SUMMARYThe mastitis caused by P. zopfii alga is a disease of highproducing, machine-milked dairy cows. It occurs worldwide in tropical and temperate climatic areas, and mostly appears sporadically in a therapy-resistant form. However, in poorly managed dairy herds it may be endemic, causing serious economic losses as a result of decreased milk quality and quantity and culling of infected animals. The biological properties of this pathogenic alga, the laboratory methods available for its isolation and identification, the pathological and clinical features of this form of mastitis, and the principles of its control are reviewed in this paper.
In order to compound a new drug combination against canine otitis externa (OE), 515 dogs affected with OE were subjected to physical examination and microbiological analysis of their ear exudates. OE was erythematous-ceruminous in 83 per cent and suppurative in 17 per cent of the patient material. Erythematous-ceruminous inflammations were characterised by severe pruritus and accumulation of brownish, greasy cerumen in the auditory canal. The yeast Malassezia pachydermatis was isolated from the ears of 76 per cent of the dogs, often in combination with Staphylococcus intermedius bacteria. M pachydermatis showed the most sensitivity, in decreasing order of efficacy, to ketoconazole, econazole, clotrimazole, miconazole and nystatin. S intermedius isolates were most sensitive to amoxycillin-clavulanic acid, enrofloxacin, cephalexin and gentamicin. The microorganism most frequently isolated from dogs with suppurative OE was Pseudomonas aeruginosa; in some cases Proteus, Streptococcus and Pasteurella were also isolated. The P aeruginosa isolates showed the highest sensitivity to gentamicin, polymyxin B and tobramycin.
In the last 2 years 223 cases of bovine mastitis caused by Prototheca zopfii infection were identified in 32 large-scale dairy herds. All of these farms were in Hungary, which has a continental type, temperate zone climate. Both the sporadic and epidemic forms of P. zopfii mastitis were observed. All the herds affected by the epidemic form had poor hygienic conditions and suffered from several managerial faults, but no specific predisposing factors could be identified. In almost all of the cases, the type II variant of this pathogen was isolated; however, the type III variant was isolated from three cows. The cows had a higher chance of new infection in the early weeks of lactation and in the summer. The P. zopfii infection usually resulted in a chronic subclinical, or mild clinical, inflammatory process in the udder, and was followed by a dramatic loss in milk production and a permanent increase in somatic cell count. The histopathological findings could be characterized as a progressive interstitial mastitis associated with alveolar atrophy. The self-recovery rate was very low.
The morphological, cultural and biochemical characteristics of 80 M. pachydermatis strains isolated from cases of canine otitis externa were studied. Microscopically, the strains could be subdivided into two phenotypes. All M. pachydermatis strains grew well on Sabouraud glucose, yeast morphology and modified malt extract agar, but formed two distinct colony types. All strains were characterized by no fermentation. Assimilation of glucose, mannitol (42 strains), sorbitol (40 strains) and peptone was observed, but no ethanol assimilation. Urease and catalase tests were positive, while indole and acetoin production was not detected. All strains showed proteinase, caseinase, lecithinase and peroxidase positivity but to varying extents. Esterase activity was observed for all Malassezia strains when using Tween 20, 40 and 60, whereas Tween 80 was hydrolysed by only 42 strains. No coagulase or haemagglutinating activities were detected. When compared for satellite phenomenon and vitamin requirements, some Malassezia strains could not grow in the absence of nicotinic acid but grew well in the presence of staphylococci. In susceptibility tests, all strains showed the highest susceptibility to ketoconazole. On the basis of the biochemical differences, M. pachydermatis seems to be a heterogeneous species and can be divided into two groups.
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