Wieland Schroedl

Trichophyton species of Arthroderma benhamiae - a new infectious agent in dermatology

In Germany, infections due to the zoophilic dermatophyte Trichophyton (T.) species of Arthroderma benhamiae are being more frequently diagnosed. The source of infection of this emerging pathogen overlaps with that of the zoophilic species T. interdigitale. The most common source are guinea pigs. T. species of Arthroderma benhamiae causes inflammatory dermatophytosis in children and adolescents. In addition to tinea capitis, it may cause both tinea corporis, tinea manus and frequently tinea faciei. In Germany, T. species of Arthroderma benhamiae is a frequent zoophilic dermatophyte, which in regions is probably more frequent than Microsporum canis. The mycological identification of the isolates with their yellow stained colonies is based on their macroscopic and microscopic features. However, some exhibit colony features consistent with those of T. interdigitale. These strains only can be identified unambiguously by means of molecular techniques. Using detection methods such as PCR‐ELISA or real‐time PCR, the dermatophyte can be identified directly from clinical material. Sequencing of the internal transcribed spacer region (ITS) of the ribosomal DNA has been approved as culture confirmation test for T. species of Arthroderma benhamiae. In addition, matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI TOF MS) is useful. Widespread dermatophytosis due to T. species of Arthroderma benhamiae, in particular of tinea capitis, requires oral antifungal agents. Terbinafine is most effective, alternatives are fluconazole and itraconazole.

Dose-dependent effects of Chlamydia psittaci infection on pulmonary gas exchange, innate immunity and acute-phase reaction in a bovine respiratory model

The respiratory pathogen Chlamydia psittaci naturally occurs in bovine herds and was recently shown to impair calf health in a dose-dependent manner. The aim of this study was to determine whether the functional consequences and immunological reactions of infection were dose related by quantifying the consequences of acute respiratory chlamydial infection on respiratory signs, disturbances of pulmonary gas exchange, response of the innate immune system, and acute-phase reaction. Fourteen calves were challenged intrabronchially with different C. psittaci doses (from 10(6) to 10(9)inclusion-forming units (ifu) per animal). Ten controls received either UV-inactivated chlamydiae or cell culture medium. Compared to the controls, all animals challenged with live C. psittaci developed hypoxaemia linked to reduced haemoglobin oxygen saturation, increased alveolar-arterial oxygen partial pressure difference (A-aO2) and pulmonary shunt, with symptoms following a dose-dependent pattern. Increases in lipopolysaccharide-binding protein (LBP) and leukocytes were also dose-dependent and accompanied by a regenerative left shift in neutrophil granulocytes. With the exception of LBP, which reflected the load of chlamydial cell components in the host, pathophysiological reactions were only detected in calves challenged with viable chlamydiae. These results indicate that the pathophysiological consequences of respiratory C. psittaci infections are strongly dependent on the challenge dose of chlamydiae. For further studies, challenge doses between 10(6) and 10(8)ifu/calf are recommended.

Evaluation of antimicrobial treatment in a bovine model of acute Chlamydia psittaci infection: tetracycline versus tetracycline plus rifampicin

Antimicrobial treatment of chlamydial infections is known to be of limited efficacy. In this study, effects of doxycycline (D), usually the drug of choice, were compared with the combined therapy of doxycycline and rifampicin (R) in a bovine model of respiratory Chlamydia psittaci infection. After intrabronchial inoculation of the pathogen, 30 animals were assigned to five groups (n = 6 per group): untreated controls, monotherapy with D (5 mg kg(-1)day(-1) or 10 mg kg(-1)day(-1)), and combination therapy of D and R (600 mg day(-1)). Treatment continued until day 14 post inoculation (d.p.i.). Clinical signs, inflammatory markers, and pathological findings confirmed successful infection in all animals. Reisolation of the pathogen was possible in 4/6 untreated animals and in 4/12 animals treated with D alone until 4 d.p.i., but in none of the calves of the two D + R groups. Pathogen detection was possible in all animals without significant differences among groups. Severity of disease and time course of its resolution, assessed by clinical and pathological findings as well as inflammatory parameters, were not significantly different between untreated controls and calves receiving D alone or in combination with R. Regardless of the treatment regimen, all groups recovered clinically and cleared the infection within 2 weeks.

Trichophyton Spezies von Arthroderma benhamiae – ein neuer Infektionserreger in der Dermatologie

In Deutschland kommen seit einigen Jahren Infektionen durch den zoophilen Dermatophyten Trichophyton (T.) Spezies von Arthroderma benhamiae vor. Das Reservoir für diesen neuen Erreger – ein emerging pathogen – überlappt mit dem des zoophilen T. interdigitale. Insbesondere Meerschweinchen sind Carrier. T. Spezies von Arthroderma benhamiae verursacht eine entzündliche Tinea bei Kindern und Jugendlichen. Neben der Tinea capitis werden Tinea corporis und Tinea manus verursacht, vor allem jedoch die Tinea faciei. T. Spezies von Arthroderma benhamiae ist in Deutschland ein häufiger zoophiler Dermatophyt, in manchen Regionen häufiger als Microsporum canis. Die Identifizierung der Isolate mit gelb gefärbten Kolonien ist anhand makro‐ und mikroskopischer Merkmale möglich. Ein Teil der Isolate weist jedoch Koloniemerkmale auf, welche mit denen von T. interdigitale übereinstimmen. Diese Stämme lassen sich nur mittels molekularer Methoden identifizieren. Mit einem PCR‐ELISA oder real‐time PCR kann der Dermatophyt direkt im klinischen Material nachgewiesen werden. Als Kulturbestätigungstest hat sich die Sequenzierung der internal transcribed spacer Region (ITS) der ribosomalen DNA bewährt. Auch die matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI TOF MS) ist dafür geeignet. Die Behandlung von ausgedehnten Dermatophytosen durch T. Spezies von Arthroderma benhamiae, insbesondere der Tinea capitis, erfolgt mit oralen Antimykotika, am besten Terbinafin; Alternativen sind Fluconazol und Itraconazol.

Molecular epidemiology of Trichophyton quinckeanum - a zoophilic dermatophyte on the rise

Formerly only referred to as a subspecies (T. mentagrophytes var. quinckeanum), T. quinckeanum once again constitutes a distinct species according to the updated taxonomy of dermatophytes.

Enrofloxacin and Macrolides Alone or in Combination with Rifampicin as Antimicrobial Treatment in a Bovine Model of Acute Chlamydia psittaci Infection

Chlamydia psittaci is a zoonotic bacterium with a wide host range that can cause respiratory disease in humans and cattle. In the present study, effects of treatment with macrolides and quinolones applied alone or in combination with rifampicin were tested in a previously established bovine model of respiratory C. psittaci infection. Fifty animals were inoculated intrabronchially at the age of 6–8 weeks. Seven served as untreated controls, the others were assigned to seven treatment groups: (i) rifampicin, (ii) enrofloxacin, (iii) enrofloxacin + rifampicin, (iv) azithromycin, (v) azithromycin + rifampicin, (vi) erythromycin, and (vii) erythromycin + rifampicin. Treatment started 30 hours after inoculation and continued until 14 days after inoculation (dpi), when all animals were necropsied. The infection was successful in all animals and sufficient antibiotic levels were detected in blood plasma and tissue of the treated animals. Reisolation of the pathogen was achieved more often from untreated animals than from other groups. Nevertheless, pathogen detection by PCR was possible to the same extent in all animals and there were no significant differences between treated and untreated animals in terms of local (i.e. cell count and differentiation of BALF-cells) and systemic inflammation (i.e. white blood cells and concentration of acute phase protein LBP), clinical signs, and pathological findings at necropsy. Regardless of the reduced reisolation rate in treated animals, the treatment of experimentally induced respiratory C. psittaci infection with enrofloxacin, azithromycin or erythromycin alone or in combination with rifampicin was without obvious benefit for the host, since no significant differences in clinical and pathological findings or inflammatory parameters were detected and all animals recovered clinically within two weeks.

Influence of the Gut Microbiota on Blood Acute-Phase Proteins

Little is known about the bovine intestinal microbiota influence on systemic innate immune responses. The objective of the present study was to determine relationships between acute‐phase proteins in blood serum of cows [C‐reactive protein (CRP), LPS‐binding protein (LBP) and haptoglobin (Hp)] and the faecal microbiota. Fifty‐two healthy cows (2–8 years old) were investigated. Faecal bacteria were determent characterized by in situ hybridization with 16S/23S rRNA‐targeted probes and by conventional culture methods. The population of Gram‐negative faecal bacteria (Enterobacteriaceae) was correlated negatively with CRP and positively with LBP in blood plasma, independent of the method used. Similar results were observed with Clostridium perfringens. No correlation was found between the faecal population of intestinal bacteria and Hp levels in blood plasma. This datum indicates that intestinal bacteria, especially Enterobacteriaceae and C. perfringens, may influence the level of CRP and LBP in blood plasma. These findings can be very important for diagnostic evaluations of the intestinal microbiota and provide specific information about its regulation.

Molekulare Epidemiologie von Trichophyton quinckeanum - ein zoophiler Dermatophyt im Aufwind: Trichophyton quinckeanum - ein zoophiler Pilz im Aufwind

Entsprechend der aktualisierten Taxonomie der Dermatophyten ist Trichophyton (T.) quinckeanum – früher lediglich als Subspezies T. mentagrophytes var. quinckeanum bekannt ‐ wieder eine eigenständige Spezies.