A. Maderner

Bio: A. Maderner is an academic researcher from University of Veterinary Medicine Vienna. The author has contributed to research in topics: Brachyspira & Tritrichomonas foetus. The author has an hindex of 12, co-authored 17 publications receiving 337 citations.

Detection of Cryptosporidium species in feces or gastric contents from snakes and lizards as determined by polymerase chain reaction analysis and partial sequencing of the 18S ribosomal RNA gene.

Abstract: Cryptosporidiosis is a well-known gastrointestinal disease of snakes and lizards. In the current study, 672 samples (feces and/or gastric contents or regurgitated food items) of various snakes and lizards were examined for the presence of cryptosporidia by polymerase chain reaction (PCR) assay targeting a part of the 18S ribosomal RNA gene. A consecutive sequencing reaction was used to identify the cryptosporidian species present in PCR-positive samples. Cryptosporidium varanii (saurophilum) was detected in 17 out of 106 (16%) samples from corn snakes (Pantherophis guttatus) and in 32 out of 462 (7%) samples from leopard geckos (Eublepharis macularius). Cryptosporidium serpentis was found in 8 out of 462 (2%) leopard gecko samples, but in no other reptile. The Cryptosporidium sp. "lizard genotype" was present in 1 leopard gecko sample, and 1 sample from a corn snake showed a single nucleotide mismatch to this genotype. Pseudoparasitic cryptosporidian species were identified in 5 out of 174 (3%) ophidian samples, but not in lizards. Other sequences did not show complete similarity to previously published Cryptosporidium sequences. The results stress the importance for diagnostic methods to be specific for Cryptosporidium species especially in snakes and show a relatively high prevalence of C. varanii in leopard geckos and corn snakes.

Application of in-situ hybridization for the detection and identification of avian malaria parasites in paraffin wax-embedded tissues from captive penguins

Abstract: In captive penguins, avian malaria due to Plasmodium parasites is a well-recognized disease problem as these protozoa may cause severe losses among valuable collections of zoo birds. In blood films from naturally infected birds, identification and differentiation of malaria parasites based on morphological criteria are difficult because parasitaemia is frequently light and blood stages, which are necessary for identification of parasites, are often absent. Post-mortem diagnosis by histological examination of tissue samples is sometimes inconclusive due to the difficulties in differentiating protozoal tissue stages from fragmented nuclei in necrotic tissue. The diagnosis of avian malaria would be facilitated by a technique with the ability to specifically identify developmental stages of Plasmodium in tissue samples. Thus, a chromogenic in-situ hybridization (ISH) procedure with a digoxigenin-labelled probe, targeting a fragment of the 18S rRNA, was developed for the detection of Plasmodium parasites in pa...

Methods for the isolation and identification of Listeria spp. and Listeria monocytogenes: a review

Abstract: Listeria monocytogenes is an important food-borne pathogen and is widely tested for in food, environmental and clinical samples. Identification traditionally involved culture methods based on selective enrichment and plating followed by the characterization of Listeria spp. based on colony morphology, sugar fermentation and haemolytic properties. These methods are the gold standard; but they are lengthy and may not be suitable for testing of foods with short shelf lives. As a result more rapid tests were developed based on antibodies (ELISA) or molecular techniques (PCR or DNA hybridization). While these tests possess equal sensitivity, they are rapid and allow testing to be completed within 48 h. More recently, molecular methods were developed that target RNA rather than DNA, such as RT-PCR, real time PCR or nucleic acid based sequence amplification (NASBA). These tests not only provide a measure of cell viability but they can also be used for quantitative analysis. In addition, a variety of tests are available for sub-species characterization, which are particularly useful in epidemiological investigations. Early typing methods differentiated isolates based on phenotypic markers, such as multilocus enzyme electrophoresis, phage typing and serotyping. These phenotypic typing methods are being replaced by molecular tests, which reflect genetic relationships between isolates and are more accurate. These new methods are currently mainly used in research but their considerable potential for routine testing in the future cannot be overlooked.

Malaria Parasites and Other Haemosporidia

Abstract: During the past two decades man has learned much about the life cycle and the physiology of his own four species of malaria as well as those of other mammals, birds, and reptiles. The electron microscope has provided a fund of morphological detail, and biochemists have answered many questions concerning the nutrition of the parasite and its resistance to chemotherapy. The use of malaria's fever in the therapy of paresis and animal studies have advanced our understanding of immunity and chemotherapeutic response. The exo-erythrocytic portion of the life cycle explains some of the perplexing clinical facets of the disease. Professor Garnham, who has made many outstanding contributions to our knowledge of malaria, brings together not only the wealth of new but also the important old research on malaria that goes back four centuries. Laveran, Ross, Grassi, and Danilewsky live again on these pages. He paints in beautiful detail (with numerous

Elucidation of Listeria monocytogenes contamination routes in cold-smoked salmon processing plants detected by DNA-based typing methods

Abstract: The contamination routes of Listeria monocytogenes in cold-smoked salmon processing plants were investigated by analyzing 3,585 samples from products (produced in 1995, 1996, 1998, and 1999) and processing environments (samples obtained in 1998 and 1999) of two Danish smokehouses. The level of product contamination in plant I varied from 31 to 85%, and no L. monocytogenes was found on raw fish (30 fish were sampled). In plant II, the levels of both raw fish and product contamination varied from 0 to 25% (16 of 185 raw fish samples and 59 of 1,000 product samples were positive for L. monocytogenes). A total of 429 strains of L. monocytogenes were subsequently compared by random amplified polymorphic DNA (RAPD) profiling, and 55 different RAPD types were found. The RAPD types detected on the products were identical to types found on the processing equipment and in the processing environment, suggesting that contamination of the final product (cold-smoked salmon) in both plants (but primarily in plant I) was due to contamination during processing rather than to contamination from raw fish. However, the possibility that raw fish was an important source of contamination of the processing equipment and environment could not be excluded. Contamination of the product occurred in specific areas (the brining and slicing areas). In plant I, the same RAPD type (RAPD type 12) was found over a 4-year period, indicating that an established in-house flora persisted and was not eliminated by routine hygienic procedures. In plant II, where the prevalence of L. monocytogenes was much lower, no RAPD type persisted over long periods of time, and several different L. monocytogenes RAPD types were isolated. This indicates that persistent strains may be avoided by rigorous cleaning and sanitation; however, due to the ubiquitous nature of the organism, sporadic contamination occurred. A subset of strains was also typed by using pulsed-field gel electrophoresis and amplified fragment length polymorphism profiling, and these methods confirmed the type division obtained by RAPD profiling.