BACKGROUND: Co-infections, secondary bacterial or fungal infections, are important risk factors for poor outcomes in viral infections . The prevalence of co-infection and secondary infection in patients infected with SARS-CoV-2 is not well understood .
AIMS: To investigate the role of co-infections and secondary infections in disease severity of hospitalized individuals with COVID-19 . MATERIALS AND
METHODS: A retrospective study was carried out between 11 January 2020 and 1 March 2020 among 408 laboratory confirmed COVID-19 patients in China . These patients were divided into three groups based on disease severity: mild or moderate, severe, or critically ill. Microbiological pathogens in blood, urine, and respiratory tract specimens were detected by the combination of culture, serology, polymerase chain reaction, and metagenomic next-generation sequencing (mNGS).
RESULTS: The median age of participants was 48 years (IQR 34-60 years). Fifty-two patients (12.7 %) had at least one additional pathogen , 8.1% were co-infected, and 5.1% had a secondary infection . There were 13 Mycoplasma pneumoniae cases , 8 Haemophilus influenzae cases , 8 respiratory viruses, and 3 Streptococcus pneumoniae cases, primarily detected in mild and moderate COVID-19 patients . Hospital-acquired infection pathogens were more common in critically ill patients . Compared to those without additional pathogens, patients with co-infections and/or secondary infections were more likely to receive antibiotics (p <0.001) and have elevated levels of d-dimer (p = 0.0012), interleukin-6 (p = 0.0027), and procalcitonin (p = 0.0002). The performance of conventional culture was comparable with that of mNGS in diagnosis of secondary infections .
CONCLUSION: Co-infections and secondary infections existed in hospitalized COVID-19 patients and were relevant to the disease severity . Screening of common respiratory pathogens and hospital infection control should be strengthened.