Legionnaires’ Disease: Update on Diagnosis and Treatment

Abstract

Legionellosis is the infection caused by bacteria of the genus Legionella , including a non-pneumonic influenza-like syndrome, and Legionnaires’ disease is a more serious illness characterized by pneumonia. Legionellosis is becoming increasingly important as a public health problem throughout the world; although it is an underreported disease, studies have consistently documented a high incidence. In addition, health costs associated with the disease are high. Diagnosis of Legionnaires’ disease is based mainly on the detection of Legionella pneumophila serogroup 1 antigen in urine. However, there have been advances in detection tests for patients with legionellosis. New methodologies show greater sensitivity and specificity, detect more species and serogroups of Legionella spp., and have the potential for use in epidemiological studies. Testing for Legionella spp. is recommended at hospital admission for severe community-acquired pneumonia, and antibiotics directed against Legionella spp. should be included early as empirical therapy. Inadequate or delayed antibiotic treatment in Legionella pneumonia has been associated with a worse prognosis. Either a fluoroquinolone (levofloxacin or moxifloxacin) or a macrolide (azithromycin preferred) is the recommended first-line therapy for Legionnaires’ disease; however, little information is available regarding adverse events or complications, or about the duration of antibiotic therapy and its association with clinical outcomes. Most published studies evaluating antibiotic treatment for Legionnaires’ disease are observational and consequently susceptible to bias and confounding. Well-designed studies are needed to assess the usefulness of diagnostic tests regarding clinical outcomes, as well as randomized trials comparing fluoroquinolones and macrolides or combination therapy that evaluate outcomes and adverse events.

All That Coughs Is Not COVID

“…Observational studies suggest no significant differences between azithromycin and levofloxacin in terms of time to defervescence, time to clinical stability, or mortality [ 9 ]. While no optimal duration of therapy is established, extended courses of up to 14 days are recommended for patients who are immunocompromised or have a severe disease [ 1 ].…”

“…Legionellosis refers to the disease caused by the bacterial genus Legionella. It can present as an influenza-like illness (Pontiac fever) or bacterial pneumonia, referred to as Legionnaires’ disease (LD) [ 1 ]. The clinical manifestations of LD include fever, myalgias, headaches, dyspnea, cough, chest pain, and diarrhea [ 2 ].…”

“…The latter does not appear to have an organized seasonal pattern and has occurred in waves in both summer and winter months, unlike LD, which more predictably occurs during warmer, humid months. Due to its nonspecific clinical presentation, the diagnosis of LD requires microbiologic testing that may not be performed routinely [ 1 ], therefore, clinical suspicion for LD must remain high and a detailed social history, including epidemiologic risk factors, must be obtained.…”

レジオネラ肺炎を契機に発症したAcute–on–chronic liver failureの救命例(A case of acute–on–chronic liver failure caused by Legionella pneumonia)

“…重症度という点に着目すると，レジオネラ肺炎はしばしば多臓器不全を合併し，致死的な経過をたどることがある2)。高柳らの報告によれば，死亡は65例中6例で，死因として敗血症性ショックや腎不全，播種性血管内凝固，多臓器不全の併発によるものであった2)。とくに，多臓器不全を合併した3例中2例が死亡しており，レジオネラ肺炎に多臓器不全を合併した場合の致死率は極めて高いことが推察される。また，レジオネラ肺炎の発症リスクとして，高齢，男性，免疫抑制状態，慢性肺疾患，アルコール多飲歴，悪性腫瘍，鉄過剰症，tumor necrosis factor–α（TNF–α）治療歴，および喫煙が挙げられている3)。本症例では，アルコール多飲歴やアルコール依存症の既往歴を認めていたことから，確定診断はされていないものの，基礎疾患としてアルコール性慢性肝硬変の存在が示唆され，発症リスクが高かったと推測された。また，肝硬変による免疫不全状態と考えれば，重症化しやすい素因も併せ持っていたと推測された。すなわち，アルコール多飲歴，肝硬変，レジオネラ肺炎の三者が，相互に悪影響を及ぼしたため，重症化に至ったと考えられた。…”

Diagnosis and Treatment of Water-Contaminated Severe Legionella Pneumonia with Digestive Symptoms as the First Symptom: A Case Report and Review of the Literature

“…Fluoroquinolones such as moxifloxacin and gatifloxacin also have good anti-legionella activity. 3 Rifampin is often used clinically in combination with macrolide antimicrobials in the treatment of severe Legionella pneumonia. However, rifampicin resistance and side effects limit its use.…”