Viral pathogens have been reported increasingly in pneumonia patients. There are few studies in Turkey on viral and atypical bacterial etiology in adult patients with community-acquired pneumonia (CAP) or hospital-acquired pneumonia (HAP). In this study, it was aimed to determine atypical and viral pathogens in patients with pneumonia requiring ICU and to research clinical progression. Materials and Methods: Adult patients admitted to adult ICUs between November 2016-October 2017 with either

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... or HAP diagnosis were included prospectively. Viral pathogens and also atypical bacterial pathogens were investigated with the in-house multiplex polymerase chain reaction method. Results: Two hundred patients were enrolled to the study, of whom 63 had CAP (31.5%) and 137 had HAP (68.5%). Viral agents were identified in 31 (15.5%) patients in total, 11 (17.5%) in CAP and 20 (14.6%) in HAP. The most identified viral etiologic agents were rhinovirus, influenza A, and coronavirus HKU. Eight patients (4%) had Mycoplasma pneumoniae. All patients were negative for Legionella pneumoniae and Chlamydophila pneumoniae. Mortality rates were 16.7% for cases with a viral etiology only, 29.2% for cases with bacterial pathogens only, and 23.5% for cases with mixed agents identified. Conclusion: Viral pathogens and M. pneumoniae should be remembered in the etiology of severe pneumonia patients.