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Nonspecific laboratory findings shall give evidence of moderate
leukocytosis with left shift, high proteinuria, hyponatremia, azotemia,
aspartate aminotransferase (AST) and bloods edimentation rate(ESR).
The Center for Disease Control and Prevention (CDC) of the USA
recommends laboratory diagnostic investigation to be performed in the
following clinic scenarios:
• Patients who have failed treatment with outpatient antibiotic therapy;
• Patientswith severe pneumonia, particularly, those requiring intensive
care;
• Immunocompromised patients with pneumonia;
• Patients with pneumonia in an outbreak of Legionellosis;
• Patients with history of travel (patients who have travelled away from
home in the period of two weeks before the onset of the disease);
• Patients with suspected pneumonia associated to health care.
6.1 - Phenotypic detection of
Legionella
in clinical samples
6.1.1 - Culture
Since 1977, the isolation of
Legionella
pneumophila in respiratory
secretion using selective media is considered the reference standard for
the diagnosis of the Legionnaires’ disease. However, this method shows
sensitivity ranging from 20 to 80%, it has a long response time (most of the
colonies of
Legionella
spp. are detected within seven days), and presents
considerable inter laboratory variations. Another limitation observed in
the cultivation of respiratory samples such as the sputum is that less half of
the patients with Legionellosis produce sputum.
