Estella Prukner-Radovčić

University of Zagreb, Zagrabia, Grad Zagreb, Croatia

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Publications (16)26.42 Total impact

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    ABSTRACT: Foodborne illness continues as a considerable threat to public health. Despite improved hygiene management systems and increased regulation, pathogenic bacteria still contaminate food, causing sporadic cases of illness and disease outbreaks worldwide. For many centuries, microbial antagonism has been used in food processing to improve food safety. An understanding of the mode of action of this microbial antagonism has been gained in recent years and potential applications in food and feed safety are now being explored. This review focuses on the potential opportunities presented, and the limitations, of using microbial antagonism as a biocontrol mechanism to reduce contamination along the food chain; including animal feed as its first link.
    Journal of the Science of Food and Agriculture 05/2014; · 1.76 Impact Factor
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    ABSTRACT: The classical microbiological method for detection of Salmonella spp. requires more than five days for final confirmation, and consequently there is a need for an alternative methodology for detection of this pathogen particularly in those food categories with a short shelf-life. This study presents an international (at European level) ISO 16140-based validation study of a non-proprietary Real-Time PCR-based method that can generate final results the day following sample analysis. It is based on an ISO compatible enrichment coupled to an easy and inexpensive DNA extraction and a consolidated Real-Time PCR assay. Thirteen laboratories from seven European Countries participated to this trial, and pork meat was selected as food model. The limit of detection observed was down to 10CFU per 25g of sample, showing excellent concordance and accordance values between samples and laboratories (100%). In addition, excellent values were obtained for relative accuracy, specificity and sensitivity (100%) when the results obtained for the Real-Time PCR-based methods were compared to those of the ISO 6579:2002 standard method. The results of this international trial demonstrate that the evaluated Real-Time PCR-based method represents an excellent alternative to the ISO standard. In fact, it shows an equal and solid performance as well as it reduces dramatically the extent of the analytical process, and can be easily implemented routinely by the Competent Authorities and Food Industry laboratories.
    International Journal of Food Microbiology 01/2014; · 3.43 Impact Factor
  • Maja Lukac, Danijela Horvatek-Tomic, Estella Prukner-Radovcic
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    ABSTRACT: Actinobacteria are common agents that cause skin diseases in captive desert lizards, including the recently described Devriesea agamarum. To date, infections caused by D. agamarum, their symptoms, and treatment have been described only by the research group from Belgium that isolated the species in 2008. This article presents the symptoms that indicate the possibility of a D. agamarum-associated infection, such as scaly changes around the mouth in a juvenile lizard (Uromastyx ocelatta) and dermatitis in the form of skin scaling around the mouth and cloaca and over the dorsal part of the body in a group of four spiny-tailed lizards (Uromastyxgeyri). In two animals, swelling of the front limbs with the loss of some toes was also noted, a symptom not previously described with D. agamarum infections. Bacteriologic analysis of dermal lesion samples confirmed the presence of D. agamarum in all subjects. Treatment with ceftazidime was carried out, and the symptoms of dermatitis resolved, followed by negative bacteriologic findings. This is the first report, to our knowledge, that describes the diagnostics, detailed clinical picture with newly described symptoms, and treatment of lizards with D. agamarum-associated skin lesions that reside outside of Belgium. The results also confirm the effectiveness of the systemic administration of third-generation cephalosporin antibiotics in combination with local chlorhexidine in the treatment of D. agamarum infections.
    Journal of Zoo and Wildlife Medicine 06/2013; 44(2):430-4. · 0.43 Impact Factor
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    ABSTRACT: Chlamydia psittaci is a zoonotic pathogen associated primarily with avian chlamydiosis. New chlamydial agents with suspected zoonotic potential were recently detected from domestic poultry in Germany and France indicating that the spectrum of Chlamydiaceae encountered in birds is not confined to a single chlamydial species. For further characterization, a specific real-time PCR targeting the conserved 16S rRNA gene was developed and validated for a specific detection of these atypical Chlamydiaceae. In order to address the epidemiological importance of the new chlamydial agents and their distribution, Chlamydiaceae-positive chicken samples collected from flocks from five different countries were examined. The results confirmed that C.psittaci is not the predominant chlamydial species among chickens examined and suggested that the new chlamydial agents could putatively be widespread in poultry flocks (France, Greece, Croatia, Slovenia and China at least) justifying their systematic investigation when poultry samples are submitted to laboratories for avian chlamydiosis diagnosis. Besides, 16S rRNA-based dendrogram, including sequences from both isolates of the new chlamydial agents or positive samples as well as representative sequences from species belonging to the order Chlamydiales, showed the new chlamydial agents to form a distinct line of descent separated from those of other chlamydial species, but clearly grouped within the family Chlamydiaceae. Finally, the phylogenetic tree inferred from the multi-locus sequence typing based on four housekeeping fragments (gatA, gidA, enoA and hflX) and the ompA-based dendrogram showed an almost identical topology of the new chlamydial agents with that recovered by 16S rRNA-based dendrogram. Interestingly, partial ompA gene sequences displayed considerable diversity among isolates.
    Environmental Microbiology 06/2012; 14(8):2212-22. · 5.76 Impact Factor
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    ABSTRACT: Faecal and vomit samples were collected from 12 griffon vultures (Gyps fulvus) in May 2002 and examined for bacteria, fungi and parasites. Bacteria present included Escherichia coli, Aeromonas salmonicidia, Proteus sp., Escherichia fergusonii, Providencia alcalifaciens, Micrococcus sp. and Streptococcus sp. Mycological examination revealed the presence of Candida sp., yeasts and in one case, Rhodotorula rubra. Strongyle eggs were found in several samples. In most faecal samples, ascarid eggs of Toxocara type were found. Tapeworm eggs of Moniezia type were present in one faecal sample. Both microbiologic and parasitic findings are most likely the result of the feeding habits of griffon vultures.
    European Journal of Wildlife Research 01/2009; 55(1):71-74. · 1.36 Impact Factor
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    ABSTRACT: The objective of four trials performed on specific-pathogen-free and commercial chickens, either of light or heavy hybrids, was to evaluate the new vaccine delivery method to newly hatched chickens using commercial La Sota vaccine. The vaccine was given by means of nebulization using an ultrasonic device producing homologous aerosol of particles ranging 3-5 microns in diameter. Chickens were exposed to the La Sota vaccine for 30, 60 or 300 s in a closed chamber of the device, thus enabling constant particle size during vaccination. No adverse reaction to the given vaccine was recorded, and the immunity, developed no later than 7 days after vaccination, lasted for at least 49 days which was confirmed by challenge infection using Herts 33 strain of Newcastle disease virus. Maternal antibodies did not influence the development of immunity. Regarding the mode of vaccination, the described method is suitable for the control of Newcastle disease in both big poultry enterprises as well as small backyard flocks when newly hatched chickens are supplied from local hatcheries. Ultrasonic nebulizer, chicks, vaccination, La Sota strain, immune response, Newcastle disease Newcastle disease (ND) still remains a serious poultry health problem, causing mortality and therefore economic loss. Appearance of virulent ND viruses (vNDV)
    Acta Veterinaria Brno - ACTA VET BRNO. 01/2009; 78(1):137-144.
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    ABSTRACT: Feral pigeons (Columba livia domestica), which thrive in most European towns and cities, are commonly infected with the zoonotic bacterium Chlamydophila psittaci, the agent of psittacosis (also known as ornithosis) in humans. A number of surveys carried out over the last thirty years across Europe have detected high seropositivity values and high percentages of infection in feral pigeon populations. Overall, when considering data from 11 European countries, seropositivity values to C. psittaci in the sampled populations ranged from 19.4% to 95.6%. In most surveys, the complement fixation test was used, and antibodies were detected in 19.4-66.3% of the samples, with a median of 46.1%. Indirect immunofluorescence and ELISA tests were employed less frequently, but led to the detection of higher percentages of seropositivity (23.7-67.7% and 35.9-95.6%, respectively). Attempts to grow C. psittaci in cell culture or embryonated chicken eggs were successful in 2-42.3% and 0-57.1% of samples, respectively, antigen detection methods were positive in 2.3-40% of samples, while conventional PCR and real-time PCR using different genomic targets detected the organism in 3.4-50% of samples. Twenty-five C. psittaci isolates from pigeons were typed as ompA genotype B (n=14), E (n=10) and E/B (n=1). The huge increase of feral pigeon populations in Europe is a major cause of concern for the detrimental effect of pigeon droppings on environmental hygiene, in addition to the extensive damage due to the fouling of buildings and monuments. The most important pathogenic organism transmissible from feral pigeons to humans is C. psittaci, with 101 cases of disease reported in the literature. Exposure to C. psittaci-contaminated dust, direct contact with pigeons through handling and, to a lesser extent, through pigeon feeding have been identified as hazardous exposures in more than half of the human cases, while loose or transient contacts with feral pigeons have been mentioned in about 40% of the cases. Education initiatives as to the communication of a health risk resulting from contact with pigeons and pigeon excreta should primarily be targeted at individuals who may be exposed to C. psittaci-contaminated dust, such as demolition/construction workers. Recommendations to this category of workers include wearing protective clothes with hoods, boots, gloves and air filter face masks when removing pigeon faeces from roofs, garrets and buildings, especially if working indoors. Monitoring for C. psittaci infections in these workers over time should also be considered. Children should be warned not to handle sick or dead pigeons, and immunocompromised individuals should be advised to carefully limit their contact to feral pigeons. Culling of pigeons by shooting or poisoning is both unethical and ineffective as the place of the killed birds in the population is quickly filled by new juveniles or immigrating birds from neighbouring areas. Pigeon-deterring systems, such as nets and plastic or metal spikes applied to buildings and monuments will prevent their fouling, and the administration of contraceptive drugs may allow size regulation of the pigeon populations. Nevertheless, the measure that will ultimately lead to permanent reduction and will establish healthy sustainable populations is the restriction of indiscriminate feeding by pigeon lovers. The erection of dovecotes and artificial breeding facilities should be considered for providing shelter and a balanced diet to the birds, as well as a chance of interaction for pigeon lovers in a hygienically controlled environment.
    Veterinary Microbiology 10/2008; 135(1-2):54-67. · 3.13 Impact Factor
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    ABSTRACT: In the last 3 yr, several outbreaks of avian poxviruses (APVs) have been observed in different parts of Croatia. Four strains of APVs, from chickens, a pigeon, and a turkey, were isolated from cutaneous lesions by inoculation onto the chorioallantoic membranes (CAM) of 12-day-old specific-pathogen-free chicken embryos. The resulting proliferative CAM lesions contained eosinophilic cytoplasmic inclusion bodies. The characteristic viral particles of poxvirus were detected in the infected CAM and also in the infected tissues by transmission electron microscopy. Further identification and differentiation of the four various APVs were carried out by the use of a polymerase chain reaction (PCR) combined with restriction enzyme analysis. Using one primer set, which framed a region within the APV 4b core protein gene, it was possible to detect APV-specific DNA from all four tested isolates. PCR results revealed no recognizable differences in size of amplified fragments between the different APVs from chickens, turkey, and pigeon. Restriction enzyme analysis of PCR products using NlaIII showed the same cleavage pattern for turkey and chicken isolates and a different one for the pigeon isolate. Multiplex PCR for direct detection of APV and reticuloendotheliosis virus (REV) was carried out to determine the possible integration of REV in the genome of isolated APVs. The obtained results revealed that REV was present in chicken and turkey strains of poxviruses, whereas the pigeon isolate was negative. It is not known whether the avipoxvirus vaccine strain used in Croatia is contaminated with REV or if the REV is naturally contaminating Croatian field strains of fowl poxvirus. The latter is indicated by the negative REV finding in the pigeon, which was not vaccinated. The results of the present study indicate the reemergence of fowlpox in Croatia, where infections have not been recorded since 1963 and never confirmed etiologically.
    Avian Diseases 10/2006; 50(3):440-4. · 1.73 Impact Factor
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    ABSTRACT: During 2003, 278 adult pigeons (Columba livia) and 54 birds of 11 other free-living species were caught in the various locations in the City of Zagreb, Croatia. Sera from 182 pigeons were tested for the presence of antibodies against Chlamydophila (C.) psittaci by ELISA test and 174 of them (95.6%) were found positive. Because of the high positivity rate in sera, cloacal swabs of 278 pigeons as well as 54 other species of free-living birds were tested for the presence of C. psittaci antigen. Fourty-four of the 278 pigeons (15.83%) were antigen positive, whereas all 54 of the wild birds were negative. Antigen-positive pigeons were euthanised and examined pathomorphologically and cytologically. Findings of specific antibodies and antigen of C. psittaci confirmed the high rate of infection among urban pigeons in the City of Zagreb, fortunately not among other free-living birds. Although the pigeon serovars of C. psittaci are considered to be of moderate pathogenicity for humans, the identification of 15.8% antigen-positive birds represents a potential source of infection to humans, especially for elderly people and immunodeficient patients, as well as for poultry in the Zagreb city area.
    Veterinary Research Communications 04/2005; 29 Suppl 1:17-21. · 1.08 Impact Factor
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    ABSTRACT: Newcastle disease (ND) epizootics in some European countries after the World War II were caused by ND virus (NDV) of multiple genotypes (IV-VIIa) occurring sequentially and/or simultaneously. This study was carried out to characterise the genetic composition of NDV strains during the outbreaks in the territory of the former Yugoslavia in order to enhance our understanding of the relationships of past epizootics in Europe. Sixty-eight NDV strains isolated between 1979 and 2002 were analysed by restriction enzyme digestion and partial sequencing of the fusion protein gene. All isolates were placed in genotype V, an exotic type, that was introduced to western Europe in 1970. Residue substitution analysis has allowed the recognition of four genetic variants, Vb1-Vb4, and the tracing of their movements. Vb1, a dominant variant in Bulgaria from the late 1970s, was also wide spread in the former Yugoslavia throughout the period under investigation. Vb2, a variant occurring in the neighbouring countries in the early 1970s could be the founder of the epidemic in Yugoslavia and it was present up to the late 1980s. Variants Vb3 and Vb4 could be found only after 1987. In conclusion, the ND outbreaks in Yugoslavia were part of the epizootic wave due to genotype V viruses that started in western Europe in 1970 and became endemic in the region. Inter-country transmission occurred for all variants, and Vb3 and Vb4 might have evolved during the endemic period.
    Veterinary Microbiology 08/2003; 94(4):269-81. · 3.13 Impact Factor
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    ABSTRACT: Chickens were fed diets having optimal, high, and low levels of calcium for 42 days. Serum samples were collected at 14, 28 and 42 days of age, and serum calcium and haemagglutination inhibition titres for Newcastle disease virus were measured. The chickens were vaccinated at 14 days for Newcastle disease. Antibody titres were significantly increased by high dietary calcium and depressed by low dietary calcium. Mean titre was 2.5 (log2) for the optimal diet, 3.2 for the high-calcium diet, and 1.6 for the low-calcium diet. Antibody titres were dependent on serum calcium concentration (r2 = 0.98 at 14 days, 0.99 at 28 days, and 0.78 at 42 days).
    Acta Veterinaria Hungarica 02/2000; 48(1):43-50. · 1.17 Impact Factor
  • Estella Prukner-Radovčić, K. Čuljak, B. Šoštarić, H. Mazija, R. Sabočanec
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    ABSTRACT: Single infections or even epizootic forms of tuberculosis are common in birds of zoological gardens and game birds in farms as well. They cause economic damage, and the most important of them,Mycobacterium avium, can cause nearly fatal disease in humans. In this article, an epidemic of tuberculosis in pheasants raised on a farm has been described. The disease appeared in a breeding flock of 800 females and 140 males. Clinically affected birds expressed depression, anorexia and loss of weight. The mortality rate was 1–5 birds per day. Blood samples taken from 20 randomly chosen pheasants were agglutinated by use of avian tuberculin, and all were positive. Pathomorphological examination of carcasses of already dead or killed moribund pheasants revealed creamy nodules, mostly in the intestine, liver and spleen, varying in size from miliary to several centimetres in diameter. Pathohistological finding can be described asTuberculosis nodularis partim nodosa et coligranuloma. The colonies that grew on selective nutrient media were identified asMycobacterium sp., most probablyM. avium-intracellulare complex. Based on the findings described, all birds of the farm were killed, the most severely affected carcasses burned and all of them buried near the farm.A recommendation was given to start constant monitoring of game birds as well as zoo birds, primarily to prevent infection in humans and free living birds.Einzelflle von Tuberkulose oder sogar ihre epizootische Form sind bei Vgeln in den zoologischen Grten und beim Federwild auf den Farmen sehr hufig. Es entstehen wirtschaftliche Schden und das wichtigste jedoch ist, da dasMycobacterium avium bei Menschen eine fatale Krankheit verursachen kann. In dieser Arbeit ist die enzootische Form der Tuberkulose bei Fasanen in Farmzucht beschrieben.Die Krankheit ist in einer Zuchtpopulation von 800 weiblichen und 140 mnnlichen Tieren ausgebrochen. Klinisch kranke Vgel zeigten Depression, Anorektie und Magersucht. Es starben ein bis fnf Vgel tglich. Die Blutproben von 20 auf Verdacht ausgesuchten Fasanen wurden mit avirem Tuberkulin agglutiniert und alle waren positiv. Die patho-morphologische Untersuchung von Kadavern oder von erkrankten getteten Fasanen zeigte gelbe Kntchen, hauptschlich an Darm, Leber und Milz mit unterschiedlicher Gre von miliaren bis einige Zentimeter Durchmesser. Den pathologischen Befund kann man alsTuberculosis nodularis partim nodosa et coligranuloma beschreiben.Die bakteriellen Kolonien auf den Nhrbden wurden alsMycobacterium avium sp., am wahrscheinlichsten als komplexM. avium-intracellulare identifiziert. Aufgrund des beschriebenen Befundes wurde die gesamte Vogel-Population geopfert und verbrannt oder in der Farmnhe vergraben.Es wurde eine Empfehlung ausgesprochen, die zur Einleitung einer umfassenden berwachung des gesamten Federwildes wie auch der Vgel in zoologischen Grten fhren soll. Dies soll eine Seuchenbertragung auf den Menschen und auf die Vgel in deren Naturlebensrumen verhindern.Des cas isols de Tuberculose, ou encore sous leur forme pizootique, sont trs frquents dans les jardins zoologiques ainsi que chez le gibier-plume de fermes d'levage. Il en rsulte, certes, des pertes conomiques mais ce qui est plus grave, c'est queMyobacterium avium peut causer une maladie mortelle chez l'homme. Dans la prsente tude, on dcrit l'expression enzootique de la Tuberculose chez des faisans vivant dans une ferme d'levage.La maladie a fait son apparition dans un levage constitu de 800 poules et de 140 coqs. Cliniquement, les oiseaux malades montraient des symptmes de dpression et d'anorexie. De un cinq oiseaux mouraient chaque jour. Les chantillons de sang prlevs sur 20 sujets suspects furent soumis un test d'agglutination et se rvlrent tous positifs. L'tude patho-morphologique de cadavres ou de sujets malades achevs montrait, principalement dans l'intestin, dans le foie et dans la rate, des nodules jaunes de taille variant de quelques millimtres quelques centimtres de diamtre. Le diagnostic pathologique peut s'noncer comme correspondant uneTuberculosis nodularis partim nodosa et coligranuloma.Les colonies bactrielles provenant de sols voisins ont t identifies comme tantMyobacterium avium sp., et trs vraisemblablement comme un complexe deM. avium-intracellulare. Suite ces constats, la totalit des oiseaux a t sacrifie, brle ou enterre dans une ferme vosine.On formule une recommandation qui devrait se traduire par un contrle gnralis de tout le gibier-plume de mme que des oiseaux vivant dans des jardins zoologiques. Ceci devrait empcher la transmission de l'pidmie l'homme et aux oiseaux dans leur habitat naturel.
    Zeitschrift f ur Jagdwissenschaft 02/1998; 44(1):33-39.
  • Estella Prukner-Radovčić, K. Čuljak, B. Šoštarić, H. Mazija, R. Sabočanec
    Zeitschrift Fur Jagdwissenschaft - Z JAGDWISS. 01/1998; 44(1):33-39.
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    ABSTRACT: Three groups of Hybro broiler chickens, of which one group were controls, a second treated intragastrically with histamine, and a third stressed by immersion in water, were used in the experiment. Serum activities of aspartate and alanine aminotransferase and creatine kinase were evaluated. Gizzard erosion length, body weight during fattening, slaughter-house or final body weight, food consumption and antibody titre after vaccination for Newcastle disease were also measured. Stress induced severe gizzard erosion and decreased body weight, especially in male birds, whilst both stressed and histamine-treated groups of chicks had decreased antibody titres that were especially pronounced in the stressed animals. Food consumption and aspartate aminotransferase and creatine kinase activities were increased in the stressed chicks.
    Avian Pathology 06/1996; 25(2):359-67. · 1.73 Impact Factor
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    ABSTRACT: The bacterium Clostridium chauvoei causes disease in certain animals, most frequently in cattle and sheep. It occurs rarely in pigs, while equines and poultry appear to be resistant to infection. Two cases are presented in which C. chauvoei was isolated from disease of complex aetiology in hens. In Case I, 15-week-old light hybrid chickens were affected with chronic respiratory disease, coccidiosis, ascariasis and inflammation of the skin on the head, with necrosis of the comb. Growth was uneven and mortality reached 24%. Clostridium chauvoei was isolated from two of three combs examined. In Case II a flock of broiler breeders aged 11 weeks developed coccidiosis and, owing to disease or death, 60% were excluded from production. Clostridium chauvoei was isolated from all of 10 livers examined. These results demonstrate that C. chauvoei can infect chickens and that its possible role as a pathogen under certain circumstances should be further investigated.
    Avian Pathology 03/1995; 24(1):201-6. · 1.73 Impact Factor
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