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One case of endophthalmitis and two cases of corneal ulceration, each occurring in a structurally altered eye, were associated with Bacterionema matruchotii, a gram-positive filamentous bacillus.
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Guinea-pigs were sensitized to CDNB and infected with D. congolensis at the site of a subsequent application of this chemical. The bacterium was recovered from the skin over a longer period of time in sensitized individuals than in nonsensitized controls. Animals rendered tolerant to the chemical gave lower yields of bacteria than sensitized animals. However, the lesions produced at the site of infection did not become chronic. The growth of D. congolensis at a contact hypersensitivity site may possibly simulate infection in skin following an arthropod bite and be relevant to the pathogenesis of chronic streptothricosis lesions in the cattle of West Africa.
When tested on solid media the growth of 19 Dermatophilus congolensis strains was inhibited by antibiotic-producing staphylococci isolated from pigs. Two strains, D congolensis D11 and D15, which were very sensitive to the producers and caused lesions of dermatophilosis in a mouse model, were further used to investigate the ability of the producers to inhibit lesion formation by the strains of D congolensis. The simultaneous application of the antibiotic-producing staphylococci and D congolensis suppressed formation of the lesions in the mouse.
Dermatophilus congolensis infection (dermatophilosis) is an acute, subacute or chronic skin disease affecting a wide range of species of animals and man. It is world widely distributed but more prevalent in the humid, tropics and subtropics. The disease is now being reviewed in detail. In the present review, the geographical distribution, history and nomenclature, animal hosts affected, aetiological agent and clinical signs of the disease are discussed extensively. Emphasis is also given on the predisposing factors such as rainfall, humidity, ectoparasites etc. under epizootiology. Pathogenesis, pathology, immunology treatment, control and prophylaxis are other areas well covered. The economic importance of the disease is also stressed and a new approach (biological approach) to treatment and control of the disease is being described in this review. It was concluded that in view of the importance of the disease for the increase of livestock and leather production in the tropical and subtropical region especially in Africa, an international centre for dermatophilosis research is highly needed.
Three antigens prepared from different phases of the life cycle of Dermatophilus congolensis were used in an enzyme-linked immunosorbent assay to measure serum and skin surface antibody responses in sheep after a first, second and third inoculation with D. congolensis. After the first inoculation, a strong antibody response to the flagella, filament and soluble antigens was detected after 7-21 days in the sera from sheep that were regularly biopsied; the antibody response at the skin surface was detected 28-42 days after inoculation, when the lesions were resolving. Strong anamnestic responses were detected in the serum of sheep that were biopsied and some of the nonbiopsied sheep after the second and third inoculations, but the skin surface antibody response at these times was variable.
The cellular response in the skin of Merino sheep was examined after three successive inoculations with Dermatophilus congolensis. There was a massive neutrophil influx into the infected epidermis and underlying dermis at 4-10 days after the first inoculation. A lymphocyte-macrophage response occurred at 10-12 days, followed by a plasma cell response at 14-38 days. Resolution of skin lesions after the first inoculation corresponded to the time when the plasma cell response in the skin was most intense. A second inoculation with D. congolensis, 70 days after the first, failed to produce skin lesions typical of dermatophilosis. Typical lesions of dermatophilosis did develop after a third inoculation of the same sheep 140 days after the first inoculation, but the lesions resolved in most sheep within 13 days. Dermatophilosis did not develop in some of these sheep at sites inoculated with 100-1000-fold lower infective doses of D. congolensis, whereas control sheep did develop lesions.
Zoospore, filamentous and soluble antigens were prepared from Dermatophilus congolensis and examined for their ability to protect sheep from challenge with D. congolensis zoospores. In 1 experiment, sheep were vaccinated with Antigens A, B and C. The number of sheep protected in the group vaccinated with Antigen B was greater (P less than 0.05) than that in the unvaccinated group after challenge. The group vaccinated with Antigen B had a higher antibody response (P less than 0.05) to Antigen B than to Antigen A or C. In a second experiment, 2 groups of sheep were vaccinated with Antigen B. All sheep in this study developed lesions after challenge, but those on the vaccinated sheep were less severe (P less than 0.05) than those on the unvaccinated sheep. The antibody response to Antigen A, 28 days after vaccination, was higher (P less than 0.05) than the response to Antigen B.
The host cell-mediated immune response was examined following experimentally-induced infection of rats with Dermatophilus congolensis, the causal agent of the skin disease dermatophilosis. Mononuclear cells (MC) isolated from Wistar rats 10 days following the induction of a third infection underwent a strong and specific proliferative response, as assessed by a [3H]thymidine incorporation assay, when cultured with various concentrations of inactivated D. congolensis cocci. Using specific monoclonal antibodies in an indirect fluorescent antibody test, this in vitro response was found to be characterised by a large expansion of the W3/25 (T-helper phenotype) population to form 56% of the total. Finally, the primed and stimulated MC were assessed for their ability to produce factors capable of inhibiting macrophage migration. The culture supernatants of D. congolensis-stimulated MC from infected rats caused significant migration inhibition of normal rat peritoneal exudate cells, whilst the supernatants of similarly-stimulated MC from naive rats failed to cause significant inhibition. The results show that a MC subpopulation becomes primed following experimentally-induced infection with D. congolensis and becomes activated after subsequent, in vitro, exposure.
Intradermal vaccination of live crude filaments (vaccine A) was compared with a vaccine (vaccine B) consisting of a 45 kD zoospore protein and mucoid material coating filaments in its ability to protect sheep from experimental Dermatophilus congolensis infection. Fourteen and 21 days after challenge, vaccine A sheep had fewer lesions (P less than 0.001) than the vaccine B sheep. The lesions on the vaccine A sheep were also less severe 14 and 21 days after challenge (P less than 0.05, P less than 0.01 respectively). In a second study, vaccine A was assessed for its ability to protect against natural challenge. Ten weeks after contact with sheep with active and generalised dermatophilosis no difference was found between the number of lesions present on the vaccine A and unvaccinated sheep and no differences were found in the number of sheep in each group with active lesions.
Cross-protection studies were conducted with vaccines prepared from two isolates of Dermatophilus congolensis (designated strain 1 and strain 2). The vaccines were prepared as either heat-inactivated, washed, formalized filamentous phase bacterium, mixed with alum as an adjuvant, and inoculated intramuscularly (type A vaccine) or sedimented live filaments inoculated intradermally (type B vaccine). The vaccinated sheep were challenged with D. congolensis zoospores of one or other strain. Challenge sites were observed for the presence and severity of lesions. Serum antibody levels to D. congolensis were monitored after vaccination and challenge. Type A and B vaccines from both strains produced some reduction in the severity of lesions when sheep were challenged with strain 1 but not with strain 2. Unvaccinated control sheep developed more severe and persistent lesions when challenged with strain 2 than controls challenged with strain 1. Serum antibody levels to the type B vaccine prepared from strain 1 were significantly higher (P less than 0.05) than antibody levels to type B vaccine from strain 2. These findings showed there was significant variation in virulence and antigenicity between these two isolates of D. congolensis.
Quantification of a T6-lymphocyte antigen in peripheral blood mononuclear cells of sheep was used to select 15 from 48 one year old Merino ewes not previously exposed to Dermatophilus congolensis infection. These sheep were compared in response to challenge with D. congolensis zoospores and levels of T-6 lymphocyte antigen in peripheral blood mononuclear cells with 15 Merino ewes of similar age and strain from a different site that had been treated and recovered from chronic dermatophilosis. The T-6 lymphocyte antigen levels were significantly lower in the chronic dermatophilosis sheep and they developed significantly more severe lesions than the selected, previously unexposed sheep despite the former sheep having high serum antibody levels to D. congolensis. Measurement of the fleece characteristics, wax and suint concentration showed no differences between the groups that might have explained the considerable differences in their susceptibility to dermatophilosis.
Zoospores of Dermatophilus congolensis were analysed by SDS-PAGE and western blotting. The electrophoretic profiles of zoospores from 13 isolates of D. congolensis were similar but not identical when stained with Coomassie blue or silver. Immunodominant polypeptides with apparent molecular masses of 76 and 31 kDa were identified in western blots of 13 of 13 and 12 of 13 isolates respectively of D. congolensis reacted with hyperimmune, ovine, antizoospore sera. Identical immunodominant polypeptides were observed in western blots reacted with sera obtained from naturally infected sheep. Initial characterisation of the 76 and 31 kDa polypeptides indicated that they were probably surface exposed because (i) antibodies eluted from the surface of live zoospores after adsorption of hyperimmune antizoospore serum, reacted principally against the 76 and 31 kDa subunit polypeptides in western blots, (ii) adsorption of hyperimmune antizoospore serum with live zoospores resulted in significant diminution of reactivity against both the 76 and 31 kDa polypeptides in western blots, (iii) indirect fluorescent immunostaining of zoospores with antiserum prepared against gel-purified 76 kDa polypeptide, resulted in intense staining of the zoospore outer coat. Immuno-gold electron microscopy of negatively stained zoospores with antiserum prepared against gel-purified 31 kDa polypeptide identified this antigen as a flagella subunit.
Recent vaccination studies with Dermatophilus congolensis showed that variation of challenge strains had a considerable influence on protection afforded by the vaccines. In this study cultural, morphological and biochemical properties of 30 D. congolensis isolates from throughout Australian were investigated. The infective dose required to produce lesions of equivalent severity by these isolates for sheep, rabbits and guinea pigs was also examined and the isolates were grouped into four clusters of similar infectivity ranking. Analysis of the relationship between cultural, morphological and biochemical characteristics and infectivity rankings of clusters was undertaken to determine if certain properties were linked to infectivity. Considerable variability was found in haemolytic activity on blood agar, mucoid nature of colonies, motility, flagella density and polarity, capsule width, restriction enzyme profiles of bacterial DNA, protein electropherotype, carbohydrate content, and enzymic activity against proteins, maltose, chondroitin-4-sulphate, phospholipids and lipids. Of these properties haemolytic activity and enzyme activity against casein, chondroitin-4-sulphate and lipids showed some link with infectivity ranking for these isolates.
Oerskovia species, which are Nocardia-like bacteria that have rarely been found to cause human disease, are usually found in association with a foreign body with removal of the infected focus being necessary for cure. We present a case of Oerskovia xanthineolytica bacteremia in a patient with metastatic breast cancer, community-acquired pneumonia, and a tunneled subcutaneous central venous catheter. Although the actual source of the bacteremia in this case is not proven, this patient's presentation with apparent lobar pneumonia and her improvement on antibiotics without catheter removal suggest that Oerskovia may be capable of causing primary pulmonary infection in the immunocompromised host.
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.
We present a case of mycetoma by Actinomadura spp. on the foot of an Albanian young man arrived to our observation approximately 5 years after the first clinical manifestations (hard tumefaction, slightly painful upon weight-bearing and palpation and cutaneous fistulas that discharged an abundant granulomatous secretion). Direct microscopic analysis and culture of the white-yellowish grains included Gram staining, which showed extensively branched Gram-positive hyphae less than 1 mm in diameter, allowing to make a diagnosis of Actinomycetoma. Since Actinomycetoma is sensitive to drug treatment, the patient was given trimethoprim-sulfamethoxazole and amikacin twice daily for 45 days. After six months of chemotherapy, the patient's general condition improved, the swelling is slightly diminished and grain extrusion has ceased. The patient has been able to resume ambulation with normal footwear. Given the absence of liver and kidney functional alterations, the patient is scheduled to continue pharmacological treatment with trimethoprim-sulfamethoxazole.
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