During the COVID-19 pandemic, antibiotic use was very common. However, bacterial co-/secondary infections with coronaviruses remain largely unknown in standard wards. We aimed to investigate the characteristics of pulmonary bacterial infections associated with COVID-19 in hospitalized patients.

A retrospective monocentric observational study was conducted in Bichat hospital, France, between February 26 and April 22, 2020. All patients hospitalized in standard wards with COVID-19 (positive nasopharyngeal PCR and/or typical aspect on CT-scan) and diagnosed with pulmonary bacterial infection (positive bacteriological samples) were included. Bacteriological and clinical data were collected from the microbiology laboratories and patient's medical records.

Twenty-three bacteriological samples from 22 patients were positive out of 2075 screened samples (1.1%) from 784 patients (2.8%). Bacterial infection occurred within a median of 10 days after COVID-19 onset. Diagnosis of pulmonary bacterial infection was suspected on increase of oxygen requirements (20/22), productive cough or modification of sputum aspect (17/22), or fever (10/22). Positive samples included 13 sputum cultures, one FilmArray® assay on sputum samples, one bronchoalveolar lavage, six blood cultures, and two pneumococcal urinary antigen tests. The most frequent bacteria were Pseudomonas aeruginosa (6/23), Staphylococcus aureus (5/23), Streptococcus pneumoniae (4/23), Enterococcus faecalis (3/23), and Klebsiella aerogenes (3/23). No Legionella urinary antigen test was positive. Four out of 496 nasopharyngeal PCR tests (0.8%) were positive for intracellular bacteria (two Bordetella pertussis and two Mycoplasma pneumonia).

Pulmonary bacterial secondary infections and co-infections with SARS-CoV-2 are uncommon. Antibiotic use should remain limited in the management of COVID-19.