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

Droplets generated from water surfaces have been implicated in a number of diseases such as Legionnaires' disease and Pontiac fever. These droplets can be inhaled by people and can deposit in the respiratory system. The physical size of the droplets is critical in determining whether the droplets can contain the bacteria, reach the breathing zone of the subject, and deposit in the respiratory tract. The present study establishes the presence of water droplets above the surface of health club whirlpools. These droplets are of the appropriate size for causing respiratory disease. Several factors including pool temperature, bubbling action during operation, and height above the water surface have been investigated. The results are related to the deposition of the droplets, and hence bacteria, in the various regions of the respiratory tract.
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PMID:Respirable droplets from whirlpools: measurements of size distribution and estimation of disease potential. 394 12

Retrospective study shows that a 1957 outbreak of pneumonia in Austin, Minnesota, was Legionnaires' disease. Between June 7 and August 9, 1957, 78 persons were hospitalized with acute respiratory disease of unknown cause. Most had fever, headache, cough, and pneumonitis; two died. Ages ranged from 14-83 years; half of the patients were aged 55 years or older. Eighty-seven per cent were men. There were no secondary cases. Forty-six (59%) of the 78 patients were employees at a local meat packing plant, in distinction to the area's total working population (32%). Serosurvey of 15 of the 1957 outbreak cases and 30 controls matched for age, sex, and either occupation or residence was carried out in 1979. Antibody titers were determined for Legionella pneumophila serogroups 1-4 by means of indirect immunofluorescence. Twelve (80%) of the 15 cases and 13 (43%) of the 30 controls had antibody titers of 1:64 or greater to one or more of the L. pneumophila serogroups. Significant differences in L. pneumophila antibody titers (prevalence and level) were found between cases and control groups matched for residence (serogroups 1-3) or occupation (serogroups 2 and 3). Only three of 20 Austin residents with pneumonia diagnosed between 1978 and 1980 had L. pneumophila antibody titers of 1:128 or greater (p less than 0.001), in comparison to cases. These serologic data and the 1957 clinical and epidemiologic observations support the contention that this is the earliest documented outbreak of Legionnaires' disease.
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PMID:A 1957 outbreak of Legionnaires' disease associated with a meat packing plant. 682 53

Aqueous suspensions of virulent Legionella pneumophila grown on solid medium retained virulence and aerosol survival characteristics for several months. Significant numbers of viable organisms were recovered from aerosols held at various relative humidities (r.h.) for up to 2 h. The organisms survived best at 65% r.h. and were least stable at 55% r.h. Exponential phase broth-grown organisms survived poorly in aerosols in comparison with stationary phase broth cultures or organisms grown on solid medium, suggesting that the metabolic status of Legionella pneumophila organisms may be an important factor affecting their ability to survive in aerosols and cause respiratory disease.
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PMID:Survival of virulent Legionella pneumophila in aerosols. 686 14

In a retrospective survey of sera collected from 126 patients under the age of 10 years, seroreactivity was first detected at 1 year of age when the geometric mean titer rose from 12 to 24. This activity increased to a titer of 102 in the 4- to 6-year-old group and was maintained in the 7- to 9-year-old group. At the time of serum collection, at least 25% of those sampled had a titer of 256 or greater, a level currently thought to be presumptive evidence of infection at some undetermined time. No difference in the geometric mean titer could be ascertained when the population was divided by clinical diagnosis or by sex. No seasonal variation was observed. Of 35 paired sera from children under the age of 5 years, three fourfold rises were observed. One rise to a titer of 128 was detected in an 11-month-old girl with a clinical diagnosis of bronchiolitis. The second rise in a 5-year-old boy with pneumonia was an increase from 256 to 2,048. The third rise in a 6-month-old with pneumonia did not meet the currently accepted level necessary for confirmed diagnosis. These data suggest that infection with Legionella pneumophila, or a closely related agent, is common in this population, occurring before 9 years of age, and may be a cause of mild respiratory disease in infants and children.
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PMID:Legionnaires' disease in children. 701 74

To learn the role of Legionella pneumophila, the agent of Legionnaires' disease, in childhood illness, a prospective study was conducted among 52 children younger than four years of age with acute disease of the lower respiratory tract. Viral, mycoplasmal, and bacterial cultures and acute- and convalescent-phase sera were obtained during 64 episodes of acute illness; additional sera were drawn annually for three to five years. On the basis of serologic evidence, none of the acute episodes appeared to be due to L. pneumophila serogroup 1 or 2. However, examination of annual serum specimens showed that 27 (52%) of the children had rises in titer of indirect immunofluorescent antibody (a fourfold or greater rise to a reciprocal titer of greater than or equal to 128). Most rises in titer were in response to the serogroup 2 antigen. These results suggest that L. pneumophila is not a common cause of acute respiratory disease in early childhood in the study area but that children are frequently exposed to the organism. Alternatively, the serologic responses might be to unrelated cross-reacting microorganisms.
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PMID:Infections with Legionella pneumophila in children. 722 38

Lower respiratory disease is a major source of morbidity in military recruits, with hospitalization rates for pneumonia more than 30 times that of the non-recruit population. The etiologic agent remains unknown in over 75% of cases. This study prospectively examined the etiology of pneumonia among recruits at Naval Training Center, San Diego, California. Recruits presenting with cough, fever, or shortness of breath and pulmonary infiltrates on chest X-ray were eligible for enrollment. A standardized scoring form and focused physical exam were completed on each subject. Sputum specimens were obtained for Gram's stain and culture, DNA probing for Legionella and Mycoplasma species, and direct fluorescent antibody staining for Legionella. Acute and convalescent serologies were performed for adenovirus, influenza A and B, Mycoplasma pneumoniae, Chlamydia group, and respiratory syncytial virus. Of 110 eligible patients, 100 consented to enrollment and 75 patients completed the study. Etiologic diagnoses were obtained in 40 of the patients (53%). M. pneumoniae, Haemophilus influenzae, and viruses accounted for the majority of infections. Mixed infections were seen in six patients. Forty-seven percent of patients had no diagnosis established. Pneumonia in this series of military recruits was frequently caused by M. pneumoniae and H. influenzae. Fifty percent of cases were undiagnosed with routinely available laboratory methods. Further studies are warranted to more clearly define the etiologic agents of recruit pneumonia and the utility of prophylactic measures.
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PMID:Pneumonia in military recruits. 787 Mar 17

Legionella species are important etiologic agents of sporadic and epidemic community-acquired and nosocomial respiratory disease. The list of species continues to expand, and tools for classification and characterization of isolates have become increasingly sophisticated. These organisms are associated with aquatic habitats and are transmitted by aerosol or direct contact. Bacterial culture is the cornerstone of laboratory diagnosis. Careful surveillance of infections is important, because infections potentially can be prevented.
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PMID:Legionella and the clinical microbiologist. 834 74

Legionella pneumophila is the most highly characterized member of a genus of bacteria that survive as intracellular parasites of freshwater protozoa. These bacteria can also multiply intracellularly in human phagocytic cells and cause respiratory disease in humans. Comparison of the invasive strategies of L. pneumophila in mammalian and protozoan cells and study of the interactions between Legionella and protozoa should prove useful in development of strategies for the prevention of legionellosis.
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PMID:The molecular ecology of legionellae. 882 38

To determine whether criteria for not admitting community-acquired pneumonia (CAP) patients diagnosed in the emergency room are appropriate, and to characterize the symptoms, etiology and course of CAP. This one-year prospective, protocol study of immunocompetent CAP patients diagnosed in the emergency room of our hospital enrolled patients not considered to require hospital admission according to the recommendations of the Spanish Society of Respiratory Disease (SEPAR). Medical histories, chest X-rays and blood analysis were obtained for all patients. Blood cultures were analyzed for antibodies against Legionella pneumophila, Mycoplasma pneumoniae, Coxiella burnetii, Chlamydia pneumoniae, Chlamydia psittaci and influenza virus types A and B. The patients received erythromycin for 14 days and were regularly checked by the pulmonologist in the outpatient clinic until signs and symptoms had disappeared. One hundred six patients were enrolled. Mean age was 36 +/- 13 years. Only 3 patients had to be admitted to hospital, after which outcome was good. The main symptoms were fever (106, 100%) and cough (83, 78%). In 46 (43.4%) chest sounds were normal. Microbiologic diagnoses were achieved for 28 (26.4%) and Coxiella burnetii was the agent most often found (19, 17.9%). Outcome was good in all cases, with faster disappearance of symptoms than of radiological signs. The SEPAR criteria for admitting patients with CAP are appropriate. The clinical symptoms of such patients are non specific, a noteworthy finding being that many patients had normal chest sounds. Coxiella burnetii was the most common causative agent. Both clinical and radiological outcomes were excellent.
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PMID:[Community acquired pneumonia. Reliability of the criteria for deciding ambulatory treatment]. 909 Nov 17

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


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