respiratory health

Legionella and Legionellosis in Brief

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Legionella: presentation	Gram-negative aerobic obligate non-fermenting bacterium, one of the major responsible for bacterial pneumonia
Etymology of the term	The name legionella is attributed to that microorganism that in 1976 caused a serious bacterial pneumonia to 221 legionaries and death to 34 of them. The name "legionella" recalls that tragic event
Legionella: description	Family : Legionellaceae Most dangerous species : Legionella pneumophila (responsible for over 90% of cases of bacterial pneumonia) Description of the bacterium: intracellular, gram-negative, obligatory and asporigenic, flagellated parasites Dimensions : variable from 0.3 to 0.9 mm in width and from 1.5 to 5 mm in length Inert beat : non-fermenting
Legionella: biochemical characteristics	Nutrition : arginine, cysteine, methionine and isoleucine Factors that affect development : iron and derivatives Growth in the laboratory : special culture media, rich in amino acids, iron salts and yeasts
Legionella: diffusion and natural habitat	The environment represents the natural reservoir of legionellae → bacteria that are particularly common in nature: hot-humid sections of ventilation systems natural aquatic environments moist soils artificial water places
Legionella: temperature and pH	Legionellae replicate at a pH between 5.4 and 8.1 Ideal replication temperature: 25-45 ° C (can live at temperatures varying from 5.7 ° C to 55 ° C)
Legionelle: transmission of the beat	The transmission between man and man is unlikely Legionella infections are related to the pollution of water distribution systems Beating is transmitted by inhalation of infected water droplets or by micro dust particles deriving from the drying of contaminated aerosols (more rare occurrence)
Legionella: possible diseases	Legionnaire's disease Pontiac fever (acute and subclinical form)
Legionellosis: general description	General term that indicates all the various types of infection generated by obligatory aerobic gram-negative bacteria belonging to the genus Legionella
Legionellosis: Legionnaires' disease	Description : the most severe and dangerous form of legionellosis Mortality : 10-50% (in case of severity) Diagnostic limit : the symptoms are very similar to the classic flu forms → the disease is underestimated Symptomatology : involvement of the lower respiratory tract, general malaise, high fever, headache, myalgia and wheezing Rare symptoms : respiratory failure and lung abscess Severe symptoms : neurological, gastric, intestinal and renal disorders Therapies : administration of erythromycin and rifampicin. Possible efficacy of fluoroquinolones Ineffective therapies : penicillin, chloramphenicol, aminoglycosides and tetracyclines
Legionellosis: Pontiac fever (acute form)	Description : slight flu-like form, generally non-fatal (benign course) but extremely contagious Symptoms : high fever, chills, general malaise, headache, sore throat and cough Prognosis : resolves spontaneously in 2-5 days, without the need for treatment Established causative agents : Legionella pneumophila Possible and hypothesized causative agents : L. micdadei, L. feelei
Legionellosis: Pontiac fever (sub-clinical form)	Description : legionellosis, even less serious than the previous ones Onset : some clinical symptoms without Symptoms : does not include pulmonary involvement and typical flu symptoms Diagnosis : diagnosed only with the detection of anti-Legionella spp
Legionellosis: epidemiology	It is estimated that legionellosis affects 8, 000-18, 000 subjects each year Legionellosis in Italy: estimated at around 1, 000 patients each year, but still underestimated
Legionellosis: prevention	The WHO has placed legionella infections under surveillance Objectives : Promote surveillance and control programs for the prevention of legionellosis Encourage and improve preventive measures aimed at limiting Legionella contamination