Legionnaires' disease in transplant recipients: A 15‐year retrospective study in a tertiary referral center

Abstract

Legionnaires' disease (LD) can be fatal among high-risk transplant recipients. To understand the epidemiology of LD, we reviewed 15-year longitudinal data from a center in Seattle, Washington that cares for both solid organ transplant (SOT) and hematopoietic cell transplant (HCT) recipients. We identified all laboratory-confirmed LD and extracted data on species, diagnostic modalities, clinical presentation, management, and outcomes from medical records. Among 32 patients with LD, transplant recipients made up the majority of diagnoses (22, 69%; SOT 10, HCT 12). Approximately 0.8% of transplant recipients who underwent Legionella-specific testing were positive. Non-pneumophila Legionella species (LNLP), which are not detected by urinary antigen test, accounted for half the cases, led by Legionella micdadei (32%). The severity and outcome between Legionella pneumophila and LNLP infections were similar (attributed mortality, 36% vs 27%); all LNLP deaths occurred in transplant recipients with L. micdadei. The clinical and radiological features mimicked other opportunistic pathogens; 32% (n=7) were not on empiric treatment at the time of diagnosis. These data add to the emerging literature describing the importance of LD and highlight the need for both routine Legionella testing on transplant recipients with pulmonary findings and empiric Legionella-active antibiotic therapy.

Emerging respiratory infections: The infectious disease pathology of SARS, MERS, pandemic influenza, and Legionella

“…69 L. pneumophila serogroup 1 is most commonly associated with human infection, although other serogroups and species together cause a substantial disease burden. 70,71 Legionella can also cause non-respiratory diseases such as Pontiac fever as well as rare wound and other infections. The organism is a facultative intracellular Gram-negative rod that is common in the environment and naturally infects several species of free-living amoeba in a process that parallels infection of the mammalian macrophage.…”

“…Many reports indicate Legionella micdadei is the second most common species to cause human disease. 70,75 Most patients are symptomatic within 2-10 days, however, incubation periods of up to 26 days have been described. 76 Complicating the diagnosis, especially early in infection, is a relative paucity of respiratory symptoms.…”

“…Most fatalities are attributed to L. pneumophila, however, death from L. micdadei is also common despite demonstrated lower virulence in in vitro models. 75,79 Treatment is with levofloxacin or azithromycin; empiric treatment with beta-lactams can delay time to effective therapy, as they are considered ineffective.…”

“…In one study, half of all sporadic cases over a 15 year period were due to species other than L. pneumophila serogroup 1. 75 Culture has the additional benefit of supporting epidemiologic investigations and infection control. It yields a bacterial isolate that can be compared to environmental isolates from hospital water sources or other human-engineered systems in question by strain typing assays.…”

Legionnaires Disease in Immunocompromised Host

“…A group in Seattle, Washington reviewed 15 year longitudinal data in a hospital that cares for transplant patients and reported 32 cases of Legionnaires disease over a period of 15 years and 10 of them were in solid organ transplant patients [14].…”