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N F Friis

Publications and source records attributed to N F Friis.

At least 37 records · Page 2Linked to original sources
PubMed1998

Antimicrobial susceptibility testing of Mycoplasma hyosynoviae isolated from pigs during 1968 to 1971 and during 1995 and 1996.

This study was conducted to compare the Minimal Inhibitory Concentrations (MICs) for enrofloxacin, lincomycin, tetracycline, tiamulin and tylosin, of Mycoplasma hyosynoviae, isolated from pigs at notably different intervals (1968-71 and 1995-96). Each group comprised 21 low passage isolates and a Danish reference strain (M60) and the type strain (S16). MICs were determined in liquid medium with both initial and final readings. Enrofloxacin, lincomycin, tetracycline and tiamulin were active against all isolates, and tiamulin showed the highest activity. For tylosin all the isolates from 1968-71 were highly susceptible, whereas the isolates from 1995-96 could be divided into a highly susceptible (nine isolates) and relatively resistant (12 isolates) group. This difference between old and new strains was statistically significant (p = 0.0000415). The remaining agents, enrofloxacin, lincomycin, tiamulin and tetracycline, showed an unaltered good activity against M. hyosynoviae. The resistance to tylosin seems now to occur so often that this antibiotic cannot be recommended for therapeutic use any more. The most probable explanation for the emergence of resistance is the intensive use of tylosin during many years for therapy and growth promotion.

Animals↗
PubMed1997

Mycoplasma hyopneumoniae infection in pigs: duration of the disease and evaluation of four diagnostic assays.

200 SPF pigs were infected by aerosol with Mycoplasma hyopneumoniae and the development of clinical signs, serological and pathological reactions were studied. Mean time to onset of coughing was 13 days. A mean delay of 9 days was observed from onset of coughing until seroconversion against M. hyopneumoniae as measured by ELISA. At an individual level, the sensitivity for this ELISA was estimated to 98-100% and the specificity to 93-100%. Pasteurella multocida was isolated from the majority of the lungs 4 weeks post inoculation with M. hyopneumoniae and the lung lesions in pigs were significantly larger when P. multocida was present as compared to pigs with M. hyopneumoniae alone. An evaluation of cultivation, immunofluorescence, ELISA and polymerase chain reaction for demonstration of M. hyopneumoniae in lungs showed that all four methods have a high sensitivity in the acute stages of pneumonia. In the later stages the sensitivity of cultivation was superior to the other methods. No differences in specificity were observed between the methods. The antigen-ELISA OD values and the immunofluorescence scores revealed a strong positive correlation. Nasal swabs were additionally used for demonstration of M. hyopneumoniae and the polymerase chain reaction was found superior to the other methods.

Analysis of Variance↗
PubMed1997

Microbiology and pathology of fibrinous pericarditis in Danish slaughter pigs.

The prevalence of fibrinous pericarditis detected at slaughter in Danish slaughter pigs is approximately 0.02%. The microbiology and pathology of this disorder was studied through 46 field cases collected at slaughter from May 1994 to August 1995. Mycoplasmas (Mycoplasma hyopneumoniae, M. hyosynoviae and M. hyorhinis) were isolated from the pericardium in 38 cases and from the joints in six. M. Hyopneumoniae dominated with 33 isolates from the pericardium. Actinobacillus pleuropneumoniae was isolated from the pericardium in three cases (as mono-infection in one and together with M. hyopneumoniae in two cases) and Actinomyces pyogenes was isolated from the pericardium twice (as mono-infection in one case and together with M. hyopneumoniae in another). A. pyogenes was also present in the lung, liver and kidney in one of these cases. Streptococcus suis was isolated together with mycoplasmas from the pericardium in three cases. The pericardium was sterile in three cases and contained a low grade mixed flora in two; the latter is believed to be a result of the slaughter procedure rather than an infection. No chlamydiae were found in connection with the microbiological examination. Parvovirus was found in one case in the pericardium and in two cases in the spleen. Forty-five cases were subacute to chronic. The gross pathological examination showed that bronchopneumonia, chronic pleuritis and synovitis or a low grade arthritis occurred in most cases. Only the arthritic lesions are believed to be pathogenetically concurrent with the pericarditis. Slight evidence of stasis of the liver and/or periangiolar edema was present in six cases. The histopathological examination confirmed the above mentioned findings. Bacterial colonies were found within the fibrinous layer on the pericardium in all cases from which either A. pleuropneumoniae, A. pyogenes or S. suis was isolated. It is concluded that in this study mycoplasmas, particularly M. Hyopneumoniae, are the more likely cause of fibrinous pericarditis in slaughter pigs.

Animals↗
PubMed1996

Swine mycoplasmoses.

Mycoplasma hyopneumoniae is the primary agent of enzootic pneumonia in pigs. The lung lesions, generally observed in young pigs, are characterised by a hyperplasia of the epithelial cells and an increased perivascular and peribronchiolar accumulation of mononuclear cells. Following M. hyopneumoniae infection, immune reactions are observed and resistance is induced in pigs. Laboratory diagnosis is generally performed by an immunofluorescent test and by enzyme-linked immunosorbent assay. Antibiotics are useful but the development of resistance has been described. Vaccination seems to be an effective method of controlling the disease. M. hyorhinis, generally transmitted by sows to piglets through nasal secretions, exists in a high percentage in the respiratory tract of healthy pigs. But some strains can induce serofibrinous to fibrinopurulent polyserositis and arthritis. M. hyorhinis is isolated from acute and subacute phase lesions and serum antibodies are detectable. M. hyosynoviae has a special affinity for joint tissue and may cause arthritic disease, leading to economic losses. This mycoplasma is generally located in the tonsils. Piglets are infected by sows after four to six weeks of life. Evidence of disease occurs in animals of between 30 to 40 kg and 100 kg, and bursae and joints are affected. A non-suppurative viscous fluid of a serofibrinous/serosanguineous nature is reported. In chronic cases, the synovial membrane is affected. M. hyosynoviae is isolated from the joints and pharyngeal/tonsillar samples and can induce antibodies in blood and joint fluid. Predisposing factors play an important role. M. flocculare is widely distributed in swine, in normal and pneumonic lungs and in nasal cavities, but no pathogenic capability has been described. There is great interest in this mycoplasma because of the great similarity to M. hyopneumoniae.

Animals↗
PubMed1994

Sensitivity of certain porcine and bovine mycoplasmas to antimicrobial agents in a liquid medium test compared to a disc assay.

The sensitivity of some porcine and bovine mycoplasmas to potent antimicrobial agents was examined. Minimal inhibitory concentration (MIC) values were estimated for M. hyosynoviae, M. hyopneumoniae, M. dispar and M. bovis against enrofloxacin, lincomycin, tetracycline, tiamulin and tylosin, in a liquid medium test and in a disc assay. All 6 examined strains of each species and the respective type strains were significantly inhibited. The greatest sensitivity was noted for tiamulin against strains of M. hyosynoviae with a final MIC50 broth value of 0.025 micrograms ml-1 and disc value of 0.03 microgram per disc. Enrofloxacin was found very potent against M. hyopneumoniae with a final MIC50 of 0.025 microgram ml-1 and 0.1 microgram per disc, and for M. dispar with 0.05 microgram ml-1 and 0.03 microgram per disc. Most disc assay estimates in micrograms per disc were similar to or moderately greater than corresponding final broth figures in microgram ml-1. It may be possible to convert observed disc assay values into representative final broth MIC values for use in the clinic.

Animals↗
PubMed1994

Mycoplasma hyorhinis in the etiology of serositis among piglets.

In a study on the involvement of Mycoplasma hyorhinis in serositis of piglets, 26 routine diagnostic animals, 3-7 weeks old, with distinct serofibrinous lesions in the pericardial, pleural and peritoneal cavities were examined. M. hyorhinis was isolated in 9 cases, non-haemolytic Escherichia coli in another 9 cases and in 4 cases both species were found. Neither of the microorganisms were found in the remaining 4 cases. The presence of M. hyorhinis in the serous cavities in the absence of non-haemolytic E. coli was always accompanied by a diagnosis of other disease conditions, mainly of the respiratory tract. In the cases infected with non-haemolytic E. coli complicating problems were absent. The pathogenicity of M. hyorhinis was further studied by inoculation of 2 young pigs in which the typical serofibrinous lesions of the serous cavities were produced. It therefore appears that M. hyorhinis can be regarded as a cause of polyserositis in piglets; under field conditions, however, the synergistic presence of other debilitating syndromes appears necessary for its haematogenous spread from the respiratory tract to the serous cavities.

Animals↗
PubMed1992

A monoclonal blocking ELISA detecting serum antibodies to Mycoplasma hyopneumoniae.

A monoclonal blocking enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to Mycoplasma hyopneumoniae in porcine serum has been developed. The monoclonal antibody (mAb) reacts with an M. hyopneumoniae specific epitope on a molecule of approximately 74 kDa. Only sera from M. hyopneumoniae infected pigs were able to block the binding of the mAb although antibodies from M. flocculare infected pigs also recognized a 74 kDa molecule. Sera from experimentally infected pigs as well as field samples were compared by the ELISA and by an indirect hemagglutination assay (IHA). In experimental pigs, the earliest detectable antibody response was found to be almost identical for both assays, but for some of the pigs the time of detection was significantly earlier by blocking ELISA than by IHA. In naturally infected herds more samples were found to be positive by ELISA than by IHA. Furthermore, the results indicate that sera from naturally M. flocculare infected pigs may give rise to cross-reactions in the IHA. The blocking ELISA appears to be a valuable and reproducible tool in the surveillance and serodiagnosis of M. hyopneumoniae infections in pigs.

Animals↗
PubMed1992

Mycoplasma hyosynoviae in joints with arthritis in abattoir baconers.

The occurrence of Mycoplasma hyosynoviae in synovial fluid of baconers with chronic arthritis was studied at an abattoir. Cultural examination of synovial fluid samples from diseased tarsal joints of 50 animals from 42 herds yielded M. hyosynoviae in 10 cases from 8 herds. Streptococci were found in 6 cases from 6 other herds. M. hyosynoviae antigen was found in 1 of 47 of the samples, and antibody to the mycoplasma was found in 14 of 40 of the samples by ELISA test. The presence of M. hyosynoviae in a joint was usually accompanied by the corresponding antibody. In joints with streptococcal infection antibody to M. hyosynoviae could not be found.

Abattoirs↗
PubMed1991

Morphological and ultrastructural studies of Mycoplasma flocculare and Mycoplasma hyopneumoniae in vitro.

Cells of Mycoplasma flocculare were found to vary in size and shape, especially in the later phases of growth, whereas those of Mycoplasma hyopneumoniae were fairly uniform irrespective of growth phases. Filamentous cells were present in cultures of M flocculare in the stationary and declining phases, but were never found in cultures of M hyopneumoniae. The filamentous and bizarre forms observed when mycoplasmas were suspended in phosphotungstic acid probably result from the action of the hypotonic solution. The surface of all cells was covered by a fuzzy coat consisting of fine hairs or bristles. An electron-lucent region was usually seen in cells negatively stained after centrifugation, but was only occasionally seen in cells negatively stained directly from the medium. Intracytoplasmic membranes were present in sectioned cells. No attachment organelle was found in cells of either species.

Animals↗
PubMed1991

A field study of Mycoplasma bovis infection in cattle.

After an outbreak of mastitis in cattle caused by Mycoplasma bovis a study was made in 5 herds with recent cases (principal herds) and in 4 control herds. In the principal herds, M. bovis was isolated from milk samples, nasal swabs, and from one vaginal swab. M. bovis was also isolated from nasal swabs of calves in 2 of the 4 control herds, whereas all milk samples and vaginal swabs from the control herds were negative. Evaluation of serum antibody titres to M. bovis among non-mastitic animals of 3 principal herds and 1 control herd showed no difference in distribution of the titre values, which generally were low. However, cows excreting M. bovis in the milk had high antibody titres. The way of introduction to the herds and the spread of the infection within the herds could not be established by the study, which was supplemented by a DNA restriction fragment analysis of a number of M. bovis isolates.

Animals↗
PubMed1991

Identification of Mycoplasma hyopneumoniae with a DNA probe.

From a genomic library of Mycoplasma hyopneumoniae a 1.3 kb DNA fragment was cloned which showed specific Southern hybridization and dot hybridization with the type strain of several porcine and bovine Mycoplasma species. This probe selectively recognized M. hyopneumoniae sequences in purified DNA or in broth-grown organisms. The 35S-labelled probe could detect as little as 100 pg of DNA or 10(5) colour changing units. This is a possible alternative diagnostic procedure for enzootic pneumonia of pigs.

Animals↗
PubMed1991

Mycoplasma hyosynoviae isolation from the upper respiratory tract and tonsils of pigs.

The occurrence of Mycoplasma hyosynoviae at different locations of the upper respiratory tract and tonsils of pigs was investigated in herds with problems of arthritis apparently caused by this microorganism. The isolation of M. hyosynoviae was facilitated by the use of a medium selectively suppressing the growth of Mycoplasma hyorhinis. M. hyosynoviae was cultured from 106 of 178 tonsils of slaughterhouse pigs from 8 herds but could not be isolated from the mucosa of the nasal cavity or the oral-pharyngeal area of 100 living, 10-20 weeks old pigs in 5 of the herds. The value of the selective principles in the medium appears from the circumstance that 86 of the 106 isolates were obtained despite the presence of M. hyorhinis. It is concluded that the tonsil is a reservoir for M. hyosynoviae and is probably the location of choice for an easy demonstration of the presence of this mycoplasma in a pig herd.

Animals↗