Low frequency of community-acquired bacterial co-infection in patients hospitalized for COVID-19 based on clinical, radiological and microbiological criteria: a retrospective cohort study

Abstract

Background: We defined the frequency of respiratory community-acquired bacterial co-infection in patients with COVID-19, i.e. patients with a positive SARS-CoV-2 PCR or a COVID-19 Reporting and Data System (CO-RADS) score ≥ 4, based on a complete clinical assessment, including prior antibiotic use, clinical characteristics, inflammatory markers, chest computed tomography (CT) results and microbiological test results.

Methods: Our retrospective study was conducted within a cohort of prospectively included patients admitted for COVID-19 in our tertiary medical centres between 1-3-2020 and 1-6-2020. A multidisciplinary study team developed a diagnostic protocol to retrospectively categorize patients as unlikely, possible or probable bacterial co-infection based on clinical, radiological and microbiological parameters in the first 72 h of admission. Within the three categories, we summarized patient characteristics and antibiotic consumption.

Results: Among 281 included COVID-19 patients, bacterial co-infection was classified as unlikely in 233 patients (82.9%), possible in 35 patients (12.4%) and probable in 3 patients (1.1%). Ten patients (3.6%) could not be classified due to inconclusive data. Within 72 h of hospital admission, 81% of the total study population and 78% of patients classified as unlikely bacterial co-infection received antibiotics.

Conclusions: COVID-19 patients are unlikely to have a respiratory community-acquired bacterial co-infection. This study underpins recommendations for restrictive use of antibacterial drugs in patients with COVID-19.

Keywords: Antimicrobial stewardship; Antimicrobial use; COVID-19; Co-infection; Community-acquired pneumonia; SARS-CoV-2.

Fig. 1

Study flow chart. In 10 patients categorization was not possible due to inconclusive data. ¹No respiratory symptoms and no altered mental status. ²No large, lobar or unilateral consolidations. ³Culture, PCR or urinary antigen tests. CT: Computed tomography scan; CRP: C-reactive protein

Fig. 2

Examples of chest CT findings. A Axial Chest CT image show multiple areas of pure ground-glass opacity (GGO). B Axial Chest CT image show peribronchovascular and subpleural patchy consolidations with GGO. Axial (C) and sagittal (D) Chest CT image show a large consolidation in the right upper lobe with air bronchograms

Fig. 3

Antibiotic use of total study population per admission day. *Other combination therapy: a combination of beta-lactam antibiotics, combination of beta-lactam antibiotic with macrolide/quinolone/glycopeptide/cotrimoxazole/metronidazole or combinations of three different antibiotic classes. **Other monotherapy: other beta-lactam antibiotics (e.g. flucloxacillin or ceftazidime) or any of the other antibiotic classes (e.g. nitrofurantoin, cotrimoxazole)