Bacterial Co-infection Increases COVID-19 Mortality Risk

The elevated neutrophil to lymphocyte ratio (≥ 15) in patients with COVID-19 bacterial coinfection is independent of dexamethasone treatment within 48 hours of hospital admission. Post-admission laboratory trends for inpatient COVID-19 encounters pooled from the UAB and OLHS cohorts and stratified by confirmed, suspected, and no coinfection bacterial coinfection and 48-hour dexamethasone treatment. Mean laboratory values ​​with standard error bars from the day of admission (day 0) to 4 days post-admission are shown for patients A with dexamethasone treatment within 48 h (solid lines) and B without dexamethasone treatment within 48 h (dashed line) , all stratified by COVID-19 co-infection status. Statistical significance was assessed using Bonferroni corrected t tests: (p < 0.0001 = ****/####, p < 0.001 = ***/###, p < 0.01 = **/ ##, p < 0.05 = */#). Reference group (red): Coinfection confirmed 48 h after admission blood culture (+). Comparison group 1 (light blue, *): No coinfection. Comparison group 2 (dark blue; #): Suspected coinfection 48 h after blood culture admission (-). UAB, University of Alabama at Birmingham cohort; OLHS, Ochsner Louisiana State University Health—Shreveport Cohort

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Having a bacterial infection at the same time as COVID-19 is a greater risk factor for COVID-19 severity and mortality than the risk factors described above, such as older age, male sex, or various comorbidities.

Bacterial coinfection is a significant risk factor for death, intensive care unit admission, and mechanical ventilation, according to a multicenter retrospective cohort study published in the journal Critical Care and led by researchers at the University of Alabama at Birmingham.

Coronavirus disease 2019, or COVID-19, has killed more than 6.3 million people worldwide.

This recent study of 13,781 hospitalized COVID-19 patient encounters from 2020 to 2022 found that bacterial co-infection in the blood, known as bacteremia, is a major risk factor for death, intensive care unit admission, and mechanical ventilation than the risk factors described above for COVID -19 severity and mortality, such as older age, male sex, or various comorbidities.

The study reviewed inpatient encounters with COVID-19 at UAB Hospital and Ochsner Louisiana State University Health Shreveport hospitals and divided them into three groups: Confirmed bacterial coinfection, as measured by a blood test 48 hours later of admission; suspected bacterial coinfection in patients receiving antimicrobials; and no bacterial coinfection.

Bacterial co-infection is a known major source of illness and death in the context of other respiratory viral infections such as influenza, parainfluenza or RSV. However, it has remained unclear regarding the frequency of bacteremic co-infection in COVID-19 and the impact it has on clinical outcomes.

"Although confirmed bacteremic co-infections are rare in COVID-19, less than 4 percent of inpatient admissions, our results show that COVID-19 patients with these co-infections have a staggering 25 percent risk of death at 30 days in UAB patients and a similar 20 percent risk at Ochsner Louisiana State University Health Shreveport, or OLHS,” said Amit Gaggar, M.D., Ph.D., Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine. the UAB. Gaggar, in collaboration with Precision Medicine Institute Director Hugh Kaul, Matthew Might, Ph.D., and infectious diseases physician and scientist Nathaniel Erdmann, M.D., Ph.D., co-led the study.

“These results strongly suggest an underestimated interaction between bacterial pathogens and the COVID-19 virus, SARS-CoV-2, and its impact on clinical outcomes,” added co-senior author Erdmann.

Specifically, the researchers found that in-hospital mortality from COVID-19 coinfections of 26 percent at UAB and 22 percent at OLHS exceeded that of suspected coinfection (UAB, 24 percent; OLHS, 12 percent) and not coinfection groups (UAB, 5.9 percent; OLHS, 5.1 percent). Additionally, a control group of 1,703 patients hospitalized at UAB with community-acquired bacteremia during a period before the COVID-19 pandemic had an in-hospital mortality rate of 5.9 percent.

The researchers also identified laboratory trends associated with COVID-19 bacterial coinfection: a neutrophil-to-lymphocyte ratio of 15 or higher, and Systemic Inflammatory Response Syndrome, or SIRS, criteria for abnormal white blood cell counts or a heart rate. greater than 90 beats per minute. These can help healthcare providers discriminate against COVID-19 bacterial co-infections within 24 hours of admission.

"These results emphasize the role of bacteria in SARS-CoV-2 mortality and highlight the potential of the neutrophil-to-lymphocyte ratio as a rapid and readily available prognostic biomarker of bacterial co-infection and, relatedly, the severity of the disease," said the co-director.

The strengths of this study were the two large, independent, demographically diverse cohorts: the UAB reflects an academic hospital and Level I trauma center serving five surrounding states, and the OLHS includes gatherings of rural, suburban, and academic medical centers in the entire state of Louisiana. Both cohorts were generally well matched for patients’ age, race, sex, and length of hospitalization.

“One of the new opportunities of the COVID-19 pandemic has been the seismic shift in the collected and searchable data captured by electronic medical record, or EMR, systems. “This resource, combined with the collaborative spirit of UAB and OLHS experts, provides the foundation for biomedical informatics studies that can produce clinically useful observations for patient improvement,” said the study’s lead and corresponding author. , Michael John Patton.