[Legionella spp: An update]. / Actualités sur les infections à Legionella.

Legionella-related disease is caused by an intracellular bacteria mainly living in water. Contamination results from inhalation of Legionella sp containing aerosolized water. Main risk factors are tobacco, immunodeficiency, and advanced age. Antigenuria is the cornerstone of the diagnosis. Immunocompromised patients, more commonly infected with non pneumophilaLegionella, present negative antigenuria, and culture and PCR are essential for the diagnosis. Legionnaires' disease may be severe, especially in elderly and/or immunocompromised patients. Mortality rate varies from 10 % in the general population to 50 % in intensive care. Treatment is based on macrolides or fluoroquinolones. Antibiotic resistance is very rare.

A case report of Legionella and Mycoplasma pneumonia: Co-incidence or co-infection?

RATIONALE: Concurrent or sequential coinfections of Legionella pneumophila and Mycoplasma pneumoniae have been reported in the past though infrequently. Distinguishing a true co-infection from cross reactivity is often challenging as the diagnosis is mostly dependent on serological testing. PATIENT CONCERNS: A 77-year-old male presented with worsening dyspnea, cough with yellow sputum, diarrhea and fever of 2-days duration. Patient had history of chronic obstructive pulmonary disease (COPD) on home oxygen, bronchiectasis, rheumatoid arthritis (on methotrexate and leflunomide), treated pulmonary tuberculosis and 30-pack-year smoking. Chest X-ray showed bilateral interstitial changes with left lower lobe infiltrate. On day 5, his urine antigen for L pneumophila serogroup 1 was reported positive. The following day his serum M pneumoniae IgM antibody titers were reported elevated at 6647 U/mL. Patient was started on antibiotics and placed on non-invasive positive pressure ventilation. DIAGNOSIS: The patient was diagnosed with possible Legionella and Mycoplasma co-infection. OUTCOMES: Sputum Mycoplasma polymerase chain reaction (PCR) and serum cold agglutinins were obtained on day 6 and later reported negative. He was treated with azithromycin for 10 days with clinical improvement. LESSONS: Serological testing alone is an indirect measure with poor sensitivity and specificity and has its own limitations. Urine antigen detection confirms L pneumophila serogroup 1 infection in a patient with suggestive symptoms. However, diagnosis of M pneumonia should be based on combination of tests including serology and PCR to confirm true co-infection.

[The epidemiology and clinical features of Legionella pneumonia (LP) in patients older than 60 years old who were hospitalized with pneumonia in northern Israel].

BACKGROUND: Risk factors associated with LP are frequent in patients older than 60 years old who are hospitalized with pneumonia. The aim of the study was to define the incidence, epidemiological and clinical features of LP in this age group in Northern Israel. STUDY DESIGN: The study was prospective and conducted for one year during the period 1.6.1999-31.5.2000. All patients older than 60 years who were hospitalized with community-acquired or nosocomial pneumonia were tested for legionella infection by the urine antigen test (which identifies Legionella pneumophila type I and 14 other Legionella serotype antigens). Data was obtained from each patient regarding risk factors and clinical feature of the disease. The data of patients with LP was compared on a 1:2 ratio to data obtained from a control group of patients with non LP according to age, sex, and week of admission. RESULTS: During the study period 202 patients and 38 patients were hospitalized with community-acquired or nosocomial pneumonia respectively. Overall, 8/240 patients (3.3%) were found to suffer from LP. All patients with LP had community-acquired pneumonia with an incidence of 8/202 (4%). Six of the 8 patients (75%) with LP were hospitalized during June-September. Significant clinical findings in patients with LP as compared to those in the control group, respectively, were: severity score, history of smoking, mental status alteration, respiration rate over 30/minute, respiratory acidosis, hypoxia, and need for mechanical ventilation (P < 0.05 in all). All patients with LP were treated with macrolides, however the death rate was 50% vs 0% in the control group (p < 0.001). CONCLUSIONS: In northern Israel, LP is infrequent among patients older than 60 years hospitalized with pneumonia. The disease occurs mostly during the summer in patients with community acquired pneumonia. Patients with LP had unique and more severe clinical features and the death rate was very high inspite of appropriate therapy.

Bilateral pleuritis caused by Legionella micdadei.

A 58-year-old woman was hospitalized because of progressive respiratory distress. She had a history of myasthenia gravis and invasive thymoma. After thymectomy, she had been administered oral prednisolone and intrathoracic anti-cancer drugs postoperatively. Her chest radiograph revealed bilateral pleural effusions. Legionella micdadei (L. micdadei) was isolated from the pleural effusions, and she was diagnosed as pleuritis caused by L. micdadei. She died despite intensive therapy with mechanical ventilation, drainage tube in the chest and intravenous erythromycin. Although only two cases of Legionellosis caused by L. micdadei have been reported in Japan, clinicians should be aware of L. micdadei as one of the candidates for infection in immunosuppressed hosts.