Secondary infection among hospitalized <scp>COVID</scp>‐19 patients: A retrospective cohort study in a tertiary care setting

Abstract

The coronavirus disease 2019 (COVID-19) is rapidly spreading around the world. Few studies have been conducted on secondary infections in hospitalized COVID-19 patients.1-3 Secondary bacterial infections were reported in 15% of hospitalized COVID-19 patients in China. The incidence was higher in non-survivors (50% vs 1%).4 We aimed to describe secondary infection among hospitalized COVID-19 patients. This study was approved by the Institutional Review Board (CNUH 2020-07-042) and informed consent was waived due to the retrospective nature of the study. A total of 140 patients confirmed with COVID-19 were identified during the study period (1 February–10 July 2020). Blood culture was done in all patients (100%) and pneumonia polymerase chain reaction (PCR) in 35 patients (25%). Of these, 31 patients (22.1%) had secondary infections, and 3 of them were tested while on a ventilator. Diagnostic examinations were done at 5.8 ± 6.7 days after hospitalization and 10.9 ± 6.6 days after symptom onset (Fig. 1). The remaining 109 patients (77.9%) had no secondary infection. Patients with secondary infection were older (62.4 ± 9.0 vs 50.8 ± 17.1, P < 0.001). Laboratory findings showed lower platelet count (176 ± 51 vs 204 ± 59, ×103/μL, P = 0.019) and higher C-reactive protein (176 ± 51 vs 204 ± 59, ×103/μL, P = 0.019) in the secondary infection group. There were no statistically significant differences in other laboratory findings and comorbidities. To identify changes in clinical state or radiology, we compared the changes of the vital sign and chest X-ray in the secondary infection group. Mean blood pressure (91.8 ± 12.0 vs 85.3 ± 12.5 mm Hg, P = 0.002) slightly decreased, but heart rate (85 ± 20 vs 82 ± 24 beats/min, P = 0.180), respiratory rate (22 ± 8, 21 ± 4 beats/min, P = 0.740) and body temperature (38.0 ± 0.9 vs 38.3 ± 0.9°C, P = 0.120) showed no significant difference. Fever occurred or persisted (54.8% vs 83.9%, P = 0.004), oxygen requirement increased (29.0% vs 38.7%, P < 0.001) and ground-glass opacity and/or consolidation on chest X-ray worsened (58.1%). Secondary bacterial infection was detected in 30 patients (21.4%) and bacterial–fungal secondary infection in one patient (0.7%). The pathogens detected were as follows: Streptococcus pneumoniae (20, 64.5%), Haemophilus influenzae (15, 48.4%), Klebsiella pneumoniae (1, 3.2%), Enterobacteriaceae (1, 3.2%), Pseudomonas aeruginosa (1, 3.2%), Mycoplasma pneumoniae (1, 3.2%), Staphylococcus species (4, 12.9%), Corynebacterium (2, 6.5%), Enterococcus faecium (2, 6.5%) and Candida (1, 3.2%). The use of norepinephrine (12.9% vs 0.9%, P = 0.009), nasal prong (54.8% vs 12.8%, P < 0.001), mechanical ventilation (25.8% vs 7.3%, P = 0.009) and extracorporeal membrane oxygenation support (12.9% vs 0.9%, P = 0.009) was higher in the secondary infection group. The rates of shock (12.9% vs 2.8%, P = 0.043) and mortality (6.5% vs 0%, P = 0.048) were also higher in the secondary infection group. The type of pathogens causing secondary infection may vary depending on the characteristics of the country and hospital setting. On the basis of these results, we believe that actively examining COVID-19 patients for secondary infection will facilitate treatment with appropriate antibiotics, thus improving patient's prognosis. Conceptualization: S.-I.L., J.E.L. Data curation: S.-I.L., J.S.K., Y.J.K., J.E.L. Formal analysis: S.-I.L., J.E.L. Investigation: S.-I.L., J.S.K., Y.J.K., J.E.L. Methodology: S.-I.L., D.H.K., D.P., J.E.L. Project administration: S.-I.L., J.E.L. Resources: S.-I.L., J.E.L. Supervision: S.-I.L., J.E.L. Validation: S.-I.L., J.E.L. Visualization: S.-I.L., H.S.P., S.S.J., J.-O.K., J.E.L. Writing—original draft: S.-I.L., J.E.L. Writing—review and editing: S.-I.L., J.S.K., Y.J.K., D.H.K., D.P., H.S.P., S.S.J., J.-O.K., J.E.L.