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Query: UMLS:C0026936 (Mycoplasma)
 14,761 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The variations in the incidence of Mycoplasma pneumoniae infections in Denmark over a period of 17 years could be demonstrated in the central serological laboratory which serves the whole of the population. This observation was made possible for the first and major part of this study by testing cold agglutinin (CA) positive sera, which had been kept frozen sine 1958, for antibodies to M.pneumoniae. The second part of the study is based upon results from routine tests for CA and M.pneumoniae antibodies on all samples which we receive. A statistical analysis of the total material indicates that four epidemics of M.pneumoniae antibodies on all samples which we receive. A statistical analysis of the total material indicates that four epidemics of M.pneumoniae infection had taken place from January 1958 to December 1974 and that these epidemics occurred at regular four and a half year intervals. By a follow-up of the study a fifth epidemic was demonstrated during the first eight months of 1975 which broke the regular periodicity by appearing two years earlier than expected. The consequences of including only CA positive sera in this study was investigated. Antibodies to M.pneumoniae were measured by either an indirect immunofluorescence test, an indirect haemagglutination test or a complement fixation test. The observed difference in sensitivity of these tests is discussed in relationship to a possible influence on the overall incidence.
Infection 1976
PMID:The incidence of Mycoplasma pneumoniae infections in Denmark over the past seventeen years: a review. 78 46

Organ cultures of ciliated tracheal epithelium derived from various animal species have been used to study several different mycoplasma infections. Human and hamster tracheal cultures have been used in particular to study Mycoplasma pneumoniae which, of all the human mycoplasmas, is the only one which damages the cultures. One reason for this is the capacity of the virulent organisms to attach to the cells; strains which are prevented from attaching or have lost this capacity do not damage the cultures. The organ culture system is therefore valuable in looking at the organisms-cell relationship but it is necessary to use animal models to study immunological processes. Hamsters, and more recently guinea pigs, have been used in this respect. The hamster model has been used to study the pathogenesis of M. pneumoniae pneumonia and also recovery from and resistance to infection. Humoral immune mechanisms seem more important than cell-mediated mechanisms in resistance, and the probable importance of local immunity is discussed. It is pointed out that it should be possible to establish the mechanisms underlying the development of M. pneumoniae sequelae where conditions, similar to those seen in man, occur in animals. Finally, the way in which the hamster model has been used to study the effect of tetracycline and erythromycin on the course of disease is discussed. As in man, therapy often improves the pneumonia but does not eradicate the organisms. This is probably due, at least in part, to the fact that the antibiotics are only mycoplasmastatic. Drugs with mycoplasmacidal properties are needed and the animal model would obviously prove helpful in evaluating these.
Infection 1976
PMID:The use of organ cultures and animal models in the study of Mycoplasma pneumoniae infections. 78 47

The incidence of respiratory tract infections in patients seeking medical advice at a community care centre (Dalby) during 1973 and 1974 was studied. About every third patient seen at this primary health station presented with signs of such infections. In the age groups less than 10, 10-19, 20-39, 40-59 and greater than or equal to 60 years, respiratory tract infections accounted for 65, 45, 32, 18 and 9% of the fotal number of diagnoses made during 1974. The aetiology of acute respiratory tract infections in a series of patients seen at this health station was studied. The series included randomly selected cases, but excluded children under seven years of age and patients presenting with signs of acute otitis media and tonsillitis. Attempts to establish the aetiology were made on the basis of the history, the clinical examination, and cultures for beta-haemolytic streptococci and Mycoplasma pneumoniae, complement foxation tests for influenza A and B, para-influenza 1, 2, and 3, adeno, cytomegalovirus and respiratory syncytial virus, and Chlamydia psittaci. Paul-Bunnell test and tests for cold agglutinins were also performed. With this test battery, an aetiological diagnosis was obtained in only 33% of the 101 patients studied. The findings suggest an infection with M.pneumoniae in 16%, with beta-haemolytic streptococci in 9%, and with viruses (adeno and para-influenza) in 7% of the patients. The present communication highlights the role of M.pneumoniae in upper respiratory infections, as few data have appeared on such infections in patients seen in general practice. The difficulty of establishing the aetiology of respiratory tract infections and the consequent treatment dilemma is discussed.
Infection 1976
PMID:The incidence and aetiology of respiratory tract infections in general practice--with emphasis on Mycoplasma pneumoniae. 78 48

The pathogenicity of mycoplasmas is caused by several factors, e.g. exotoxin, toxic properties of membrane components, exoenzymes, peroxide, and immunological factors. The absence of a rigid cell wall and the small genome tend to influence the interactions between mycoplasmas and host tissue. Mycoplasmas do not have a cell wass and are therefore resistant to the action of the host's lysozymes. They appear in some patients to be immunologically inconspicuous and in other patients they have been reported to have an immuno-suppressive effect. Recently there have been reports of central nervous system disorders due to mycoplasma. The pathogenic factors involved in these reactions have not been elucidated. Other aspects of Mycoplasma pneumoniae pathogenicity are also discussed.
Infection 1976
PMID:Pathogenicity factors of mycoplasmas. 78 49

Knowledge of the pathogenesis of pneumonia due to Mycoplasma pneumoniae has been derived primarily from experimental infection of rodents. As part of an effort to establish a model with a closer resemblance to man, three seronegative, young, adult rhesus monkeys (Macaca mulatta) were inoculated with M. pneumoniae (10(7.4) cfu per animal) by oropharyngeal administration of coarse-particle aerosol. Five to six days after exposure of the animals, cultures obtained from the upper respiratory tract were positive for M. pneumoniae. Each animal subsequently developed a serologic response, as determined by complement fixation, complement-mediated killing, and tetrazolium-reduction inhibition techniques. Infection was subclinical, and serial chest roentgenograms failed to disclose pneumonia throughout the course of infection. Blood cell counts and titers of cold agglutinins remained unchanged. Althought M. pneumoniae was recovered from the upper respiratory tract of two monkeys for 50 days, there was no evidence of transmission of infection to cage-mate controls inoculated with broth.
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PMID:Experimental production of respiratory tract infection with Mycoplasma pneumoniae in rhesus monkeys. 81 46

The distribution of Mycoplasma pneumoniae infection in the respiratory tract and the extent of pulmonary pathology were determined by the site of deposition and the number of organisms administered to hamsters. Infection of the upper and lower areas of the respiratory tract occurred when organisms were introduced into both areas by small-particle aerosol (2.3 micrometer) or by intranasal (i.n.) instillation of a 200-microliter inoculum. In contrast, when organisms were delivered primarily to the upper respiratory tract by large-particle aerosol (8 micrometer) or by i.n. instillation of a small volume of inoculum (2 or 20 microliter), infection remained limited to this area in most or all instances. When the lungs became infected after i.n. administration of a 200-microliter inoculum, the most extensive pulmonary lesions were seen in the animals given the largest number of organisms. Each of the modes of administration of M. pneumoniae initiated an infection which conferred measurable resistance to a subsequent challenge capable of inducing extensive pulmonary disease. The most effective resistance was induced by the two modes of administration which produced an infection involving the entire respiratory tract, i.e., small-particle aerosol or i.n. instillation of a 200-microliter inoculum.
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PMID:Immunoprophylaxis of experimental Mycoplasma pneumoniae disease: effect of aerosol particle size and site of deposition of M. pneumoniae on the pattern of respiratory infection, disease, and immunity in hamsters. 87 19

Pathogenicity trials in poultry are reported with an isolate of mycoplasma, designated 'W8', which is serologically unrelated to Mycoplasma gallisepticum, M synoviae or M meleagridis. W8 killed fowl and turkey embryos when injected into the yold sacs of embryonating eggs. Infection of one-day-old fowls, turkeys and pheasants by the air sac route caused marked growth depression and a high incidence of osteomyelitis of the vertebral column in all species. A large proportion of infected turkeys and a smaller proportion of infected pheasants also developed chondrodystrophic changes of the long bones similar to those of turkey syndrome '65. Infection did not cause mortality or macroscopic air sacculitis. No obvious pathological changes occurred in fowls following W8 infection by the air sac route at two weeks of age and only minimal changes when infection was given at one week. Infection did not appear to spread to in-contact controls. W8 was recovered most frequently and in greatest profusion from the air sacs, tracheas, kidneys and vertebral columns of fowls and turkeys following air sac infection at one day of age.
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PMID:Pathogenicity studies in poultry with an undefined serotype of Mycoplasma. 93 70

In two separate experiments, broiler-type chickens were vaccinated at 11 days old with either the B-1 or LaSota strain of Newcastle disease virus (NDV) by aerosol, drinking water, or eyedrop and simultaneously infected with Mycoplasma synoviae (MS). The MS-infected and aerosol-vaccinated chickens had the highest mean lesion scores for airsacculitis. The aerosol-vaccinated groups had the highest hemagglutination-inhibition titers against NDV. Infection with MS had no effect on antibody titers against NDV, and there were no consistent effects on weight gains.
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PMID:Effect of route of Newcastle disease vaccination on the incidence of airsacculitis in chickens infected with Mycoplasma synoviae. 93 86

Six cases of miliary pneumonia are reported, in which the marked increase in antibody titers showed that Mycoplasma pneumoniae was the probable cause. The clinical picture of these patients showed an acute and severe onset, with the appearance of diffuse alveolitis. The outcome of the disease depended on the time of initiation of treatment in relationship to the onset of symptoms. One case was seen to progress to fibrosing alveolitis with persistent impairment of diffusion. This observation suggests the possibility that some cases of pulmonary fibrosis of unknown aetiology may be due to previous mycoplasmal infection.
Infection 1976
PMID:Miliary mycoplasmal pneumonia: a report of six cases. 95 95

The effect of Mycoplasma pneumoniae infection on cell-mediated immunity was examined by two methods: the first method was the tuberculin skin test and the other was the measurement of the in vitro lymphocyte stimulation response to purified protein derivative (PPD) of tuberculin. Twenty-nine patients out of a total of 47 patients with a lower respiratory tract illness caused by M. pneumoniae had a negative tuberculin skin test when first tested. Twenty-three out of 26 patients with a negative tuberculin reaction in the early phase of the illness had a positive skin test when they were retested several weeks or months after the illness. The lymphocyte stimulation response to PPD was examined in 13 patients. In eight of these cases the lymphocyte response to PPD was significantly lower during illness than after recovery. Six control subjects showed no significant difference in their lymphocyte responsiveness to PPD when examined on two different occasions. These studies show that M.pneumoniae infection causes transient depression of cell-mediated immunity.
Infection 1976
PMID:Effect of Mycoplasma pheumoniae infection on cell-mediated immunity. 95 96


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