importantes como actividad hemolítica, lipasa y amilasa, además de susceptibilidad in vitro a antifúngicos del tipo azoles. En pacientes inmunosuprimidos que presenten otitis externa es necesario realizar cultivos microbiológicos para hongos ambientales, además de evaluar a nivel fenotípico la característica patógena, lo cual ayude a establecer un correcto abordaje terapéutico y monitoreo de enzimas hepáticas por posibles efectos adversos.