Bacteremia and Blood Culture Utilization during COVID-19 Surge in New York City

Abstract

A surge of patients with coronavirus disease 2019 (COVID-19) presenting to New York City hospitals in March 2020 led to a sharp increase in blood culture utilization, which overwhelmed the capacity of automated blood culture instruments. We sought to evaluate the utilization and diagnostic yield of blood cultures during the COVID-19 pandemic to determine prevalence and common etiologies of bacteremia and to inform a diagnostic approach to relieve blood culture overutilization. We performed a retrospective cohort analysis of 88,201 blood cultures from 28,011 patients at a multicenter network of hospitals within New York City to evaluate order volume, positivity rate, time to positivity, and etiologies of positive cultures in COVID-19. Ordering volume increased by 34.8% in the second half of March 2020 compared to the level in the first half of the month. The rate of bacteremia was significantly lower among COVID-19 patients (3.8%) than among COVID-19-negative patients (8.0%) and those not tested (7.1%) (P < 0.001). COVID-19 patients had a high proportion of organisms reflective of commensal skin microbiota, which, when excluded, reduced the bacteremia rate to 1.6%. More than 98% of all positive cultures were detected within 4 days of incubation. Bloodstream infections are very rare for COVID-19 patients, which supports the judicious use of blood cultures in the absence of compelling evidence for bacterial coinfection. Clear communication with ordering providers is necessary to prevent overutilization of blood cultures during patient surges, and laboratories should consider shortening the incubation period from 5 days to 4 days, if necessary, to free additional capacity.

Keywords: COVID-19; SARS-CoV-2; bacteremia; blood culture; sepsis.

FIG 1

Number of blood cultures ordered by day in 2019 and 2020. Blood culture groups are identified according to the legend on the figure.

FIG 2

Frequency of microorganisms identified from positive blood cultures stratified by SARS-CoV-2 status. Each microorganism was counted once per patient, and microorganisms are grouped as indicated. (A) All microorganisms isolated were counted. (B) Likely skin contaminants were excluded. ***, P < 0.001 (Pearson’s chi-square test).

FIG 3

Time to positivity of positive blood cultures stratified by SARS-CoV-2 status. Time to positivity was calculated from the time of collection to the first positive signal as recorded by the Gram stain date and time. The cumulative distribution of positivity over time is represented.