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

A bacterium with growth characteristics similar to, but genetically distinct from, either Legionella pneumophila or WIGA (a "rickettsia-like agent") was obtained from a postmortem lung specimen of a patient with fatal atypical pneumonia at the M. D. Anderson Hospital and Tumor Institute in Houston, Texas. This bacterium and WIGA have essentially the same cellular fatty acid composition, which is distinct from that of L. pneumophila. Deoxyribonucleic acid-reletadness studies show that the isolate from Texas is only about 10% related to both L. pneumophila and WIGA and there fore may represent a new species. This new bacterium should be considered in selecting laboratory procedures in the diagnosis of atypical pneumonia.
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PMID:A newly identified bacterium phenotypically resembling, but genetically distinct from, Legionella pneumophila: an isolate in a case of pneumonia. 39 Nov 15

Over a two year period, we studied prospectively 80 cases of diffuse pneumonia at Memorial Sloan-Kettering Cancer Center. In 72 per cent of these, the patient had leukemia or lymphoma. Diagnostic procedures consisted of extensive serologic testing for antibody to known respiratory pathogens, including the agent of Legionnaire's disease, and culturing of biopsy specimens for bacteria, viruses, mycoplasmas and fungi. Of 44 cases in which open lung biopsy was performed, a specific cause was found in 61.4 per cent: Pneumocystis carinii in 38.6 per cent, other infections in 9.1 per cent and tumor involvement in 13.7 per cent. There were nonspecific pulmonary changes in 38.6 per cent. Of the 56 cases in which biopsy, autopsy or both were performed, a specific diagnosis was made in 69.7 per cent: P. carinii infection in 37.5 per cent and other infections in 12.5 per cent. In cases in which neither biopsy nor autopsy was performed, a specific infection was diagnosed in 33 per cent; no specific diagnosis was made in the remainder. One patient in the entire group had a significant antibody titer for Legionnaire's disease. Although diagnostic in some cases, extensive serologic testing proved relatively unfruitful. Pneumocystosis was the most frequent diagnosis in this study. The cause of some cases remained obscure, even after lung biopsy.
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PMID:Diffuse pulmonary infiltrates in immunosuppressed patients. Prospective study of 80 cases. 42 Feb 37

Previous reports have suggested a role for natural killer (NK) cells in directly lysing host cells infected with bacteria and other intracellular microorganisms. Here, we determined the inability of a highly homogeneous population of lymphokine activated killer (LAK) cells to kill macrophages infected with the following intracellular parasites: Mycobacterium avium, Listeria monocytogenes, Legionella pneumophila, Toxoplasma gondii, and Trypanosoma cruzi. In parallel cytotoxicity assays, LAK cells lysed the tumor targets YAC-1 and P815 effectively. Furthermore, we were able to demonstrate that influenza-specific cytotoxic T lymphocytes (CTL), but not LAK cells, were efficient killers of influenza virus-infected macrophages.
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PMID:A homogeneous population of lymphokine-activated killer (LAK) cells is incapable of killing virus-, bacteria-, or parasite-infected macrophages. 210 76

L. pneumophila is a facultative intracellular opportunistic pathogen ubiquitously present in the environment. Much is now known concerning the ecological niche of this organism as well as many other characteristics of these bacteria, including physiology and biochemistry. However, much less is known about immune mechanisms responsible for host resistance vs susceptibility. Not only outer membrane protein rich fractions but also LPS-rich components are potent immunogens, both in experimental animals such as susceptible guinea pigs and more resistant rodent species like rats and mice. Immunity to these organisms can be readily observed by a variety of serologic techniques. Antibody titers increase rapidly after exposure of individuals to these bacteria either by infection or immunization. However, such antibody does not appear to play an important role in host resistance. Serum antibody plus complement is not lytic for the bacteria in vitro. Furthermore, antibody appears to promote the phagocytosis of the bacteria by monocytes and/or macrophages in culture but such phagocytosis does not result in killing of the bacteria, merely an enhanced uptake and subsequent replication of the organisms. Studies on cellular immunity have focused attention on the role of T lymphocytes, monocytes and macrophages. In addition, cutaneous hypersensitivity is readily induced by infection or immunization of experimental animals with Legionella or antigenic components. In vitro correlates of hypersensitivity is also readily evident after infection or immunization. Although lymphoid cells from guinea pigs only show evidence of responsiveness to Legionella antigens by the lymphocyte blastogenic reaction after animals have been sensitized, peripheral blood monocytes from man as well as splenocytes from mice show evidence of responsiveness to Legionella even before known infection or sensitization. However, higher blastogenic responses become evident after sensitization or infection. In addition, interleukins, such as interleukin 1 and 2, as well as interferon and tumor necrotizing factor, appear in response to Legionella antigens and seem to play a role in resistance mechanisms. Cellular replication of Legionella in monocytes from man as well as macrophages from susceptible animals seems related to susceptibility or resistance to these organisms. Further analyses of the nature and mechanism of humoral vs cellular immune responses to Legionella antigens will provide valuable information about immunity and resistance to these intracellular pathogens in susceptible individuals.
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PMID:Legionella pneumophila immunity and immunomodulation: nature and mechanisms. 305 72

Legionella pneumophila has been shown to induce gamma interferon (IFN-gamma) both in vitro and in vivo during experimental infections of mice. With complement-mediated serologic depletion of murine splenocytes, the cellular sources of IFN-gamma following in vitro stimulation with L. pneumophila antigens were Thy-1.2+, Lyt-2-, L3T4-, and asialo-GM1+, which is consistent with the natural killer (NK) cell phenotype. Additionally, Percoll density discontinuous centrifugation demonstrated that maximal production of IFN coincided with high NK activity in fractions which were enriched for large granular lymphocytes. Furthermore, 18- to 24-h incubation of splenocytes with L. pneumophila whole-cell vaccine resulted in augmented NK cytotoxic activity against YAC-1 tumor target cells in a 51Cr release assay. The addition of macrophages to purified large granular lymphocyte populations augmented both IFN-gamma production and NK activity, suggesting that antigen is required for optimal responses. In an experimental infection model using an intratracheal inoculation route, NK activity was enhanced in the spleen, peripheral blood, and lung cells of infected mice, with maximal stimulation in the lung leukocytes at the site of infection. The results of the present study indicate that NK cells respond in vivo and in vitro to stimulation by L. pneumophila by producing IFN-gamma and by increased cytolytic activity.
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PMID:Role of gamma interferon in induction of natural killer activity by Legionella pneumophila in vitro and in an experimental murine infection model. 312 79

The present study was an in vitro attempt to define the effector mechanisms against the intracellular bacterium Legionella pneumophila. Monocytes from human peripheral blood leukocytes (PBL) were infected in vitro with L. pneumophila and cultured for 2 days to allow intracellular replication of the bacterium. Cells were then labeled with 51Cr and used as targets in a 4-h 51Cr-release assay. We report here that autologous nonadherent PBL effectively lysed infected monocytes, and this activity was enhanced when the effector cells were precultured with IL 2 for 2 days. The IL 2-activated killer cells were also cytolytic against uninfected cultured monocytes, but cytotoxicity was higher against Legionella-infected target cells in a dose-dependent manner. The effector cells were located in Percoll density fractions that were enriched for large granular lymphocytes. The phenotype of the effector cell activated by IL 2 was determined to be OKM1+, OKT11+, partially Leu-11+, and negative for Leu-M1, OKT4, OKT8, and Leu-7, indicating that it is neither a T cell nor a monocyte, and is possibly and NK subset that is Leu-11+ and Leu-7-. Cold target inhibition studies indicated that a similar recognition structure is shared by both infected and uninfected monocytes, but differs from that on K562 tumor target cells. Thus, in addition to tumor surveillance and controlling viral infections, killer cells can be activated to provide protection against intracellular bacterial infections.
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PMID:Cytolytic activity of human peripheral blood leukocytes against Legionella pneumophila-infected monocytes: characterization of the effector cell and augmentation by interleukin 2. 349 84

In a clinical demonstration, case reports on 3 patients are presented: 1. In a 27-year-old male who developed severe multicentric atypical pneumonia, CNS, liver and renal involvement and signs of rhabdomyolyses suggested infection with Legionella pneumophila. Diagnosis was confirmed by the presence of Dieterle-stain positive organisms and positive culture of lung biopsy tissue. Antibiotic treatment, especially erythromycin, and prolonged mechanical respiration produced complete recovery. 2. The presence of chylomycrons Rin ascitic and pleural fluid in a patient with epimembranous glomerulonephritis and nephrotic syndrome was the first sign of malignant non-Hodgkin lymphoma. Chemotherapy with cyclophosphamid, oncovin and prednisone induced remission of tumor and nephrotic syndrome, which promptly recurred parallel to later reactivation of the malignancy. Paraneoplastically induced nephrotic syndrome, especially due to lymphoma, may precede the malignancy by months. 3. In a 52-year-old male with terminal renal failure due to primary oxalosis a cadaver renal transplant functioned for only 14 months because of oxalate deposits in the transplant. Hemodialysis before and after transplantation modified the clinical course. In place of uremia, the clinical picture was dominated by oxalate-induced gangrenous arteriopathy, arthritis, and heart disease.
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PMID:[Clinical demonstrations. Legionnaires' disease. Tumor-associated nephrotic syndrome. Primary oxalosis]. 703 33

The authors report on their institution's experience with 53 lung biopsies, including 26 open, 22 transbronchial, and five trephine air drill biopsies, performed in immunocompromised patients with roentgenographic pulmonary infiltrates. Open biopsy was far more likely to provide a specific etiologic diagnosis (81%, P less than 0.001) than transbronchial biopsy (32%), or trephine biopsy (20%). Infection (17 biopsies), neoplastic disease, (7) or drug-related pneumonitis (2) were identified most frequently. Patients with myeloproliferative disease, granulocytopenia, or those who had not received prior immunosuppressive therapy were most likely to have a nondiagnostic biopsy (P less than 0.05 for each factor). The overall complication rate of biopsy procedures was 15% and was comparable with all three methods. Survival in this series was not significantly lower if a specific etiologic diagnosis could not be established, but correlated with the respiratory rate (less than 20 per minute), pO2 (greater than 60 torr), and the roentgenographic pattern (other than bilateral diffuse disease) at the time of biopsy (P less than 0.05 for each factor). There were 18 cases (34%) in which a clearcut etiologic diagnosis would not be established at the time of biopsy; based on serologic tests performed ex post facto, 2 of 12 of these cases (17%) were Legionnaire's disease. Lung biopsies were helpful in the management of the majority of the cases, although nondiagnostic biopsies continue to be a problem. The authors propose an approach to the management of compromised patients with pulmonary infiltrates.
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PMID:Lung biopsy in immunocompromised patients: one institution's experience and an approach to management of pulmonary disease in the compromised host. 727 48

Familiarity with the natural history of common pneumonias is obligatory for the clinician to determine whether a specific case of pneumonia is resolving at the expected rate. To many clinicians, the term slowly resolving pneumonia conjures an association with underlying neoplasm and/or less common pathogens. In reality, host factors or common pathogens such as Streptococcus pneumoniae and Legionella pneumophila are more likely responsible for delayed resolution. Familiarity with the pattern of resolution of pneumonias caused by these organisms should allow the clinician to follow such patients and avoid premature invasive evaluation. In contrast, Mycoplasma pneumoniae and Chlamydia species rarely result in slowly resolving pneumonia. Chronic bacterial pneumonia is an infectious syndrome that may present in the absence of systemic symptoms. The presentation is varied and may mimic neoplasm, interstitial lung disease, or chronic fungal or mycobacterial infection. Bacteria most commonly associated with chronic pneumonia include Haemophilus influenzae, Staphylococcus aureus, alpha-hemolytic streptococci (not S pneumoniae), and Pseudomonas aeruginosa.
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PMID:Infectious diseases that result in slowly resolving and chronic pneumonia. 837 74

We initiated a prospective study with a group of practitioners to assess the etiology, clinical presentation, and outcome of community-acquired pneumonia in patients diagnosed in the outpatient setting. All patients with signs and symptoms suggestive of pneumonia and an infiltrate on chest X-ray underwent an extensive standard workup and were followed over 4 weeks. Over a 4-year period, 184 patients were eligible, of whom 170 (age range, 15-96 yr; median, 43 yr) were included and analyzed. In 78 (46%), no etiologic agent could be demonstrated. In the remaining 92 patients, 107 etiologic agents were implicated: 43 were due to "pyogenic" bacteria (39 Streptococcus pneumoniae, 3 Haemophilus spp., 1 Streptococcus spp.), 39 were due to "atypical" bacteria (24 Mycoplasma pneumoniae, 9 Chlamydia pneumoniae, 4 Coxiella burnetii, 2 Legionella spp.), and 25 were due to viruses (20 influenza viruses and 5 other respiratory viruses). There were only a few statistically significant clinical differences between the different etiologic categories (higher age and comorbidities in viral or in episodes of undetermined etiology, higher neutrophil counts in "pyogenic" episodes, more frequent bilateral and interstitial infiltrates in viral episodes). There were 2 deaths, both in patients with advanced age (83 and 86 years old), and several comorbidities. Only 14 patients (8.2%) required hospitalization. In 6 patients (3.4%), the pneumonia episode uncovered a local neoplasia. This study shows that most cases of community-acquired pneumonia have a favorable outcome and can be successfully managed in an outpatient setting. Moreover, in the absence of rapid and reliable clinical or laboratory tests to establish a definite etiologic diagnosis at presentation, the spectrum of the etiologic agents suggest that initial antibiotic therapy should cover both S. pneumoniae and atypical bacteria, as well as possible influenza viruses during the epidemic season.
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PMID:Community-acquired pneumonia. A prospective outpatient study. 1130 90


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