The Adequacy of Current Legionnaires' Disease Diagnostic Practices in Capturing the Epidemiology of Clinically Relevant : A Scoping Review.

is an underdiagnosed and underreported etiology of pneumonia. serogroup 1 (LpSG1) is thought to be the most common pathogenic subgroup. This assumption is based on the frequent use of a urinary antigen test (UAT), only capable of diagnosing LpSG1. We aimed to explore the frequency of infections in individuals diagnosed with pneumonia and the performance of diagnostic methods for detecting infections. We conducted a scoping review to answer the following questions: (1) "Does nucleic acid testing (NAT) increase the detection of non- serogroup 1 compared to non-NAT?"; and (2) "Does being immunocompromised increase the frequency of pneumonia caused by non- serogroup 1 compared to non-immunocompromised individuals with Legionnaires' disease (LD)?". Articles reporting various diagnostic methods (both NAT and non-NAT) for pneumonia were extracted from several databases. Of the 3449 articles obtained, 31 were included in our review. The most common species were found to be , , and unidentified species appearing in 1.4%, 0.9%, and 0.6% of pneumonia cases. Nearly 50% of cases were caused by unspecified species or serogroups not detected by the standard UAT. NAT-based techniques were more likely to detect than non-NAT-based techniques. The identification and detection of and serogroups other than serogroup 1 is hampered by a lack of application of broader pan- or pan-serogroup diagnostics.