Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023241 (Legionella)
 6,990 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chlamydia psittaci infection typically causes a mild respiratory illness in humans. Severe respiratory failure requiring mechanical ventilation or intensive care therapy is an uncommon development. The aetiological agents causing severe community acquired pneumonia often remain undetermined. Serological tests may aid in diagnosis. We present two cases of fulminant psittacosis, one demonstrating early cross-reactivity with Legionella longbeachae.
 ...
PMID:Fulminant psittacosis requiring mechanical ventilation and demonstrating serological cross-reactivity between Legionella longbeachae and Chlamydia psittaci. 1038 41

The most common atypical pneumonias are caused by three zoonotic pathogens, Chlamydia psittaci (psittacosis), Francisella tularensis (tularemia), and Coxiella burnetii (Q fever), and three nonzoonotic pathogens, Chlamydia pneumoniae, Mycoplasma pneumoniae, and Legionella. These atypical agents, unlike the typical pathogens, often cause extrapulmonary manifestations. Atypical CAPs are systemic infectious diseases with a pulmonary component and may be differentiated clinically from typical CAPs by the pattern of extrapulmonary organ involvement which is characteristic for each atypical CAP. Zoonotic pneumonias may be eliminated from diagnostic consideration with a negative contact history. The commonest clinical problem is to differentiate legionnaire's disease from typical CAP as well as from C. pneumoniae or M. pneumonia infection. Legionella is the most important atypical pathogen in terms of severity. It may be clinically differentiated from typical CAP and other atypical pathogens by the use of a weighted point system of syndromic diagnosis based on the characteristic pattern of extrapulmonary features. Because legionnaire's disease often presents as severe CAP, a presumptive diagnosis of Legionella should prompt specific testing and empirical anti-Legionella therapy such as the Winthrop-University Hospital Infectious Disease Division's weighted point score system. Most atypical pathogens are difficult or dangerous to isolate and a definitive laboratory diagnosis is usually based on indirect, i.e., direct flourescent antibody (DFA), indirect flourescent antibody (IFA). Atypical CAP is virtually always monomicrobial; increased IFA IgG tests indicate past exposure and not concurrent infection. Anti-Legionella antibiotics include macrolides, doxycycline, rifampin, quinolones, and telithromycin. The drugs with the highest level of anti-Legionella activity are quinolones and telithromycin. Therapy is usually continued for 2 weeks if potent anti-Legionella drugs are used. In adults, M. pneumoniae and C. pneumoniae may exacerbate or cause asthma. The importance of the atypical pneumonias is not related to their frequency (approximately 15% of CAPs), but to difficulties in their diagnosis, and their nonresponsiveness to beta-lactam therapy. Because of the potential role of C. pneumoniae in coronary artery disease and multiple sclerosis (MS), and the role of M. pneumoniae and C. pneumoniae in causing or exacerbating asthma, atypical CAPs also have public health importance.
 ...
PMID:The atypical pneumonias: clinical diagnosis and importance. 1666 25

Community-acquired pneumonia (CAP) may be caused by typical or atypical pathogens. The three most common zoonotic atypical pathogens are Chlamydophila psittaci (psittacosis), Francisella tularensis (tularemia), and Coxiella burnetii (Q fever). Atypical CAPs are suggested by a distinctive pattern of extrapulmonary organ involvement. Zoonotic CAP may be differentiated from nonzoonotic CAP (Chlamydia pneumoniae, Mycoplasma pneumoniae, Legionnaire's disease) by a recent zoonotic vector contact history. Zoonotic atypical CAP occurs sporadically, but not randomly, and require close association with the appropriate zoonotic vector to transmit the infection. CAP accompanied by the extrapulmonary finding of splenomegaly in a normal host limits differential diagnostic possibilities to Q fever and psittacosis. Splenomegaly does not occur with other typical or atypical CAP. Another common extrapulmonary finding occurs with some atypical pneumonias, that is, Q fever, psittacosis, and Legionnaire's disease is early mild/transient elevations of serum transaminases indicative of (hepatic) extrapulmonary organ involvement. The case presented is a middle-aged man with longstanding Crohn's disease who was further immunosuppressed by chronic prednisone therapy. The patient presented with CAP and extrapulmonary findings, that is, splenomegaly and increased serum transaminases. He denied recent contact with birds or animals. Because Crohn's disease and Q fever CAP may be accompanied by splenomegaly, the cause of his splenomegaly was a diagnostic dilemma. The patient was treated with levofloxacin. Serologic tests for atypical pathogens (Q fever, psittacosis, Legionnaire's disease, C. pneumoniae, and M. pneumoniae) were ordered. Enzyme-linked immunosorbent assay serology for Q fever was positive with elevated acute immunoglobulin-M (phase II) titers. Re-questioning of the patient revealed a recent exposure to a neighbor's parturient cat, providing the necessary zoonotic vector contact history for Q fever. The patient responded to levofloxacin, which resulted in resolution of the patient's symptoms, right lower lobe pneumonia, and splenomegaly. Because a prior abdominal computed tomography scan indicated no splenomegaly and his splenomegaly resolved with antimicrobial therapy, the splenomegaly was related to Q fever CAP.
 ...
PMID:Q fever community-acquired pneumonia in a patient with Crohn's disease on immunosuppressive therapy. 1762

Atypical community-acquired pneumonia (CAP) may be caused by zoonotic or nonpulmonary pathogens. However, atypical pathogens are systemic infectious disease accompanied by pneumonia in contrast with typical bacterial pathogens with infection limited to the lungs and absent extrapulmonary findings. Clinically and radiologically, the atypical CAP pathogens that most closely resemble each other are psittacosis, Q fever, and Legionnaires' disease. Psittacosis can usually be readily suspected or eliminated on the basis of a recent psittacine bird contact history. The 2 atypical pneumonias that most closely resemble each other clinically are Q fever and Legionnaires' disease. The epidemiology of Q fever is related to livestock, and sporadic cases are related to contact to parturient cats. In nonendemic areas, Q fever CAP mimics Legionnaires' disease most closely. Both Q fever and Legionella CAP have several clinical and laboratory features in common. However, there are subtle but important differences that allow the astute clinician to differentiate between these 2 disorders on the basis of clinical and nonspecific laboratory findings before definitive diagnostic tests results are reported. We report a case of severe Q fever CAP mimicking Legionnaires' disease in a young adult normal host. Her initial zoonotic contact history was negative, and her clinical presentation suggested Legionnaires' disease as the most likely diagnosis. Against the diagnosis of Legionnaires' disease was the patient's age and occurrence of the disease in spring time. In contrast, Legionnaires' disease is usually an infection of older individuals and occurs in late summer/fall. Although the patient did not have splenomegaly, a common finding in Q fever CAP, she did have mild hepatomegaly. Hepatomegaly is a uncommon in Q fever CAP but is not a feature of Legionnaires' disease. In the absence of a positive zoonotic contact history, the cardinal findings pointing to the diagnosis of Q fever in this case were "multiple round opacities" on chest computed tomography scan and thrombocytosis during her hospitalization. Against the diagnosis of Legionnaires' disease was the absence of hypophosphatemia and highly elevated ferritin levels. In patients with atypical pneumonias in whom the clinical presentation and nonspecific laboratory findings suggest Legionnaires' disease, but in addition have findings not associated with Legionnaires' (eg, hepatomegaly, thrombocytosis), Q fever serology should be ordered. We conclude that Q fever may closely mimic Legionnaires' disease. Severe atypical CAP with "multiple round opacities" on chest x-ray/computed tomography chest scan with elevated anti-smooth muscle antibodies or thrombocytosis should suggest the diagnosis of Q fever and prompt specific testing for Q fever. Rarely, Q fever CAP may be associated with elevated cold agglutinin titers.
 ...
PMID:Severe Q fever community-acquired pneumonia (CAP) mimicking Legionnaires' disease: Clinical significance of cold agglutinins, anti-smooth muscle antibodies and thrombocytosis. 1957 8

Infectious respiratory pathogens were the suspected cause of 480 outbreaks investigated by the Centers for Disease Control and Prevention's Epidemic Intelligence Service officers during 1946-2005. All epidemic-assistance investigation reports and associated articles from scientific journals were reviewed. Investigations identified 25 different infectious respiratory pathogens including, most frequently, tuberculosis, influenza, and legionellosis. Other bacterial-, viral-, and fungal-related pathogens also were identified. Epidemic-assistance investigations were notable for first identifying Legionnaires disease and Pontiac fever, hantavirus pulmonary syndrome, and new strains of human and avian influenza, as well as emerging challenges (e.g., multidrug-resistant tuberculosis and pneumococcus). The investigations provided clinical insights into such diseases as pulmonary anthrax and identified high risks of serious respiratory illnesses for persons infected with human immunodeficiency virus, other immunocompromised persons, and persons with diabetes. They identified settings placing persons at high risk of acquiring disease, including nursing homes, prisons, homeless shelters, and hospitals. Travel also placed persons at risk. Key environmental factors related to spread of diseases and occupational risks for brucellosis and psittacosis were identified. The outbreak investigations constitute a wealth of prevention experience and provide the basis for recommendations to mitigate outbreaks and reduce future risks.
 ...
PMID:Epidemic Intelligence Service investigations of respiratory illness, 1946-2005. 2213 92

Whenever the cardinal manifestations of a disorder occur in similar disorders, there is potential for a disease mimic. Legionnaire's disease has protean manifestations and has the potential to mimic or be mimicked by other community acquired pneumonias (CAPs). In CAPs caused by other than Legionella species, the more characteristic features in common with legionnaire's disease the more difficult the diagnostic conundrum. In hospitalized adults with CAP, legionnaire's disease may mimic influenza or other viral pneumonias. Of the bacterial causes of CAP, psittacosis and Q fever, but not tularemia, are frequent mimics of legionnaire's disease.
 ...
PMID:Legionnaire's Disease and its Mimics: A Clinical Perspective. 2815 79

Psittacosis, parrot fever, is an infectious disease caused by Chlamydophila psittaci, a common pathogen among birds. The clinical course ranges from a mild flu-like illness to severe disease that requires intensive care in humans. We report three cases of severe pneumonia where C. psittaci was unexpectedly detected during routine validation of a new C. psittaci PCR assay. Psittacosis is a notifiable disease in Sweden and national statistics show that 96% of Swedish psittacosis cases were identified in five of the 24 microbiological laboratories available in the country. These five laboratories perform PCR for C. psittaci routinely in panels with other atypical pneumonia agents and/or Legionella, suggesting that psittacosis is an underdiagnosed infection in Sweden.
 ...
PMID:[Psittacosis - a forgotten diagnosis in Sweden?] 3048 Jul 46


<< Previous 1 2