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

Legionella is a common cause of community- and hospital-acquired pneumonia. New information on the pathogenesis of infection and the host immune response is reviewed. Specialized laboratory tests, especially culture, are necessary for diagnosis since the clinical presentation is nonspecific. New antimicrobial agents and innovative approaches to disinfection of water distribution systems are presented.
Infect Dis Clin North Am 1991 Sep
PMID:Legionellosis. 195

The genetic relatedness of Legionella longbeachae isolated in Australia since 1987 was investigated by restriction fragment length polymorphism (RFLP) analysis and allozyme electrophoresis. Three radiolabeled probes were used in Southern hybridizations for the RFLP studies. They were Escherichia coli 16S and 23S rRNA and cloned fragments of L. longbeachae selected empirically from genomal banks in lambda and a cosmid. The legionellae included in the study comprised 11 Legionella longbeachae serogroup 1 organisms isolated from humans, 28 L. longbeachae serogroup 1 isolates from environmental sources, and 3 L. longbeachae serogroup 2 environmental isolates. These were compared with the American Type Culture Collection reference strains of both serogroups and some other related Legionella species. Results of allozyme and RFLP analysis showed that all the isolates from humans and all but three of the environmental L. longbeachae serogroup 1 isolates were closely related. They were also closely related to L. longbeachae serogroup 1 ATCC 33462. There was wider variation among the three L. longbeachae serogroup 2 environmental isolates. One of these was closely related to L. longbeachae serogroup 2 ATCC 33484. RFLP studies with the rRNA probe provided the most discrimination among isolates but did not distinguish between the two serogroups.
Appl Environ Microbiol 1990 Sep
PMID:Genetic relatedness of Legionella longbeachae isolates from human and environmental sources in Australia. 198 Apr 3

Legionella anisa and the amoeba Hartmannella vermiformis were isolated from an indoor fountain implicated as the infectious reservoir in an outbreak of Pontiac fever. We evaluated the ability of this strain of L. anisa to multiply in cultures of an amoeba (H. vermiformis), a ciliated protozoan (Tetrahymena pyriformis), and human mononuclear cells and to infect guinea pigs. These bacteria multiplied in the culture of H. vermiformis but failed to infect guinea pigs or the cultures of T. pyriformis and human mononuclear cells. These findings suggest that some Legionella spp. may multiply only in specific protozoan hosts. The inability of this strain of L. anisa to multiply in human phagocytic cells may be related to the development of Pontiac fever rather than pneumonic legionellosis in exposed individuals. Further studies are necessary to determine whether the ability of legionellae to infect certain host cells can be correlated to differences in human disease.
Infect Immun 1990 Sep
PMID:Virulence of a Legionella anisa strain associated with Pontiac fever: an evaluation using protozoan, cell culture, and guinea pig models. 211 80

Gene htpB, which encodes the 58-kilodalton protein of Legionella pneumophila, was cloned in Escherichia coli and its complete nucleotide sequence was determined. Analysis of this sequence revealed an open reading frame of 1,644 nucleotides encoding a protein with a predicted molecular mass of 57,952 daltons. Data obtained by amino-terminal sequencing of the purified 58-kilodalton protein agreed, except for one amino acid residue, with the predicted amino acid sequence, identifying this open reading frame as htpB. A comparison of the primary structure of this protein to other proteins of similar molecular weights from E. coli, Mycobacterium leprae, M. tuberculosis, and Coxiella burnetii revealed significant regions of sequence similarity, which are discussed.
Infect Immun 1990 Sep
PMID:Nucleotide sequence of htpB, the Legionella pneumophila gene encoding the 58-kilodalton (kDa) common antigen, formerly designated the 60-kDa common antigen. 211 82

We have examined whether a molecule that is capable of inducing immune protection, the major secretory protein (MSP) of Legionella pneumophila, is required for virulence in a guinea pig model of Legionnaires' disease. To do so, we have compared the virulence in guinea pigs of an isogenic pair of L. pneumophila, Philadelphia 1 strain, one of which produces MSP (MSP+) and one of which does not (MSP-). Both the MSP- strain and the MSP+ strain of L. pneumophila are highly virulent for guinea pigs, inducing similar signs and progression of illness. Both strains are lethal and have comparable LD50s and LD100s. Both strains multiply in the lungs of guinea pigs at a similar rate, and both strains produce indistinguishable pathological lesions in the lungs. Both strains maintain a stable phenotype with guinea pig passage, i.e., the MSP- strain does not regain the capacity to secrete MSP and the MSP+ strain retains its capacity to secrete MSP after lung passage. Although vaccination with MSP induces strong protective immunity in the guinea pig against lethal aerosol challenge with L. pneumophila, this protective immunogen is not required in its intact proteolytically active form for the expression of virulence by the intracellular pathogen L. pneumophila. This demonstrates that a protective immune response need not necessarily be directed against a virulence determinant and suggests that any molecule that allows the host immune system to detect and act against an intracellularly sequestered pathogen may potentially serve as a protective immunogen against such a pathogen.
J Clin Invest 1990 Sep
PMID:An immunoprotective molecule, the major secretory protein of Legionella pneumophila, is not a virulence factor in a guinea pig model of Legionnaires' disease. 220 24

Three hundred fifty-nine consecutive patients with community-acquired pneumonia admitted to university, community, and VA hospitals underwent a standardized evaluation, including specialized tests for Legionella spp. and Chlamydia pneumoniae (TWAR). The most common underlying illnesses were immunosuppression (36.3%), chronic obstructive pulmonary disease (32.4%), and malignancy (28.4%). The most frequent etiologic agents were Streptococcus pneumoniae (15.3%) and Hemophilus influenzae (10.9%). Surprisingly, Legionella spp. and C. pneumoniae were the third and fourth most frequent etiologies at 6.7% and 6.1%, respectively. Aerobic gram-negative pneumonias were relatively uncommon causes of pneumonia despite the fact that empiric broad-spectrum combination antibiotic therapy is so often directed at this subgroup. In 32.9%, the etiology was undetermined. Antibiotic administration before admission was significantly associated with undetermined etiology (p = 0.0003). There were no distinctive clinical features found to be diagnostic for any etiologic agent, although high fever occurred more frequently in Legionnaires' disease. Clinical manifestations for C. pneumoniae were generally mild, although 38% of patients had mental status changes. Mortality was highest for Staphylococcus aureus (50%) and lowest for C. pneumoniae (4.5%) and Mycoplasma pneumoniae (0%). We document that specialized laboratory testing for C. pneumoniae and Legionella spp. should be more widely used rather than reserved for cases not responding to standard therapy. Furthermore, realization that C. pneumoniae and Legionella spp. are common etiologies for community-acquired pneumonia should affect empiric antibiotic prescription.
Medicine (Baltimore) 1990 Sep
PMID:New and emerging etiologies for community-acquired pneumonia with implications for therapy. A prospective multicenter study of 359 cases. 220 84

Micro-organism counts of bronchoalveolar lavage (BAL) and microbrush swabs were obtained from 40 immunocompetent (group A) and 23 immunosuppressed (group B) patients with nosocomial pneumonia, and a control group consisting of 40 patients with noninfectious pulmonary infiltrates. The sensitivity of BAL was high: 77.5% for group A and 85% for group B, while microbrush swabs gave many false-negative results. Microorganism counts were at or above 10(5) cfu/ml in 32 of 44 examinations (bacterial or mycotic pneumonia), but in only one case of the control group. Lower counts were obtained with localized infection and microorganisms difficult to culture (Aspergilla and Legionella). Granulocytosis in the lavage fluid was demonstrated in 38 of 41 patients with bacterial pneumonia and thus proved useful in the differential diagnosis. In 16 of 40 immunocompetent and 13 of 23 immunosuppressed patients with pneumonia the results were therapeutically of importance. Thus, invasive diagnosis is indicated especially in complicated or treatment-resistant nosocomial infections.
Dtsch Med Wochenschr 1990 Sep 28
PMID:[Bronchoscopic diagnosis of pneumonia with quantitative microbial count determination]. 220 28

Although 18 cases of Legionnaires' disease have been reported in Japan, these have included none from the northern areas of Japan. The first confirmed case of Legionnaires' disease in Hokkaido district, a northern island of Japan, is reported. A 48 year-old male was admitted for fulminant pneumonia, and died the next day. Legionella pneumophila, serogroup 1, was cultured and determined from the sputum and lung tissue obtained at autopsy. Postmortem examination by means of the indirect immunofluorescent method, using group specific antisera against Legionella pneumophila as a primary antibody, revealed phagocytized bacilli in the alveoli of the lung.
Kansenshogaku Zasshi 1990 Sep
PMID:[A case of Legionnaires' disease, the first case in Hokkaido Prefecture--an experience of isolation of Legionella pneumophila and identification by indirect immunofluorescence antibody method]. 224 86

Immunogenic properties of cytolysin were studied in experiments on guinea pigs. Preliminary immunization with cytolysin led to the suppression of response to ConA in lymphocytes not adhering to nylon wool and to the stimulation of response to Legionella antigens in lymphocytes adhering to nylon wool. For a month after infection with L. pneumophila the suppression of the proliferative activity of lymphocytes in the spleen of the immunized animals in response to ConA and Legionella antigens was observed, while in the lungs transitory suppression of response to ConA and Legionella antigens was followed by the restoration and then stimulation of proliferation in response to T-cell mitogen and specific antigens. The data obtained in these experiments indicate the capacity of cytolysin for modulating the development of immune response.
Zh Mikrobiol Epidemiol Immunobiol 1990 Sep
PMID:[The immunologic properties of Legionella cytolysin]. 225 6

Three commercial diagnostic fluorescein-labeled antibodies, one monoclonal and two polyclonal, were compared to evaluate their abilities to detect Legionella pneumophila in environmental samples. The monoclonal conjugate failed to detect L. pneumophila in the 12 environmental samples studied by direct immunofluorescence. In contrast, the two polyclonal conjugates detected L. pneumophila in all 12 samples by both direct and indirect immunofluorescence. However, isolates recovered by culture from the 12 samples demonstrated equal immunofluorescence with all three conjugates. The reason for the failure of the monoclonal antibody to detect L. pneumophila in the environmental samples remains unknown. Laboratories considering the use of the monoclonal conjugate to screen environmental samples for L. pneumophila should be aware of this finding.
Appl Environ Microbiol 1990 Sep
PMID:Failure of a diagnostic monoclonal immunofluorescent reagent to detect Legionella pneumophila in environmental samples. 227 36


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