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

Legionella pneumophila is an inhabitant of the aquatic environment and the causative agent of a bacterial pneumonia. We identified the presence of an L. pneumophila homologue of csrA of E. coli and rsmA of Erwinia carotovora, genes which regulate gene expression by destabilising mRNA and which have been shown to relate to environmental fitness and pathogenicity. The Legionella csrA was able to complement a csrA-negative mutant of E. coli. Overproduction of csrA in L. pneumophila lead to a reduction of flagellation and pigmentation and an increase in bacterial cell size. csrA overproduction was associated with a reduction of fliA and flaA transcripts. This suggests that similar to E. coli and Erwinia, L. pneumophila csrA is a regulator of gene expression and may contribute to the capability of the pathogen to rapidly adapt to changing environments.
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PMID:Overexpresssion of a Legionella pneumophila homologue of the E. coli regulator csrA affects cell size, flagellation, and pigmentation. 1172 19

We performed an observational analysis of prospectively collected data on 1,474 adult patients who were hospitalized for community-acquired pneumonia; 1,169 patients were under 80 years of age and 305 (21%) patients were over 80 years ("very elderly"). Mean patient ages were 60 years in the former group and 85 years in the latter group. Severely immunosuppressed patients and nursing-home residents were not included. Comorbidities significantly associated with older age were chronic obstructive pulmonary disease, chronic heart disease, and dementia. The most common causative organism was Streptococcus pneumoniae (23% in both groups). Aspiration pneumonia was more frequent in the very elderly (5% in younger patients versus 10% in the very elderly); Legionella pneumophila (8% in younger patients versus 1% in the very elderly) and atypical agents (7% in younger patients versus 1% in the very elderly) were rarely recorded in the very elderly. While very elderly patients complained less frequently of pleuritic chest pain, headache, and myalgias, they were more likely to have absence of fever and altered mental status on admission. No significant differences were observed between groups as regards incidence of classic bacterial pneumonia syndrome (60% versus 59%) in 343 patients with pneumococcal pneumonia. The development of inhospital complications (26% in younger versus 32% in very elderly patients) as well as early mortality (2% in younger versus 7% in very elderly patients) and overall mortality (6% in younger versus 15% very elderly patients) were significantly higher in very elderly patients. Acute respiratory failure and shock/multiorgan failure were the most frequent causes of death, especially of early mortality. Factors independently associated with 30-day mortality in the very elderly were altered mental status on admission (odds ratio, 3.69), shock (odds ratio, 10.69), respiratory failure (odds ratio, 3.50), renal insufficiency (odds ratio, 5.83), and Gram-negative pneumonia (odds ratio, 20.27).
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PMID:Community-acquired pneumonia in very elderly patients: causative organisms, clinical characteristics, and outcomes. 1279 2

A prospective study was initiated to analyse the bacterial aetiology and clinical picture of mild community-acquired pneumonia in Slovenia using the previously described Pneumonia Severity Index. Radiographically confirmed cases of pneumonia in patients treated with oral antibiotics in seven study centres were included. An aetiological diagnosis was attempted using culture of blood and sputum, urinary antigen testing for Streptococcus pneumoniae and Legionella pneumophila, and antibody testing for Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila in paired serum samples. One hundred thirteen patients were evaluable for clinical presentation and 109 for aetiological diagnosis. At least one pathogen was detected in 62.4% patients. The most common causative agents were Mycoplasma pneumoniae in 24.8%, Chlamydia pneumoniae in 21.1%, and Streptococcus pneumoniae in 13.8% of patients. Dual infection was detected in 8.3% of patients. Most patients suffered from cough, fatigue, and fever. Patients with atypical aetiology of pneumonia differed from those with typical bacterial pneumonia or pneumonia of unknown aetiology in age, presence of dyspnea, and bronchial breathing on lung auscultation. Patients with pneumococcal, chlamydial, and mycoplasmal infections differed in age, risk class, presence of dyspnea, bronchial breathing, and proteinuria. There was an overlap of other clinical symptoms, underlying conditions, and laboratory and radiographic findings among the groups of patients classified by aetiology. Since patients with mild community-acquired pneumonia exhibit similar clinical characteristics and, moreover, since a substantial proportion of cases are attributable to atypical bacteria, broad-spectrum antibiotic treatment seems to be recommended.
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PMID:Aetiology and clinical presentation of mild community-acquired bacterial pneumonia. 1368 Mar 99

This report updates, expands, and replaces the previously published CDC "Guideline for Prevention of Nosocomial Pneumonia". The new guidelines are designed to reduce the incidence of pneumonia and other severe, acute lower respiratory tract infections in acute-care hospitals and in other health-care settings (e.g., ambulatory and long-term care institutions) and other facilities where health care is provided. Among the changes in the recommendations to prevent bacterial pneumonia, especially ventilator-associated pneumonia, are the preferential use of oro-tracheal rather than naso-tracheal tubes in patients who receive mechanically assisted ventilation, the use of noninvasive ventilation to reduce the need for and duration of endotracheal intubation, changing the breathing circuits of ventilators when they malfunction or are visibly contaminated, and (when feasible) the use of an endotracheal tube with a dorsal lumen to allow drainage of respiratory secretions; no recommendations were made about the use of sucralfate, histamine-2 receptor antagonists, or antacids for stress-bleeding prophylaxis. For prevention of health-care--associated Legionnaires disease, the changes include maintaining potable hot water at temperatures not suitable for amplification of Legionella spp., considering routine culturing of water samples from the potable water system of a facility's organ-transplant unit when it is done as part of the facility's comprehensive program to prevent and control health-care--associated Legionnaires disease, and initiating an investigation for the source of Legionella spp. when one definite or one possible case of laboratory-confirmed health-care--associated Legionnaires disease is identified in an inpatient hemopoietic stem-cell transplant (HSCT) recipient or in two or more HSCT recipients who had visited an outpatient HSCT unit during all or part of the 2-10 day period before illness onset. In the section on aspergillosis, the revised recommendations include the use of a room with high-efficiency particulate air filters rather than laminar airflow as the protective environment for allogeneic HSCT recipients and the use of high-efficiency respiratory-protection devices (e.g., N95 respirators) by severely immunocompromised patients when they leave their rooms when dust-generating activities are ongoing in the facility. In the respiratory syncytial virus (RSV) section, the new recommendation is to determine, on a case-by-case basis, whether to administer monoclonal antibody (palivizumab) to certain infants and children aged <24 months who were born prematurely and are at high risk for RSV infection. In the section on influenza, the new recommendations include the addition of oseltamivir (to amantadine and rimantadine) for prophylaxis of all patients without influenza illness and oseltamivir and zanamivir (to amantadine and rimantadine) as treatment for patients who are acutely ill with influenza in a unit where an influenza outbreak is recognized. In addition to the revised recommendations, the guideline contains new sections on pertussis and lower respiratory tract infections caused by adenovirus and human parainfluenza viruses and refers readers to the source of updated information about prevention and control of severe acute respiratory syndrome.
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PMID:Guidelines for preventing health-care--associated pneumonia, 2003: recommendations of CDC and the Healthcare Infection Control Practices Advisory Committee. 1504 56

Bacterial pneumonia in immunocompromised patients as well as elderly persons often becomes a life threatening disease, even when effective antibiotics are used extensively. In addition, the appearance of antibiotic-resistant bacteria in medical facilities as well as in patients requires another approach to treat such patients besides treatment with antibiotics. In this regard, green tea catechins, such as epigallocatechin gallate (EGCg), may be one of the potential agents for such purpose due to its possible potential immunomodulatory as well as antimicrobial activity. The studies by us showed that EGCg enhanced the in vitro resistance of alveolar macrophages to Legionella pneumophila infection by selective immunomodulatory effects on cytokine formation. Furthermore, the tobacco smoking-induced impairment of alveolar macrophages regarding antibacterial as well as immune activity was also recovered by EGCg treatment. These results indicate that EGCg may be a possible potential immunotherapeutic agent against respiratory infections in immunocompromised patients, such as heavy smokers.
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PMID:Protective effects of green tea catechins on alveolar macrophages against bacterial infections. 1563 Jan 81

Community-acquired pneumonias (CAP) are still caused by Streptococcus pneumoniae, Hemophilus influenzae, or Moraxella catarrhalis. Legionella and Chlamydia pneumoniae have been defined as important atypical pathogens causing CAP. Klebsiella causes CAP primarily in patients with chronic alcoholism or in chronic care facilities. Normal hosts do not present with "unusual pathogens'' e.g., Staphylococcus aureus or Pseudomonas aeruginosa. The clinical severity of a bacterial pneumonia has important prognostic implications and predicts admission to intensive care units, duration of therapy, and complications. The factors that determine the severity of a CAP are less related to the pathogen than the underlying cardiopulmonary status of the patient as well as the patient's humoral immunity. Relatively avirulent pathogens may result in severe CAP in patients with diminished/absent splenic function or significant cardiopulmonary disease. A critical concept is to appreciate that the selection of antimicrobial therapy is not dependent on co-morbidities since the antimicrobial therapy is directed against the pathogen and not the co-morbidities. Therefore the treatment of CAP, whether moderate or severe is with the same antibiotic at the same dose. Many antibiotic regimens are equally efficacious in the treatment of CAP. The most cost effective optimal regimen covers both typical and atypical pathogens, e.g., levofloxacin, and is currently the preferred antibiotic approach to moderate or severe CAP in the CCU.
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PMID:The antibiotic treatment of severe community-acquired pneumonia admitted to the critical care unit. 1608 19

Legionnaires' disease (Legionellosis) is a bacterial pneumonia that acquired its name following an outbreak of pneumonia among army veterans attending an American Legion convention in Philadelphia in 1976. The previously undiscovered bacterium that caused this form of pneumonia was therefore named Legionella. There are more than 45 species of Legionella bacteria and these are natural inhabitants of water supplies throughout the world (Fliermans, 1981). About half of these have been associated with infection, although the most common cause of Legionnaires' disease is Legionella pneumophila, which is the causative strain in around 90 per cent of cases (Fields et al, 2002).
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PMID:Legionella bacteria and water systems in health care premises. 1621 22

Legionella pneumophila, a causative agent of bacterial pneumonia, survives inside phagocytic cells by avoiding rapid targeting to the lysosome. This bacterium utilizes a type IVB secretion system, encoded by the dot/icm genes, to replicate inside host cells. DotL, a critical component of the Dot/Icm secretion apparatus, functions as the type IV coupling protein. In contrast to most dot/icm genes, which are dispensable for growth on bacteriological media, dotL is required for the viability of wild-type L. pneumophila. Previously we reported that DeltadotL lethality could be suppressed by inactivation of the Dot/Icm complex via mutations in other dot/icm genes. Here we report the isolation of non-dot/icm suppressors of this phenotype. These DeltadotL suppressors include insertions that disrupt the function of the L. pneumophila homologs of cpxR, djlA, lysS, and two novel open reading frames, lpg0742 and lpg1594, that we have named ldsA and ldsB for lethality of DeltadotL suppressor. In addition to suppressing DeltadotL lethality, inactivation of these genes in a wild-type strain background causes a range of defects in L. pneumophila virulence traits, including intracellular growth, implicating these factors in the proper function of the Dot/Icm complex. Consistent with previous data showing a role for the cpx system in regulating expression of several dot/icm genes, the cpxR insertion mutant produced decreased levels of three Dot/Icm proteins, DotA, IcmV, and IcmW. The remaining four suppressors did not affect the steady-state levels of any Dot/Icm protein and are likely to represent the first identified factors necessary for assembly and/or activation of the Dot/Icm secretion complex.
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PMID:Identification of non-dot/icm suppressors of the Legionella pneumophila DeltadotL lethality phenotype. 1699 51

Legionnaires' disease (LD) is an aetiology of community-acquired bacterial pneumonia in adults, with a high case-fatality ratio (CFR). We conducted a matched case-control study to identify risk factors for sporadic, community-acquired LD. Cases of sporadic, community-acquired and biologically confirmed LD, in metropolitan France from 1 September 2002 to 31 September 2004, were matched with a control subject according to age, sex, underlying illness and location of residence within 5 km. We performed a conditional logistic regression on various host-related factors and exposures. Analysis was done on 546 matched pairs. The CFR was 3.5%. Age ranged from 18-93 years (mean 57 years), with a 3.6 male:female sex ratio. Cases were more likely to have smoked with the documentation of a dose-effect relation, to have travelled with a stay in a hotel (OR 6.1, 95% CI 2.6-14.2), or to have used a wash-hand basin for personal hygiene (OR 3.5, 95% CI 1.6-7.7) than controls. Tobacco and travel have been previously described as risk factors for LD, but this is the first time that such a dose-effect for tobacco has been documented among sporadic cases. These findings will provide helpful knowledge about LD and help practitioners in identifying patients at high risk.
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PMID:Sporadic community-acquired Legionnaires' disease in France: a 2-year national matched case-control study. 1821 25

CEM-101 is a novel fluorinated macrolide-ketolide with potent activity against bacterial pathogens that are susceptible or resistant to other macrolide-lincosamide-streptogramin B (MLS(B))-ketolide agents. CEM-101 is being developed for oral and parenteral use in moderate to moderately severe community-acquired bacterial pneumonia. The objective of this study was to assess the activity of CEM-101 and comparators against contemporary respiratory tract infection (RTI) isolates. A worldwide sample of organisms was used, including Streptococcus pneumoniae [n=168; 59.3% erythromycin-resistant and 18 multidrug-resistant (MDR) serogroup 19A strains], Moraxella catarrhalis (n=21; 11 beta-lactamase positive), Haemophilus influenzae (n=100; 48 beta-lactamase positive), Haemophilus parainfluenzae and Haemophilus haemolyticus (n=12), and Legionella pneumophila (n=30). Testing and interpretation were performed using reference Clinical and Laboratory Standards Institute methods. CEM-101 was very potent against S. pneumoniae [minimum inhibitory concentration for 90% of the organisms (MIC90)=0.25 mg/L; highest MIC at 0.5 mg/L] and was 2- and > or =32-fold more active than telithromycin and clindamycin, respectively. CEM-101 also demonstrated potent activity against S. pneumoniae MDR-19A strains (MIC90=0.5 mg/L). CEM-101 was the most potent antimicrobial agent tested against L. pneumophila, with all MIC values at < or = 0.015 mg/L (telithromycin MIC90=0.03 mg/L). CEM-101 was as potent as azithromycin against Haemophilus spp. RTI pathogens (MIC90=2 mg/L), with no variations for beta-lactamase production. CEM-101 MIC values against M. catarrhalis were all at < or =0.5mg/L. Interestingly, CEM-101 potency was ca. 6 log(2) dilutions greater than telithromycin MIC results among 44 beta-haemolytic streptococci having telithromycin MICs > or = 2 mg/L. CEM-101 exhibited the greatest potency and widest spectrum of activity against RTI pathogens among the tested MLS(B)-ketolide agents (azithromycin, clarithromycin, erythromycin, telithromycin, clindamycin and quinupristin/dalfopristin) and was comparable overall with levofloxacin.
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PMID:Antimicrobial characterisation of CEM-101 activity against respiratory tract pathogens, including multidrug-resistant pneumococcal serogroup 19A isolates. 2021 48


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