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Query: UMLS:C0023241 (Legionella)
 6,990 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In addition to providing a powerful approach for identifying bacterial factors required for full infectivity and disease production, genetic analysis of Legionella pathogenesis should also lend critical insight into the biology of the macrophage and into the pathogenesis of other intracellular parasites. The interaction between L. pneumophila and the macrophage exhibits many features found in a wide variety of prokaryotic and eukaryotic intracellular human pathogens. For example, binding to complement receptors has been shown to occur for Mycobacterium tuberculosis, M. leprae, Leishmania donovani, Leishmania major and Histoplasma capsulatum. Coiling phagocytosis has been observed during entry of L. donovani. Phagosomes that contain Toxoplasma gondii or M. tuberculosis fail to fuse with lysosomes and, in the case of T. gondii, have been shown to remain close to neutral pH. Although the molecular bases for these phenomena are unknown, their functional similarities to the L. pneumophila-macrophage interaction provide optimism that generally applicable principles are involved. The genetic techniques reviewed here will provide the molecular tools with which such questions of a general biologic nature can be framed and eventually answered. Together with more traditional methods in biochemistry, microbiology and cell biology, molecular genetics offers a robust means toward identifying and understanding the bacterial factors involved in the pathogenesis of Legionnaires' disease. Molecular studies of L. pneumophila can also help address questions concerning the epidemiology, diagnosis and prevention of disease. For example, the distribution of virulence factors might help explain and predict the attack rates of different L. pneumophila strains or Legionella species. Moreover, bacterial genes/factors that are shown to be conserved in Legionella strains could be used to develop such diagnostic tools as DNA probes. Novel types of vaccines consisting of genetically constructed, avirulent L. pneumophila strains or subunit vaccines based on the molecular characterization of virulence factors might be developed and tested as protective immunogens. In this way, the capacity to analyze and to manipulate L. pneumophila genetically may facilitate the use of Legionnaires' disease as a model infection for studying protective cell-mediated immunity. Apart from its clinical significance as the etiologic agent of Legionnaires' disease, L. pneumophila may be a key to broader understandings in microbial pathogenesis and human cell biology and immunology. Although the extremely complex processes of bacterial infection and virulence are best understood when a variety of experimental approaches are employed, we believe that the evolving molecular genetic techniques reviewed here will be critical elements in many important breakthroughs in the future.
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PMID:Genetics and molecular pathogenesis of Legionella pneumophila, an intracellular parasite of macrophages. 269 60

The objective of this study was to assess whether bacterial infection stimulates oxygen consumption and brown adipose tissue (BAT) activity. Guinea pigs infected with Legionella pneumophila showed marked fever and a significant (33%) increase in resting oxygen consumption (VO2), 24h after infection. At this time, food intake and body weight were normal and the in vitro thermogenic activity of BAT taken from infected animals was elevated by 64% above that of control guinea pigs. VO2 and BAT activity fell to control values by 48h as infected animals became moribund and over this period food intake was markedly reduced.
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PMID:Bacterial infection (Legionella pneumophila) stimulates fever, metabolic rate and brown adipose tissue activity in the guinea pig. 277 Apr 24

Four patients developed legionnaires' disease after bone marrow transplantation. Two cases occurred early after transplant and were considered as part of a hospital epidemic due to contamination of water supply. The other two cases were considered to be sporadic because they occurred 3-4 weeks after hospital discharge. The outcome was good in two patients. In the third patient, recurrent disease was probably due to acquired resistance to macrolides, and complete cure was achieved after treatment with pefloxacin and rifampicin. The fourth patient died of overwhelming infection despite early treatment with erythromycin and pefloxacin. During the same period we treated 14 patients with pefloxacin for prevention of bacterial infection, of whom none developed Legionella pneumophila infection, while three of the patients reported here were in a group of 11 patients who received only oral non-absorbable antibiotics for gut decontamination. The fourth patient in this report was receiving no antibiotics. Thus pefloxacin seems to be effective as prophylaxis against L. pneumophila infection. When the hospital water supply was heated to 60 degrees C and chlorinated, the nosocomial cases in the hospital completely disappeared.
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PMID:Legionnaires' disease after bone marrow transplantation. 333 77

The primary manifestation of the immunodeficiencies is undue susceptibility to infection. This means too many, too severe, too prolonged, too complicated and too unusual infections. Infections in immunodeficiency have a characteristic cause depending on the nature of the immune deficiency. Antibody deficiencies are associated with infections with gram-positive infections. Cellular immune deficiencies are associated with mycobacterial, protozoan, fungus, virus, and opportunistic bacterial infection. Phagocytic disorders are associated with staphylococcal, fungal, and gram-negative organisms. Complement disorders are associated by neisserial infections. Infections have also been implicated in the pathogenesis of some immunodeficiencies in some circumstances. These include human T lymphotropic virus type III (HTLV-III), rubella virus, cytomegalovirus, and Epstein-Barr virus. Several infectious syndromes in specific immunodeficiencies have been identified. Examples include enteric cytopathic human orphan (ECHO) virus encephalitis in agammaglobulinemia, and meningococcal meningitis in C6 deficiency. Infections can also be induced by live vaccines given in immunodeficiency (e.g., paralytic polio in agammaglobulinemia.) Unusual infectious syndromes will be illustrated including parainfluenza infection in severe combined and immunodeficiency, Legionella pneumonia in chronic granulomatous disease, and Cryptosporidium infection in hyper-IgM immunodeficiency.
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PMID:Infectious complications of the primary immunodeficiencies. 352 71

Sixty-four episodes of bacterial infection were identified over a 44-month period in 16 of 28 patients with the acquired immune deficiency syndrome (AIDS) and 14 of 31 patients with AIDS-related complex. Nineteen of the 30 infected patients were parenteral drug abusers, 10 were from Caribbean Islands and had no identified risk factor, and one was a homosexual male. Fourteen patients had 21 episodes of community-acquired pneumonia: Streptococcus pneumoniae (10), Haemophilus influenzae (three), other Haemophilus species (three), group B beta-hemolytic streptococci (one), Staphylococcus aureus (one), Branhamella catarrhalis (one), Legionella pneumophila (one), and Mycoplasma pneumoniae (one). Seven patients had eight episodes of nosocomial pneumonia caused by gram-negative bacilli. Twenty-five episodes of community-acquired bacteremia and nine episodes of nosocomial bacteremia were associated with specific sites of infection. Other infections included meningitis (two), urinary tract infection (one), and abscesses involving subcutaneous and deep tissues (12). Sixteen patients had recurrent infections; 11 of these had or eventually had AIDS. Community-acquired bacterial infections in patients with AIDS or AIDS-related complex are common and may be recurrent but have low fatality rates. In comparison, nosocomial bacterial infections occur primarily in patients with AIDS and have high fatality rates.
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PMID:Bacterial infections in adult patients with the acquired immune deficiency syndrome (AIDS) and AIDS-related complex. 357 59

Bacterial infection in the adult respiratory distress syndrome (ARDS) is associated with the occurrence of multiple organ failures and death. We studied 108 infections in 129 patients with ARDS and evaluated the organisms responsible, the body sites involved, and the outcomes of therapy. Gram-negative bacilli represented 57% of the microbial pathogens and gram-positive cocci 36%. Only 7% of infections were caused by other organisms (fungi, viruses, Pneumocystis, Legionella). Gram-negative organisms were more common in the lung, abdomen, and pleura. Bacteremia was more common in abdominal infections (11 of 17, 67%) than in infections at other sites (18 of 65, 28%), (p less than 0.01); ;9 patients were bacteremic from clinically undetected sites. Ten of 17 (59%) patients with abdominal infections survived compared with 7 of 56 (13%) patients with lung infections (p less than 0.001). A retrospective review of in vitro organism susceptibility and the antibiotics administered revealed that the patients who received adequate antibiotic therapy did not have a higher survival rate (20 of 69, 29%) than those who received inadequate antibiotic therapy (3 of 13, 23%). These data suggest that further investigation of infections in patients with ARDS is required and that emphasis should be placed on pathogenesis, prevention, and host responses.
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PMID:Incidence, site, and outcome of infections in patients with the adult respiratory distress syndrome. 375 10

The incidence of infection in the renal transplant patient is directly related to the net immunosuppressive effect achieved and the duration of time over which this therapy is administered. A second major factor in the causation of infections in this population is the nosocomial hazards to which these patients are exposed, ranging from invasive instrumentation to environmental contamination with Aspergillus species, Legionella pneumophila, Pseudomonas aeruginosa and other microbial pathogens. Careful surveillance is necessary to identify and eliminate such nosocomial sources of infection. The major types of infection observed can be categorized according to the time period post-transplant in which they occur: postsurgical bacterial infection in the first month after transplantation; opportunistic infection, with cytomegalovirus playing a major role, and transplant pyelonephritis in the period one to four months post-transplant; and a mixture of conventional and opportunistic infections in the last post-transplant period. Conventional infection in this late period occurs primarily in patients with good renal function who are receiving minimal immunosuppressive therapy; opportunistic infection occurs primarily in patients with poor renal function who are receiving higher levels of immunosuppression.
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PMID:Infection in the renal transplant recipient. 625 32

Legionella pneumophila infections frequently manifest themselves as a multisystem disease with acute pneumonia. Certain clinical and laboratory features are helpful in diagnosis but none are pathognomonic. Diagnosis frequently must be made clinically and erythromycin given presumptively because of the delay in seroconversion but culture and direct fluorescent antibody testing are quite useful for rapid diagnosis. Epidemiologic and laboratory investigations will undoubtedly yield considerable information about this fascinating bacterial disease.
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PMID:Legionnaires' disease. 699 7

Legionnaires disease, which is commonly manifested as pneumonia, was only recently recognized to be a bacterial infection. Diagnosis can be difficult because Gram's stain does not readily stain the bacterium in pulmonary secretions, the organism is not readily cultured, and legionellae is not affected by many commonly used antibiotics. In a retrospective review of all of our transplant patients, we identified 14 cases of Legionnaires' disease after 101 renal transplants. The patients characteristically had high fever, polymorphonuclear leukocytosis, dyspnea and an unproductive cough accompanied by radiographic changes of consolidating pneumonia. Legionnaires' disease can be diagnosed by direct immunofluorescent antibody staining, culture on special media or increases in serum titers of legionella antibodies in surviving patients. Since the recognition of Legionnaires' disease in 1977, we have successfully treated seven renal transplant patients using erythromycin with or without rifampin.
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PMID:Legionnaires' disease in renal transplant patients. 701 9

Specific etiologic diagnosis in ventilator-associated pneumonia is critical to optimal patient care, and a wide array of microbiologic procedures are available to aid in diagnosis. In bacterial infection, direct stains, particularly the Gram stain, provide rapid presumptive information, and cultures provide definitive identification. Specimen selection is critical; endotracheal or ordinary bronchoscopic aspirates provide nonspecific information, and quantitative analysis of protected specimen brushes or bronchoalveolar lavage provides more accuracy. Specialized procedures for other groups of organisms, such as Chlamydia, Legionella, mycobacteria, fungi, and viruses, also may be indicated in some cases.
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PMID:Microbiologic diagnosis of ventilator-associated pneumonia. 834 72


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