Incidence and Risk Factors for Secondary Pulmonary Infections in Patients Hospitalized with Coronavirus Disease 2019 Pneumonia

Chong, Woon H.; Chieng, Hau; Tiwari, Anupama; Beegle, Scott; Feustel, Paul J.; Ghalib, Sana; Al-Tarbsheh, Ali Hani; Jain, Esha; Mullins, Jeannette; Keenan, Megan; Chopra, Amit

BACKGROUND: Secondary pulmonary infections (SPI) have not been well described in COVID-19 patients. Our study aims to examine the incidence and risk factors of SPI in hospitalized COVID-19 patients with pneumonia. METHODS: This was a retrospective, single-center study of adult COVID-19 patients with radiographic evidence of pneumonia admitted to a regional tertiary care hospital. SPI was defined as microorganisms identified on the respiratory tract with or without concurrent positive blood culture results for the same microorganism obtained at least 48 hours after admission. RESULTS: Thirteen out of 244 (5%) had developed SPI during hospitalization. The median of the nadir lymphocyte count during hospitalization was significantly lower in patients with SPI as compared to those without SPI [0.4 K/uL (IQR 0.3-0.5) versus 0.6 K/uL (IQR 0.3-0.9)]. Patients with lower nadir lymphocyte had an increased risk of developing SPI with odds ratio (OR) of 1.21 (95% CI: 1.00 to 1.47, p=0.04) per 0.1 K/uL decrement in nadir lymphocyte. The baseline median inflammatory markers of CRP [166.4 mg/L vs. 100.0 mg/L, p=0.01] and D-dimer (18.5 mg/L vs. 1.4 mg/L, p<0.01), and peak procalcitonin (1.4 ng/mL vs. 0.3 ng/mL, p<0.01) and CRP (273.5 mg/L vs. 153.7 mg/L, p<0.01) during hospitalization were significantly higher in SPI group. CONCLUSIONS: The incidence of SPI in hospitalized COVID-19 patients was 5%. Lower nadir median lymphocyte count during hospitalization was associated with an increased OR of developing SPI. The CRP and D-dimer levels on admission, and peak procalcitonin and CRP levels during hospitalization were higher in patients with SPI.