Bacterial Infection Less Prevalent in COVID 19 Pneumonia than Non-COVID 19 Pneumonia

Over the last 2 decades, the world has experienced at least six major viral epidemics, including SARS-CoV, MERS, H1N1, Ebola, Zika, and the current SARS-CoV-2. Bacterial super-infections during these viral illnesses have been associated with poor outcomes. However, data on the prevalence of bacterial superinfection in Covid-19 positive patients is not well established. Because it is difficult to determine the co-existence of bacterial pneumonia, many of these patients are initially treated with antibiotics. Therefore, Dr Adam J. Singer and his team conducted a study and compared the rates of bacterial infections and mortality in Covid-19 patients with pulmonary infiltrates versus patients diagnosed with 'pneumonia' the year previously.

In this retrospective electronic medical record review, the researchers included patients admitted with Covid-19 (n=1398) and a pulmonary infiltrate and compared them with patients (n=1001) diagnosed with pneumonia admitted in the prior year before the pandemic. They assessed the demographics, comorbidities, signs and symptoms, laboratory and microbiological results, and imaging findings. The major outcome assessed was bacterial infections and mortality. They used univariable and multivariable analyses to compare patients presenting with and without Covid-19.

Key findings of the study:

• Upon analysis, the researchers found that bacterial infections were fewer Covid-19 than non-Covid-19 patients (8% vs 13%) and most infections in Covid-19 were nosocomial as opposed to community-acquired in non-Covid-19 patients.
• However, they noted that chest X-Ray was more often read as abnormal and with bilateral infiltrates in patients with Covid-19 (82% vs 70%and 81% vs 48%).
• They further found high mortality rate in patients with COVID 19 than without (15% vs 9%).
• Upon multivariable analysis, they noted that the predictors of mortality(Odds ratio) were age (1.04/year), tachypnea (1.55), hypoxemia (2.98), and bacterial infection (2.80).
• Compared with non-Covid-19 patients with pneumonia, they observed a high death rate in patients with Covid-19 (2.68).

The authors concluded, "The rate of bacterial infections is lower in Covid-19 patients with pulmonary infiltrates compared with patients diagnosed with pneumonia prior to the pandemic and most are nosocomial. Mortality was higher in Covid-19 than non-Covid-19 patients even after adjusting for age, tachypnea, hypoxemia, and bacterial infection."

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DOI:https://doi.org/10.1016/j.ajem.2021.09.040