COVID-19 bacterial coinfection elevates risk for death, mechanical ventilation

Key takeaways:

• A bacterial coinfection with COVID-19 led to more death than pre-pandemic.
• A neutrophil-to-lymphocyte ratio of 15 or more within 48 hours of hospitalization signaled higher COVID-19 bacterial coinfection odds.

A high risk for in-hospital mortality, ICU admittance and mechanical ventilation was found in patients with COVID-19 plus a community-acquired bacterial infection, according to study results published in Critical Care.

“Although confirmed bacteremic coinfections are rare in COVID-19, less than 4 percent of inpatient admissions, our results show that COVID-19 patients with these coinfections have a staggering 25 percent risk of death at 30 days in [The University of Alabama at Birmingham (UAB)] patients and a similar risk of 20 percent at Ochsner Louisiana State University Health Shreveport, or OLHS,” Amit Gaggar, MD, PhD, of the department of medicine division of pulmonary, allergy and critical care medicine at UAB, said in a university press release.

In a multicenter, retrospective cohort study, Gaggar and colleagues analyzed 13,781 adult COVID-19 inpatient encounters from two hospitals between 2020 and 2022 to determine if community-acquired bacteremic coinfection plus COVID-19 is linked to a higher risk for in-hospital mortality, ICU admission and mechanical ventilation.

Of the total cohort, 4,075 patients came from UAB, and 9,706 patients came from OLHS.

Based on blood cultures taken 48 hours after hospital admission, researchers split patients into three groups categorized by evidence of a community-acquired bacteremic coinfection: confirmed coinfection (recovery of bacterial pathogen, 2.5%), suspected coinfection (negative culture with ≥ 2 antimicrobials administered, 46%) and no evidence of coinfection (no culture, 51.5%).

To find out the risk factors for a COVID-19 bacterial coinfection, as well as how this type of infection influences mortality, ICU admission and mechanical ventilation, researchers utilized multivariate logistic regressions.

Compared with patients with community-acquired bacteremia before the pandemic (n = 1,703), researchers found a greater mortality rate among patients with a suspected COVID-19 bacterial coinfection (UAB: 5.9% vs. 24%).

In terms of risk factors, patients who had high neutrophil-to-lymphocyte ratios (≥ 15) within 48 hours of admission in both hospital cohorts faced greater odds for a COVID-19 bacterial coinfection (UAB: OR = 1.95; 95% CI, 1.21-3.07; P < .0001; OLHS: OR = 3.65; 95% CI, 2.66-5.05; P < .0001), according to researchers.

“These results emphasize the role of bacteria in SARS-CoV-2 mortality, and highlight the potential for neutrophil-to-lymphocyte ratio as a rapid and easily available prognostic biomarker of bacterial coinfection and, relatedly, disease severity,” Matthew Might, PhD, of the UAB department of medicine, said in the release.

Additional risk factors for coinfection included a heart rate measuring more than 90 beats per minute, temperature less than 36°C, temperature greater than 38°C and a white blood cell count less than 4, according to researchers.

Prior to hospital admission, researchers found that patients with a history of diabetes (UAB: OR, 1.51; 95% CI, 0.95-2.38; OLHS: OR = 1.5; 95% CI, 1.12-1.97) and renal disease (UAB: OR, 1.59; 95% CI, 1.02-2.53; OLHS: OR = 1.53; 95% CI, 1.08-2.14) also had higher odds for coinfection.

Compared with risk factors linked to COVID-19, including older age, male sex and multiple comorbidities, researchers found that patients with confirmed coinfection had higher odds for in-hospital mortality (UAB: OR = 3.7; 95% CI, 2.42-5.46; P < .001; OLHS: OR = 4.05; 95% CI, 2.29-6.97; P < .001), admission into the ICU (UAB: OR = 4.47; 95% CI, 2.87-7.09; P < .001; OLHS: OR = 2.65; 95% CI, 2-3.48; P < .001), and mechanical ventilation (UAB: OR = 3.84; 95% CI, 2.21-6.12; P < .001; OLHS: OR = 2.75; 95% CI, 1.87-3.92; P < .001).

Lastly, looking at the alpha, delta and omicron SARS-CoV-2 variants, each one paired with a bacterial coinfection showed high odds for death in the hospital (alpha OR = 4.12; 95% CI, 2.71-6.04; delta OR = 3.23; 95% CI, 1.65-5.74; omicron OR = 5.49; 95% CI, 1.98-13.8; P < .001 for all), according to researchers.

“One of the novel opportunities of the COVID-19 pandemic has been the seismic shift in collected and searchable data captured by electronic medical record, or EMR, systems,” Michael John Patton, BA, of the UAB Medical Scientist Training Program, said in the release. “This resource, in combination with the collaborative spirit of experts from UAB and OLHS, provides the bedrock for biomedical informatic studies that can produce clinically useful observations for the betterment of patients.”

Reference:

• COVID-19: Bacterial co-infection is a major risk factor for death, ICU admission and mechanical ventilation. https://www.uab.edu/news/research/item/13445-covid-19-bacterial-co-infection-is-a-major-risk-factor-for-death-icu-admission-and-mechanical-ventilation. Published Feb. 28, 2023. Accessed March 1, 2023.