Sterol composition in polyene antibiotic-sensitive and resistant strains ofMalassezia pachydermatis

The membrane sterol compositions of ten strains ofMalassezia pachydermatis were analysed by gas-liquid chromatography. Six of these were wild-type strains from clinical sources that were sensitive to polyene antibiotics, whereas the other four strains were resistant mutants that had arisen after treatment withN-methyl-N-nitrosoguanidine or UV radiation.The wild-type strains contained 838.8 to 1291.7 µg of sterol per gram of freeze-dried mycelium. The sterols were composed of 79% ergosterol, 19% fecosterol and 2% lichesterol. The mutant strains contained 277.1 to 348.8 µg/g of sterols composed of 76% ergosterol and 24% fecosterol.Abbreviations MIC minimum inhibitory concentration - UV ultraviolet     

北京地区犬马拉色菌耳炎的流行病学调查

马拉色菌耳炎是犬常见的一种疾病,试验对北京地区犬马拉色菌耳炎流行病学进行调查。临床病例分析结果表明,马拉色菌耳炎12个月均有发病,但有一定的季节性,其中6、7月份为发病高峰;患犬性别差异不大;不同品种对马拉色菌易感性不一样,可卡犬和北京杂品种犬发病率最高,其次是松狮犬;发病年龄主要集中在5岁以下;发生马拉色菌感染时,通常还发生其它部位的感染,统计结果发现,背部是最易发生感染的地方,其次是面部和胸部。     

Antimicrobial effect of combinations of EDTA-Tris and amikacin or neomycin on the microorganisms associated with otitis externa in dogs

Combinations of EDTA-Tris and two aminoglycoside antibiotics (amikacin and neomycin) were tested for synergistic activities against the microorganisms associated with otitis externa in dogs and for the solutions' stability over time. Synergistic activity was observed when EDTA-Tris plus amikacin and EDTA-Tris plus neomycin were tested againstStaphylococcus intermedius, Proteus mirabilis, Pseudomonas aeruginosa, andEscherichia coli, but not againstCandida albicans. Stability studies over a 3-month period indicated that the test solutions were stable at room temperature and that their antimicrobial activity was maintained.Abbreviations CFU colony-forming units - EDTA (ethylenedinitrilo)tetraacetic acid, disodium salt - FIC fractional inhibitory concentration - MBC minimal bactericidal concentration - MIC minimal inhibitory concentration - Tris tris(hydroxymethyl)aminomethane     

The use of fluoroquinolones in veterinary dermatology

The fluoroquinolones are a group of antibiotics with considerable application for use in veterinary dermatology. They are rapidly bactericidal against a wide variety of clinically important organisms including Staphylococcus intermedius and gram-negative enteric bacilli by virtue of interference with the supercoiling of bacterial chromosomal material. Their favourable pharmacokinetic features make them applicable in many animal species, and in a range of dose formulations. The only major clinical contraindication is that fluoroquinolones should not be given to young, rapidly growing dogs as they can induce a noninflammatory, erosive arthropathy. For many years the only veterinary-labelled fluoroquinolone available was enrofloxacin. The selection of a fluoroquinolone has become more complex now that there are more choices available. Orbifloxacin, difloxacin and marbofloxacin now join enrofloxacin on the veterinary market, although not all of these are licensed in every country. The use of fluoroquinolones in dermatology remains controversial. The authors recommend that fluoroquinolones be considered in circumstances where canine pyoderma has been refractory to appropriate 'first line' antibiotics. They are most useful in the management of recurrent pyoderma and in chronic, deep pyoderma with extensive scar tissue. In addition, fluouroquinolones frequently are the drugs of choice for canine ear infections caused by Pseudomonas aeruginosa.     

Surgical management of 43 cases of chronic otitis externa in the dog

: Over a seven-year period, chronic otitis externa was surgically managed in 43 dogs at the University Veterinary Hospital of University College Dublin. Lateral ear canal resection (LECR) was undertaken in nine of the 43 dogs: results were unsatisfactory, with a failure of the surgery in five of eight dogs and one dog lost to follow-up. Once end-stage otitis externa, with or without otitis media, is diagnosed, total ear canal ablation and lateral bulla osteotomy (TECA/LBO) is the best treatment option. In this series, 37 of 43 dogs underwent TECA/LBO and of the 29 dogs for which follow-up results were obtained 27 (93%) had an excellent or improved outcome to surgery. Complications following all procedures were most common in cases with a concurrent dermatopathy; therefore, definitive diagnosis and medical treatment for skin and ear disease is essential.     

Factors affecting the adherence of Malassezia pachydermatis to canine corneocytes in vitro

Abstract Suspensions of Malassezia pachydermatis adhered to canine corneocytes attached io adhesive tape in a dose (P < 0.001) and time-dependent (P < 0.01) manner; adherence was maximal after 2 h. M. pachydermatis cells were approximately 10 times more adherent than Saccharomyces cerevisiae (P < 0.001) cells after 2 h incubation. The adherence of formalin-treated and frozen-thawed M. pachydermatis cells was comparable with untreated controls. Stationary-phase cells adhered better (P < 0.05) than exponential-phase cells. Pretreatment of the yeasts, or corneocytes, with 0.1% trypsin for 30 min reduced (P < 0.01) the adherence of four, and two, out of five strains, respectively, whereas incubation with 300 mM solutions of D(+) mannose, sucrose and N-acetyl D-glucosamine had no consistent effect. These results suggest that trypsin-sensitive proteins or glycoproteins on the yeast cell wall, and on the corneocyte surface, play an important role in the adherence of M. pachydermatis to canine corneocytes in vitro, whereas a role for carbohydrate receptors was not demonstrated. Résumé— Des suspensions de Malassezia pachydermatis adhérant à des cornéocytes des chiens sont attachées à des rubans adhésifs de façon significative en function du nombre (P < 0,001) et de la durée (P < 0,01). L'adhérence est maximale après 2 heures. Les levures du genre Malassezia pachydermatis sont approximativement dix fois plus adhérentes que les levures du genre Saccharomyces cerevisiae (P < 0,001) après une incubation de 2 heures. L'adhérence des Malassezia pachydermatis traitées par le formol et congelées - décongelées, est comparable à celle des témoins. Les levures qui ne sont pas en phase de croissance adhérent mieux (P < 0,05) que celles qui le sont. Le traitement préalable des levures ou des cornéocytes avec une solution de trypsine pendant 30 minutes réduit (P < 0,01) l'adhérence tandis que l'incubation avec des solutions à 300 mM de D + mannose, sucrose et de N acétyl D glucosamine n'a pas d'effets. Ces résultats suggèrent que des protéines sensibles à la trypsine ou des glycoprotéines sur la paroi des levures et à la surface des cornéocytes jouent un rôle important in vitro dans l'adhérence des Malassezia pachydermatis aux cornéocytes du chien, alors que le rôle des récepteurs glucidiques n'a pas été démontré. [Bond, R., Lloyd, D. H. Factors affecting the adherence of Malassezia pachydermatis to canine cornéocytes in vitro (Facteurs influençant l'adhérence de Malassezia pachydermatis aux cornéocytes du chien in vitro). Veterinary Dermatology 1996; 7 : 49–56.] Resumen Las suspensiones de Malassezia pachydermatis se adherian a cinta adhesiva de forma dependiente de la dosis (P < 0.001) y del tiempo (P < 0.01); su adherencia fue máxima a las 2 h. Las células de M. pachydermatis fueron aproximadamente 10 veces más adherentes que las de Saccharomyces cerevisiae (P < 0.001) a las 2 h de incubación. La adherencia de células de M. pachydermatis tratadas con formalina y congeladas-descongeladas fue comparable con los controles no tratados. Las células en estadio estacionario se adherian mejor (P < 0.05) que las de fase exponencial. El tratamiento previo de las levaduras o los corneocitos con 0.1% de tripsina durante 30 min redujo (P < 0.01) la adherencia de cuatro, y dos, de cinco cepas, respectivamente, mientras que su incubación con soluciones 300 mM de D(+) manosa, sucrosa y N-acetil D-glucosamina no tuvieron un efecto constante. Estos resultados sugieren que proteinas o glieoproteinas sensibles a la tripsina en la pared de la levadura, y en la superficie del corneocito, juegan un papel importante en la adherencia de M. pachydermatis a los corneocitos caninos in vitro, mientras que no se pudo demostrar un papel por parte de los receptores de carbohidratos. [Bond, R., Lloyd, D. H. Factors affecting the adherence of Malassezia pachydermatis to canine corneocytes in vitro (Facto res que afectan la adherencia de Malassezia pachydermatis a los corneocitos caninos in vitro). Veterinary Dermatology 1996; 7 : 49–56.] Zusammenfassung— Suspensionen von Malassezia pachydermatis zeigten eine Adhärenz an kanine Korneozyten, die an einem Klebeband befestigt waren, in dosisabhängiger (P < 0,001) und zeitabhängiger Weise (P < 0,01). Die Adhärenz erreichte ein maximum nach 2 Stunden. M. pachydermatis-Zellen waren ungefähr 10 mal stärker adhärent als Saccharomyces cervisiae-Zellen nach Zstündiger Inkubation (P < 0,001). Die Adhärenz von formalinbehandelten und gefrorenen/aufgetauten M. pachydermatis-Zellen war vergleichbar mit unbehandelten Kontrollzellen. Zellen der stationären Phase waren besser adhärent (P < 0,05) als Zellen der exponentiellen Phase. Eine Vorbehandlung der Hefen oder Korneozyten mit 0,1% igem Trypsin über 30 Minuten reduzierte die Adhärenz (P < 0,01) von 4 bzw. 2 aus 5 Linien, während eine Inkubation mit 300 mm Lösungen von D(+)Mannose, Sucrose und N-Acetyl-D-Glukosaminen keinen entsprechenden Effekt hatte. Diese Ergebnisse legen nahe, daß Trypsin-sensible Proteine oder Glykoproteine an der Zellwand der Hefe und auf der Korneozytenoberfläche eine wichtige Rolle für die Adhärenz von M. pachydermatis an kanine Korneozyten in-vitro spielen, während eine Bedeutung für Kohlenhydrat-Rezeptoren nicht demonstriert werden konnte. [Bond, R., Lloyd, D. H. Factors affecting the adherence of Malassezia pachydermatis to canine corneocytes in vitro (Einflußfaktoren auf die Adhärenz von Malassezia pachydermatis an kanine Korneozyten in vitro). Veterinary Dermatology 1996; 7 : 49–56.]     

Cytologic Features of a Meningioma in a Dog

Meningiomas are one of the most common nervous system tumors in dogs. They are mostly solitary, benign, intracranial tumors of the transitional type. Tentative diagnosis can usually be made on historical data, clinical and neurological signs, and radiographs, with an antemortem diagnosis confirmed by exploratory surgery and histologic evaluation of biopsy. The literature contains many reports of the gross, histological and ultrastructural morphology of canine meningiomas, but little on the cytologic features of these tumors. This report describes the cytologic appearance of an intracranial meningioma in a 9-year-old Miniature Schnauzer.     

Synergistic effects of Miconazole and Polymyxin B on microbial pathogens

The therapeutic value of antibiotics depends on the susceptibility of the infecting microorganism and the pharmacological profile of the drugs. To assess the value of an antibiotic combination of polymyxin B and miconazole this study examined the in vitro synergistic potential of the two drugs on Gram-negative and Gram-positive bacteria and yeast. Antifungal and antibacterial activity was tested by minimum inhibitory concentration (MIC) of broth macrodilution and urea broth microdilution, by fluorescence microscopy and flow cytometry. Synergism was calculated using the fractional inhibitory concentration index (FICi). With Staphylococcus intermedius as target we found up to an eightfold reduction of the individual MICs when both drugs were combined. However, the FICi was 0.63 suggesting no real interaction between the two drugs. With Escherichia coli, Pseudomonas aeruginosa, and Malassezia pachydermatis as targets the antimicrobial drug combination reduced the MICs of polymyxin B and miconazole from fourfold to hundredfold resulting in FICi between 0.06 and 0.5 which defines a synergistic action. Thus, if polymyxin B and miconazole are combined their effect is greater than the sum of the effects observed with polymyxin B and miconazole independently, revealing bactericidal and fungicidal synergism. Our results indicate a strong therapeutic value for the combination of these antimicrobial agents against Gram-negative bacteria and yeast and a weaker value against Gram positive bacteria for clinical situations where these pathogens are involved.