A zoonotic ringworm outbreak caused by a dysgonic strain of Microsporum canis from stray cats.

BACKGROUND: Cats are frequent carriers of Microsporum canis and veterinary students are at high risk of exposure and acquisition of the organism a la infección. OBJECTIVES: An outbreak of zoonotic ringworm carried by a litter of stray cats is described. Four veterinary students, four dogs, and six cats living in five separate locations were affected. All had direct or indirect contact with the infected kitten litter. We tried to identify the causal dermatophyte. METHODS: Conventional and mycological culture methods were used. RESULTS: Microscopic features of scrapings and hairs treated with 20% KOH strongly suggested a M. canis etiology, and a diagnosis of ringworm was empirically supported by successful treatment of humans and animals. Nevertheless, cultures failed to show the expected morphology. CONCLUSIONS: Culture features of our strain are compared with those described by other authors for dysgonic M. canis strains. Epidemiological features are also discussed.

Evaluation of randomly amplified polymorphic DNA and pulsed field gel electrophoresis techniques for molecular typing of Dermatophilus congolensis.

This study aimed to evaluate molecular typing methods useful for standardization of strains in experimental work on dermatophilosis. Fifty Dermatophilus congolensis isolates, collected from sheep, cattle, horse and a deer, were analyzed by randomly amplified polymorphic DNA (RAPD) method using twenty-one different primers, and the results were compared with those obtained by typing with a pulsed field gel electrophoresis (PFGE) method using the restriction digest enzyme Sse8387I. The typeability, reproducibility and discriminatory power of RAPD and Sse8387I-PFGE typing were calculated. Both typing methods were highly reproducible. Of the two techniques, Sse8387I-PFGE was the least discriminating (Dice Index (DI), 0.663) and could not distinguish between epidemiologically related isolates, whereas RAPD showed an excellent discriminatory power (DI, 0.7694-0.9722). Overall, the degree of correlation between RAPD and PFGE typing was significantly high (r, 0.8822). We conclude that the DNA profiles generated by either RAPD or PFGE can be used to differentiate epidemiologically unrelated isolates. The results of this study strongly suggest that at least two independent primers are used for RAPD typing in order to improve its discriminatory power, and that PFGE is used for confirmation of RAPD results.

Characterisation of an extracellular serine protease gene (nasp gene) from Dermatophilus congolensis.

A partial amino acid sequence of a serine protease from Dermatophilus congolensis allowed the design of oligonucleotide primers that were complemented with additional ones from previously published partial sequences of the gene encoding the enzyme. The polymerase chain reaction (PCR), using combinations of specific and degenerate oligonucleotide primers, allowed the amplification of a 1738-bp internal fragment of the gene, which was finally characterised by inverse PCR as the first full-length sequenced serine protease gene (nasp) from Dermatophilus congolensis. The deduced amino acid sequence of this enzyme, probably involved in the pathogenesis of dermatophilosis, links it to the subtilisin family of proteases.

Identification of an alkaline ceramidase gene from Dermatophilus congolensis.

A random amplified polymorphic DNA (RAPD) procedure was used to identify a specific 0.6 kb DNA fragment unique to Dermatophilus congolensis. This 0.6 kb fragment was evaluated as a specific DNA probe and used to design oligonucleotide primers for polymerase chain reaction (PCR) amplification. The nucleotide sequences adjacent to this DNA fragment were determined by inverse PCR allowing the identification of a 4.1 kb sequence. Analysis of this revealed a complete open reading frame (ORF) with a high similarity to an alkaline ceramidase from Pseudomonas aeruginosa. The molecular weight of the enzyme derived from the predicted amino acid sequence is 74,662 Da, its pI is 9.81. The predicted N-terminal sequence of the enzyme contains a signal sequence indicating that the enzyme is exported by the bacterium. Since ceramides have important protective and cell regulatory roles in the epidermis we suggest that this ceramidase may have a role in the pathogenesis of dermatophilosis. It is the first completely sequenced gene described for D. congolensis.

A zoonotic ringworm outbreak caused by a dysgonic strain of Microsporum canis from stray cats

Antecedentes Los gatos son frecuentemente portadores de Microsporum canis. Los estudiantes de veterinaria están especialmente expuestos a la infección. Objetivos Se describe un brote de tiña zoonótica difundido por una camada de gatos callejeros. Cuatro estudiantes de veterinaria, cuatro perros y seis gatos de cinco localizaciones diferentes se vieron afectados. Todos tuvieron contacto directo o indirecto con la camada de gatitos infectados. Se intenta identificar el dermatofito causal. Métodos Se utilizan los procedimientos micológicos morfológicos y de cultivo convencionales. Resultados Los hallazgos microscópicos en pelo y raspados cutáneos aclarados en KOH al 20% sugirieron fuertemente una etiología por M. canis, y el diagnóstico de tiña fue apoyado empíricamente por el éxito en el tratamiento de humanos y animales. Sin embargo, los cultivos no mostraron la morfología esperada. Conclusiones Los caracteres del cultivo de nuestra cepa son comparados con los descritos por otros autores en cepas disgónicas de M. canis. Las características epidemiológicas son discutidas también(AU)

Background Cats are frequent carriers of Microsporum canis and veterinary students are at high risk of exposure and acquisition of the organism a la infección. Objectives An outbreak of zoonotic ringworm carried by a litter of stray cats is described. Four veterinary students, four dogs, and six cats living in five separate locations were affected. All had direct or indirect contact with the infected kitten litter. We tried to identify the causal dermatophyte. Methods Conventional and mycological culture methods were used. Results Microscopic features of scrapings and hairs treated with 20% KOH strongly suggested a M. canis etiology, and a diagnosis of ringworm was empirically supported by successful treatment of humans and animals. Nevertheless, cultures failed to show the expected morphology. Conclusions Culture features of our strain are compared with those described by other authors for dysgonic M. canis strains. Epidemiological features are also discussed(AU)