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Query: UMLS:C0023241 (Legionella)
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Concern about emerging and reemerging respiratory pathogens prompted the development of a respiratory disease reference laboratory at the Naval Health Research Center. Professionals working in this laboratory have instituted population-based surveillance for pathogens that affect military trainees and responded to threats of increased respiratory disease among high-risk military groups. Capabilities of this laboratory that are unique within the Department of Defense include adenovirus testing by viral shell culture and microneutralization serotyping, influenza culture and hemagglutination inhibition serotyping, and other special testing for Streptococcus pneumoniae, Streptococcus pyogenes, Mycoplasma pneumonia, and Chlamydia pneumoniae. Projected capabilities of this laboratory include more advanced testing for these pathogens and testing for other emerging pathogens, including Bordetella pertussis, Legionella pneumoniae, and Haemophilus influenzae type B. Such capabilities make the laboratory a valuable resource for military public health.
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PMID:The Naval Health Research Center Respiratory Disease Laboratory. 1092 Jun 35

In the course of respiratory infections, the efficacy of microbiologic diagnosis has increased years after years, in term of specificity, sensitivity and rapidity. New pathogenic agents have been described such as: Legionella pneumophila, Chlamydia pneumoniae, Hantavirus. Some viruses have been well characterized as responsible for seasonal outbreaks using rapid tools for identification. Needs for efficient diagnostic tools became more obvious when specific antiviral drugs appeared on the market. So technologic developments improved the efficacy of microbiologic diagnosis and anticipate a better specificity as well as sensitivity with the help of molecular biology. Respiratory syncytial virus is one of the major infectious agents found in respiratory infections in young children and newborns. On the whole it was detected in more than one third of pediatric nasopharyngeal aspirations received in our laboratory and more than 50% during the peak of the winter epidemics. The method of direct antigen detection by immunofluorescence with the help of monoclonal antibodies allowed us to establish an incidence curve of these recurrent outbreaks, beginning in December to stop usually by the end of April. During this same period, influenza A virus, seldom influenza B virus, were detected in many nasopharyngeal specimens. Other viruses, parainfluenza 1 to 3 and Adenovirus, were irregularly detected all along the year. In the great majority of nasopharyngeal aspirations with a positive virus detection, one virus only was observed. Antigen detection methods were also developed for some bacteria such as Chlamydia pneumoniae, Legionella pneumophila. Although serology is not frequently used by pediatricians, it is still necessary for the diagnosis of Mycoplasma pneumoniae infections. A direct antigen detection test is now available, but its sensitivity needs to be evaluated. On the other hand serologic diagnosis may be extremely useful when long lasting or treatment resistant respiratory infections occur. Seroconversion or four-fold increasing titers to one pathogen may be observed when a second serum sample is tested together with the first serum of this patient. The diagnostic yield will be all the more efficient that time between both samples is long. Molecular biology techniques will significantly change the way to investigate an infection. Presently these methods are used in research laboratories, but automated technologies will facilitate routine laboratory workload. Screening methods using multiplex PCR are also promising.
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PMID:[Serological diagnosis and nasopharyngeal washings in pediatric infections]. 1102 83

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

The severe pulmonary disease caused by the inhalation of the different Legionella species is called Legionella pneumonia, while the name of the pulmonary disease caused by the most common Legionella (L. pneumophila) is Legionnaires' disease. Another type of disease caused by legionellae is Pontiac fever with influenza-like symptoms. Legionella spp. are facultative intracellular parasites. They survive within both monocytes in the human organism and amebae in the environment. To prevent and control the occurrence of legionelloses, legionellae should be surveyed and detected in the environmental (water pipes, air-conditioning systems, cooling towers, respiratory equipments, etc.) and clinical (blood, bronchoalveolar lavage, sputum, abscess, etc.) samples. Laboratory diagnosis is complicated by the limitations of the available assays. Thus, it is proposed that the microbiological laboratory diagnosis should be based on the simultaneous application of at least three methods (culturing [on BCYE medium], followed by biochemical assays, serology, molecular biologic methods, such as polymerase chain reaction [PCR], direct demonstration [immunofluorescence microscopy], antigen determination are the most important ones) and on the simultaneous demonstration from three different samples (e.g. lower respiratory tract secretions, sputum, urine, blood culture, serum, moreover, water samples from all potential infectious sources, sediment of hot water tanks, as well as swab samples of faucets and shower heads). The advantage of PCR is that is gives reliable results in one day, in contrast to conventional culturing. However, its sensitivity can not be improved by increasing the sample volume, and neither can it give quantitative results nor can it produce strains for epidemiologic studies, contrary to the method of culturing. It is concluded that PCR and culturing do complement, but do not substitute each other.
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PMID:[Epidemiology and laboratory diagnostics of legionellae]. 1140 64

It was reported that two mechanics working on a cargo ship under repair in the port of Barcelona had died after having fever. An investigation was made into the possibility of any additional cases and the presence of Legionella pneumophila in the ship they were repairing and in their hotel. The contaminated water system was treated with sodium hypochlorite. Both patients died after having been repeatedly diagnosed as having influenza. The two cases occurred among those who had been working with the pump of the ship's water system, while no cases were observed among the other workers (p = 0.02). Various serogroups of L. pneumophila were isolated from the ship's water pump and distribution system. However, organism of serogroup 1, subgroup Pontiac (Knoxville) were identified with identical deoxyribonucleic acid (DNA) patterns in the lung tissue of one patient and in the cooling water circuit valve of the ship's water pump. The first postintervention control water samples showed no further growth of legionella, but serogroups 4 and 8 were identified 8 months later. This legionellosis outbreak, although small, was highly lethal, probably due to the high levels of bacteria to which the patients were exposed and also because of the failure of correct diagnosis. International recommendations on prevention and control of legionellosis, which include ships under repair, are required.
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PMID:A small outbreak of Legionnaires' disease in a cargo ship under repair. 1149 Nov 80

Legionnaire's disease is a life-threatening disease, observed in up to 15% of patients with pneumonia. Legionella pneumophila serogroup 1 is the most frequently implicated species among the genus Legionella. Legionella can cause two clinical pictures: Legionnaire's disease, a severe pneumonia, or Pontiac fever, a self-limiting disease. The attributable mortality of Legionnaire's disease is between 5-30%. Patients with typical Legionnaire's disease present with fever > 39 degrees C, cough and flu-like symptoms that do not respond to betalactam antibiotics. Neurological disorders may accompany severe cases. Laboratory findings include non-purulent sputum, increased liver enzymes and hyponatriemia. However, most patients do not fulfill all of these signs, symptoms and laboratory finding. Patients present with Legionella are frequently missed in the microbiology laboratory because clinicians do not ask for the specimen to be tested for Legionella. Established risk factors for Legionnaire's disease are chronic obstructive pulmonary disease (COPD), smoking and immunosuppressive therapy. New diagnostics tools such as the Legionella antigen in the urine, as well as PCR of a sputum sample allow rapid and accurate diagnosis. Such investigations are recommended for patients with severe pneumonia and those requiring hospitalization. State-of-the-art treatment includes a second generation macrolide, or alternatively, newer quinolones which are recommended as first-line drug for transplant patients. Prevention of Legionella requires a multi-faceted approach: The warm water should be kept at 60 degrees C in the boiler; the warm water should reach 50 degrees C at the faucet two minutes of opening the handle and the shower heads should be preferably made of stainless steel. In the hospital, the warm water supply should be free of Legionella at least for severely immunocompromised patients.
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PMID:[Legionelloses]. 1169 89

An incidence of between 2 and 44 per 1000 population has been reported for community-acquired pneumonia. Epidemiologic studies describe a wide range of causative organisms, including Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, Legionella spp., Moraxella catarrhalis, Chlamydia pneumoniae and viruses such as influenza A and B. However, the frequency with which they are reported varies widely. On analysis of these studies, the variation can be explained by a number of factors. The results depend on the definition of pneumonia and the criteria for assigning a causative role to any particular organism. Older studies have not included diagnostic methods for newly described organisms such as C. pneumoniae and Legionella spp. The improved diagnostic methods for these organisms and for Mycoplasma pneumoniae are reflected in more recent studies. Further variation depends on the population studied. As many patients with mild pneumonia are successfully treated in the community, those studies that are hospital-based include patients with more severe pneumonia often in the elderly or in patients with underlying diseases such as chronic obstructive pulmonary disease. The prior use of antibiotics not only contributes to the high percentage of cases for which no etiologic agent is found, but also ensures that treatment failures are selected for hospitalization. This further changes the result, depending on the antibiotic agents used most commonly in the community. The inclusion of nursing home patients or groups where alcoholism is more common will also favor particular organisms. Finally, the timing of the study may be such that an epidemic is included. This has relevance mostly for Mycoplasma pneumoniae, C. pneumoniae, Legionella spp. and influenza. In the assessment of the patient with community-acquired pneumonia, any one of the above organisms can be considered to be responsible. As initial treatment is empirical, other information can be used to ensure that an antibiotic with an adequate spectrum is chosen. Factors of importance are age, underlying illness, severity of disease and any locally recognized epidemics or endemic organisms. Differences in clinical presentation are not sufficiently distinct to allow for accurate prediction of the causative agent. Similarly, chest radiograph changes are not sufficiently specific to discriminate reliably between diverse organisms such as S. pneumoniae, Mycoplasma pneumoniae and Legionella spp. Current recommendations for choice of an empirical antibiotic agent are therefore based, not on the assumption of a single etiologic agent indicated by clinical presentation or radiographic appearances, but on age of the patient, severity of illness, the presence of underlying conditions and the range of possible organisms in that patient group.
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PMID:Community-acquired pneumonia: epidemiologic and clinical considerations. 1186 96

Diagnostic tests are important tools for surveillance in healthcare epidemiology. Recent studies regarding the use of diagnostic tests for detecting the following epidemiologically important conditions or pathogens are reviewed: vancomycin-resistant enterococci, Legionella, influenza, ventilator-associated pneumonia, Clostridium difficile, bloodstream infection, and tuberculosis.
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PMID:Diagnostic tests for healthcare epidemiology. 1196 63

It is important to diagnose the pathogen as quickly as possible to accelerate the start of appropriate treatment of patients with infectious diseases. Recently, rapid diagnostic tests improve the accuracy of diagnosis of the pathogen. Furthermore, it is also available to do the test with very simplified method by using portable kits. Many PCR and antigen detection techniques have been developed to improve the diagnosis of specific pathogens, such as influenza virus, Legionella, Chlamydia, Mycoplasma, Helicobacter pylori and Mycobacterium tuberculosis. Especially, urinary antigen detection kits are useful at the site of outpatient clinics.
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PMID:[Rapid diagnosis of infectious diseases at the site of outpatient clinics]. 1207 43

The main causative microorganisms of Community-acquired pneumonia are Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus. Especially the causative microorganisms affecting whole body basic disease, persons of advanced age, and alcoholic patients are Moraxella catarrhalis, Klebsiella pneumoniae, Pseudomonas aeruginosa, Candida spp., Cryptococcus spp., Aspergillus spp., Pneumocystis carinii and anaerobic bacteria. Other microorganisms involved in epidemic disease, action condition (travel around hot springs etc.) and pet breeding environments are Mycoplasma pneumoniae, Legionella pnumophila, Chlamydia spp., respiratory syncytial virus, influenza virus, and adeno virus. We suggest methods of advancing the microscopic and microbiological examination and report, and quickly obtaining clinical information and extracting the clinical specimen. We also describe the inspection method for a case "Legionella pneumonia" that was discussed during this symposium.
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PMID:[Community-acquired pneumonia--from medical technologist]. 1218 4


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