Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
The Legionellaceae are ubiquitous in natural fresh water habitats, allowing them to colonize man-made water supplies, which may then serve as the source for human infections.
Legionella pneumophila and the related species, Legionella bozemanii, Legionella dumoffii, Legionella gormanii, Legionella micdadei, Legionella longbeachae, and Legionella jordanis have been isolated from patients with pneumonia (Legionnaires disease). The organism has been isolated from lung tissue, bronchoalveolar lavage, pleural fluid, transtracheal aspirates, and sputum. The signs, symptoms, and radiographic findings of Legionnaires disease are generally nonspecific.
Diagnosis of Legionnaires disease
Because examination by rapid PCR increases sensitivity and provides faster results, Mayo Medical Laboratories strongly recommends also ordering LEGRP / Legionella species, Molecular Detection, PCR.
Identification of Legionella species from respiratory specimens provides a definitive diagnosis of Legionnaires disease.
Organisms isolated are identified as Legionella species as determined by 16S rRNA gene sequencing.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Although a semiselective media is utilized, recovery of Legionella in specimens heavily contaminated with indigenous flora (ie, sputum) may be difficult.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Positive specimens will be identified/speciated by 16S rRNA gene sequencing.
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Edelstein PH: Legionella. In Manual of Clinical Microbiology. Tenth edition. Edited by J Versalovic. ASM Press, Washington, DC. 2007, pp. 770-785
2. CLSI Document MM18-A, Interpretive Criteria for Identification of Bacteria and Fungi by DNA Target Sequencing; Approved Guideline, Vol 28, Number 12, April 2008. CLSI, Wayne, PA