Short Report PNEUMON Pneumon 2021;34(2):6 https://doi.org/10.18332/pne/136152 ABSTRACT Coronavirus Disease 2019 (COVID-19) has been classifed as a global threat, afecting millions of people and killing thousands. It is caused by the SARS- CoV-2 virus, which emerged at the end of 2019 in Wuhan, China, quickly spreading worldwide. Patients’ clinical features var, and secondar infections represent a constant risk of increased mortality among those who need hospitalization. Damaged respirator epithelium and dysregulation of the immune response are the main pathophysiological mechanisms of increased microbial adhesion to the airway epithelial cells and the development of secondar infections. However, the exact incidence of secondar infections in COVID-19 patients is not thoroughly known (3.2%–80%) due to limited and heterogeneous studies that lead to conficting or non-comparable results. Infection-risk stratifcation in critically ill patients includes early ICU admission (within 48 hours from hospitalization), age, comorbidity, immunosuppressive drugs administration, and disease severity indexes (oxygenation, infammation, and cytolysis score). In treating secondar infections, the local epidemiology (which usually includes multidrug-resistant strains) and the modifcation of any antibiotic regimen according to the cultures’ results are critical. Prompt and appropriate antimicrobial agents represent the cornerstone in secondar infection treatment for COVID-19 hospitalized patients. Published by European Publishing. © 2021 Lachana A. et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution NonCommercial 4.0 International License. (http://creativecommons.org/licenses/by-nc/4.0) Secondar bacterial infections in patients with COVID-19 Alexandra Lachana 1 , Evangelia Chrsanthopoulou 1 , Fotini Vakiarou 1 , George Dimopoulos 1 INTRODUCTION During the period December 2019–December 2020, the SARS-CoV-2 has infected more than 70 million people and caused far more than 1.6 million deaths worldwide 1 . SARS- CoV-2 contains monoclonal RNA, has a spherical structure with characteristic corona-like glycoprotein projections, hence the name Corona Virus (CoV), and causes the disease COVID-19 (Corona Virus Disease-19) 2-4 . SARS-CoV-1, another coronavirus, was responsible for the outbreak of Severe Acute Respirator Syndrome (SARS) in 2003 and the Middle East Respirator Syndrome (MERS) in 2007 5 . Although mostly asymptomatic, COVID-19 sometimes presents with mild symptoms, myalgias, taste and smell changes in some cases, or moderate pneumonia. Less commonly, COVID-19 manifests as severe pneumonia and Acute Respiratory Distress Syndrome (ARDS), mainly affecting older patients and people with previous comorbidities and inducing high mortality 6 . Specifc treatment for COVID-19 is currently not available, and its management mainly consists of preventing transmission by avoiding exposure to the virus. The WHO (World Health Organization) recommends adopting hygiene measures, such as frequent and thorough handwashing with soap and water, antiseptics use, smoking cessation, social distancing, and application of face-nose masks 7 . The recommended treatment for non-critically ill patients includes oxygen, dexamethasone, and remdesivir administration. Dexamethasone appears to increase patients’ survival requiring oxygen therapy or invasive mechanical ventilation, while remdesivir may reduce their hospital stay 8,9 . Newer antiviral drugs and monoclonal antibodies are under evaluation. In ICU patients with COVID-19 additional hemodynamic and organ support is often necessary 5 . In intubated and non-intubated patients, the prone position appears useful, while extracorporeal oxygenation (ECMO) benefits selected patients. During their hospitalization, patients with COVID-19 develop secondary bacterial infections. The present article attempts to provide a comprehensive review of the currently available literature on secondar bacterial infections in COVID-19 patients. REVIEW Secondar infections in patients with COVID-19 Data on the frequency and characteristics of secondary infections in patients with COVID-19 are limited and conficting. Initially, studies in China, the United States, and the United Kingdom identifed bacterial infections in this group of patients as minor 10-13 . A retrospective study from the UK included 836 patients with confrmed SARS-CoV-2 infection and a control group of fu patients of the same period (2019–2020). In the frst fve days of hospitalization of patients with COVID-19, the rate of bacterial infections was 3.2%. This percentage amounted to 6.1% throughout their hospitalization, without reported fungal infections. The results were similar to those of the control group 14 . AFFILIATION 1 Department of Critical Care, Attikon University General Hospital, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece CORRESPONDENCE TO Alexandra Lachana. Department of Critical Care, National and Kapodistrian University of Athens, School of Medicine, Attikon University General Hospital, 1 Rimini Street, Athens, 12462, Greece. E-mail: alekalahana2013@gmail.com KEYWORDS COVID-19, severely ill, secondar infections Received: 28 Januar 2021 Revised: 31 Januar 2021 Accepted: 3 Februar 2021