The prevalence of serious bacterial infections in infants 90 days and younger with viral respiratory tract infections.

Objectives: To determine the prevalence and risk factors of serious bacterial infections (SBIs) in infants 90 days and younger with a confirmed respiratory tract infection (RTI).

Methods: A retrospective cross-sectional study was carried out of infants 90 days and younger who were admitted to King Abdullah Specialized Children's Hospital, Riyadh, Saudi Arabia, from January 2019 to December 2020, with polymerase chain reaction (PCR)-proven RTI. Cultures from the urine, blood, and cerebrospinal fluid were reviewed with the patients' demographic information and clinical presentation.