SARS-CoV-2–Legionella Co-Infections: A Systematic Review and Meta-Analysis (2020–2021)

Abstract

Legionnaires’ Disease (LD) is a severe, sometimes fatal interstitial pneumonia due to Legionella pneumophila. Since the inception of the SARS-CoV-2 pandemic, some contradictory reports about the effects of lockdown measures on its epidemiology have been published, but no summary evidence has been collected to date. Therefore, we searched two different databases (PubMed and EMBASE) focusing on studies that reported the occurrence of LD among SARS-CoV-2 cases. Data were extracted using a standardized assessment form, and the results of such analyses were systematically reported, summarized, and compared. We identified a total of 38 articles, including 27 observational studies (either prospective or retrospective ones), 10 case reports, and 1 case series. Overall, data on 10,936 SARS-CoV-2 cases were included in the analyses. Of them, 5035 (46.0%) were tested for Legionella either through urinary antigen test or PCR, with 18 positive cases (0.4%). A pooled prevalence of 0.288% (95% Confidence Interval (95% CI) 0.129–0.641), was eventually calculated. Moreover, detailed data on 19 co-infections LD + SARS-CoV-2 were obtained (males: 84.2%; mean age: 61.9 years, range 35 to 83; 78.9% with 1 or more underlying comorbidities), including 16 (84.2%) admissions to the ICU, with a Case Fatality Ratio of 26.3%. In summary, our analyses suggest that the occurrence of SARS-CoV-2–Legionella infections may represent a relatively rare but not irrelevant event, and incident cases are characterized by a dismal prognosis.

A Patient with Concurrent Legionella and COVID-19 Infection in a UK District General Hospital

“…Without having the full clinical picture of all other Legionella and SARS-CoV-2 coinfections, however, it is difficult to truly be able to compare our cases to those around the world. Very recent meta-analyses of Legionnaire's disease and SARS-CoV-2 coinfections [ 21 ] have identified only 18 cases across PubMed and EMBASE, which highlights the rarity but significance of Legionnaire's disease and COVID-19. We believe that our case report has expanded our knowledge as well as broadened the discussion regarding the global differences in Legionnaire's disease and SARS-CoV-2 coinfection.…”

Resurgence of Legionella: A Post-COVID-19 Concern

“…One of the lessons we learned from the COVID-19 pandemic is that when dealing with patients who have immunosuppression and other comorbidities, it is important to consider the possibility of co-infection with other respiratory pathogens. , COVID-19 may affect multiple organ systems, resulting in a diverse array of symptoms, including cough, fever, myalgia, and shortness of breath, as is typical of many respiratory pathogens, including Legionella , making their differential diagnosis troublesome. A handful of Legionella and SARS-CoV-2 co-infection cases with poor prognoses have been reported since the inception of the pandemic . A recent meta-analysis of SARS-CoV-2– Legionella co-infection studies found a pooled Legionella prevalence of 0.228% among 10 936 individuals with SARS-CoV-2 .…”

“…A handful of Legionella and SARS-CoV-2 co-infection cases with poor prognoses have been reported since the inception of the pandemic. 9 A recent meta-analysis of SARS-CoV-2−Legionella co-infection studies found a pooled Legionella prevalence of 0.228% among 10 936 individuals with SARS-CoV-2. 9 A majority of these co-infected cases required ICU admission, intubation, and mechanical ventilation with a casefatality ratio of 26%.…”

“…9 A recent meta-analysis of SARS-CoV-2−Legionella co-infection studies found a pooled Legionella prevalence of 0.228% among 10 936 individuals with SARS-CoV-2. 9 A majority of these co-infected cases required ICU admission, intubation, and mechanical ventilation with a casefatality ratio of 26%. This indicates that superimposed Legionella infections may be relatively rare but significant.…”

Editorial: Special Issue: “Legionella pneumophila: A Microorganism with a Thousand Faces”

“…The observations indicate that the occurrence of co-infections of SARS-CoV-2 and Legionella may correspond to a comparatively rare but not irrelevant case, outlined by a severe prognosis [21]. The risk of co-infection has been measured, particularly focusing on risk factors, and two main outcomes-ICU admission and the case fatality ratio (CFR)-have been noted [22].…”