X-Band local area weather radar--preliminary calibration results.

DHI has developed a cost-effective X-Band Local Area Weather Radar (LAWR) with a typical range (radius) of 60 km, 500 x 500 m areal resolution and 253 reflection levels. The development is performed in a co-operation with a number of European partners, including Danish Meteorological Institute. The specifications of the weather radar and preliminary results from the calibration are presented. Good calibration results have been obtained using high-resolution rain gauges.

Geographical variation in the presence of genes encoding superantigenic exotoxins and beta-hemolysin among Staphylococcus aureus isolated from bovine mastitis in Europe and USA.

The object was to examine the geographical variation in the presence of superantigenic exotoxins and beta-hemolysin among epidemiologically independent Staphylococcus aureus isolates from bovine mastitis. A total of 462 S. aureus isolates from nine European countries and USA were examined for the presence of genes encoding staphylococcal enterotoxins A-E, and H, toxic shock toxin-1 (TSST-1), and beta-hemolysin, and 128 of these were examined for exfoliative toxins A and B. The detection was done by PCR. Phenotypic methods were used to confirm the PCR-results. None of the 128 isolates carried the genes for exfoliative toxin A or B. The total proportion of isolates in which superantigenic exotoxins were detected varied from 2% (one isolate) of the Danish isolates to 65% (32 isolates) of the Norwegian isolates. This marked and highly significant geographical variation was also present for the individual exotoxins. The genes encoding enterotoxin C, TSST-1, and enterotoxin D were the most common superantigens. The present and earlier studies demonstrate that the superantigenic exotoxins that were investigated in this study, do not play a role in the pathogenesis of bovine S. aureus mastitis. In contrast to the geographical variation among superantigenic exotoxins, 97% of the isolates were PCR-positive for and/or produced beta-hemolysin on 5% calf blood agar. Except for three isolates, the Norwegian isolates were PCR-negative, but positive on 5% calf blood agar. Sequence variation in the primer regions in the beta-hemolysin encoding gene of the Norwegian isolates is suggested, and should be investigated further. The consistent presence of beta-hemolysin suggests that this factor, or a co-existing gene correlated to beta-hemolysin, may be an active virulence factor in the pathogenesis of bovine S. aureus mastitis.

Radar based rainfall forecast for sewage systems control.

There has been an increasing demand for accurate rainfall forecast in urban areas from the water industry. Current forecasting systems provided mainly by meteorological offices are based on large-scale prediction and are not well suited for this application. In order to devise a system especially designed for the dynamic management of a sewerage system the "RADAR" project was launched. The idea of this project was to provide a short-term small-scale prediction of rain based on radar images. The prediction methodology combines two methods. An extrapolation method based on a sophisticated cross correlation of images is optimised by a neural network technique. Three different application sites in Europe have been used to validate the system.

Differences between Danish bovine and human Staphylococcus aureus isolates in possession of superantigens.

PCR-assays for the detection of staphylococcal enterotoxins A-E, and H, toxic shock toxin 1, and exfoliative toxins A and B were evaluated against phenotypic methods, and performed well. Four hundred and fourteen isolates of Staphylococcus aureus from Danish cases of bovine mastitis were screened for genes encoding these superantigens. One hundred isolates from Danish human carriers were also included in the study. In contrast to the frequent presence of genes encoding and in vitro expression of superantigens among the human carrier isolates, only one of 414 isolates from bovine mastitis carried the genes encoding enterotoxin C and toxic shock toxin-1. These results further support the hypothesis that the bovine and human S. aureus reservoirs constitute two separate sub-populations of the species S. aureus. The results also show that these superantigens are generally not present in Danish S. aureus isolates from bovine mastitis, and thus play no essential role in the pathogenesis of bovine S. aureus mastitis.

Abscess disease, caseous lymphadenitis, and pulmonary adenomatosis in imported sheep.

The occurrence of abscess disease, caseous lymphadenitis, and pulmonary adenomatosis in sheep in Denmark is reported for the first time. Subcutaneous abscesses were observed in imported 4- to 5-month-old lambs of the Lacaune breed 10 days after arrival in Denmark. Abscesses were mostly located in the head, neck and shoulder regions close to the regional lymph nodes. Bacteriological examinations revealed growth of Staphylococcus aureus ssp. anaerobius in all animals with subcutaneously located abscesses containing a viscous white-yellow odourless mass. In addition, Corynebacterium pseudotuberculosis was isolated from abscesses in one animal and lesions consistent with pulmonary adenomatosis were found in four animals.

The dynamics of Staphylococcus aureus intramammary infection in nine Danish dairy herds.

The aim of the present study was to examine the diversity of Staphylococcus aureus isolates from bovine intramammary infections (IMI) in nine dairy herds, and compare these with isolates from other sites on the cows by phage- and ribotyping. Whether colonisation of milkers with S. aureus could be a source of infection for bovine IMI was investigated. In addition, 100 epidemiologically unrelated S. aureus isolates from asymptomatic human carriers were also phage- and ribotyped to compare the human and bovine reservoir of S. aureus in Denmark. A total of 625 S. aureus isolates from bovine IMI, bovine skin lesions, milking personnel, and non-farm-related human carriers were included in the study. Certain types predominated in one or several herds during the study period of one-and-a-half to two years, whereas the presence of other types was of a more sporadic nature. Within the individual herds, there was a close correspondence between ribo- and phage types of S. aureus isolated from bovine intramammary infections and skin lesions. Isolates from milking personnel, however, were not identical to any of the predominant intramammary strains. Furthermore, several of the isolates from milking personnel showed ribo- and phage patterns identical to S. aureus isolates from human carriers. The findings of the present study underline the importance of strict milking hygiene and improvement of current mastitis therapy. The results support the hypothesis that some S. aureus mastitis strains are more contagious, virulent or persistent than others. The human reservoir of S. aureus does not play a major role as a source of bovine intramammary infections.

Initial lung lesions in two calves experimentally infected with Haemophilus somnus.

The initial lung lesions in two calves intrabronchially inoculated with Haemophilus somnus are described. The animals were euthanized within 7 h after challenge. The in situ location of H. somnus and accompanying lesions were examined by light microscopy, immunohistochemistry and transmission electron microscopy (TEM). Inoculation with H. somnus resulted in the development of acute pulmonary lesions within 3.5 h. H. somnus antigen was demonstrated only within the luminal spaces of the airways and in one area of bronchio-associated lymphoid tissue (BALT). As observed by TEM, the bacteria were phagocytized by both neutrophils and alveolar macrophages. Antigen was never demonstrated in the pulmonary intravascular macrophages.

The need for a veterinary antibiotic policy.

The international recognition of the 'stable to table' approach to food safety emphasises the need for appropriate and safe use of antibiotics in animal production. An appropriate use of antibiotics for food animals will preserve the long-term efficacy of existing antibiotics, support animal health and welfare and limit the risk of transfer of antibiotic resistance to humans. Furthermore, it may promote consumer confidence in the veterinary use of antibiotics. In advancing these arguments, the authors of this article argue that there is a need for a visible and operational policy for veterinary use of antibiotics, paying particular attention to the policies that are being developed in Denmark.

The pharmacodynamic effect of amoxycillin and danofloxacin against Actinobacillus pleuropneumoniae in an in-vitro pharmacodynamic model.

The pharmacodynamic effect of amoxycillin and danofloxacin against two strains of Actinobacillus pleuropneumoniae was evaluated in an in-vitro pharmacodynamic model. For amoxycillin peak concentrations of 0.5, 1, and 4 microg ml(-1)and half-lives of 3 and 15 hours were examined. For danofloxacin peak concentrations of 0.125, 0.5, and 1. 5 microg ml(-1)and half-lives of 1.5 and 7 hours were evaluated. The initial bactericidal effect was measured as the reduction in colony count (log CFU ml(-1)) during the first three hours, and the overall pharmacodynamic effect as the area under the bacterial growth versus time curve (AUBC). The initial bactericidal effect of amoxycillin was maximal at peak concentrations of two to four times the MIC. Peak concentration and half-life only influenced the pharmacodynamic effect of amoxycillin if the antibiotic concentration fell below the MIC during the experiments, which is consistent with time >MIC as the most important parameter of pharmacodynamic effect of beta-lactam drugs. For danofloxacin maximal bactericidal effect initially was observed at peak concentrations of at least eight times the MIC. The pharmacodynamic effect was dependent on the peak concentration. The half-life only influenced the pharmacodynamic effect of danofloxacin in experiments with a peak concentration MIC ratio of less than eight. This indicated that for danofloxacin the peak concentration was the major determinant of pharmacodynamic effect.

Experimental infection of pregnant cows with Bacillus licheniformis bacteria.

To study the abortifacient potential and fetoplacental tropism of Bacillus licheniformis bacteria, eight cows in the sixth to eighth month of gestation were inoculated intravenously either once (n = 4) or on four successive days (n = 4) with B. licheniformis at doses ranging from 10(9) to 10(12) colony-forming units. Cows were euthanatized and necropsied prior to abortion (n = 2), at the time of abortion (n = 2), or at calving (n = 4). Live-born calves (n = 5) were euthanatized immediately after delivery and necropsied. B. licheniformis was reisolated from placentomes/endometrium in six of eight (75%) cows and from one fetus aborted 43 days after inoculation. Lesions associated with B. licheniformis were restricted to the pregnant uterus, with the exception of one cow, which developed pneumonia. Necrosis in the fetal compartment of the placenta were present in three of four (75%) cows of both inoculation groups. Lesions were mainly restricted to fetal membranes and especially to the fetal side of the placentomes. Necrosis and diffuse neutrophil infiltrations of both villi and intervillous areas occurred in the fetal part of the placenta, and the placentomal interface was distended by bacteria, neutrophils, erythrocytes, and debris. Within trophoblasts, bacteria were located both free in the cytoplasm and in cytoplasmatic vesicles. Inflammation was present in three of eight (38%) calves. Placental and fetal lesions were similar to those found in cases of spontaneous abortions associated with B. licheniformis. The abortifacient potential of B. licheniformis and the tropism for the bovine placenta is demonstrated here for the first time.

Characterization of Staphylococcus simulans strains isolated from cases of bovine mastitis.

This study was conducted to characterize Staphylococcus simulans isolated from cases of bovine mastitis. A total of 134 isolates of S. simulans selected from 80 quarters from 61 cows or heifers in 37 different herds were characterized by EcoRI ribotyping. From 22 quarters two to seven consecutive isolates taken at weekly intervals were selected. Furthermore, three isolates from clinical infections in humans and two reference strains were included. A total of 16 different ribotypes were found, however, two types predominated. In most herds more than one type was found. From the 22 different quarters, where 76 paired or multiple isolates were at disposal, the same ribotype was constantly found in the same quarter. This study showed that S. simulans causing bovine mastitis could be divided into relatively large number of different types, but that two types predominated. More than one type could be found in the same herd and within different quarters of the same cow, but ribotyping confirmed that S. simulans could be the cause of persistent and stable infections.

Frequency of alpha- and beta-haemolysin in Staphylococcus aureus of bovine and human origin. A comparison between pheno- and genotype and variation in phenotypic expression.

The phenotypic expression of haemolysins and the presence of genes encoding alpha and beta-haemolysin were determined in 105 Staphylococcus aureus isolates from bovine mastitis, 100 isolates from the nostrils of healthy humans, and 60 isolates from septicaemia in humans. Furthermore, the possible change in expression of haemolysins after subcultivation in human and bovine blood and milk was studied in selected isolates. Alpha-haemolysin was expressed phenotypically in 39 (37%) of the bovine isolates, in 59 (59%) of the human carrier isolates, and in 40 (67%) of the isolates from septicaemia. Beta-haemolysin was expressed in 76 (72%) bovine, 11 (11%) carrier, and 8 (13%) septicaemia isolates. Significantly more bovine than human isolates expressed beta-haemolysin and significantly fewer expressed alpha-haemolysin. Genotypically, the gene encoding alpha-haemolysin was detected in all isolates. A significant difference in the prevalence of the gene encoding beta-haemolysin between the bovine (96%), human carrier (56%) and isolates from septicaemia (57%) was found. Of the bovine isolates, 75% of those carrying the gene encoding beta-haemolysin expressed beta-haemolysin phenotypically, whereas only 20% of the carrier isolates and 24% of the septicaemia isolates did so. No change in expression of haemolysins could be observed after subcultivation of bovine isolates in human blood and milk. After 5 to 10 subcultures in bovine blood and 1 to 4 in bovine milk, 9 of 10 human isolates originally phenotypically beta-haemolysin negative initiated the expression of beta-haemolysin. This study showed that a larger proportion of S. aureus of bovine origin carry the beta-haemolysin gene compared to isolates from humans. Furthermore, a larger number of the isolates of bovine origin carrying the beta-haemolysin gene express this gene phenotypically compared to isolates of human origin.

Susceptibility testing of Actinobacillus pleuropneumoniae in Denmark. Evaluation of three different media of MIC-determinations and tablet diffusion tests.

This study was conducted to compare the applicability of three different media in sensitivity testing of Actinobacillus pleuropneumoniae by means of MIC and tablet diffusion tests. The media used were: modified PPLO agar, chocolatized Mueller-Hinton-II and Columbia agar supplemented with NAD. Seven antimicrobial agents were tested: ceftiofur, enrofloxacin, penicillin, spectinomycin, tiamulin, trimethoprim + sulfadiazine and tylosin, against 40 randomly selected A. pleuropneumoniae isolates. In general, good agreement was found between results obtained with all combinations of media, most antimicrobials tested and the two-test systems. Some variations between media were observed for spectinomycin, tiamulin and tylosin. For ceftiofur and trimethoprim + sulfadiazine some isolates with low MIC-values were classified as resistant using tablet diffusion, indicating that the break points of resistance for these antimicrobials using the tablet diffusion tests need adjustment. Using current break points for resistance with MIC-determinations, all isolates tested susceptible to ceftiofur, enrofloxacin, penicillin, tiamulin and trimethoprim + sulfadiazine. A larger number of isolates tested resistant to spectinomycin and tylosin on all three media using both MIC determinations and tablet diffusion.

Associations of Streptococcus suis serotype 2 ribotype profiles with clinical disease and antimicrobial resistance.

A total of 122 Streptococcus suis serotype 2 strains were characterized thoroughly by comparing clinical and pathological observations, ribotype profiles, and antimicrobial resistance. Twenty-one different ribotype profiles were found and compared by cluster analysis, resulting in the identification of three ribotype clusters. A total of 58% of all strains investigated were of two ribotypes belonging to different ribotype clusters. A remarkable relationship existed between the observed ribotype profiles and the clinical-pathological observations because strains of one of the two dominant ribotypes were almost exclusively isolated from pigs with meningitis, while strains of the other dominant ribotype were never associated with meningitis. This second ribotype was isolated only from pigs with pneumonia, endocarditis, pericarditis, or septicemia. Cluster analysis revealed that strains belonging to the same ribotype cluster as one of the dominant ribotypes came from pigs that showed clinical signs similar to those of pigs infected with strains with the respective dominant ribotype profiles. Furthermore, strains belonging to different ribotype clusters had totally different patterns of resistance to antibiotics because strains isolated from pigs with meningitis were resistant to sulfamethazoxazole and strains isolated from pigs with pneumonia, endocarditis, pericarditis, or septicemia were resistant to tetracycline.

Design of a system for monitoring antimicrobial resistance in pathogenic, zoonotic and indicator bacteria from food animals.

DANMAP is a Danish programme for integrated monitoring of and research on antimicrobial resistance in bacteria from food animals, food and humans. The paper describes how bacteria from broilers, pigs, and cattle are collected, as well as the procedures for data handling and presentation of results. The bacteria from animals include certain pathogens, selected so that they are representative for submissions to Danish diagnostic laboratories, as well as zoonotic bacteria (Campylobacter, Salmonella and Yersinia) and indicator bacteria (E. coli, E. faecium and E. faecalis), from samples collected at abattoirs. The latter samples are selected so that they are representative of the respective animal populations. Therefore, the apparent prevalence of antimicrobial resistance in the populations may be calculated. The isolates are identified to species level and the results of susceptibility testing are stored as continuous variables. All isolates are maintained in a strain collection so that they are available for subsequent research projects. The data handling facilities makes it possible to present results as percent resistant isolates or as the apparent prevalence of resistance in the population, or alternatively as graphical distributions of mm inhibition zones or MIC values. Computer routines have been established that make it possible to detect specific phenotypic expressions of resistance that may be of particular interest.

Pathological and microbiological studies on pneumonic lungs from Danish calves.

During 1 year, the association between microbiological and pathological findings in 72 lungs from calves submitted to the Danish Veterinary Laboratory for diagnostic purposes was studied. All cases were evaluated pathologically and bacteriologically, whereas only 68 cases were examined for the presence of bovine respiratory syncytial virus (BRSV), parainfluenza-3 virus (PI-3 virus) and bovine coronavirus, 62 cases for bovine viral diarrhoea virus (BVD), 45 cases for bovine adenovirus and 51 cases for mycoplasmas. Based on histopathological examination, the cases were diagnosed as fibrinous and/or necrotizing bronchopneumonia, suppurative bronchopneumonia, embolic pneumonia and others. The diagnoses were based on the dominating and most severe lesions in each lung. Haemophilus somnus, Pasteurella multocida, Actinomyces pyogenes, P. haemolytica and BRSV were the most commonly found bacterial and viral lung pathogens, respectively. Pasteurella spp. and H. somnus were often associated with the more severe fibrinonecrotizing type of bronchopneumonia, whereas BRSV was primarily detected in cases of suppurative bronchopneumonia. Mycoplasma bovis was isolated from one case only, whereas M. dispar, M. bovirhinis and Ureaplasma diversum were present, often concomitantly, in the majority of cases. Aspergillus fumigatus was isolated from one case.

Diagnosis of enzootic pneumonia in Danish cattle: reverse transcription-polymerase chain reaction assay for detection of bovine respiratory syncytial virus in naturally and experimentally infected cattle.

A reverse transcription-polymerase chain reaction (RT-PCR) assay was developed for detection of bovine respiratory syncytial virus (BRSV) in lung tissue of naturally and experimentally infected cattle. Primers were selected from the gene coding the F fusion protein, which is relatively conserved among BRSV isolates. The RT-PCR assay was highly specific, it yielded positive reactions only when performed on BRSV-infected cell cultures or tissues. The detection limit of the RT-PCR assay was assessed as 5 TCID50. BRSV was detected in tissues of the respiratory tract and in the tracheobroncheal lymph node of calves euthanized 2-8 days after experimental infection with BRSV, whereas samples of other tissues and samples from mock-infected animals were negative at all time points. Examination of lung samples from 8 different regions of the lungs revealed that although the virus was most often found in the cranioventral lobules, it was frequently present in all lung lobules. Microbiologic examinations of all acute fatal cases of pneumonia (135 animals) in cattle submitted for diagnostic purposes during 1 year revealed that Actinomyces pyogenes (11%), Haemophilus somnus (10%), Pasteurella sp. (7%), and Pasteurella haemolytica (7%) were the most common bacterial agents found in the lungs. BRSV was identified using a conventional antigen enzyme-linked immunosorbent assay (ELISA) in 23 (17%) animals. The established BRSV-specific RT-PCR assay yielded positive results for the same 23 animals. In addition, 10 animals that were negative with the ELISA were positive with the RT-PCR assay. These results indicates that the RT-PCR assay can be a sensitive, reliable alternative to conventional diagnostic procedures.

Development of penicillin resistance among Staphylococcus aureus isolated from bovine mastitis in Denmark and other countries.

This review gathers the published information regarding penicillin resistance among Staphylococcus aureus isolated from bovine mastitis from 43 different countries worldwide. For selected countries, trends over time are shown. The occurrence of resistance in the different countries is discussed in relation to the potential value of penicillin for therapy.

Trends in the resistance to antimicrobial agents of Streptococcus suis isolates from Denmark and Sweden.

This study was conducted to determine the MIC values of historical and contemporary Streptoccocus suis (serotypes 2 and 7) from Denmark and S. suis (serotype 2) from Sweden. A total of 52 isolates originating from 1967 through 1981 and 156 isolates from 1992 through 1997 in Denmark and 13 isolates from Sweden were examined for their MICs against 20 different antimicrobial agents. Most antimicrobials were active against most isolates. A frequent occurrence of resistance to sulphamethoxazole was observed, with most resistance among historic isolates of serotype 7 and least resistance among isolates from Sweden. A large number of the isolates was resistant to macrolides. However, all historic serotype 2 isolates from Denmark were susceptible, whereas 20.4% of the contemporary isolates were resistant. Among serotype 7 isolates 23.3% of the historic isolates were resistant to macrolides, whereas resistance was found in 44.8% of the contemporary isolates. All isolates from Sweden were susceptible to macrolides. Time-associated frequency of resistance to tetracycline was also found. Only a single historic isolate of serotype 2 was resistant to tetracycline, whereas 43.9% of the contemporary serotype 2 isolates and 15.5% of the contemporary serotype 7 isolates were resistant. Only one (7.7%) of the isolates from Sweden was resistant. The differences in resistance between historic and contemporary isolates from Denmark were statistically significant. This study demonstrated a significant serotype-associated difference in the susceptibility to macrolides and tetracycline and demonstrated that an increase in resistance among S. suis isolates has taken place during the last 15 years to the two most commonly used antimicrobial agents (tylosin and tetracycline) in pig production in Denmark.