The frequency of serious bacterial infection in febrile infants less than 90 days infected with SARS-CoV-2 and other respiratory viral pathogens

Background: The primary aim of this study was to compare the groups, SARS-CoV-2-positive and -negative patients, in terms of the frequency of SBI. The SARS-CoV-2-positive group was compared with the other-RVPs-positive group as a secondary evaluation in terms of serious bacterial infection (SBI).

Methods: This retrospective multicenter cohort study was conducted at four university hospitals from March 2020 to December 2021. Patients under 90 days old, with a measured fever of ≥ 38 °C, who were tested for SARS-CoV-2 and had blood and urine cultures taken, were included in the study. The patient groups who tested positive and negative for SARS-CoV-2 were compared regarding clinical characteristics, laboratory data, and the frequency of serious bacterial infections. As a secondary analysis, among patients tested for other respiratory viruses, the SARS-CoV-2-positive group and other respiratory virus-positive groups were compared in terms of the frequency of SBI.

Results: A total of 208 patients met the inclusion criteria. Two distinct comparisons were conducted among the patients included in the study: the first between the SARS-CoV-2-positive and SARS-CoV-2-negative patient groups, and the second between the SARS-CoV-2-positive and other RVPs-positive patient groups. In the first comparison, fifty-five patients were SARS-CoV-2-positive and 153 were SARS-CoV-2-negative. The rate of SBI in the SARS-CoV-2-positive patients was 16.4%, whereas that in the SARS-CoV-2-negative patients was 47.1%. The laboratory parameters for infection suspicion were significantly lower in the SARS-CoV-2-positive group than the SARS-CoV-2-negative group. In the second comparison, 90 patients who were tested for both SARS-CoV-2 and other RVPs were evaluated. The mean WBC, ANC and CRP levels were significantly lower in the SARS-CoV-2-positive group than the other RVPs-positive group, however, there was no significant difference in the mean ALC, NLR and PCT levels and the frequency of SBI between the SARS-CoV-2-positive and other RVPs-positive patient groups.

Conclusions: These results suggest that febrile infants younger than 90 days with SARS-CoV-2 have lower rates of SBI than patients without SARS-CoV-2. These data are consistent with previous studies describing lower risks of SBI in febrile infants with RVPs.

Trial registration: Not applicable.